Lecture 3: Emotion and neuroscience

Why neuroscience?

In the end, all our behavior is produced by the brain.

Neuroscience can help remove terminological vagueness  (emotion vs. cognition, basic vs. complex)

Discover underlying mechanism of emotion (and psychopathology)

MacLean’s stage of evolution

Reptilian brain: Respiration, heart (basic bodily functions)

Limbic system: store dangerous situations, hunger (adaptive survival functions)

Neocortex: consciousness, reasoning, predicting the future (high-order thinking)

Problem with MacLean’s view: Limbic system is present in reptilians too, and it’s similar to ours

Limbic system

Parts:

Fornix: carries information from hippocampus to hypothalamus

Septal area: pleasure, reward, reinforcement.

Corpus Callosum: connects both brain hemispheres.

Thalamus: relay station that determines which information can pass through to sensory areas or not. What is salient? (sleep and awake function)

Hippocampus: important for delivery of information from short-term to long-term memory! No hippocampus, no new memory

Hypothalamus: secretion of hormones related to arousal and sleep, direct connection to autonomic nervous system

Amygdala: Emotion regulation

Functions:

• Evolutionary old and universal system
• Similar in different animals (incl. humans)
• Emotion processing: direct adaptive functions to interact with environment
• Not all parts are directly involved in emotions
• Limbic system is not unique in processing emotions
• Limbic system helps in detecting biologically salient stimuli

Panksepp’s idea

Not only the limbic system, but all layers are important for emotion

Reflexes: startle reflex (protect the eye), pain, hunger, taste

Midbrain & Limbic system: fear, anger, sadness, joy, affection, interest (reward) à very simple expressions to communicate with others

Neocortex: shame, guilt, contempt, envy, humor, empathy, sympathy à all require planning, to do with future and bonding and materialism

Is there a difference between human and animal brains?

Humans are more cognitive when it comes to emotions

• According to Berridge only humans have a neocortex

Humans have:

• Lots of Sulci and Gyri
• Lots of neural connections
• More associative than sensory areas

Sensory areas still have relatively the same size as animals

Association areas are much bigger and connected in humans

• Those areas are important for planning, bonding, appraisal

Component Process Model (Scherer)

Components of emotion representations:

1. 1. Neurophysiological support/regulation
   2. Expression (facial, bodily and vocal expression)
   3. Subjective feeling and appraisal (top-down monitor)
   4. Information processing (bottom-up processing & attention)
   5. Motivational executive action (motor planning/preparation)

According to Scherer sensory processing and attention and controlled planning are important for emotion too (besides phenomenal experience, physiological pattern and verbal/nonverbal expression).

• All must be active at the same time to call the mental state an emotion

LeDoux’ short cut theory

There are two types of emotional processing:

1. 1. 1. 1. High (cognitive) road: identifying stimulus à emotional evaluation à action
         2. Low (raw) road: direct evolutionary shortcut via thalamus & amygdala to action

Expression and physiological response happen at the same time

If LeDoux’s theory is true then:

• Humans should be able to respond more quickly to emotional stimuli (threats) than neutral stimuli (shortcut)
• Amygdala should recognize threat and signal body for fast response
• We don’t need a visual cortex and still react adequately to stimuli of threat

Evidence for Ledoux’ idea:

• Children find snakes and spiders faster than normal. As children have had  little experience with snakes and spiders, this must be an innate pathway
• When presented with a sequence of visual stimuli in rapid succession at the same spatial location on a screen, a participant will often fail to detect a second salient target occurring in succession if it is presented between 180-450 ms after the first one.
• Healthy observers demonstrate robust benefits for the perception of verbal stimuli of aversive content compared with stimuli of neutral content. In contrast, a patient with bilateral amygdala damage has no enhanced perception for such aversive stimulus events. 

Amygdala

It is connected to almost all brain functions that are necessary to elicit emotions

Amygdala recognizes threat and signals body for fast response

Amygdala is part of the “quick & dirty” route of visual processing

Emotions depend on a network of brain areas (also see Scherer’s idea)

• Emotion needs cognition

Amygdala is at the heart of this network

Kluver-Bucy Syndrome: Without amygdala, animals lose their natural fear response

Symptoms:

• Monkey’s have increased tendency to approach threats
• No nurturing and abuse of offspring
• Rats cannot associate danger with stimulus
• Human children show no affection with or attachment to their parents
• Human adult: placidity (undisturbed), hypersexuality

Emotion recognition is impaired in patients with amygdala damage

Blindsight

If LeDoux’s theory is true then affective blindsight is possible.

Affective blindsight: the residual visual ability of patients with damage to the primary visual cortex to react reliably to the emotional valence of stimuli presented to their blind visual fields and whose presence they are unable to report

Orbitofrontal cortex (OFC)

Clinical characteristics of the Orbitofrontal Syndrome

• • Disinhibited, impulsive behavior (pseudopsychopathic)
  • Inappropriate humor, euphoria
  • Emotional lability
  • Poor judgment and insight
  • Distractibility

Damasio discovered a patient with damaged OFC who’s intelligence and emotion recognition skills were intact but he could not make decisions.

Damasio’s theory:

• OFC lesions impair decision-making
• Impaired acquisition of somatic/bodily markers
• Emotions necessary for appropriate decisions

Somatic markers: Interplay between OFC and amygdala

When individuals make decisions, they must assess the incentive value of the choices available to them, using cognitive and emotional processes. When the individuals face complex and conflicting choices, they may be unable to decide using only cognitive processes, which may become overloaded.

Damasio on emotion: There is an interaction between action, goal, and emotion. The emotion does not “mark” the action and memories of the action in patients with frontal lobe damage

Testing Damasio’s theory on emotions: The Iowa gambling task

• Gambling task where the long term gain is much better than the short-term
• Patients with amygdala and ventromedial frontal cortex lesions do not perform well on the gambling task.

Dissociation between OFC and Amygdala

• OFC and amygdala damage increases risk taking
• OFC and amygdala damage impairs decision SCR
• Only amygdala damage impairs reward SCR
• OFC: decision-making and expectations
• Amygdala: marks emotional outcomes
• Amygdala, a kind of emotional memory
• The amygdala is involved in implicit emotional learning (e.g., fear conditioning)

Anterior Cingulate Cortex (ACC) and Ventral Tegmental Area (VTA)

ACC:

Just above the corpus callosum

Functions:

• Anticipating unexpected
• painful events
• Memorizing  painful  events
• Error monitoring
• Empathy (someone else in pain)

VTA:

VTA is part of the midbrain

It is involved in motivation

Oxytocin

Oxytocin’s release station is the pituitary gland

Oxytocin and amygdala:

• No oxytocin in amygdala causes social recognition deficits in mice
• Oxytocin acts on the amygdala to reduce fear (McCarthy et al., 1996) and to modulate aggression (Bosch et al., 2005)
• Oxytocin inhibits neural firing in connections to brainstem sites mediating fear responses (Huber et al., 2005)
• Oxytocin regulates emotional responses