Physiologists of the mind: which important scientists examined the brain in the period between Gall and Penfield? - Chapter 3

Nowadays, we see the brain as the organ responsible for our intelligence and higher mental possibilities. However, it took about 200 years before this concept was accepted. Aristotle could hardly believe how a bloodless, numb and generally not impressive-looking organ could be the source of the highest human faculties. He supposed these functions were to be contributed to the heart. Descartes saw a number of important functions in the brain, however attributed the greatest functions to the rational soul.

Who is Franz Jozef Gall?

Locke's teacher, Thomas Willis (1621-1675), paid more attention to the brain and was in 1664 the first to accurately publish a detailed work about it, named 'Anatomy of the Brain'. Willis saw that the brain tissue was not undifferentiated, as Aristotle thought, but consisted of two kinds of substances. Firstly, there is a fleshy, grey mass that forms the outer layer, also know as the cortex, (the inner part of the spinal cord and several discrete centres within the brain). Secondly, there is a fibrous white mass in the other areas. He speculated that this white mass consisted of narrow channels whose function is to distribute the "souls" that are created in the grey mass. In addition, he also accurately described the blood vessels in the brain, which proved that the brain is not a bloodless organ. Other doctors discovered that strokes can occur in the brain, and that, in case of injuries on one side of the brain, there are often paralysis or loss of feeling on the other side of the body. However, the brain only really became a topic of interest around 1800, in which the German physiologist Franz Josef Gall (1758-1828) played a big part.

Gall confirmed and developed many of Willis' basic ideas about the grey and white matter. He showed that the two halves of the brain are linked by stems of white matter that are called commissures and that other, narrower pieces of white fibres connect the two halves of the brain to the opposite sides of the spinal cord. This helped explain why damage on one side of the brain can lead to paralysis on the other side of it body. He also showed that the brain is in fact the centre for higher mental activity (by describing that animals with a larger brain tend to be more complex, more flexible and display more intelligent behaviour). Gall's anatomical findings were the basis for the later discovery that the brain and spinal cord consist of billions of neurons. Neurons are connected by dendrites, which receive signals from other neurons via axons. Axons tend to cluster together and thus form the white matter, while the cell bodies and dendrites form the grey matter. 

Gall was also the first comparative brain anatomist. He discovered that higher mental functions correlate with the size and health of the brain in question, and in particular of the cortex (outer brain layer). So animals with larger brains portray more complex, more flexible and more intelligent behaviour. This confirmed once and for all that the brain was indeed the centre of higher mental activity. His ideas also led to the emergence of phrenology (literally: the science of the mind) and physiology (reading the character of a person through his or her physical characteristics).

According to phrenology, predisposition and character are determined by the growth of certain parts of the brain. According to Gall, specific parts of the brain were associated with specific functions, also called faculties. When one of these parts was large and well developed, the specific function must also be strong. In this way, Gall identified parts of the brain that were responsible for, for example, lust, greed and goodwill. Gall therefore sought similarities between certain lumps in the brain and the psychological characteristics of the people who have these had lumps / protrusions. Phrenology became very popular but was by not taken seriously strict scientists. The art of physiognomy, reading someone's character his or her physical characteristics, was effectively promoted during the 1770s by Johann Kaspar Lavatar (1741-1801), and remained popular during the 1800s. However, Gall's theory proved to be weak by the hand of three factors. 

First, Gall incorrectly assumed that the shape of the skull reflected the exact shape of the brain. Secondly, the faculty solution was too simple. An adequate classification of psychological characteristics was missing in the phrenology, which doomed attempts to to localize features in the brain. Finally, the methods with which the hypotheses were tested were simply horrendous. Gall never denied though, that his theory was completely based on observation. That does mean, however, that the observations, and therefore the theory, unfortunately are less valuable as due to selectivity and arbitrariness. There was a lot of criticism of Gall's theories. Pierre Flourens (1794-186) was one of the scientists who did not agree with a number of Gall's specific hypotheses. Flourens' research lay at the basis of a classic controversy about the nature of the brain that is still alive today.

Who was Flourens?

After Flourens graduated at the age of nineteen, he had his first scientific article published and moved to Paris, he became the protege of Georges Cuvier (1769-1832), who was also known as the "dictator of biology". Flourens investigated the functions of the brain by means of experiments. For this he used the technique of removal, where specific small parts of the brain of a test animal were surgically removed. Then the subsequent changes in the behaviour and functioning of the animal were observed. Thus, it was possible to state whether or not the removed part is normally involved in producing that certain function or behaviour. Flourens tested the hypotheses of Gall by removing those brain areas associated with specific phrenological faculties. One of Gall’s theories, that the cerebellum was linked to sexual excitement, he dismissed completely on the basis of an experiment in which he concluded that the cerebellum is indeed the centre of a specific function, but this function was to help with discrete movements. 

Flourens also did removal experiments with the cortex. After removing the entire cortex from a bird, he stated that this animal had lost its will, its possibility of consciousness. He also made the observation that every piece of the cortex, regardless of how big it is, is linked to many cortical regions simultaneously, producing a general effect. According to Flourens, his results completely dismantled Gall's phrenology. He found that all separate functions were distributed within each organ, so there were not many different specificities within the cortex organs, as Gall had claimed. Thus, a removal of a small part of the cortex should lead to a more specific effect than what was currently the case. 

He also noticed that, sometimes, defects that arise in animals because something has been removed, can improve over time. This especially happens when the animal was young and the removal relatively small. This suggested that intact parts of the brain may take over specific functions. Finally, he saw collaboration and communication between the cerebellum and the cortex. Actions that arise from the 'will' of the cortex had to be merged and integrated by the cerebellum. The loss of coordination that is caused by damage to the cerebellum must be taken care of by voluntary reactions in the cortex.

In the book of the English author Jonathan Swift (1667-1745), a number of stories are described, in which the link is made between language and an organ for verbal memory. Despite Flourens’ attack on phrenology, the hypothesis of Gall was kept alive by his former student Jean Baptiste Bouillaud (1796-1881) by publishing all the evidence that he could find about the area that controls language in the frontal regions of the cortex. Nobody, except his son-in-law Dr. Ernest Aubertin (1825-1893), took him seriously. Aubertin found a patient with symptoms that seemed to confirm Bouillaud's theory.

A patient with similar symptoms as the Aubertin patient entered Paul Broca’s practise five days later (1824-1880), so the story of Aubertin was soon forgotten. Paul Broca was head of surgery at a hospital in Paris. He was interested in variations in between people’s skulls and had invented several instruments to measure them. The patient who was brought in to him could, besides cursing when he was angry, only say 'tan' when he wanted to speak. This gave him his nickname, Tan. Ten years after Tan's loss of speech, his right arm and leg became paralyzed. He was also blinded and confined to bed. When Tan died, Broca did an autopsy on his brain and saw damage, very close to the area that Gall called the 'organ of the verbal memory'. Despite that this cannot be proven, it is plausible that the speech problem of Tan is caused by a progressive brain deterioration starting in this area. Broca collected more patients with speech loss, to have stronger evidence for his findings. Despite the fact that the degree of brain damage differed, it usually came from the same area in the frontal lobe. A surprising discovery is that right - handed patients usually have a damage that has arisen on the left side of the brain. This crucial area became known as the area of ​​Broca. The weakened speech because of damage was later called aphasia. Broca was also known for promoting of the idea that difference in brain size correlates positively with difference in intelligence. He also stated that European men are superior (because they have a larger average brain size) to women and to men with a different ethnic background.

In 1870, the Germans Gustav Fritsch (1837-1927) and Eduard Hitzig (1838-1907) came up with the idea that the brain might not be a completely insensitive organ, as Aristotle had thought. According to them, it could therefore be possible to respond to direct electrical stimulation. By electrical stimulation at specific places of a particular area in the brain, now known as the motor strip, specific movements on the other side of the body could be elicited. In 1870, they stimulated the cortex of a dog electrically, through which they discovered the motor projection area. David Ferrier (1843-1928) showed that the occipital cortex contains a visual area. He also discovered an auditory area in the temporal lobe and a strip directly behind the motor strip that controls the sensory functions for the same body parts. Removal of this sensory strip causes loss of sensitivity in specific parts of the body while removal of the adjacent part of the motor strip causes paralysis. The brain gets sensory information from different sensory centres, after which it is stored in it the surrounding areas. Thus, visual memories are presumably stored in specific ones areas around the visual area and auditory memories around the auditory area. These localized memories are thought to be connected with other areas through fibres and white matter. Brain areas with a lot of white matter are also called association areas. It was thought that the frontal lobe contained the large association area that was responsible for the superiority of people about other animals when it comes to thinking and intelligence.

What was Wernicke’s influence?

The German Carl Wernicke (1848-1905) noted that the area of ​​Broca was positioned directly in front the part of the motor strip lay that was responsible for movement of the mouth, tongue and face. This would mean that damage in only the area of ​​Broca should not influence the physical ability of speech, which was the case with Tan and Jonathan Swift. Wernicke described a group of ten patients who had a different kind of language disorder. This he called sensory aphasia, in contrast to Broca's motor aphasia. These patients could speak fluently with correct syntax, but their understanding of spoken language was limited, and their speech was marked by several peculiar words and wrong statements, which he called paraphasia.

Wernicke showed that the patients with sensory aphasia had damage on a part of the left temporal lobe, near the auditory area. This is also the area where the auditory memory for words theoretically should be. They can therefore hear and recognize what is happening is said but cannot remember what the words mean. When the area of Broca remains intact, they also retain the motoric memories of words which are needed to give fluent spoken responses. But because they do not understand what has been said to them their reactions are bizarre for the listener. These patients often had a misdiagnosis of psychological mental illnesses, for example psychosis. The brain area that causes sensory aphasia became known as the area of ​​Wernicke. The concepts of motor aphasia and sensory aphasia are still used but are sometimes called Broca's aphasia and Wernicke's aphasia.

Wernicke discovered another type of aphasia too. Between the motor area of ​​Broca and the sensory speech memory in Wernicke's area, were, according to Wernicke, association fibres that linked these two areas. This connection makes a silent arrangement and correction of one’s own speech possible. When these association fibres get damaged while the areas of ​​Broca and ​​Wernicke remain intact, there is a condition Wernicke called conduction aphasia. This is characterized by paraphasia through the loss of self-control, but there is an unblemished understanding and general fluency. This is a relatively mild one condition, making it often go by unnoticed. These patients cannot repeat words that haven been spoken to them. 

From then on, other scientists also followed the Wernicke theories and no longer searched for the higher levels of 'faculties' in the brain. Instead, they strove to demonstrate how complex psychological processes are created by the basic elements of sensations, movements. They also tried to trace the memory.

In 1902 the American Stepherd Ivory Franz (1874-1933) published an investigation about the effects of cortical removal in cats, who had previously been trained in escaping from the 'puzzle box'. This study was very much in the tradition of Flourens - except that he did not look at generalized effects of removal, but on the effects on a specific, learned reaction. Franz was interested in the effects on specific, learned reactions. His innovation was to combine the removal with the training of animals. The study only found a very general type of localization, in which damage to the frontal cortex caused the loss of reactions, while this did not happen with damage elsewhere. In addition, Franz thought that the animals whose frontal lobe had been removed were able to recover quickly and easily learn to escape. This led to Franz questioning the localization theory and coming back at the idea of ​​Flourens that the brain functions as a whole. Franz continued to work for a long time the hospital and remained very impressed by the plasticity and flexibility of the brain. He saw that, in patients who lost functionality due to brain damage, these functions are sometimes able to partially or completely recover, especially in young patients.

In 1915 Franz got a colleague named Karl Spencer Lashley (1890-1958), who was friends with John. B. Watson (1878-1958). Franz and Lashley experimented on white rats that had been trained in getting out of mazes and removing various parts of the brain. They only looked towards strictly observable and objective behaviour. Animals like white rats were their favourite subjects because they can easily be observed, their environment can be controlled, and they do not show subjective reactions, like dogs might. Lashley described his findings in the book 'Brain Mechanisms and Intelligence '. In this, he concluded that the memory seemed to penetrate into the whole cortex and not selectively localized. There where Broca, Ferrier and Wernicke revitalised Gall's previous localizations and concept of memory, Lashley fell back on Flourens and the action commune (communication) of the brain. Lashley contributed to two new terms that Flourens would undoubtedly have approved. First, he stated that the brain is remarkably good in equipotentiality, which he explained as "the apparent power of every intact part of one functional brain for performing ... the (memory) functions that are lost by the destruction of (other parts). "In other words, this means that the brain is capable of such neural plasticity, that when parts become damaged, other parts are capable of take over these functions. But the equipotentiality of the brain can sometimes be compensated by the law of mass action, "where the efficiency of the performance of a whole complex function can be reduced in accordance with the degree of brain injury. "Simple this means: the greater the brain damage, the less chance of equipotentiality.

Some successors of Lashley found his theory too simple. Criticism of Lashley is that a rat could associate multiple different stimuli (such as touch, smell, hearing and vision) with the "right" motor reactions. So, there are multiple connections at different locations in the brain for one single act; such as solving a maze. Damage to a small part of the brain can therefore only remove a few compounds, so it only has a small effect on it overall learning. This so-called redundancy hypothesis gives a similar explanation, suggesting that each individual memory is stored in multiple locations in the cortex. This number of locations is larger if the memory is better established and is more widely associated with other memories. The removal of a part of the brain area will therefore be a part of, but do not delete all the specific memory. It is certain that every final solution for this problem must take into account a number of very non-behaviourist experiments, including the electrical stimulation of the conscious human brain.

The doctor Roberts Bartholow (1831-1904) had a female patient with a part of her brain that was visible through an opening in her skull. Bartholow thought that it would be possible to penetrate her cerebral mass with thin needles. He attached the needles to an electricity supply of moderate strength and stimulated the exposed area. When the needle went deeper, she complained of an unpleasant tingling in her arm. Her condition got worse after the experiment and she died before Bartholow could repeat the experiment. He examined her brain after her death and concluded that she had not died because of the experiment, but because of the spread of her cancer. However, it caused a lot of uproar.

How did Penfield treat Epilepsy?

Wilder Penfield (1891-1976) started searching for new surgical treatments for epilepsy in 1930. He knew that epilepsy was caused by abnormal activation of cerebral neurons. This activation starts on a narrow 'focus', after which it then spread to ever increasing areas of the brain. When it spreads too far, the patient loses consciousness and gets convulsions. Just before these convulsions take place, patients regularly experience peculiar subjective warning signs, which are also called auras. Penfield thought these auras were the result of an earlier activation on that focus before it spread. He also thought that the specific content of an aura possibly depends on the location of the focus. By means of electrodes he could enter the brain areas in which auras were caused to identify and remove. He saw these areas as responsible for epilepsy. Often the consequence of the removal was that the patient, for example, suffered from aphasia, because the area was next to a language area. Most patients did have less trouble with the epilepsy after the operation. 

His experiments also gave a lot of information about the localization of functions in general. Penfield stimulated a lot of normal areas of the cortex during the search for auras and observed the effects in healthy individuals. By stimulating the motor strip, patients experienced involuntary movements on the other side of their body. Stimulation of the sensory strip caused tingling, vibrating or pressure different parts of their body. Stimulating the visual area produced light flashes, colour and abstract patterns, while stimulation in the auditory area clicks, hums, chirps, drumming, among other sounds. Surprisingly, when Penfield stimulated the area mainly around the visual and auditory area, patients experienced complete visual or auditory hallucinations.

Stimulating the temporal lobe yielded the most surprising effects. Here he found something he called the interpretive cortex, a temporal area whose stimulation gave two kinds physical responses. First of all, these were interpretative responses, in which patients suddenly and unexpectedly saw their immediate situations in new light. Depending on the precise location in the brain, these feelings could be like a déjà vu, a euphoric feeling or a fear. This also showed that very specific emotional and orientating attitudes are localized in the brain, just as sensations and movements are. Secondly, these stimulation experiential responses, such as hallucinatory 'dreams' or 'flashbacks' or real events the past, were often very common. Unlike normal 'memories' these scenes were vividly subjective and were not only experienced in thought. Penfield had difficulty to see these experiences as 'memories', especially because his patients themselves saw their experiential responses as qualitatively different from their normal memories. Penfield personally thought that the electrical stimulation and the abnormal epileptic discharges both inhibited the normal functioning of the neurons in question instead of activating them.

Who was Brenda Milner?

Brenda Milner (born in 1918) met Donald O. Hebb (1904-1985) in 1947 at the University of Montreal. Hebb had the design for his book 'The Organization of Behavior' with him, which he finally published in 1949. The book was about related learning and other types of behaviour in the hypothetical functioning of neurological networks in the brain, which he called cell collections. Milner and Penfield became in their joint work aware of the possible importance of the hippocampus in the functioning of the brain.

They observed two cases where damage to the hippocampus had caused memory defects for recent events, and they presented these cases in a paper in 1955. They then were called by Scoville about a patient he had just operated, who showed similar symptoms of memory loss. Milner then travelled to Connecticut to engage in the fascinating case of H.M. - perhaps the most famous case study in the history of memory research. H.M. had had minor epilepsy attacks since a fall when he was ten years old but were found increasing at the age of sixteen. These attacks included biting on the tongue, incontinence, convulsions and loss of consciousness. At the age of 27, H.M. was completely handicapped. They decided to perform a brain operation in which large parts of the hippocampus and surrounding tissue from both sides were removed. The patient was relieved of his attacks, but experienced serious flaws in his memory. He could not create new memories, nor remember recent events or experiences. He could not move the information from his working memory to the long-term memory. They found a number of other patients to confirm the findings. The larger the part of the hippocampus that was removed, the more severe the memory loss was. They concluded that the ability to form recent memories is located in this brain area. 

H.M.’s personality remained largely unchanged. Milner provided evidence for two separate memory processes, one is a, mainly mental, process with rapid deterioration, the other is an overlapping second process in which the storage of memories into the long-term memory takes place. Milner was also able to demonstrate that the deterioration of the patient did not apply to every type of task. With this she showed that while the declarative memory (the ability to remember and to describe something verbally) was deteriorating, his procedural memory (taking advantage of practicing and repeating new learned actions) was not.  Milner showed that there are several and several memory systems exist.

In contrast to what Penfield described earlier in 1975, he had his doubts. Certain elements of experience, especially the conscious will or decision to do something, or believe in something, were things never produced by electrical stimulation or any other mechanical process. Penfield doubted whether this could ever happen. He therefore formed the opinion that 'brain' and 'mind' are two independent, yet interacting entities, each with its own separate levels of explanation. He thus came to a dualism that, apart from the details, was not much different from that of Descartes. Penfield admitted that he could not prove his theory and many other neuroscientists would therefore challenge it.

What are recent developments?

Despite the disagreement about whether the mind-brain relationship will ever be fully understood and which form this of understanding will assume, there is no doubt that these two are connected. The question still stimulates scientists today. Much of the new techniques are covered by tomography, the images of objects that as sets of cross-sections / 'slides', created by different types of penetrating waves. Below are some of  the most well-known types of tomography, including CT (computed tomography), or 'CAT' scans that are based are on X-rays, and MRI (magnetic resonance imaging) scans, which use radio waves. PET scans are used when the object is under observation of a physiological organ like the brain. The fMRI (functional MRI) provides images of oxygen in the blood, showing neural activity in certain areas of the brain.

At the same time as these technological developments, there was a change in the field of academic psychology, often called the cognitive revolution.  In the late 1970s, the cognitive psychologist George Miller and the neuroscientist Michael Gazzaniga came with the term cognitive neuroscience to describe a new interdisciplinary field. This happened and was assisted by PET studies of brain activity, during various states of attention and memory, which were done by the psychologist Michael Posner and neurologist Marcus Raichle in 1980. The psychologist Stephen Kosslyn used fMRI techniques to demonstrate that most of the brain’s processes are accompanied by mental imagination. Which is not unified or localized in a single area but can be found in several areas instead. Each area is responsible for different aspects of this imagination process.

Scientists began to merge their ideas on how the brain processes social information. They brought this together under the term social neuroscience. Their goal was to explore underlying neural mechanisms of social thought and behaviour. Magazines on these areas called ‘Social Neuroscience’ and ‘Social Cognitive and Affective Neuroscience’ began to be published. The American Psychological Association declared 2000-2010 the 'decade of behaviour'.

ExamTips

• Though Flourens and Gall opposed each other for most of their lives, you must not forget that they did work on the same topic/issue and did have their similarities. Try to find those.
• Draw up a (rough) drawing of the brain and try to identify the areas in the brain that this chapter discusses. It will help you understand it better.