Knowledge Clips Part 2: Amygdala and Emotional Processing
Amygdala Structure:
- Part of the limbic system
- Studied as a single structure in humans
- Evolutionary changes in amygdala size (BLA vs. CeA)
Low and High Routes (LeDoux):
- Visual processing routes in threat perception
- High route: Thalamus to visual cortex to amygdala
- Low route: Thalamus directly to amygdala for rapid fear response
Fearful White Eyes Experiment:
- Amygdala responds to fearful eyes unconsciously
- Urbach Wiethe disease impairs fear recognition
- Patient SM and South African patients show different responses due to specific amygdala damage
Amygdala and Threat Conditioning:
- Reactivity, attention, recognition, learning, memory, and regulation
- Amygdala's role beyond fear: emotionally intense stimuli, positive/negative experiences
Insula:
- Linked to disgust traditionally
- Also involved in taste, pain perception, and general bodily awareness
- Main node of the salience network
Reward System and Motivation:
- Midbrain, striatum, cortex involvement
- Dorsal striatum for motivated behavior and habit formation
- Ventral striatum (nucleus accumbens) for reward experience and anticipation
Orbitofrontal Cortex (OFC):
- Computes/predicts current reward value
- Activity correlates with transitions in reward value
- Importance in behavioral flexibility
Anterior Cingulate Cortex:
- Cognitive and affective parts for conflict monitoring
- Adjusts behavior and updates based on conflicts
Emotions and Decision Making: Traditional View:
- Emotional decision making for intuitive, fast decisions
- Rational decision making for calculated, slower decisions
- Somatic marker theory suggests combining emotional and rational elements for optimal decisions
Somatic Marker Theory (Damasio):
- Emotional and rational parts combined for decision-making
- Importance of ventromedial prefrontal cortex in updating behavior based on somatic signals
- Conflict between ratio and affect in morality dilemmas
Morality and Decision Making:
- Ventromedial prefrontal cortex damage leads to more utilitarian decisions
- Interplay between emotions and rationality in decision-making
- Criticisms of somatic marker theory but general acceptance of vmPFC's role in integrating affective and cognitive information for decision-making.
