BulletPointsummary of Fundamentals of Human Neuropsychology by Kolb and Wishaw - 7th edition

BulletPoint summary of Fundamentals of Human Neuropsychology - Kolb & Whishaw - 7th edition

How did Neuropsychology develop? - BulletPoints 1

• The brain consists of two equal halves, called hemispheres, which are almost symmetrical. Brain fluid (cerebrospinal fluid; CSF) is a saline fluid in the brain. The cerebrospinal fluid acts as a shock absorber and helps to remove metabolic waste. The cerebral cortex is the outer layer of the brain which is folded and resembles the bark of a tree. The folds in the cortex are called gyri (singular: gyrus; windings). The notches between the gyri are called sulci (singular: sulcus; grooves). A number of large sulci are called fissures (singular: fissures; deep grooves). The longitudinal fissure separates the two hemispheres from each other. The lateral fissures divide the two hemispheres into two. Both hemispheres are connected to each other by the corpus callosum, also known as callosal commissure.
• The nervous system can be divided into two other parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system consists of the brain and the spinal cord and is connected to the rest of the body by nerve fibers. These nerve fibers are the peripheral nervous system. A major difference between the peripheral and central nervous systems is that the peripheral tissue can regrow after damage. The peripheral nervous system ensures the transmission of information between the central nervous system and the body. The peripheral nervous system can be divided into the somatic (SNS) and the autonomic nervous system (ANS). The somatic nervous system can once again be divided into the parasympathetic nervous system and the sympathetic nervous system. The autonomic nervous system controls and manages body tasks which are performed unconsciously such as blinking with the eyes, stomach contractions, heartbeat, breathing, etc. The somatic nervous system consists of motor and sensory nerve fibers which enable the brain to have an awareness of the world and to react to it. 
• Broca's area is a specialized language area which lies on the border of the left temporal lobe and the left frontal lobe. Damage to this area leads to Broca's aphasia. Patients can understand language, but they can no longer talk or articulate. Broca's aphasia is often accompanied by contralateral paralysis of the right arm and leg. Wernicke's area is also a specialized language area which is in line with the left ear and on the first temporal gyrus. In the case of a Wernicke aphasia, a person can speak words, but they no longer have any language comprehension. They are fluent in speaking, but what they say is confusing and illogical. Furthermore, they cannot understand or repeat. There are no paralysis symptoms. Wernicke's and Broca's areas are lateralized: brain functions localized and dominant on one side of the brain. Wernicke also described condition (conductive) aphasia. This means that the sound of speech and the necessary movements to perform speech are maintained, but that the speech is affected by the fact that no conduction between the language regions is possible. The arcuate fasciculus is the connection from Wernicke's to Broca's area.
• The idea of hierarchical organization in the brain means that there are different levels of functioning. Higher, more complex, brain processes have basal processes underlying as their basis. Diseases or damage that affect higher levels of the hierarchy cause dissolution: there is still a behavioral repertoire, but this repertoire is simpler than before. Distributed hierarchy also mentions the distribution of neuronal networks, in which different networks determine different types of behavior.
• The neuron hypothesis consists of 3 parts. 1) Neurons are separate autonomous cells that cooperate with each other. 2) Neurons transmit information using electricity; the signals they transmit are chemical. (3) Communication between neurons is based on these chemical signals. The nervous system consists of 2 classes of cells. 1) neurons produce behavior and ensure plasticity. 2) Glia cells support the neurons, hold them together and clear away waste of the neurons. Neurons consist of a cell body where an axon (output) enters from one side and several dendrites (input) on the other side exit the cell body. The different parts can be colored with different materials and can thus be made visible with a microscope. By electrically stimulating different parts of the cortex, it is possible to stimulate parts of the human body and make them move. Topographical organization on the cortex of movements, among other things, can be explored in this way.
• Brain imaging makes it possible to link behavior to regions of the brain, to make brain structures visible, to see electrical activity, cell density and chemical activity (for example the amount of glucose or oxygen) and can be used as a diagnostic tool. A disease such as multiple sclerosis (MS) has been mapped out for the first time by means of imaging. In CT (computed tomography) X-rays pass through the head. Brain trauma can be seen because dead cells become darker (blacker) on a scan than living cells. A CT can form images in 3D and is fast and inexpensive. In PET (positron emission tomography), radioactive material is injected into the blood. Radioactive oxygen can be injected, for example. Active sites in the brain light up as most oxygen is needed there. Damaged parts will not light up as much because less oxygen is needed there. PET can also be used to measure blood flow in the brain to investigate behavior such as speaking, reading and writing. Many different chemical substances can be used with PET, which makes it possible to visualize many different disorders. MRI (magnetic resonance imaging) measures the location of moving molecules by measuring their electrical charge. Because of the differences in tissue structure, molecules move differently, which causes images of the brain to be viewed. MRI gives a very detailed picture. This has led to the mapping of the brain because of MRI images. Functional MRI measures relative oxygen and carbon dioxide concentrations and can therefore determine regional differences in brain activity.

What kind of research is there about the origins of the human brain and behaviour? - BulletPoints 2

• Several scientific fields of research contribute to the knowledge of human evolution. Using skull size, soil types and utensils around found bones, archaeologists can say something about the behavior, living environment and time of onset of a species. Biochemical research can be used to determine changes in the structure of amino acids and thus determine how old a species is. Genetic research uses DNA (deoxyribonucleic acid) to investigate the degree of similarity between species. For example, 99% of the DNA of chimpanzees and humans is the same. If one can describe the genome (the entire gene package of a species) as a whole, one can determine which gene mutations have led to the evolution of the modern man. Finally, behavioral researchers give a picture of the similarities in the behavior of, for example, people and chimpanzees. The similarity in behavior between species is a proof of the existence of evolutionary theory.
• Like the absolute size of the nervous system, the relative size of the nervous system does not say much about associated behavior. The encephalisation quotient (EQ) is the ratio of the actual brain size to the size of the brain that is expected in an animal of a certain size. It can be assumed that when a body grows, the brain grows 2/3th of the body weight. An EQ above the trend line (brain larger than the expected size based on body weight) means that a kind has a relatively larger brain than expected. The brain of the modern man is relatively the largest on the EQ scale. This is due to the growth of our bodies, but also our brain. The first homo sapiens had a spurt of growth of the body, but also of the brain. Next to that, the homo sapiens also had a relatively rapid growth of only the brain. This rapid growth shows that a large brain had a direct and decisive advantage.
• There is no relationship between brain size and intelligence. There is also no relationship between brain size and the intelligence of men and women. Men generally have larger brains. There are a few explanations for this: 1) Gould said that the difference in brain size can explain differences in behavior. For example, a salamander can walk, but an eel cannot. This can explain part of the difference in brain size. But within species the behavior is equal, so the same behavior can be compared. For example, how well one salamander can run in comparison to another salamander. 2) Gardner indicated that the use of an IQ test is one-sided, because it only measures functions of the left hemisphere. In order to get a good image of intelligence, 7 types of intelligence would have to be measured. Namely verbal, mathematical, musical, spatial, motor, interpersonal and extrapersonal intelligence.
• Each gene pair consists of two alleles, variants of a gene. When these variants/alleles are the same, the alleles are called homozygous. When they are not the same, we call the alleles heterozygous. The most common allele in a population is called the wild type allele. Another version of an allele, which occurs much less frequently, is called a mutation. These mutations are sometimes beneficial to the organism, but usually result in hereditary diseases. Alleles can be dominant and recessive. Dominant alleles are generally expressed and recessive alleles are not. If both alleles of a gene are recessive, the recessive allele will come to expression. Tay-Sach's disease is caused by a mutation in which the genes encoding a certain enzyme (HexA) are not present. As a result, certain fats in the brain cannot be effectively broken down. It is a recessive mutation, so it only manifests itself when both parents pass on the recessive allele to their children. Huntington's disease is caused by a build-up of an abnormal version of a protein. Symptoms include: abnormal unwanted movements, amnesia, complete change of behavior until premature death. Huntington's disease is inherited dominantly, so only one parent needs to pass on the dominant allele for the disease to become manifested. Down's syndrome is caused by a change in the number of chromosomes, usually by having an extra chromosome 21. One of the parents (usually mother) passes on two chromosomes 21, instead of one, onto the child. People with this syndrome have characteristic facial expressions and are usually smaller. Learning difficulties also occur, as do heart problems.

How does the nervous system work? - BulletPoints 3

• When talking about locaties of structures in the brain, the following definitions are used:
  • Dorsal: on the backside
  • Ventral: to the front or belly
  • Superior: positioned above
  • Inferior: positioned below
  • Lateral: from the middle of the brain to the side
  • Medial: from the side of the brain to the middle
  • Anterior: in front of
  • Posterior: behind 
• The nervous system, just like the body, is symmetrical, with a left and a right side. Structures on the same side are called ipsilateral, and structures on the opposite side are called contralateral structures. If a structure can be found in both the right and left hemispheres, this is called bilateral.
• The brain and spinal cord are protected from injury and infection in four different ways:
  • The brain is located in the skull, a thick layer of bone. The spinal cord is surrounded by a row of vertebrae, consisting of bone. The central nervous system (CNS) is surrounded by bone, while the PNS, which is connected to the CNS, is not. As a result, the PNS is more vulnerable to injury. However, the PNS is able to recover well after damage, while CNS's ability to recover is much more limited.
  • Underneath the skull lie three layers of membranes, which are called meninges. The outer layer, connected to the brain, is the dura mater. This is a hard, double layer of tissue that surrounds the brain as a kind of bag. The layer below is the arachnoid membrane. This is a very thin layer of vulnerable tissue that follows the contours of the brain. The inner/lower layer is the pia material. This is fairly tough tissue that is attached to the brain.
  • Cerebrospinal fluid circulates within the four ventricles in the brain, the spinal cord and in the subarachnoid spaces (the spaces between the meninges). The cerebrospinal fluid protects the brain and spinal cord from shocks and pressure differences. The cerebrospinal fluid is continuously renewed and removed. If the fluid discharge is blocked somewhere, as can be seen for example in an individual with hydrocephalus, serious intellectual limitations can occur. This can even lead to death.
  • The blood-brain barrier limits the passage of substances from the body into the CNS. This prevents harmful substances from entering the brain. The barrier arises because small blood vessels in the brain are strongly attached to each other and because of this many substances cannot just cross the barrier and enter the CNS.
• There are three basic types of neurons, each with a specific shape and location in the nervous system:
  • Somato-sensory neurons ensure that physical stimuli arrive at the brain
  • Motor neurons control movements
  • Interneurons link the activities of sensory and motor neurons
• In the primitive, developing brain, three areas can be described:
  • The prosencephalon (the forebrain)
    • Responsible for smell
  • The mesencephalon (the midbrain)
    • Responsible for eyesight and hearing
  • The rhombencephalon (the hindbrain)
    • Responsible for movement and balance
• The spinal cord is divided into segments. These segments are called dermatoms and surround the spinal cord like stacked rings. Each segment receives nerve impulses from afferent sensory receptors in part of the body and sends impulses to efferent receptors in the muscles. There are 30 spinal cord segments:
  • 8 cervical (C1 to C8)
    • Contain nerves, especially for the arms
  • 12 thoracic (T1 to T12)
    • Contain the nerves for the trunk
  • 5 lumbar (L1 to L5)
    • Contain the nerves for the hips, front of the legs and part of the feet
  • 5 sacral (S1 to S5)
    • Contain the nerves for the back of the legs and part of the feet
• In case of injury, the damaged segment of the spinal cord is detected by investigating where in the body the feeling or movement no longer functions as normal. This does not apply to internal organs because they do not contain sensory representation in the spinal cord. The pain one feels in internal organs is felt as if it comes from the outside of a dermatome. This is called referred pain because pain is referred to a part of the body via a dermatome. When, for example, one is suffering from heart pain, one feels this in the shoulder or arm and a doctor can use this as a basis for diagnoses about internal organs.
• Movements that only depend on the action of the spinal cord are called reflexes. These are certain movements that are expressed by specific forms of sensory stimulation. Within the body there are several sensory receptors. For example, they record pain, temperature, pressure and feeling when touched. Receptors for pain and temperature are often smaller than those for touch and sensation. When pain or temperature receptors are stimulated, flexion movements are produced. This results in flexion (bending movement, towards the body) of the limb concerned, away from what causes the injury. This is in contrast to the feeling of touch. Touching results in extension (stretching movement, away from the body) of the limb.
• The brain stem starts where the spinal cord enters the brain. The brain stem has more influence on behaviour than the spinal cord and is responsible for more complex movements. Functions of the brainstem are the following:
  • Responding to external sensory stimuli
  • Regulating vital body functions, such as:
    • Body Temperature
    • Sleep 
    • Eating and drinking
  • Regulating of gross motor skills, such as running and walking
• The cerebellum forms the major part of the hindbrain. The cerebellum is made up of a collection of narrow folds called folia. The folia can be seen as smaller versions of the sulci and gyri of the cortex. Nuclei within the cerebellum send information to other parts of the brain. The cerebellum is occupied with:
  • Coordination
  • Posture
  • Learned motor skills
  • Body balance
  • Sleep-wake system
• The diencephalon contains three inner chambers, or thalamus structures. These are the thalamus (inner chamber), the hypothalamus (lower chamber) and the epithalamus (upper chamber). The hypothalamus consists of 22 small nuclei. The fibre pathways that run through it are in contact with the pituitary, so it plays a role in the hormonal system. In addition, the hypothalamus regulates almost all aspects of motivated behaviour, such as eating, sleeping, sex and temperature regulation. The thalamus is the largest structure of the diencephalon. All information that goes to the cortex is first fed through the thalamus. The thalamus consists of 20 nuclei which are representative of a part of the cortex. Information goes to the thalamus and the nucleus responsible for the part of cortex to which the information must go to ensure that the information arrives there.
• The basal ganglia have two functions:
  • Motor functions
    • Controlling and coordinating movements
  • Learning
    • The basal ganglia have a function in associative learning, also called stimulus response or habitual learning
      • This means that relationships can be established between stimuli and their consequences
• The nuclei that form the amygdala and septum play a role in emotional and species-specific behaviour. It is assumed that the hippocampus plays a role in memory and orientation in space. The hippocampus is also vulnerable to the effects of stress. From other structures input can be given to the limbic system which can then be interpreted as emotion. These emotions influence the thalamus, which in reaction to this excretes hormones to trigger the physical reaction that fits the emotion.
• The location of the input and output that the cortex receives can be made representative by a map of the brain, which is called a projection map. This can be used to see which parts of the cortex are sensory and which are motoric. Roughly speaking, this means that the frontal lobes are mainly motor lobes and the other lobes are mainly sensory. There are three types of areas:
  • Primary areas
    • These receive their projections from the largest sensory areas and transmit motor projections to the muscles.
  • Secondary Areas
    • Located next to the primary areas and connected to them
    • These interpret the sensory information and organize the movements
  • Tertiary areas (also known as association cortex)
    • Covers all areas which are not specialised in motor or sensory functions.
    • They mediate complex activities such as the use of language, planning, memory and attention.
• The connection between the hemispheres is made via the corpus callosum and the anterior commissure. Most interhemispheric connections are made by means of homotopic points. These are points in a hemisphere that are each others mirror image. The hemispheres work contralaterally. This means that the left hemisphere controls the right side of the body. For example, the left hemisphere provides the right field of view. This contralateral control requires the sensory and motor nerve fibres to cross in order to reach the right hemisphere. This happens in the middle of the central nervous system and is called decussation.

What are neurons and what do they do? - BulletPoints 4

• With electrical signals neurons are able to receive and distribute information within the CNS. A neuron consists of 1 to 20 dendrites, a cell body and an axon. The cell body contains a small bulge, called an axon hillock, from which the axon is formed. A cell body always consists of only one axon, but it can branch off, which are called axon collaterals. These axon collaterals can branch off further in teleodendria. At the ends of the teleodendria are the terminal buttons, which come very close to dendrites of other neurons, but don't touch them. This creates a space between axons and dendrites, which is called the synaptic cleft. Dendrites receive information, axons transmit information, and the cell body processes and integrates information. This information consists of electrical impulses. When an impulse reaches the terminal buttons, a chemical substance is released. This is called a neurotransmitter and it carries the information over the synaptic cleft from neuron to neuron. Synapses can be inhibitory or excitatory, meaning they can reduce or increase the ability of a neuron to pass information to other neurons.
• On a strand of DNA, adenine is always associated with thymine and guanine with cytosine. Series of hundreds to thousands of these bases together create the genetic code. A gene is part of a strand of DNA and encodes the synthesis of a certain type of protein molecule. The code contains a specific order of the 4 bases. This code describes how the amino acids, the building blocks of proteins, must be composed in order to create a certain protein. The production of a protein goes as follows (see page 92 in the book for an illustration):
  • A certain gene of a segment from the DNA wraps itself off the double helix
  • This causes the bases to become loose and they can function as a mould
  • Separate nucleotides attach themselves to these bases
  • The order of the bases coming from the completed strand of DNA are copied (transcription) and form a strand of RNA
    • The difference between the RNA produced by the transcription and the DNA is that thymine has been replaced by the base uracil (U)
  • The copied RNA is called mRNA (messenger RNA)
    • mRNA transports the genetic code from the nucleus to the endoplasmic reticulum (ER)
  • In the ER, translation of the mRNA takes place using tRNA (transfer RNA).
    • A set of three bases is called a codon
      • Each codon is translated into 1 of the 20 different available amino acids
    • The amino acids are connected to each other to form a polypeptide chain.
    • A combination of polypeptide chains eventually becomes a protein
• Three methods are responsible for the movement of ions in and out of the cell:
  • Differences in concentration gradient
    • This is done by diffusion. Diffusion occurs because molecules always want to move from a high concentration to a low concentration. The result of this is that a substance dissolves proportionally within a liquid so that the concentration is the same everywhere.
  • Differences in voltage gradient
    • As with a difference in concentration, there can be a difference in the charge of ions within a liquid. Here too, the following applies: Ions move from an area with a high charge to an area with a low electrical charge. The result is that the liquid contains a proportional number of positively charged ions as well as negatively charged ions.
  • The way in which the membrane is constructed
    • Due to the specific structure of the membrane, some substances cannot pass through the membrane, others can. The hydrophobic tails ensure watertightness.
• The extracellular fluid has a charge of 0mV and the intracellular fluid has a charge of -70mV. The latter is also known as the resting potential of the membrane. This works as follows:
  • Anions remain in the intracellular fluid
  • The membrane does not allow sodium ions to pass through it.
    • But there is free access to the cell for potassium ions and chloride anions that move freely in and out of the cell by means of the concentration gradient.
  • The diaphragm contains a sodium-potassium pump
    • When the pump is active, 3 sodium ions are pumped out of the cell and 2 potassium ions are pumped into the cell
    • The sodium ion cannot return after it has been pumped out of the intracellular fluid.
• A graduated potential is created when the ion flow barrier changes and thus the charge of the membrane changes. Two changes of are possible:
  • Hyperpolarization
    • An increase in the negative charge over the membrane
    • A stimulus causes the potential to be charged even more negatively. This can be done, for example, by an efflux of potassium out of the cell or by an influx of chloride into the cell.
    • The potential of a cell then, for example, becomes -73mV
  • Depolarization
    • A reduction in the negative charge over the membrane
    • The potential is charged more positively because of a stimulus. This is because gates open into the membrane allowing sodium to enter the cell.
    • The potential of a cell then, for example, becomes -65mV
• When an action potential occurs and the threshold of -50mV is reached, a depolarization period occurs during which sodium ions enter the cell and the potential becomes more positive. In response, potassium ions open up and the potential becomes more negative again: the repolarization period. After the repolarization period there is a very short hyperpolarization period, after which the potential comes to rest again. During depolarization or repolarization periods, a membrane cannot react to new action potentials because the ports are insensitive in these periods. This is called a recovery period (refractory period).
• A nerve impulse is a series of action potentials in succession on the membrane of an axon. In one direction the action potential spreads over the axon so that the information goes from one side to the other side of the axon. After an impulse, sodium or potassium-sensitive channels open up. Because channels are opened in an area of the axon membrane, the impulse can spread over the adjacent area of the membrane. This can be seen as if an action potential is born from the previous action potential and this follows along the whole axon. After an action potential has been transferred, a cell must recover and at that moment is not able to respond to an impulse so that the action potential can only go in one direction.

How do neurons communicate? - BulletPoints 5

• The end (terminal) of an axon and the beginning of a dendrite do not touch each other. The space between the axon and dendrite is called the synaptic cleft. There are three areas of a synapse which presented below in the order of which information is sent:
  • Presynaptic membrane
    • This is the end of the membrane of the axon.
    • Contains mainly large protein molecules that act as channels and pumps to direct information about the membrane towards the dendrite
    • Also contains mitochondria and synaptic vesicles, which contain chemical neurotransmitters
    • Sometimes it also contains granules, which can hold synaptic vesicles as storage.
  • Synaptic cleft
    • This is the space between the end of the axon and the beginning of the dendrite.
  • Post-synaptic membrane
    • This is the beginning of the dendrite
    • Here you will mainly find large protein molecules that specialize in receiving chemical information.
• Neurotransmitters end up in the synaptic cleft through an action potential. The process goes as follows:
  • An action potential over the axon initiates the opening of calcium-sensitive gates
  • Positively charged calcium ions enter the cell from the extracellular fluid.
  • These calcium ions bind to other molecules and form complexes.
  • Formed complexes give rise to two chemical reactions:
    • Release of synaptic vesicles attached to the presynaptic membrane.
    • Release of vesicles attached to filaments at the terminal node of the axon.
  • The contents of the vesicles are emptied into the synaptic cleft, which is called exocytosis (see page 120).
• There are different types of synapses. All of them have their own specialisation with regard to location, structure and function. A number of synapses can be distinguished:
  • Axodendritic synapse
    • An axon terminal makes contact with the dendrite of another neuron.
  • Auxiliary cellular synapses
    • This is an axon terminal without a specific purpose.
    • Release the neurotransmitters in the extracellular fluid.
  • Axosomatic synapse
    • Here an axon terminal ends on a cell body
  • Axosynaptic synapse
    • An axon terminal ends up at another axon terminal.
  • Axoaxial synapse
    • In this case an axon terminal ends on another axon
  • Axosecretory synapses
    • An axon terminal ends up on small blood vessels and excretes the neurotransmitters directly into the blood.
  • Axomuscular synapses
    • An axon terminal ends up on a muscle and can thus provide it with nerve impulses.
• In order to ensure that motor neurons do not excite themselves and thus excite muscles continuously, a negative feedback loop is applied, the Renshaw loop. An motor neuron is attached to both a muscle and an inhibitory Renshaw neuron. When the motor neuron fires an action potential to the muscle, the Renshaw Neuron is activated at the same time. This in turn releases inhibitory neurotransmitters to the motor neuron, causing it to stop exciting.
• In terms of structure, ionotropic receptors can be compared to voltage sensitive channels. They have pores that can open and close and let charged atoms pass through the membrane when neurotransmitters bind to the receptors of the pores. Ionotropic receptors are usually excitory and therefore increase the chance that a neuron will produce an action potential. The metabotropic receptors are almost always inhibiting. A metabotropic receptor consists of a single protein that covers the entire cell membrane. They have no pores through which ions can flow, so receptors have to be indirect.
• The specific neurons and specific tasks they perform often have certain groups of neurotransmitters that match them. Motor neurons, for example, are cholinergic, with acetylcholine as the primary neurotransmitter. There are also a number of groups of systems in the CNS in which some neurotransmitters play a major role. There are 4 groups of systems to name with all their own important functions (see page 133 for an overview). The systems are:
  • The dopaminergic group is active in the coordination of movement.
    • Is of influence in schizophrenia
  • The noradrenergic group plays a role in learning and planning
    • Is of influence on OCD
  • The serotonergic group plays a role in consciousness
    • Is of influence depression or mania
  • The cholinergic group plays a role in sleep-wake cycle and memory
    • Is of influence on Alzheimer's disease

What are the effects of medication and hormones on behaviour? - BulletPoints 6

• The study that studies how medication affects the nervous system and behaviour is called psychopharmacology. The effect of medication depends, among other things, on the way it is used, the circumstances and the quality of the medication. Medication consists of a chemical composition and is administered to bring about a change in the body. Medication is administered for a variety of purposes:
  • To diagnose
  • To treat
  • To prevent disease
  • To relieve pain and suffering
  • To improve aversive physical states
• In order to achieve neurological goals, a drug must be able to enter the extracellular fluid from the blood, which involves a number of obstacles. It is important that they are able to pass the blood-brain barrier. This can be done in two ways:
  • Small molecules like oxygen, which are not ionized and can pass fat soluble through the wall of capillaries (very small blood vessels).
  • Other molecules such as glucose and amino acids pass through an active transport system, such as the sodium potassium pump.
• Most psychoactive drugs owe their efficacy to the influence they can exert on the chemical reactions within the synapse. Medicine can exert their influence within the synapses when:
  • A neurotransmitter is synthesized
  • A neurotransmitter is stored
  • A neurotransmitter is excreted in the synapse from the axon
  • A neurotransmitter binds to the receptor of the dendrite
  • A neurotransmitter is deactivated
  • Reuptake of a neurotransmitter has been carried out by the cell for reuse
  • Any remaining neurotransmitter and any byproducts are removed by the synapse
• Antipsychotics are prescribed in the case of psychotic diseases. Psychoses are characterized by hallucinations or delusions. The mechanism of action of antipsychotics is not yet fully understood. The dopamine hypothesis of schizophrenia indicates that some forms of the condition are the result of excessive dopamine activation. Evidence stems from the fact that some substances that increase dopamine activity, such as amfetamine, lead to symptoms similar to schizophrenia. Furthermore, the drugs in this group are dopamine antagonists and prevent the adhesion of dopamine to receptors leading to less symptoms of psychosis.
• Many people in the world suffer from depression and 30% of the population will experience a period of depression one day in their lives. There are three types of medication that can be prescribed to people with depression:
  • Monoamine oxidase inhibitors (MAO inhibitors)
    • Inhibits the enzyme monoamine oxidase, which breaks down serotonin in an axon.
  • Tricyclic antidepressants 
    • Blocks reuptake of serotonin, keeping it active longer in the synaptic cleft
  • Selective serotonin reuptake inhibitors (SSRIs)
    • Also called second generation antidepressants
    • The same effect as tricyclic antidepressants
• Previously opioid analgesics were called narcotic analgesics because they are sleep-inducing (narcotic) and pain-relieving (analgesic). The drugs are mainly based on opium. Codeine and morphine are derived from the opium poppy and have strong pain relieving properties. Heroin is also an opium and enters the brain's bloodstream faster than morphine. Because this medication is so pain relieving, it often results in addiction and abuse of the opioid analgesics.
• Psychedelics cause changes in sensory perception and cognitive processes. In this way, they can cause hallucinations. The psychedelics are divided into five groups:
  • Acetylcholine psychedelics
    • Working in on the muscarinic receptors
    • Can be used by the blood-brain barrier and in high dosage also as poison
    • For example atropine or nicotine
  • Anandamide psychedelics
    • Prevent memory systems from being overloaded with all the information we have to process on a daily basis
    • For example, tetrahydrocannabinol (THC), a major component of marijuana
      • Has some clinical effects such as reducing nausea, increasing appetite, treating pain, lowering eye pressure etc.
  • Glutamate psychedelics
    • Phencyclidine (PCP) and ketamine
    • Giving hallucination and out-of-body experiences
  • Norepinephrine psychedelics
    • Mescaline
    • Giving a sense of spatial limitlessness ('higher states') and visual hallucinations
  • Serotonin psychedelics
    • LSD, MDMA (XTC) and psilocybin
    • Stimulate serotonin receptors
• Hormones are chemical substances that come from hormone glands and move through blood vessels. Hormones can also be used to prevent or cure diseases. Hormones are classified according to their behaviour in one of the following three functional groups:
  • Homeostatic hormones
    • For example insulin
    • Ensuring the internal metabolic balance in the body and regulating physiological systems
  • Gender Hormones
    • Have control over the reproductive functions
    • They take care of the physical development into a man or woman and everything that has to do with this.
  • Glucocorticoids
    • Issued in case of stress
    • They are important for the protein and carbohydrate metabolism and the control of blood sugar levels.
    • Also have an impact in emergency situations such as the fight-flight response

How can brain activity be made visible? - BulletPoints 7

• There are several modern methods to make the brain visible:
  • Recording of electrical activity
    • The detection of lectrical activity in the neurons
  • Brain stimulation
    • This involves making changes in the electrical activity of the brain
  • X-rays
    • Works by looking at the differences in density of parts of the brain
  • Dynamic methods
    • These methods measure and manipulate changes in brain activity at the time of measurement
• Research through EEG provides information about the electrical activity of a large part of the brain. Electrodes are glued to the scalp and are connected to a machine called an electroencephalograph. Neurons emit electricity, which can be expressed in waves. The electroencephalograph registers these wave patterns and the height of a wave (amplitude) indicates the number of microvolts. The number of waves per second (hertz) indicates the frequency of the electrical signals. The waves of an EEG are expressed on a polygraph. Different wave patterns have to do with different behaviour. A regular, larger (high amplitude) and slower rhythm of about 11 hertz is called an alpha rhythm. This can be seen when someone is relaxed and has closed eyes. An irregular, smaller and high-frequency rhythm is called a beta rhythm. This can be seen when someone is alert or excited. Higher waves with a frequency of 4-7 Hertz are called theta waves and when the waves have a frequency of 1-3 Hertz they are called delta waves.
• By electrically stimulating the brain tissue, it will carry out actions. Because of this, we were able to make a functional map of the brain and to indicate which region of the cortex controls what: the homunculus. There are 2 ways to stimulate the brain:
  • Brain stimulation from the inside (intracranial)
    • This is an invasive form of brain stimulation in which electrodes are placed in the brain.
      • This is called deep brain stimulation (DBS)
    • It is used for it:
      • Mapping of functional regions of the brain
      • Treatment of epilepsy and brain trauma
      • Treatment of tremors in, for example, Parkinson's disease
    • The disadvantage of this is that the skull has to be opened up, which can result in infections and damage to the brain.
  • Brain stimulation from outside (transcranial)
    • This is a non-invasive way in which stimulation of the brain from outside the skull can take place by means of magnetism and electricity.
    • Initially, it was used by neurosurgeons to study brain functionality during or after surgery.
    • It is now used for:
      • Pain Treatment
      • Damage after strokes
      • Movement disorders
      • Depression
• There are different forms of X-ray techniques:
  • Conventional Radiography
    • This involves taking an X-ray of the brain.
    • The density of the tissue determines how dark the tissue is depicted in the image
      • Bone is white, brain is grey, ventricles are black
  • Pneumo-encephalography
    • This is a technique to improve conventional radiography.
    • Some brain fluid is removed and replaced by some air
      • This allows the ventricles to be depicted much more clearly.
  • Angiography
    • This is a technique to make blood vessels visible.
    • A substance that absorbs X-rays is injected into the bloodstream and is therefore clearly visible.
  • Computer tomography (CT scan)
    • In this case, an X-ray is sent from different angles through the same object
    • This results in many cross-sections/images of the brain and a computer is used to make a 3D version of it.
      • It is read as an X-ray where brain tissue is grey, bone white and ventricles (liquid) black.
    • The resolution (sharpness) is expressed in voxels, the size of the pixels
    • A CT scan can be used to detect tumours and brain damage.
• It is not the case that one of the imaging techniques is the best. They all have advantages and disadvantages. EEG, ERP and fNIRS, for example, are very cheap, while MEG, MRI and PET are very expensive. There are often differences between spatial and temporal resolution. Techniques that work by means of X-rays are good at localizing skull damage, intracranial bleeding, tumors etc. PET and fMRI are very good at imaging the functional tasks of brain areas. Which method is most useful depends on what needs to be investigated.

How do sensory systems function? - BulletPoints 8

• Incoming energy is converted into action potentials by a receptor. This is done as follows in the various systems:
  • Visual system
    • Light energy is converted into chemical energy in the retina by photonceptors, after which it is converted into action potentials.
  • Hearing System
    • Sound waves enter the ear and are first converted into mechanical energy and then into action potentials.
  • System for sense of touch
    • Also called somatosensory system
    • Mechanical energy is converted into action potentials via somatosensory receptors.
  • Olfactory system
    • Chemical molecules in the air or in food sit on receptors and provide action potentials
• Receptors can be divided into two factors in relation to the body:
  • Exteroceptive receptors
    • These are receptors that respond to external stimuli (outside the body).
    • They react to objects we see, touch, smell or taste
  • Interoceptive receptors
    • These are receptors that respond to stimuli produced by organs and muscles in the body itself.
    • This makes it possible to feel what is happening in our body and makes it possible to distinguish internal and external stimuli from each other.
• The retina of the eye contains two types of receptive cells, rods and cones. The distribution of rods and cones is different in the retina. High-density cones are packed together in the fovea (part of the yellow spot). Rods are not found in the fovea at all, but are thinly spread over the rest of the retina. The photoreceptive cells have a synapse on the bipolar cell. This is where graduated potentials are formed. The bipolar cell activates retinal ganglion cells and axons are then sent to the brain. From the retina, these axons form two optic nerves. These nerves cross each other and form what is called the chiasma optic. Approximately half of both nerves cross and the other half do not. This results in the right field of view of both eyes being controlled by the left hemisphere and the left field of view of both eyes by the right hemisphere.
• The ear consists of three areas:
  • The outer ear
    • Here is the pinna (auricle) and the outer ear canal
    • The auricle captures waves from air pressure and guides these waves to the ear canal, which slightly amplifies the sound, after which it vibrates via the eardrum to the middle ear.
  • The middle ear
    • This is a space filled with air which contains three small bones which conduct the sound further to the inner ear:
      • Hammer
      • Anvil
      • Stirrup
  • The inner ear
    • This contains the cochlea, which contains the auditory sensory receptors known as hair cells.
      • The axons of the hair cells leave the cochlea and form an auditory nerve which the action potentials send to the temporal cortex
• The somatosensory receptors consist of more than 20 different types, but can all be summed up in three groups of sensory perception:
  • Nociception
    • This makes you feel pain, temperature and itching
    • There are approximately eight different types of nerve fibres for pain, each with its own applications
    • Internal organs have tracts for pain that discharge into the tracts for pain of the body's surface. This makes it impossible for the body to distinguish between signals coming from the inside or from the outside of the body.
      • Therefore one feels internal pain as if it comes from the surface of the body what is referred to as pain.
        • Think of people with a heart attack who have pain in their jaw or left arm.
    • The brain itself has no pain receptors
  • Hapsis
    • This ensures the tactile/tactile perception of objects
  • Proprioception
    • This is the awareness of the location of the body and its movements
• The somatosensory cortex can be represented as a map, which is also called a homunculus. This homunculus indicates the extent to which sensory parts of the body are represented on the cortex. Hands, for example, have a lot of feeling and therefore take up a larger part of the cortex. The somatosensory cortex is divided into four parts that provide different ways of feeling:
  • Area 3a
    • Adjusts the feeling of the muscles (position and movement of the muscles).
  • Area 3b
    • Controls the sensation of the skin
      • Here you will find both slow and fast skin receptors
  • Area 1
    • Controls the sensation of the skin
      • Here you will only find fast skin receptors
  • Area 2
    • This provides the joints and deeper sensing sensors
• The vestibular system is made up of two parts and works as follows. Semicircular canals are oriented in all three spatial planes in which we can move (X, Y and Z). These are sensitive to the movements of the head. The otolite organs are sensitive to the static position of the head in space and detect linear acceleration of the head. Of all these structures, the hair cells bend when the head changes position. These structures send information to the nuclei in the brainstem which ensures that we can maintain our balance and store and relive previous movements we have made. Vertigo is a sensation in which one has nausea and balance problems without moving. Ménière's disease is a condition in which vertigo occurs.
• The receptors of taste are the taste buds and these lie around the lumps on the tongue. The stimuli for taste and odour perception are chemical and come from food and air. When the tongue is dry, it is difficult to taste. This is because food has to be broken down via saliva so that the chemicals in it can reach the taste buds. There are five receptors for taste: sweet, sour, salt, bitter and unami. Unami is sensitive to proteins and especially to food containing monosodium glutamate.

How does the motor system function? - BulletPoints 9

• Different parts of the brain work together to produce movement. There are four areas that cooperate in the execution of a movement:
  • Posterior cortex
    • This area creates concrete goals for movement  and sends sensory information from sight, feeling and hearing to the frontal regions via different routes.
      • The direct routes are utilized more for automatic movements
      • The indirect routes provide the movements that require conscious control
  • Prefrontal cortex (PFC)
    • Based on instructions from the posterior cortex the PFC plans movements
    • The PFC then transmits its information to the premotor and primary motor cortex
  • Premotor cortex
    • This functions by organizing movements.
  • Primary motor cortex
    • This produces the specific movements
• In order to map the motor cortex even better, experiments were carried out in which the motor cortex was stimulated with electrical impulses. Then it was examined which electrical impulses in what locations in the brain caused which movements. In this way Penfield mapped out in the 1950s which areas in the primary motor and premotor cortex caused which movements. He created a homunculus, comparable to the sensory homunculus. This is a picture of a human being on which parts of the body that cover a large part of the primary motor cortex are depicted enlarged and parts that cover only a small part of the primary motor cortex are depicted small. For example, hands, lips and tongue are depicted very large and legs, arms and diaphragm are depicted small. This is because a larger part of the primary motor cortex is needed to move the hands, lips and tongue than it takes to move the legs, arms and diaphragm. The homunculus is mirrored on both hemispheres. This means that the homunculus of the right hemisphere is a direct mirror image of the left hemisphere.
• The basal ganglia are located in the forebrain and consist of a collection of neurons. These connect the sensory regions of the neocortex with the motor cortex and send information to the substantia nigra by means of a dopamine pad. An important structure of the basal ganglia is the caudate putamen. The caudate putamen has a kind of 'tail' which ends in the amygdala. The main function of the basal ganglia is to modulate movement. Two types of movement disorders can occur in basal ganglia disorders:
  • Dyskinesia (hyperkinesia)
    • These are unintentional, choreiform (floundering, pulling) movements. 
    • It occurs when cells of the caudate putamen are damaged
    • Examples of diseases with dyskinesia are Huntington's disease and Tourette's disease
  • Hypokinesia
    • Results in difficulties in starting movements
    • This occurs when the cells of the basala gangline are intact, but the input to it is broken.
    • Parkinson's disease is an example of this
• The cerebellum is part of the motor system and ensures the acquisition and retention of learned skills. In addition, it carries out checks on behaviour and movements. It deals with the timing of movements and helps to execute movements accurately. For example, behaviour is matched to each other or a movement is corrected if it does not correspond to the movement one wanted to perform. The cerebellum is located in the brainstem and consists of two cerebellar hemispheres and the flocculus, all of which are specialised in a certain part of movement. The medial parts of the hemispheres are concerned with the middle part of the body (head and trunk). The parts that are more lateral are concerned with the extremities (arms and legs) and the hands, feet, fingers and toes. The flocculus is concerned with the movement of the eye and with keeping balance.
• The axons of the two pathways from the cortex to the spinal cord, the corticospinal and corticobullary pathways, originate from layer V pyramid cells from the neocortex. The corticospinal tract descends further down the brain stem. In the brainstem axons of the corticospinal tract end up on large bumps, which are called pyramids. This is why the above pathways are also called the pyramidal tracts. At this point in the brainstem, about 95% of the motor axons cross from the left hemisphere to the right side of the brainstem. The crossing axons form the lateral corticospinal tract. The axons from the right hemisphere follow the opposite route, from right to left. These form the anterior corticospinal tract. The tract that cross to the other side of the body allow for movements of the hand, arm, leg and foot regions of the homunculus, while the tract that does not cross provide for the movements of the regions of the torso of the homunculus. So, both hemispheres provide the movements of the arms and legs from the opposite side of the body, but the torso is cared for by the hemisphere on the same side of the body.

What are the principles of cortical functioning? - BulletPoints 10

• A hierarchical brain structure stands at the basis of the degree of complex behaviour that can be shown. There are two reasons why extreme brain damage affects higher brain functions, but somehow one can still function reasonably well:
  • Levels of functioning
    • The highest (high-order) brain functions provide precision and flexibility of behavior, control and make it possible to execute intentional movements in organized patterns
    • The lowest (low-order) brain functions are involved in the execution of reflexes.
    • Between the highest and lowest brain functions there is a kind of 'hierarchical staircase' with different steps. This staircase determines the degree of functioning that a person still has at when certain areas of the CNS were damaged.
      • If high-order brain areas are damaged, someone can still function because of their lower brain functions, but is no longer able to carry out very complex behaviour.
  • Plasticity
    • This is the ability of the brain to adapt after damage has occurred.
      • In this way, the brain can compensate, as it were, for lost functions.
• The spinal cord is responsible for the execution of reflexes. When the connection between the spinal cord and the brain is broken, the reflexes remain intact despite the fact that someone is paralyzed. However, voluntary movements are no longer possible if the connection between the spinal cord and the rest of the CNS is broken. When a cat with such a broken connection is hung on a hammock over a slow treadmill and the legs touch the treadmill very lightly, the legs start to walk automatically. The movements may still exist, but they can no longer be made voluntarily because the brain cannot coordinate the movements.
• When all parts of the CNS, including the basal ganglia, are in contact, but are separate from the cortex, this is called decortication. Animals are able to eat and drink, have sleep-wake rhythms, can run, climb and swim and can even solve simple mazes. They can even perform series of movements, such as taking care of themselves (washing, cleaning, etc.). On first glance, there seems to be nothing wrong with these animals, but there is. They are not able to automatically link behaviour and cooperate it with voluntary behaviour so that biological adaptive behaviour is created. An example is that lab rats walk towards food and then inhibit walking so that they can eat it. These two types of behaviour cannot be carried out at the same time. The basal ganglia inhibit or facilitate seemingly voluntary behaviour, but this cannot take place at the same time as automatic behaviour.
• In order to gain insight into the functional areas of the cortex, maps of the brain have been made. This indicates at which location functional areas are located on the cortex and what these areas control. According to Flechsig (1920), the functions of the cortex are subdivided according to a hierarchical system. Primary areas are concerned with sensorimotor functions and secondary and tertiary areas are concerned with higher mental processes:
  • The primary areas
    • Including the motor cortex and a region for the visual, auditory and somatosensory cortex
    • This one is the first to myelinate
  • Secondary zones adjacent to primary zones
    • This one is next to myelinate
  • A tertiary zone called the association zone
    • This one is the last to myelinate
• The cortex contains six layers where neocortical cells may be located. In each layer of the cortex, the neurons have different functions and different in- and outputs. The layers are aligned from top to bottom, starting at layer I and ending at layer VI. In general, the following applies:
  • Layer I to III
    • These are superficial
    • They integrate the information they receive from other cortical areas
  • Layer IV
    • This layer is located in the middle
    • It receives sensory information as input from other cortical regions and the brain
  • Layer V and VI
    • These are the deepest layers
    • This is an output zone and they send axons to other areas of the brain.
• The areas of the cortex exchange information about different characteristics of stimuli. Areas that have a certain function in the brain (such as vision) function together with other sensory areas (such as feeling). They operate in more than one mode. These areas are called multimodal cortex or polymodal cortex. An example is the fact that we can visually identify an object when we have never seen it, but have only felt it. These systems therefore seem to work together. It appears that multimodal cortex is a basic characteristic of cortical function and is found in lab monkeys in both the primary and secondary cortex.
• The cortex is filled with systems and subsystems, in which all kinds of connections are made. Why is it that we do not see fragmented images of all these different systems from all these specific connections and different regions? How can it be that all our senses are combined and translated into a perception of reality in general, a total picture? This question is called the binding problem and the most logical explanation is that in the connections between cortical and subcortical systems there is an intracortical network. This is most logical for the following reasons:
  • All cortical areas contain internal connections between the individual units which contain the same properties
    • These connections ensure that neurons that lie side by side are connected to each other and synchronized according to their activity.
  • There is a mechanism called reentry, which ensures that each cortical area can influence the area it receives input from.
    • This means that when area A sends a message to area B, area B can reply by sending a message back to area A.
• According to Luria, the cortex contains two functional units:
  • The sensory unit
    • It is located in the parietal, occipital and temporal lobes.
    • The sensory unit receives, processes, and stores incoming sensations
  • The motor unit
    • This is located in the front lobe
    • The motor unit makes plans, organises them and eventually executes them.
• Both functional units of the cortex consist of a hierarchical structure. An example of this hierarchy is the following: when you see a football game, the primary visual area makes sure you see the movement of the ball and the players. The secondary visual sensory area allows you to recognize that this is the game of football. In the tertiary area, all the sounds and movements of the game are integrated and you understand that one team has scored and therefore is ahead and that this match is important for the championship. In the tertiary area, all information has become much more than just sensory information. So the hierarchical structure is as follows:
  • A primary cortex
    • Information enters in here first
  • A secondary cortex
    • Information is expanded and processed here
  • A tertiary cortex
    • Information is integrated here

What parts does cerebral asymmetry consist of? - BulletPoints 11

• There are many differences between the two hemispheres. Examples are the primary auditory cortex and Wernicke's area. Wernicke's area, or planum temporale, lies behind the primary auditory cortex in the lateral fissure and is 1 cm longer in the left than in the right hemisphere. The primary auditory cortex, however, is larger in the right hemisphere. With MRI up to eight major anatomical differences between the hemispheres were found:
  • The right hemisphere is slightly larger and heavier
    • However, the left hemisphere contains slightly more grey matter (neurons).
  • The left and right temporal lobes are asymmetric
    • Because of their specialization in respectively language and music
  • The thalamus is asymmetric, in line with the temporal lobes
    • The left thalamus is more dominant for language
  • The slope of the lateral fissure is less steep in the left hemisphere
  • The frontal operculum (region of Broca) is asymmetric
    • This has to do with the fact that the left side is responsible for grammar and the right side is responsible for the tone of the voice
  • Neurotransmitters in cortical and subcortical areas are asymmetrically distributed
  • The right hemisphere extends more forward and the left hemisphere extends further to the back
    • In addition, the occipital horns of the lateral ventricles are usually larger in the right hemisphere.
  • Gender and dexterity influence anatomical asymmetry
• The existence of cerebral asymmetry was revealed by studying patients with neurological diseases. A lot of knowledge comes from people who could no longer perform certain behaviour after a stroke or surgery. This revealed that left hemisphere lesions from right-handed patients led to defects that did not occur after right-handed lesions. Language problems with right-handed people do occur after lesions in the left hemisphere, but not after lesions in the right hemisphere. The performance of spatial tasks, singing, playing musical instruments and discrimination between sound patterns is in fact disturbed by lesions in the right hemisphere. The principle that lesions of the left hemisphere result in the inability to perform certain tasks that can still be performed after lesions of the right hemisphere and vice versa is called double dissociation. This also applies to damage within the same hemisphere. Damage to different areas within the same hemisphere does not lead to the same dysfunctions either.
• With brain stimulation, where an electric current passes through the cortex, four general effects became visible. Three excitatory and one inhibitory:
  • The brain has both symmetrical and asymmetrical functions
    • Stimulation of the primary motor-, primairy somatosensory-, visual- and auditory areas can produce localized movements, localized dysthesies (numbness or tingling of the skin), flashes of light and buzzing sensations
  • The right hemisphere has perceptual functions that are not shared by the left hemisphere
    • Stimulation can evoke interpretative and experiential responses, which means that patients retrieve a specific memory in response to a particular stimulation.
    • This results in phenomena such as déja vu, fear and dreams, which are more often produced by the right temporal lobe.
  • Stimulation of the left frontal lobe or left temporal lobe may accelerate speech production.
  • Stimulation blocks functions
    • This only occurs when stimulating the left front ottemporal areas when someone is performing complex operations such as speech.
      • Then that complex action is inhibited
• Left hemisphere lesions can lead to apraxia. Apraxia are serious defects in the making or copying of successive (series of) movements. Discovering asymmetries in motor systems is difficult. This is because the brain hemispheres already have large differences in sensory systems. If differences are found between two motor functions, this may already be entirely due to the sensory systems with which they work closely. There are two ways to measure differences in motor functions between hemispheres:
  • Direct observation
    • This found that in a verbal test most of the movements are made by the right hand, while in a non-verbal test the left hand makes the most of the movements.
      • So the two hemispheres complement each other in the movements
    • Another observation showed that the right side of the mouth opens faster and wider than the left side when making verbal and non-verbal sounds.
      • This indicates that the left hemisphere is important in the selection, programming and production of verbal and non-verbal oral movements.
  • Interference Tasks (or Multitasking)
    • This involves looking at the execution of two complex tasks at the same time
    • An experiment that was carried out to measure this was the following:
      • Musicians were taught a piece of music for each hand to play on the piano. These pieces had to be played with two hands at the same time. During playing with both hands, the musicians sometimes had to speak and sometimes buzz. When they spoke the right hand stopped playing and when they buzzed the left hand.
    • Interference effects need to be investigated much more extensively to see which hemisphere is better in what kind of motor functions
• Interaction models assume that both hemispheres have the capacity to perform all functions, but do not do so. There are three versions of this model:
  • The two hemispheres work simultaneously, but on different aspects of processing
    • However, this does not explain how information is combined into a single perception.
  • The two hemispheres inhibit certain activity of the other hemisphere
    • How this would be physiologically constructed is not yet clear.
  • The two hemispheres have a preference for certain information that allows them to perform several analyses at the same time, or there is a mechanism that ensures that each hemisphere pays more attention to specific types of information.
    • Again, it is unclear how this would be physiologically constructed.

What are variations in cerebral asymmetry? - BulletPoints 12

• There are different theories about the reason for hand preferences:
  • Environmental Theories
    • Hand preference is useful for carrying out behaviour
      • In the past, people used their right hands more often to perform movements:
        • Soldiers held their shield in their left hand to protect the heart
        • Mothers held their child in their left hand so that they became calm from their mothers heartbeat
    • Environmental reinforcement
      • Children used to be forced to write with their right hand
    • Due to cerebral defects or accidents during development
      • There is a genetic bias to right-handedness and cerebral defects or accidents cause left-handedness
  • Anatomical theories
    • Because the left hemisphere has matured and developed further, right-handedness is created
    • There is a development preference for the left side of the body of many animals which is not genetically explainable.
      • Such as the side of the heart, the size of the left-temporal cortex etc.
      • This would result in the left hemisphere being more dominant and right-handedness more common.
  • Hormonal theories
    • Geschwind and Galaburda argued that in early life brain plasticity affects cerebral asymmetry leading to abnormal patterns of hemispheric organization. Central to this is the hormone testosterone, which would change the cerebral organization. Higher levels of testosterone than normal would inhibit the left hemisphere, allowing the right hemisphere to grow faster. This leads to changes in hemispheric organisation and, in some cases, left-handedness.
      • There is no evidence for this theory
  • Genetic theories
    • The best model is from Annett (2000) which assumes a dominant gene for the preference of speech to the left hemisphere (rs+).
      • She indicated that when speech is in the left hemisphere there is also a motor preference for the right hand.
      • If someone has the recessive variant of rs+ there would be no preference for hand or speech
        • So different combinations of alleles are possible, namely: both alleles dominant (occurs in 50% of the population), one allele dominant (occurs in 25% of the population) and both alleles recessive (occurs in 25% of the population).
          • If both alleles are recessive, there is no preference and about half the people, based on probability, will be left-handed: 12,5%
          • This is released close to the actual percentage of 10% in the population.
• There are five different options as to why there are differences between the sexes:
  • Hormonal effects
    • The effect of sex hormones on the brain and behaviour is called an inductive/organising effect.
      • This would lead to sexual differences
    • The largest gender differences can be seen in brain regions with the most estrogen receptors during development
      • High levels of estrogen are related to less spatial skills and better articular and motor abilities
    • Estrogen also directly affects the neuronal structure
    • Scores for spatial testing and mathematical skill appear to fluctuate with changing testosterone levels
    • Lower testosterone levels lead to better scores for spatial understanding and mathematical skill in men
      • Women with higher testosterone levels than normal also have better spatial understanding. This shows that there is an optimal level of testosterone for quality of spatial understanding. 
  • Genetic Effects
    • If a gene for a particular trait (a kind of skill) such as spatial understanding is located on the X chromosome and is recessive, this is not reflected when a girl does not possess both recessive X genes
      • In a boy it is always expressed when the mother possesses both recessive X chromosomes. In the case of a girl, the fathers X chromosome must be recessive as well.
    • However, it has not yet been proven that this process works in this way.
  • The degree of cerebral maturation
    • Girls mature faster than boys and are physically more mature
      • Boys' brains may mature more slowly than girls' brains
        • Girls start talking earlier, develop larger vocabularies and use more complex linguistic constructions
        • It is possible that the slower a brain matures, the more asymmetry is created in the brain.
  • Environmental Influences
    • Environmental influences determine to a large extent differences in behaviour between sexes.
    • Even if environmental or social factors cannot be ignored to explain differences, these experience effects are less influential than biological effects
  • Cognitive preferred methods
    • As discussed earlier, people have different strategies to solve problems and use cognitive analysis
    • In cognitive preferred methods differences between the sexes exist
• The cognitive functions of both hemispheres are hierarchically divided. The lower-order functions are those of the primary cortex. Higher-order functions are always one step higher up the hierarchy. From the beginning of development, when one is still an embryo, the brain can only perform low-order functions and the functions of the hemispheres still overlap strongly. From the age of 5 and onwards, higher-order functions have been developed to such an extent that they hardly overlap anymore. And the older one gets, the more specialized the hemispheres become until they really have their own functions. When brain damage occurs at an early age, brain functions still overlap to such an extent that the other hemisphere can take over functions. The more specialized the hemispheres become, the less they can take over after damage. One reason for this may be that one hemisphere suppresses another, so that they do not develop the same functions. This is called the interactive parallel development hypothesis. 

How do the occipital lobes function? - BulletPoints 13

• There are several parts of the occipital lobe. First, there is the primary visual cortex (V1). V1 is special because it contains a complex layered structure. Normally the cortex consists of six layers, but in V1 there are many more to be seen. Layer IV alone consists of four different layers, which resemble a thick stripe. This has given the visual cortex its name: striate cortex. V1 consists of cytochrome-oxidase (blobs) which distinguishes itself from less rich cytochrome-oxidase areas (interblobs). These blobs provide colour perception and the interblobs provide shape and the perception of movement. This heterogeneity in function of V1, that one cortical area can have multiple functions, was not expected. The second area, V2, also has this heterogeneity and does not consist of blobs, but of stripes. The functions of V2 are the same as those of V1, but they are organized differently, namely in stripes and not in blobs. The distribution of the function of colour is seen in the areas V1, V2 and V4, but also outside of these areas. Colour plays an important role in the analysis of the position, depth, movement and structure of objects.
• How does the occipital lobe function?
  • V1 and V2 both have the same functions, namely processing colour, form and movement.
    • Here, all information is collected and transmitted to the more specialised areas.
    • This is done with three parallel paths, which are displayed below
  • Path 1: Information on colour is sent via the blobs from V1 to V4 (the area for colour).
    • V4 not only processes color, but also sometimes form and color
  • Path 2: Movement information goes from V1 to V2 and from there to V5 (specialised in movement).
  • Path 3: Information on dynamic form (the form of moving objects) goes from V1 to V2 and then to V3 (specialised in dynamic form).
• Vision was first created in order to be able to execute movements, not to recognize objects. There are two types of visual streams:
  • Dorsal stream
    • This goes from V1 to the parietal lobe.
    • This stream is responsible for guiding or controlling movements.
  • Ventral stream
    • This goes from V1 to the temporal lobe.
    • This system is responsible for recognizing objects.
• Visual information is not only processed in the occipital lobe. Vision is also processed outside the occipital lobe in various specific forms. Five forms can be distinguished:
  • Vision for action
    • Visual processing is used to control specific movements.
      • Like when picking up objects or catching moving objects
    • This requires the eyes, movements of the head and movements of the whole body.
    • To catch a ball, for example, information must be observed and processed regarding the location, speed, direction and shape of the object
    • Vision for action is a function of parietal visual areas in the dorsal flow
  • Action for vision
    • These are the eye movements and brain processing we do (viewing behaviour) in order to locate target objects and to selectively pay attention to what is important to these objects.
      • This is not an arbitrary process and we look at the characteristics of an object with all kinds of different eye movements.
      • In people with agnosia, eye movements are completely random when focusing on the same objects as people without agnosia.
  • Visual recognition
    • We are able to recognize objects  
      • There are a number of specialised regions for this purpose
      • They are located in the temporal lobe
  • Visual space
    • We are able to focus on objects that are located in specific locations in the space.
    • Object location is possible in two different ways:
      • Relative to the individual (egocentric space)
        • This is necessary in order to carry out our own actions (in relation to objects).
      • Relative to each other (allocative space)
        • This is necessary to get an idea of the spatial location (i.e. how do objects stand with respect to each other)?
    • This takes place in the parietal and temporal visual areas
  • Visual attention
    • It is important that we can selectively focus on information because we cannot process all available information at the same time.
      • We can do this because neurons have different mechanisms for attention
        • For example, they can react selectively to certain places, at certain times or with certain movements.
• In case of visual agnosia, the most damaged area is the tissue in the occipitotemporal edge, which is in the ventral stream. There are all kinds of different forms of agnosia:
  • Object agnosias
    • Apperceptive agnosia
      • This is caused by major bilateral damage to the occipital lobes.
        • Occurs frequently after carbon monoxide poisoning
      • It is not possible for patients to recognize objects 
        • Visual functions such as colour, movement and sharpness are intact.
      • Objects cannot be traced, recognized or simple shapes linked together.
      • Often patients also have simultagnosia.
        • Patients can see the shape of an object, but can no longer see more than one object at a time.
          • So if two objects are presented at the same time, only one object can be seen at a time.
            • These patients experience the world as if they were blind.
    • Associative agnosia
      • This is probably caused by damage to the structures of the ventral stream, which are high up in the hierarchy.
      • In this case, someone cannot recognize an object even though they do have a clear perception of the object
        • So someone can draw an object, but they can't identify it.
      • It is likely that the memory for objects has been damaged.
  • Prosopagnosia
    • Caused by bilateral damage to the area under the calcarine fissure at the temporal crossing
    • Patients can no longer recognize the faces of others, and not even their own faces
      • They can recognize others by facial information such as a mole, moustache or very characteristic hairstyle
    • These patients cannot accept that they cannot see themselves in the mirror.
      • This is probably because they know they should see themselves and therefore still see themselves.
    • They can recognise facial expressions and see the difference between human and animal faces.
  • Alexia
    • This occurs after damage to the left fusiform- and language areas.
    • In case of this disorder, people can no longer read
    • One can still see the letters individually, but is no longer able to combine them into words.
    • It is a kind of object agnosia in which it is no longer possible to make a combination of objects.
      • Word memory is either damaged or inaccessible.
  • Visuospatial agnosia
    • Caused by damage to the right medial occipitotemporal area
    • This means that there is no longer any spatial perception or orientation.
      • It is a form of topographical disorientation and people are no longer able to find their way.
      • t is also no longer possible to recognize landmarks in the environment.
    • Often there are also problems in facial recognition

What is the function of the parietal lobe? - BulletPoints 15

• More than 100 inputs and outputs have been described within the parietal lobe, but there are some basic principles:
  • The lobus parietalis superior (area 5 and part of area 7; called PE) is somatosensory
    • It receives information from the primary somatosensory cortex (areas 3, 1 and 2)
    • It sends information to the primary motor cortex (area 4), but also to the additional motor and premotor areas (6 and 8).
    • Area PE plays a role in guiding movements
      • It does this by providing information about the position of a limb
  • Part of posterior parietalis (part of area 7; called PF)
    • It receives information from field 3, 1 and 2 via field PE, from the motor and premotor cortex and some small visual information from field PG
    • It sends information such as field PE and this concerns motor information
  • Area PG (part of area 7 and visual areas)
    • It receives all kinds of information such as
      • Visual information
      • Somesthetic information (sensations of the skin)
      • Proprioceptive information (internal stimuli)
      • Auditory Information
      • Vestibular information (balance)
      • Oculomotor information (eye movements)
      • Cingulate information (this may possibly be about motivation)
    • It plays a role in the control of behaviour in space in relation to visual information and touch.
  • There is a connection between the posterior parietalis and the prefrontal cortex
    • This connection probably has an important role in the control of behaviour in space.
• Two areas of the parietal lobe can be functionally distinguished from each other:
  • Anterior parietal area
    Posterior parietal area
    • It handles the processing of somatic stimuli and observations
    • This is also called the somatosensory cortex
    • It mainly integrates the sensory input of the somatic and visual areas as well as the sensory information of other areas.
      • It uses this information primarily for the purpose of controlling movements.
        • For example, to reach and grab objects, but is also used to make full body movements in space.
• Spatial information is used to estimate the distance between objects. According to Milner, we need this in order to be able to focus our attention on objects, to be able to attach a meaning to them and to be able to estimate their importance. Information must be selected and in the case of a visual-motor inspection, for example, an estimate of orientation, movement and location is continuously made. This assessment is made by allowing the body and eyes to be constantly in motion. In such a situation, the focus is on the acting person and the location of an object in relation to the person is determined. In this way, the brain also ensures that there is no overload of information.
• Evidence of the possible involvement of the parietal lobe in mathematical and language skills is that patients with injuries to the parietal lobe are not able to solve mathematical sums, which is called acalculia. Language has many of the same principles as mathematics. After all, a series of letters forms a word and a series of words form a sentence. But words are also actually just spatially different sequences of letters. Think, for example, of the words 'pat' and 'tap'. These contain the same letters, but in a different spatial order. Sentences are also the same words, but in different spatial orders. Patients with parietal lobe injury have difficulties understanding a sentence when its syntax is important. These patients also often have difficulties exhibiting subsequent movements. A polymodal field of posterior parietal cortex is likely to be responsible for these skills.
• Injury at the postcentral gyrus leads to disruption of the somatosensory systems:
  • Astereognosis
    • It is not possible to recognize an object on the basis of touch.
  • Simultaneous extinction
    • In a series of sensory stimuli, it is difficult for a patient to keep an eye on an aspect of one particular stimulus
    • Is usually associated with injury to the somatic secondary cortex PE and PF of the right-parietal lobe
  • Tactile blindsight
    • Blindsight is the fact that people with visual impairment can identify the location of visual stimuli even though they indicate that they cannot see it.
    • With tactile blindsight, people can feel touch despite the fact that they no longer have any feeling
      • If they are touched in a place without feeling (due to paralysis) they can still point out where they were touched despite indicating that they did not feel it
      • This indicates that there are two systems for touch:
        • An observation System
        • A system for localization
    • Asomatognosia
      • One has loss of knowledge or loss of feeling of ones own body or physical condition
      • This disorder affects either one or both parts of the body, but usually the left part
      • There are several forms of asomatognosia:
        • Anosognosia
          • Patient is unaware or in denial of illness
        • Anosodiaphoria
          • The patient is indifferent to illness
        • Autopagnosia
          • The patient has an inability to locate and name his own parts of the body.
          • This is an exception and is usually caused by damage to the left-parietal cortex and not the right hemisphere as the other forms of asomatognosia
          • Most common form is finger agnosia
            • The patient is not able to point at the different fingers of both hands and cannot show his own fingers to others.
        • Asymbolia of pain
          • The patient has an absence of typical reactions to pain (such as reflexes)
• There are some disorders and symptoms that one sees at the time there is damage to the right posterior parietal lobe which will follow below:
  • Balint's syndrome
    • Despite the fact that someone has a normal visual field of vision, there are three separate symptoms:
      • Patient can move the eyes, but not fix on a certain visual stimulus
      • Patient has simultagnosia (unable to see several objects at the same time)
      • Patient has optical ataxia
        • In this case, someone is able to recognise objects, but is not able to manipulate them (e.g. grasping, turning around, etc.).
  • Contralateral neglect
    • Is caused by problems in the right-parietal lobe
    • People ignore the part of the body and the part of the world that is on the other side of the damage to the brain.
      • For example, one can only draw the left side of a clock or put on clothes only on the left side of their body etc.
      • Patients cannot form figures with blocks (constructive apraxia) and cannot draw freely by hand.
      • Patients have hardly any topographical capabilities
    • Neglect often goes hand in hand with a denial of the limitations
    • There are two stages of recovery in neglect:
      • Allesthesia
        • Patients will react to stimuli on the ignored side if the stimuli occur on the not affected side.
        • When there is neglect for the left people react to stimuli from the left as if they come from the right side.
      • Simultaneous extinction
        • The patient will focus on the ignored side, except when stimuli are presented simultaneously on both sides, then the patient will respond to the stimuli on the non damaged side
    • There are two causes of neglect:
      • Observation impaired
        • This is because the parietal lobe processes stimuli from the visual areas into observations (morphosynthesis) and in case of injury this is no longer the case (amorphosynthesis).
      • Impairments in ability for attention or orientation
        • Patients ignore stimuli because the system which normally causes people to be alerted to stimuli no longer works

Chapter 15 - 

• The temporal lobes contain many internal connections. They receive information from the sensory systems and send information to the parietal and frontal areas, the limbic system and the basal ganglia. The neocortex of the temporal lobes is connected by the corpus callosum and the medial temporal cortex and amygdala are connected by the anterior commissure.
  • There are five connections from cortex to cortex:
  • The hierarchical-sensory path
    • This allows the recognition of stimuli
      • It arises in the primary and secondary auditory and visual areas and ends in the temporal temporal temporal 'pole'.
  • The dorsal auditory path
    • Provides control of movements following auditory stimuli
      • Goes from the auditory areas to the posterior parietal lobe
  • Polymodal path
    • This causes the categorization of stimuli
      • Goes from the visual and auditory areas to the regions of the superior temporal sulci
  • A medial temporal projection
    • This is important for long-term memory
    • Goes from the auditory and visual areas to the limbic areas
      • Ending in the hippocampus and/or amygdala area
  • A frontal lobe projection
    • This is necessary for parts of motion control, short-term memory and affect control.
    • Goes from the association territories to the frontal lobe
• Object recognition goes through the ventral visual path in the temporal lobe, also called the 'what' path. An important part of object recognition is the categorization of objects, which happens in the superior temporal sulcus. When categorizing, one uses perception and memory. One must be able to draw attention to a selection of the properties of an object. Thus, when seeing two yellow birds, one should be able to draw attention away from color and focus on size, shapes etc. When there is damage of the temporal cortex, categorization of stimuli becomes more difficult. Sometimes it is necessary to link information from auditory systems and visual systems to each other to recognize stimuli, which is called cross-modal linking. Finally, one must involve memory in order to be able to recognise stimuli and objects. These memory processes run through the ventral visual stream and the paralimbic cortex of the medial temporal area.
• Face recognition is a complex process and we can recognise faces despite all facial expressions, accessories and facial hair. The importance of facial recognition may even run through a special path. There are several reasons why this is thought to be the case:
  • There appear to be cells that fire at different faces
    • Some of these cells specialize in identity of the face and others for expression
  • Reversing a photo makes it more difficult to recognize what it says, but this is not proportional when recognizing faces
• There are several disorders of the temporal lobe:
  • Disorders of auditory- and speech perception
    • Damage to the primary visual or somatic cortex makes it difficult to consciously perceive stimuli.
      • When the injury is bilateral, there is cortical deafness
        • However, auditory hallucinations may also occur in the case of damage caused by spontaneous activity in the auditory areas
          • Auditory hallucinations mean that you hear sounds that do not exist
  • Disturbances in the perception of music
    • When the primary auditory cortex is damaged because of lesions to the right temporal lobe, different tones can't be observed.
    • Distinguishing rhythm is most affected by lesions of the right posterior temporal gyrus and distinguishing musical styles is most affected by lesions of the anteurior side of either temporal lobes
    • About 4% of the population is congenitally amusical, which means that they are tone deaf
  • Disturbances in visual perception
    • Lesions in the right temporal lobe can lead to problems in interpreting strange aspects of drawings
      • They also have trouble copying a drawing exactly
      • They also have difficulty with facial recognition and memory of faces
      • Furthermore, they have difficulty interpreting subtle social signals
        • Like when someone takes a look at his watch to indicate that he should go and end the conversation
  • Disturbances in the selection of visual and auditory output
    • Because of the large range of stimuli we are able to unconsciously make a selection of what is important
      • For auditory input this can best be understood by listening to two conversations in which the auditory system uses two options:
        • One conversation is ignored and the other is listened to 
        • The system continuously moves attention from one conversation to another
      • The above also happens in the visual system
    • After temporal damage, problems arise in selective attention
      • This can be tested by presenting dichotomous sounds (see previous chapters)
    • The right temporal lobe is more involved than the left temporal lobe in the selection of visual information
  • Problems with categorizing sensory input
    • Patients with temporal lobe damage have difficulty categorizing
      • This makes it very difficult to remember words because one can no longer remember them in categories, but must remember everything as separate concepts.
        • This occurs mainly in lesions to the left temporal lobe
  • Problems with the use of contextual information
    • It is no longer possible to put words in a certain context 
  • Memory problems
    • Bilateral removal of the medial temporal lobes, hippocampus and amygdala, results in anterograde amnesia
      • This is the loss of memory of all events before the deletion
    • Lesions of the inferior temporal cortex leads to the impossibility of consciously retrieving information that is remembered
      • Lesions of the left temporal lobe lead to problems in retrieving verbal material such as short stories and word lists,regardless of whether they are presented visually or auditory
      • Lesions to the right temporal lobe lead to difficulty in retrieving nonverbal material such as geometric drawings and faces
  • Changes in affect and personality
    • Damage to the temporal lobe can lead to problems in emotion regulation and changes in personality
    • The anterior and medial temporal cortex play a role in anxiety
    • There also is a 'temporal lobe personality'.
      • There are the following symptoms
        • Egoistic behaviour
        • Constant talking about personal problems ('sticky' behaviour)
        • Paranoia
        • Exaggerated care about religion
        • Sensitivity and aggressive outbursts
      • Usually not all of these symptoms are present in someone
  • Changes in sexual behaviour
    • Occurs in case of bilateral temporal damage with lesions to the amygdala
      • Leads to excessive sexual behaviour

How do the frontal lobes function? - BulletPoints 16

• De frontal lobes make up 35% percent of the neocortex and consists of four different categories:
  • The motor area (M1)
    • Is also called area 4
    • Is responsible for the most basic movements such as those of the mouth and limbs
    • Also has connection with subcortical motor structures such as the basal ganglia, red nucleus and spinal cord
  • The premotoric area (PM)
    • Also called area 6, 8 and 44 in the human brain and lies directly in front of M1
    • Area 6 of PM consists of
      • Premotor cortex
      • Supplementary motor cortex
    • Area 8 of PM consists of 
      • The frontal visual field
      • Supplementary visual field
    • Area 44 is Broca's area
    • PM kan influence movement in two ways:
      • Direct
        • Through corticospinal connections
      • Indirect
        • Through it's connection with M1
    • Next to that are there connection with the posterior parietal areas
      • They take care of the execution of limb movements
  • The prefrontal area (PFC)
    • Consists of three areas:
      • Dorsolateral prefontal cortex
        • areas 9 en 46
        • Has strong relations with the posterior parietal cortex
        • There are also connections with the superior temporal sulcus, cingulate cortex, basal ganglia and superior colliculus
      • Orbitofrontal cortex
        • Area 47 and parts of area 11, 12 and 13
        • Receives input from the temporal lobes
          • But also input from the auditory and visual areas, superior temporal suclus, amygdala and hypothalamus
          • Has an important role in regulating the autonomic system
            • It controls changes in blood pressure and sweating for example
      • Ventromedial prefrontal cortex
        • Areas 10, 14 and 25 and parts of 11, 12, 13 and 32
        • Receives information from the dorsolateral prefrontal cortex, posterior cingulate cortex and medial temporal cortex
        • Plays a role in regulating emotional behaviour
  • Anterior cingulate cortex
    • Is a specialized part of the cortex
    • Consists of area 24 and part of 32
    • Has extended bilateral connections to M1, PM and PFC
• There is a difference in the asymmetry between the frontal lobes:
  • Left frontal lobe
    • Mainly involved in language-related movements such as speech
    • Has a greater role in imprinting information into memory
  • Right frontal lobe
    • Has a greater role in non-verbal movements as facial expressions
    • Has a greater role in deepening information
• The motor problems after frontal lobe lesions can be divided into different forms:
  • Loss of fine motor skills, speed and power
    • Occurs in case of damage to M1
      • Leads to loss of skill in performing fine motor actions and individual finger movements
      • Leads further to loss of speed and strength in both hands and limbs on the contralateral side
  • Programming of movement
    • The two premotor cortexes both affect the programming of movements
      • This makes it possible that lesions to the supplementary motor areas lead to very rapid recovery in terms of programming of movements
    • The only permanent obstacles that one still has are very rapidly changing movements of the hands or fingers and there is still difficulty with memories and imitating movements of the face, such as facial expressions
  • Voluntary staring
    • Lesions to the frontal lobe can lead to problems with pointing the gaze
      • It is then difficult to focus on relevant stimuli and people find it difficult to ignore irrelevant stimuli.
  • Problems in corollary discharge
    • The world stops at the moment you move your eyes, but when you press against your eyeball it seems as if the world is moving
      • This is because with eye movements a neural signal is sent indicating that the movement of the eyes is going to happen, which is called corollary discharge
    • Teuber indicated that a command from the brain to start moving and corollary discharge together ensure that the world around us remains still when we move ourselves
    • Lesions of the frontal lobe can lead to problems in the corollary discharge signal, causing movement problems
  • Problems in speech
    • The frontal lobe contains two speech areas:
      • Broca's area
        • Damage here leads to an inability to conjugate verbs and use grammar
    • The additional speech area
      • Lesions here combined with Broca's area leads to a complete loss of speech
        • After unilateral damage, speech usually returns after a number of weeks, but bilateral damage does not result in a return
• Patients with lesions of the frontal lobes more or less retain the IQ they had before the injury, yet they appear to be doing 'stupid' things. This has to do with the fact that IQ tests measure convergent thinking where there is only one correct answer per question. Divergent thinking is different as there are multiple possible answers to a question. An example of this is the creation of a list of applications for a coat hanger. Frontal lobe lesions probably lead to difficulties in divergent and not convergent thinking.
• Previously it was assumed that the intelligence was attached to the frontal lobes, but this does not seem to be the case. Damage to the frontal lobes where the intelligence did not seem to be affected is the reason for this theory. Spearman (1927) thought that intelligence was related to a general factor (g) which included all cognitive activity. Damage to the frontal or parietal lobes is associated with a loss of fluid intelligence. He thought there were two types of intelligence:
  • Fluid intelligence
    • The skill to see abstract relationships and make logical conclusions
  • Crystallized intelligence
    • The ability to remember and use knowledge one has learned or experienced prior
      • This looks like the Wechsler IQ-score

How do cortical networks function and what are disconnection syndromes? - BulletPoints 17

• There are three types of major connections between the parts of the neocortex:
  • Association paths
    • These can be divided into two forms:
      • Long fibre paths connecting far apart neocortical areas
      • Short, subcortical U-connections connecting near areas
  • Projection paths
    • These are ascending nerve fibers from lower brain centers to the neocortex
      • Such as projections from the thalamus
    • They can also be descending fibres from the neocortex to the brainstem or spinal cord.
  • Commissural paths
    • These are the paths that connect the two hemispheres
      • This includes the corpus callosum:
        • The corpus callosum
        • The anterior committee
        • The hippocampal commissions
• The anterior part of the corpus callosum (called genu) contains fibres originating from the prefrontal cortex. Projecting fibres run through the corpus callosum and through the premotor, motor, somatosensory and posterior parietal cortexes. Fibres from the posterior portion of the corpus callosum (called splenium) project from the superior temporal, inferior temporal and visual cortexes. The anterior commissure is much smaller than the corpus callosum and provides the connections between the anterior temporal lobe, the amygdala and the paralymbalmbal cortex. In people born without corpus callosum, the anterior commissure is much larger to connect a larger area of the neocortex.
• There are three reasons why hemispheres can be separated:
  • Commissuretomy
    • Epilepsy often starts in a small area in one hemisphere and spreads via the corpus callosum or the anterior commissure to the other hemisphere
    • In a commissurotomy the hemispheres are separated as a treatment of epilepsy
      • When medication is not working, both the corpus callosum and anterior commissure are cut to prevent the spread of electrical activity
    • After this procedure the following things change:
      • Hemispheres can only receive information and control movements from one side of the body
      • Speech areas are isolated
      • Hemispheres have their own sensations, perceptions, thoughts and memories which are not accessible by the other hemisphere
      • The performance of the hemispheres remains at a high level
  • Collosal agenesis and early resections
    • Callosal agenesis is the congenital absence of the corpus callosum
    • The other commissures are present and enlarged so that there are still interhemispheric connections.
      • Transport of complex information is more difficult, such as information processing and motor skills.
    • When the corpus callosum is cut at a young age this has less consequences because new connections can be formed or the existing connections become more sensitive.
    • Lateralisation also occurs, even if one hemisphere can no longer suppress another.
  • In animals it is carried out to investigate the absence of a hemispheric compound.
• There are a number of things that happen when disconnection of the sensory motor systems occurs:
  • The olfactory system
    • This system is the only sensory system that is not crossed.
      • Input from the left nostril goes to the left hemisphere and from the right nostril to the right hemisphere
    • When disconnecting the anterior commissure, the odor entering the right nostril can no longer be named because the information can no longer reach the right hemisphere
      • You can still pick up the object with the left hand what you smell with the right nostril
        • In this situation, one cannot do this with the right hand, which is then anosmic (lack of sense of smell) for smells that enter the right nostril
  • The visual system
    • This system is completely crossed
    • Disconnection of the corpus callosum causes the following problems:
      • The visual information of the left field of vision (which enters the right hemisphere) can no longer be brought into contact with the verbal associations
        • Verbal material in the left field of view can no longer be read
        • Objects in the left field of view can no longer be named
      • Complex visual material in the right field of vision is no longer processed properly because the left hemisphere does not have any visual-spatial capabilities
        • Only the left hand can trace another complex figure
    • A separation of the hemispheres thus leads to aphasia, alexia and agnosia when information falls into the field of vision of the hemisphere that this material cannot process
  • Somatosensorial system
    • This system is completely crossed
    • Disconnection of the hemispheres leads to:
      • Left and right somatosensory functions become independent of each other
      • A blindfolded person can:
        • Recognize an object felt with the left hand later by grasping it in the left hand, but not with the right hand
        • Name an object when it is in the right hand, but not when it is in the left hand
        • When one hand is put in a certain position, this position is not imitated with the other hand.
  • The auditory system
    • Is partially crossed and partially not crossed
    • The left hemisphere receives most of the input from the right ear, but also part of the left ear
      • Dichotone listening tasks show that disconnection suppresses all input in the left ear, which is strange given the bilateral processing of sound.
  • The motor system
    • This system is for the most part crossed
    • After disconnection the following problems occur:
      • The left hand can no longer react to verbal material and the right hand cannot recreate geometric shapes.
        • These defects decrease in severity over time, probably because the left hemisphere will use ipsilateral control.
      • Movements requiring both arms are more difficult
        • The degree of difficulty depends on heir:
          • Age
          • The amount of extracallosal damage
          • Time elapsed since separation

How does one learn and how does memory work? - BulletPoints 18

• There are several forms of amnesia:
  • Child amnesia or infantile amnesia
    • This is the inability of people to remember things of their baby-/childhood
    • This is probably because memory systems develop at different times and speeds
      • The memory system for episodic memory may therefore not be sufficiently developed in childhood
    • Another reason may be that the brain actively removes these memories to make room for new ones
  • Fugue state (dissociative fugue)
    • Fugue state can be translated as flight
    • People are found far from home with no memories of their present life
      • Their skills and language knowledge are still intact
    • They have 'fled' from their present life to build a new life, as it were.
    • This can occur because memory systems of the medial temporal lobe are temporarily suppressed
      • It is transient and therefore reversible
  • Anterograde amnesia
    • Here one is no longer able to form new memories
    • A form is global anterograde amnesia
      • When memory problems and anterograde amnesia are very serious
      • No more new words can be remembered
      • Spatial learning is limited
  • Retrograde amnesia
    • Here one is no longer able to recall memories
      • Memories long before trauma are often better to remember than more recent ones
    • A form of this is time-dependent retrograde amnesia
      • Frequent in traumatic brain injury
      • It depends on how long one has been unconscious and the severity of the injury
      • Usually gets less as more time passes after the trauma
  • Old timers disease
    • This is a form of amnesia in the elderly where one often can't come to certain names or don't know where they left something
      • Often starts by forgetting names of people you know well
• There are three theories about the independence of anterograde and retrograde amnesia:
  • System consolidation theory
    • This theory indicates that the hippocampus consolidates (strengthens) new memories, making it permanent
    • After this process, they are stored somewhere else in the brain
      • They are consolidated somewhere in the neocortex
  • Multiple track theory
    • This theory gives three reasons for differences in amnesia:
      • When one learns to be at different locations in the brain parallel to each other memories formed
        • Thus autobiographical memory depends on the hippocampus and frontal lobes
        • Actual semantic memory depends on temporal lobe structures
        • General semantic memory depends on the remaining cortical areas
      • Memories change in someones life when they are retrieved, re-evaluated and saved again
        • Even the processes of storage change: for example autobiographical memory can be stored as actual semantic memory
        • In this way memories are transformed
      • Different forms of memory are stored in different locations and are susceptible to brain damage in different ways
  • Reconsolidation Theory
    • It states that memories are almost never on one track
      • Every time we use a memory, it is consolidated.
        • This means that the memory enters a kind of unstable phase and is then stored again as a new memory.
        • As a result, different traces of an event are constantly emerging
          • This allows a memory to make changes every time it is retrieved
• The long-term memory consists of three types:
  • The implicit memory
    • Related to automatic, unconscious behavior
      • Such as cycling and talking
    • Is data-driven processed which is also called bottom-up
      • This means that it depends only on sensory or motor information and is not dependent on manipulation of the higher-order cortical systems
  • The explicit memory
    • This memory contains conscious, spontaneous memories
    • It is processed top-down
      • This means that someone reorganizes the data and stores it afterwards
        • For this type of information, the retrieval of information depends heavily on the way in which it was initially processed
    • Can be subdivided into:
      • Semantic memory
        • Contains all knowledge about the world and facts
          • Such as recognizing people, all the information they learned at school, knowledge about historical facts etc.
      • Episodic (autobiographical) memory
        • This part of the memory contains all the memories that one has of single events
    • Emotional memory
      • This part of memory contains the affective characteristics of stimuli or events
      • It is mainly processed bottom-up, but also top-down
      • Emotional memories can be stored both consciously and unconsciously

How is language processed? - BulletPoints 19

• One must have four skills to be able to produce language:
  • Categorization
    • The brain must link the incoming sensory input to external objects
    • Information about the characteristics of, for example, an animal or plant should be linked to the appropriate category in which these objects fall
    • This categorization is also important when remembering input
  • Labelling of categories
    • By labelling categories we are able to place concepts or words in boxes which makes it easier to keep an overview
  • Execution of sequential behaviour
    • In order to be able to pronounce syllables at all, it is important that certain lip and mouth movements can be made in sequence in the right order
  • Imitation
    • Imitating the speech of others is important in learning language
    • This is seen in children trying to repeat other people
• There is also a neurological model based entirely on the localization of lesions. This model is called the Wernick-Geschwind model, developed by Geschwind (1960) and contains three parts:
  • Area of Wernicke
    • This area is responsible for the understanding of words and phrases
      • Sound of words go through auditory pathways to the primary auditory cortex
      • After this it goes to the gyrus of Heschl and eventually ends up in the area of Wernicke
  • From here it is transported via the arcuate fasciculus path to the area of Broca
  • Area of Broca
    • This area is responsible for articulating words
      • From here instructions are sent to the motor cortex
        • This sets the motor neurons of the brainstem to work and eventually the facial muscles are set in motion to form words
• Language is a very complex process in which sensory integration, symbolic association, motor skills, patterns of sentences and a verbal memory have to work together. When somewhere in the whole language process there is aphasia, it is called aphasia. Aphasia can occur in speech, in writing (agraphia) or in reading (alexia). All other disorders that are often accompanied by aphasia, such as loss of vision or hearing, paralysis of the facial muscles or paralysis of the hand are not forms of aphasia. Aphasia can be divided into three types:
  • Fluid aphasia
    • There is fluid speech here, but there are problems in either verbal understanding or in the repetition of being, sentences or expressions spoken by others
    • Forms of flowing aphasia are:
      • Wernicke's aphasia
        • In this case one is not able to understand words or produce sounds that mean something cohesive
          • Word production, however, is still intact
        • Luria (1977) indicated that there are three key characteristics in Wernicke's aphasia:
          • One must be able to recognize phonemes to distinguish different sounds in language. This is no longer possible with Wernicke's aphasia
          • One can talk, but makes mistakes in the phonetic characteristics and mixes them up creating a word salad
            • People are going to say all kinds of words that do not fit together so that an incoherent mess is formed
          • One has writing problems because one can not combine the graphemes into words
            • This is because a grapheme is a written representation of a phoneme and one confuses the characteristics of phonemes and makes mistakes in them
      • Transcortical aphasia (isolation syndrome)
        • It is possible to repeat and understand words, but one cannot speak spontaneously or understand words. Or they cannot understand words, but they can repeat them
        • Understanding language is bad because words do not evoke associations
        • In addition, production of meaningful speech is poor
          • This is because words are not associated with other cognitive activities in the brain
      • Conduction aphasia
        • People can talk well, understand speech and name objects, but they can't repeat words
        • The explanation is probably a bad connection between the perceptual word image and the motor systems that produce the words
      • Anomalous aphasia (amnestic aphasia)
        • People can understand speech, form meaningful speech and repeat speech but have difficulty finding names of objects
          • This not being able to find nouns has to do with a damage to the temporal cortex while problems in finding verbs has to do with damage to the left frontal lobe
  • Non-fluent aphasia
    • This form of aphasia is also called Broca's aphasia or expressive aphasia
    • There is difficulty with articulation and there is relatively good verbal understanding
      • Only the keywords needed for communication are used
      • The disorder stems from not being able to switch from one sound to another sound to make different words
  • Pure aphasia
    • There are selective damages in the reading, writing or recognition of words without other language disorders that can explain these damages.
      • It can be so selective that for example one has alexia, but not agraphia

How do emotions and the social brain function? - BulletPoints 20

• Experiencing emotions has four behavioural components:
  • Psychophysiological
    • There is activity in the central and autonomic nervous system
    • Emotions, for example, affect:
      • Heart rate
      • Sweating
      • Food digestion
    • Emotions can also lead to the secretion of hormones
  • Motor behaviour
    • There are changes in motor behavior that occur when experiencing emotions, such as:
      • Facial expressions
      • Voting tone
      • Body posture
  • Self reported cognitions
    • The thoughts that someone has are interpreted from someones own self-reporting
  • Unconscious behaviour
    • Cognitions of which we are not aware can influence our behaviour
      • For example, we make decisions based on intuition
      • Emotions can also occur unconsciously
• By means of experiments the perception of emotions was mapped. In an experiment in which expressions were presented to either the left field of vision or the right field of vision only, it appeared that expressions are best interpreted by the left field of vision, or by the right hemisphere. Another experiment was performed using contact lenses that can offer movies to either the left or right hemisphere only. Subjects had to indicate whether a film was funny, fun, unpleasant or horrible. Films offered to the right hemisphere were more often labelled as unpleasant or horrible. Furthermore, the autonomous nervous system became more active when the same film was offered to the right hemisphere. This outcome gave rise to the idea that both hemispheres have a different emotional image of the world.
• Mood is mainly derived by others from facial expression, voice height and the frequency in which someone talks. Damage to the brain often leads to changes in the brain:
  • Lack of affect
    • After left hemisphere injury (mainly left frontal)
    • This can be interpreted as a depression
  • Reduced facial expressions
    • Mainly because of anterior lesions, but also posterior lesions
    • Intensity and frequency of facial expressions is reduced
  • Changes in spontaneous speech
    • After both left and right frontal hemisphere injury
      • Injury at the left front leads to less spontaneous speech
      • Injury at the right front leads to more spontaneous speech
  • Changes in spoken language
    • Prosody (rhythm, emphasis and intonation)
      • Right hemisphere injury can lead to aprosody
        • They speak language without emotion or pitch
      • Injury to the right area of Broca leads to motor aprosody
        • People can no longer produce the emotional components of language
      • Injury to the right area of Wernicke leads to sensory aprosody
        • People can no longer interpret the emotional components of language
    • Content
      • Is mainly a task of the left hemisphere
  • Interpretation of behaviour
    • Damage to the left hemisphere leads to difficulty in interpreting behaviour in social situations

What is spatial behaviour? - BulletPoints 21

• There are some forms of disorientation, which are disturbances in spatial behaviour:
  • Topographical disorientation
    • Here there is an inability to find your way, even in familiar environments
    • There are two forms:
      • Topographical agnosia
        • The inability to identify landmarks in the space
      • Topographical amnesia
        • The inability to establish topographical relationships between landmarks
          • Not being able to estimate the distance between certain landmarks or not being able to map out a route on a map
    • The inability to navigate has two forms:
      • Retrograde spatial amnesia
        • It is not possible to navigate in familiar environments in which one could navigate before
      • Anterograde spatial amnesia
        • It is possible to navigate in known environments, but not in unknown environments
  • Egocentric disorientation
    • This involves difficulty in seeing oneself relative to the location of other objects
    • Created by uni- or bilateral injury in the posterior parietal cortex
    • Is accompanied by some symptoms:
      • It is no longer possible to accurately reach for objects in the central or peripheral field of view
      • Left and right are confused
      • You can no longer find your way around in known and unknown environments and can get lost in your own home
  • Heading disorientation
    • One is no longer able to plan a route and has no sense of direction anymore
      • Even though they are able to recognize landmarks, determine their own location relative to landmarks and can explain where they want to go
    • There is damage to the posterior cingulate cortex.
  • Landmark agnosia
    • The inability to use prominent features of the environment to determine routes
      • They are able to recognize landmarks but can no longer use them in determining their movements and routes
    • Created by either bilateral lesions or lesions to the court medial part of the occipital lobe
  • Anterograde disorientation
    • No problems navigating in previously known environments, but problems in unknown environments because one is no longer able to remember and store unknown objects
    • Caused by damage in the parahippocampal gyrus of the inferior ventral cortex in the right hemisphere
      • The hippocampus is important in spatial learning
        • Possibly the whole hippocampus is needed with the more complex spatial memory
        • Furthermore, the hippocampus is also important in being able to find its way back in both the light and the dark
  • Spatial distortion
    • Here one sees oneself distorted in relation to the spatial environment
      • It is seeing yourself too big or too small compared to objects
    • Occurs with damage left medial parietal and damage to the cingulate cortex
• There are several types of cells that are important in spatial behaviour that are active at locations and viewing directions, for example. Interactions between these types of cells lead to spatial behaviour:
  • Place cells
    • These are cells that fire when an animal enters a specific location in its environment
      • It does not matter whether an animal has walked to it or carried to it, the cells are firing regardless
    • They are needed to determine relations between environment signals during navigation and thus to make allocentric spatial behaviour possible
    • They are located in the entorinal cortex, the subiculum and the hippocampus
    • The cells are bound to some things:
      • These cells indicate not only the location, but also the direction and speed of the animals movement
      • When there are big changes in an old environment and it has become a new environment, then the cells fire again
      • These cells are mainly activated by visual stimuli   
        • But they can also be activated by stimuli of the other senses
    • Place cells are only active when the animal has the ability to move
  • Head direction cells
    • These cells fire off a potential when the head of an animal points in a certain direction
      • Different cells fire in different head directions and has its own preferred direction
    • They are needed to estimate the own spatial position in relation to the environment during navigation and thus make self-centered spatial behaviour possible
    • They are located in the lateral mamillary nuclei, anterior thalamus, cingulate cortex and post-subicular regions of the hippocampus
    • The cells are bound to some things:
      • The firing does not depend on the position of the torso and whether the rat moves or not does not affect either
        • Furthermore, they are not dependent on the passage of time
          • As long as the head points in a certain direction, the cells responsible for the respective direction fire
        • In addition, they do not respond to objects or locations
      • However, they do respond to certain environmental signals
        • When an animal enters a new environment, the main direction cells determine which orientation of the head is preferred in that environment
  • Grid cells
    • These divide the environment into a kind of grid
    • They ensure that an animal is able to estimate the size of an environment and determine its location in space
    • These are located in the medial entorinal cortex
    • The cells are bound to some things:
      • They fire off a potential at regular intervals
        • In this way they form a grid of the environment in which the animal is located and it classifies the environment accordingly
          • So it makes a kind of map of the environment
      • They are not dependent on changes in direction of movement, movement or speed
        • But they do depend on environmental signals and the direction an animal is looking at

What are attention and consciousness? - BulletPoints 22

• Humans are only able to process a limited amount of information at the same time. For routine tasks, such as driving on a quiet road, little attention is needed for the task and one can make a phone call at the same time. When it suddenly becomes a lot busier on the road, the phone call should be interrupted from time to time to give more attention to driving. When there is divided attention, attention for several tasks at the same time, the performance on the tasks performed will deteriorate.
• Loss or lack of attention can lead to major problems such as accidents. Sometimes it is clear why the attention was not there, like someone playing with his smartphone while driving, but sometimes there is no clear cause. There are a few examples:
  • Absence of visual attention
    • The executive attention system selectively activates areas in the ventral flow
      • This leads to some of the information remaining stuck in our subconscious which can lead to some problems
    • Inattentional blindness
      • In this case, a person does not see an event when he is performing another task
        • If subjects have been warned in advance that unusual events may occur, then the events will be noticed
    • Change blindness
      • Here, someone does not see any changes in the presence, identity or locations of objects in a space
        • For example, an experiment in which a test subject talks to someone who is exchanged with another person after a short obstruction (e.g. someone walks through a door through the conversation).
          • Approximately 50% of the subjects in a study did not notice that their conversational partner had changed
    • Attentional blink
      • This is the inability to detect a second visual stimuli at the moment it is presented within 500ms of a previous stimuli
        • This does not happen when one is asked to ignore the first stimuli
  • Sensory neglect
    • In this case, someone does not respond to sensory stimulation
      • A lesion to the parietal temporal cortex, for example, causes neglect of the left part of the environment.
    • As described earlier, in case of damage to the right parietal lobe, there is no backup system for the left side of the environment, which causes neglect
    • One can cure this neglect by placing prisms on the eyes of people and animals
      • When used, the sensory neglect largely disappeared
    • The frontal lobe influences attention, but also influences the control of movements
      • Damage to the frontal lobes led to neglect of the peripersonal space
• Consciousness may be one of our most familiar mental processes, but the how and why it works remains mysterious. Everyone has a vague idea of what consciousness is, but consciousness can easily be identified and defined. The book defines it as 'the level of responsiveness of the mind based on impressions it receives from our senses'. Our consciousness provides an adaptive benefit. How we experience the sensory world around us and our entire selection of behavior has been enlarged and expanded thanks to our consciousness. But not all our behavior is conscious. For example, the dorsal current is, in contrast to the ventral current, unconscious. This current reacts much faster and this can be seen for example in baseball batsmen who see a ball coming at 160 km/h and have to hit it. This goes so fast that they have to do this unconsciously because their consciousness would need too much time. But of course there is also behavior needed where consciousness plays an important role. An example is picking up a cup or something like that.

How does the brain develop an what is plasticity? - BulletPoints 23

• From the moment of fertilization of the egg by a sperm cell, development begins:
  • From the moment of fertilisation, the embryo consists of a single cell
    • This cell begins to divide
  • After 14 days the embryo consists of several layers of cells
    • It developed here the primitive body
  • After about 3 weeks the embryo contains the primitive brain which is actually a layer of cells at one end of the embryo
    • This primitive brain rolls up into a neural tube
  • After 7 weeks the embryo already looks like a miniature of a human being
  • After 100 days, the brain resembles that of a human being
  • From 7 months the gyri and sulci develop in the brain
  • At the end of the ninth month, the brain looks like that of an adult human being
    • However, the cellular structure is still different
• Up to about 4.5 months before birth, neuroblasts are produced that eventually form the cerebral cortex. The cell migration (movement to the right place) of these cells can even last up to 8 months after birth. During the last 4.5 months before birth, the brain is also extra vulnerable to damage, mainly due to asphyxia (lack of oxygen). The brain is apparently more vulnerable during the migration period than during the generation of the cells. One reason for this is that once neurogenesis (cell production) has stopped, the damaged cells can no longer be replaced. Differentiation of the cells starts after neurogenesis. During this differentiation neuroblasts are formed into specific types of neurons. The differentiation is complete just before birth, but the further maturation of the cells and the growth of axons, dendrites and synapses continues after birth.
• Our cerebral cortex contains 10 to the power 14 different synapses. To create all these synapses, there are five different phases for synapse formation:
  • Phase 1 and 2
    • Take place early in the embryotic life
    • There is a low density of the number of synapses
    • The synapses that are formed during phase 1 and 2 are different in origin
  • Phase 3
    • During this phase the number of synapses grows very rapidly
      • The speed can reach the development of 40,000 synapses per second
    • This phase starts just before birth and runs until about the age of 2 years
  • Phase 4
    • This phase begins with the plateau of the number of synapses that a human will ever have
      • After reaching the plateau, the number of synapses drops very fast
        • This decrease can go so far until about 50% of of synapses of the plateau is left
        • Up to 100,000 synapses per second can be lost in an adolescent brain
    • This phase runs until the end of puberty
  • Phase 5
    • In this phase there is a constant number of synapses up to about the age of 50
      • After this, the number of synapses steadily decreases
    • When one is quite old and in the last phase of life the number of synapses decreases very quickly once more
• The plasticity shown by the brain in response to damage can be done in three ways:
  • Reorganisation of brain circuits
    • The brain reorganizes the brain circuits that are still intact after damage
      • The brain does this only in those circuits that are in any way involved in the damaged area.
    • The problem with this reorganisation is that a lot of research shows that such a reorganisation is rather rare and that if there is already a reorganisation, it can also lead to deviating functioning
  • Developing new brain circuits
    • Experiences or medication would stimulate the brain to generate new circuits
      • Again, new circuits are only formed at the damaged location and not in the entire brain
  • Developing new neurons and glial cells
    • These should then replace the lost neurons
      • This is called neurogenesis

Which disorders exist in children? - BulletPoints 24

• Learning difficulties are generally described as having performance on (part of) the school components that is far below average due to abnormal brain development. Not all learning problems are caused by developmental disorders. Problems can also arise after, for example, problems in the home situation, finding school boring or having an annoying teacher. One of the central disorders is dyslexia, problems in reading, because reading is such a big part of education. Dyslexia may also be associated with aphasia, a language proficiency problem caused by brain damage. When dyslexia is already present at birth, there is developmental dyslexia, and when dyslexia is caused by brain damage after someone could already read, it is called acquired dyslexia. About 10-15% of the population that goes to school eventually needs special help to deal with these problems. About 2% of all pupils go to special education.
• The following are causes of reading problems:
  • Phonological defects
    • There are problems in consistently disassembling words in the individual parts of which words are composed
    • Here there is an insensitivity to rhythm and alliteration
    • Training in phonological processing of letters can reduce the backlog
  • Deficiency in attention
    • People do not have enough attention to distinguish auditory stimuli and make a selection of letters and sounds
  • Sensory deficiency
    • Children with learning difficulties may have difficulty detecting sensory events that followed each other quickly
      • Tallal let children follow two tones that followed each other quickly and these children heard only one tone
    • They need more time between two tones to distinguish them from each other
      • But in language the sounds follow each other faster than they can perceive
    • Children and adults therefore have difficulty distinguishing stop-consonants (parts of language that contain a transition period in which sound changes very quickly) from each other
      • They have no trouble detecting vowels
      • This probably has to do with the operation of the left hemisphere
      • Improving sound discrimination led to improving language skills
• What is ADHD?
  • In ADHD the child shows behavioural problems at school and in all areas of school there are problems
  • This is characterized by symptoms such as:
    • Impulsiveness
    • Hyperactivity
    • And/or attention deficits
  • Girls are more likely to lack attention and boys are hyperactive and impulsive
  • The DSM-5 provides two characteristic diagnostic criteria:
    • Attention deficit
      • Six or more symptoms present for children up to 16 years of age
      • At least five symptoms present for persons older than 16 years of age
      • Symptoms should be present for six months and inappropriate for the developmental level
      • Symptoms include, but are not limited to:
        • Avoiding tasks
        • Difficulty listening, following instructions, organizing and completing tasks
    • Hyperactivity and impulsivity
      • Six or more symptoms present for children up to 16 years of age
      • At least five symptoms present for persons older than 16 years of age
      • Symptoms should be present for six months and inappropriate for the developmental level
      • Symptoms include:
        • Running around
        • Talking a lot
        • Not being able to wait for their turn
        • Having difficulty playing with peers
        • Not being able to sit still
• The following factors can influence the development of a learning disorder:
  • Exposure to toxic substances
    • By substances of nature
    • But also by alcohol or drug use
  • Hormonal effects according to the Geschwind-Galaburda theory
    • Increases in testosterone would lead to a decrease in left hemisphere development in embryos
      • This allows the right hemisphere to grow better.
        • This could lead to language problems
      • More testosterone could also lead to brain disorders
      • Furthermore, testosterone would affect the development of the immune system
        • This increases the risk of autoimmune disorders
  • Maturation lag
    • Cognitive functions of language and reading develop together, but if one of the two develops a problem, the other will also have more difficulties in development
      • This may be due to delayed myelination or delayed development of cortical connections.
  • Poor parenting environment
    • Such as an orphanage or developing countries
  • Birthday effect
    • Children born after October first have preschool for an extra year
      • Children born before this can attend school earlier
        • Because they go to school younger, they can develop sooner
  • Genetic aptitude

How does recovery of brain injury work? - BulletPoints 25

• The absorption of information brings about a change in the cells of the nervous system. This is because the brain contains a degree of plasticity, a kind of adaptability of the brain to new environmental influences or damage. For example, we are very skilled at adapting to a visual environment that is different. In a study by Köhler, people were given prism glasses, after which the world was shown upside down and left and right were reversed. During the first days with glasses on, test subjects had a lot of trouble moving through space. After a few days they had already adapted and were able to dress themselves, eat and walk around. Eventually the brains were adapted so that they could go skying and cycling. After the glasses were taken off again after the experiment it took a few days before people got used to the old vision. Probably people are able to adapt because of changes in the premotor cortex and posterior parietal cortex. Furthermore, cells in V1, which normally only react to contralateral stimuli, also reacted to stimuli in the ipsilateral field. This disappeared again when the glasses were no longer worn. Because people are so dependent on the ability to adapt and because the brain of people can do this so consistently, it suggests that the connections for change are already present in the brain and do not need to be newly formed. This would mean that adaptation is nothing more than increasing the efficiency of these connections and we could use training to address these connections in case of brain damage.
• Some functional recovery is possible after damage to the nervous system but how this system works is still very unclear. An example of recovery can be seen when a cat has to amputate a leg after an accident. In the beginning the cat can't do much, but after a while it looks like he just has four legs and he has fully adapted. In case of damage to the brain this is different. After a stroke, for example, several areas of the brain can be affected. In the first few minutes of a brain infarction the ion balance, the pH and the properties of the cell membrane of the affected areas change. Calcium channels open and too much potassium flows into the cells, which is toxic to the cell. In the following minutes to hours, too much mRNA is stimulated, which may also be toxic to the neurons. The brain tissue starts to inflame and swells, which also leads to damage. Finally, there is a kind of neural shock, which is called diaschisis. Damaged areas and the areas around them stop exciting or inhibiting, which leads to (temporary) loss of function. It appears that metabolic activity in damaged areas has decreased by 25%.
• Recovery also depends on some variables:
  • Age
    • In general, the following applies: the younger the patient, the more chance of recovery
    • However, age is not always significant in recovery
    • Furthermore, it is difficult to investigate recovery of brain damage on the basis of age because many brain injuries only occur at a later age
  • Hand preference and gender
    • Women and left-handed people are more likely to have bilateral brain activity and therefore more chance of recovery
  • Intelligence
    • Intelligent people have a better chance of recovery than less intelligent people
      • The reason for this is unclear
    • Intelligent people often have more difficulty with recovery because they cannot reach their old level of thinking
  • Optimism and extraversion
    • This seems to be related to better chances of recovery
      • One reason for this seems to be that patients who are optimistic are better at adhering to the recovery programme
    • Brain damage can have a negative influence on recovery because people can become depressed

What are possible neurological disorders? - BulletPoints 26

• Vascular problems can affect the nervous system. When the supply of glucose and oxygen is blocked for longer than 10 minutes, all cells in the affected area die off. Most diseases occur in the arterial regions. There are various forms of vascular problems:
  • Cerebrovascular accident (CVA) or stroke
    • This is the sudden development of neurological symptoms because the blood flow is interrupted
    • In the affected area an infarction occurs
      • This is an area with dead tissue because blood can no longer reach it
    • There are several causes for CVA:
      • Cerebral ischemia (brain infarction)
        • There is a blockage of the blood vessels
        • Is the reason for a CVA in 75% of the cases
        • May also come from atherosclerosis
          • This results in the deposition of fat on the inside of a blood vessel, causing it to slowly clog up.
      • Cerebral bleeding (brain bleeding)
        • This is a spontaneous bleeding in the brain tissue
        • Is usually caused by hypertension (high blood pressure)
          • Other causes include leukaemia, trauma and toxic chemicals
        • The prognosis is bad
          • Especially when a patient is unconscious for more than 48 years
      • Angiomas and aneurysm
        • An angioma is a congenital collection of abnormal blood vessels that scatter the normal blood flow
          • This can lead to strokes
        • An aneurysm is a vascular expansion in which a blood vessel inflates like a balloon
          • It may tear over time, causing bleeding.
• Traumatic Brain Injury (TBI) is caused by car accidents, industrial accidents, sports injuries or other accidents. Both age and gender have an impact. Men, for example, are more likely to be affected and, in general, younger people are more likely to have a TBI. There is also a mild form of TBI known as concussion. There are two forms of TBI:
  • Open head trauma
    • These are all TBIs where there is penetration of the skull or when pieces of bone tissue penetrate the brain
    • In many cases it does not lead to unconsciousness
    • It can in many cases lead to remarkably fast and good recovery
    • Symptoms often resemble those that would be seen if the affected area had been removed by surgical intervention
  • Closed head trauma
    • This occurs after a blow to the head which causes different forces on the head:
      • Coup
        • There is damage at the location where the blow hit the head
          • This is because the bone is pushed against the brain by the blow
      • Contrecoup
        • The force exerted by a coup can cause the brain to collide with the skull at the location opposite the coup
      • Microscopic lesions
        • Movements of the brain cause cracks or twists of fiber paths
        • Most common in the frontal and temporal lobes
        • Forces can also cause cracks in the corpus callosum and the anterior commissure
          • This can lead to disconnection syndromes
      • Haematoma
        • The blow can lead to a tearing of blood vessels, causing blood to flow into the skull
          • This creates a growing mass of blood in the skull which exerts pressure on the brain
      • Oedema
        • Edema can occur in the brain as well as it would after a blow to another part of the body
• Some forms of epilepsy are the following:
  • Partial epileptic seizure
    • Also called a focal insult
    • Caused by a local disorder in a cerebral hemisphere
    • Symptoms are related to the location of the disorder
      • If a disorder is located in the motor cortex, motor phenomena occur
  • Complex partial epileptic seizure
    • Also called a focal insult
    • Occurs mainly in the temporal lobe and sometimes in the frontal lobe
    • There are three symptoms:
      • Subject experiences prior to the attack
      • Automatic behaviour
      • Changes in posture (catatonic, frozen posture)
  • Generalized epileptic seizures
    • These are bilaterally symmetrical
    • There are often three stages:
      • Tonic stage
      • Clonic stage
      • Post-attack
• A tumor, or neoplasm, is a mass of new tissue that continues to grow, independent of surrounding structures, which has no physiological function whatsoever. Brain tumours originate from glia cells or supporting cells, but not from neurons. The growth rate varies greatly, depending on the cell from which it originates. Tumors can be encapsulated and pronounced and detached from other tissues, putting pressure on other structures, or infiltrating and not detached from surrounding tissue, and these can destroy healthy cells and get into place and even interfere with the function of healthy cells.
• Migraine is an important example of headache:
  • There are some forms of migraine:
    • Classic migraine
      • Occurs in about 12% of people with migraine
      • Usually starts with an aura that lasts 20-40 minutes
        • The aura is caused by vasoconstriction of one or more cerebral arteries that cause ischemia of the occipital cortex which is not dangerous
      • Actual headache occurs when the vasoconstriction changes into vasodilatation
      • The headache is often an intense pain on one side of the head
        • This pain often spreads out
      • The headache can go together with nausea and vomiting
    • Common migraine
      • Occurs in about 80% of people with migraine
      • There is no real aura, but a signal in the stomach and intestines can precede an attack
    • Cluster headache
      • This is a severe, unilateral headache which usually does not last longer than 2 hours
      • This headache usually recurs regularly within a few weeks or months and then disappears
        • Sometimes a long period can occur between one series of vane cluster headaches and the next
    • Hemiplegic migraine and opthalmological migraine
      • These are rare forms of migraine
      • Here there is unilateral loss of movement in the body or eyes
• Some important motor disorders are the following:
  • Myasthenia Gravis (severe muscle weakness)
    • The motoric impulse transfer is disrupted
    • Usually occurs in people in their thirties and is more common among women
    • Characteristics of the disease are:
      • Changing muscle weakness
      • Quickly exhausted muscles
      • Weakness of the voice
      • Difficulty chewing and swallowing
      • It is hard to hold up the head
    • After sleep one often feels better
    • It is an autoimmune disease in which the own body destroys the acetylcholine receptors
  • Multiple sclerosis (MS)
    • This is a disease of the CNS in young adults
    • The symptoms vary, but the first symptoms are often:
      • Loss of sensation in the face, body or extremities
      • Blurred vision
      • Loss of control in one or more extremities
    • Sometimes the above symptoms disappear for several years before returning, but sometimes the disease continues progressively and quickly until someone can only lie in bed
    • The cause is still unclear, but inflammations of the myelin sheath of the CZS is a big candidate
    • Alemtuzumab might possibly be a good treatment of MS

What are possible psychiatric disorders? - BulletPoints 27

• The DSM-5 gives the five symptoms of schizophrenia:
  • Delusions
    • Beliefs that distort reality
  • Hallucinations
    • Distorted perceptions that someone has for which no suitable external stimuli are available
  • Unorganised speech
    • This includes, for example, inconsistent remarks or empty rhymes
  • Disorganised or excessively rushed behaviour
  • Other symptoms causing dysfunction at work or social events
• The main symptoms of depression are:
  • Feelings of worthlessness and guilt
  • Change of normal appetite
  • Sleep problems
  • Slowing down of behavior
  • Frequent thoughts of death or suicide
• About 4 in 10 people have an anxiety disorder at some point in their lives. The most common are:
  • Panic disorder
    • Recurring attacks of intense anxiety that occur without warning under certain circumstances
  • Posttraumatic stress disorder (PTSD)
    • Here there is fear because of recurring memories of traumatic experiences in the past
  • Generalised anxiety disorder
    • There is a continuous state of anxiety associated with at least three fear symptoms:
      • Restlessness
      • Less energy
      • Concentration problems
      • Increased irritation
      • Sleep problems
  • Obsessive compulsive disorder
    • Repeatedly performing actions or experiencing unpleasant thoughts
  • Specific Phobias
    • Fears of a specific object or situation
• There are a couple of relevant motor disorders that are divided into two groups. Below are the two groups and the best-known disorder in the group:
  • Group 1 - Hyperkinetic disorders
    • These are characterized by increased motor activity
    • Huntingtons disease
      • Progressive, hereditary disease
      • Arises between the 30th and 40th year of life
      • Appears in about 4-7 out of 100,000 people
      • Symptoms are:
        • Intellectual degradation
        • Chorea (abnormal movements)
        • Personality changes and behavioural problems
        • Emotional problems and psychotic characteristics
        • Coordination problems
        • Writing and speech disorders
        • Ultimately it leads to dementia
      • Suicide rate is 5 to 10 times higher than average
      • There is degeneration of the small cells in the cortex and frontal area and of the basal nuclei
      • There is a deficiency of neurotransmitter GABA in the basal nuclei
  • Group 2 - Hypokinetic disorders
    • These disorders are accompanied by a reduction in motor activity
      • Parkinsons disease
        • This disease is common in older people
        • Symptoms can be classified into positive and negative symptoms
          • Positive symptoms
            • Resting tremor
            • Muscular rigidity
            • Involuntary movements
          • Negative symptoms
            • Postural problems
            • Difficulty standing upright
            • Locomotor disorders
            • Speech problems
            • Akinesia

What is the essence of neuropsychological research? - BulletPoints 28

• There are some goals that one wants to achieve with neuropsychological research:
  • Mapping someones general cerebral functions
    • The aim is to map the cerebral dysfunction and localize it
  • Taking responsibility of the care and recovery of the patient
  • Identifying mild disorders that would otherwise not be visible
  • Identifying unusual brain organisation in, for example, people who are left-handed or people who have suffered a trauma in their youth
  • Confirmation of an abnormal EEG in for example, people with epilepsy
  • Documenting and maintaining the restoration of function during treatment
  • To clarify the effectiveness of the treatment and its outcomes