The Amygdaloid Complex Flashcards
Name the 3 subgroups of the amygdaloid complex
Basolateral complex
Cortico-medial complex
Central nucleus
What are the effects of a bilateral amygdaloid complex lesion in monkeys?
Tameness
Hypoemotionality
Hyperphagia
What are the effects of adult-acquired bilateral amygdala lesions in humans?
Hypersexuality, hypoemotionality, oral tendency
Milder than Kluver-Bucy syndrome - but same symptoms
What is the effect of electrically stimulating the amygdala in awake humans?
Positive and negative feelings
Which type of neurons does the basolateral complex contain?
Glutamatergic
What type of neurons do the central nuclei contain?
GABAergic
The central nuclei form part of which system?
Autonomic
The cortical and medial nuclei form part of which system?
Olfactory
Where in the amygdala does the main olfactory bulb project to?
Cortical nuclei
Where in the amygdala does the accessory olfactory bulb project to?
Medial nuclei
What is the role of the medial nuclei?
Project to hypothalamic regions involved in affilative and defensive behaviours
What is the role of the cortical nuclei?
Coordinate responses involving odour-driven innate aversive and appetitive behaviours
The basolateral complex forms part of which system?
Frontotemporal system
What is the role of the basolateral complex?
Integrates multimodal interoceptive and exteroceptive sensory information - mediates learning about sensory cues
Where does the lateral nucleus receive sensory inputs from?
S1
Association cortices
Thalamus
Hippocampus
Where does the lateral nucleus project to?
Basal and accessory basal nuclei
NAc and PFC - directly and via dorsomedial thalamus
Where does the whole basolateral complex project to?
Central nucleus
Where does the central nucleus project to?
Hypothalamus
Midbrain
Pons
Medulla
What mediates CS-US association?
Basolateral complex
What mediates defensive response performance (e.g. freezing, escape)?
Central nucleus
What is the predominant serial view of amygdala processing?
Lateral -> basal -> central -> hypothalamus/brainstem
What is Killcross and Balleine’s (2006) alternative parallel view of amygdala processing?
Basolateral and central nuclei work in parallel
Basolateral complex recognises cues predicting US
Central nucleus mediates affective reactions to CS - encodes prediction of future affective event - no specification of what event is
How does a basolateral complex lesion affect Pavlovian fear conditioning to a tone in mice?
No association between US and CS
Does not learn to fear tone
How does central nucleus inhibition affect Pavlovian fear conditioning to a tone in mice?
No freezing (fear expression) Learning still occurs
How do PFC inputs modulate the basolateral complex?
Extinguish fear conditioned response (fear extinction)
Association never removed from amygdala
What is Urbach-Wiethe disease?
Progressive bilateral amygdala calcification - from young age
How did Urbach-Wiethe disease affect Patient SM?
Deficits in recognising facial expression of fear
No fear behaviour
Increased trustworthiness of positive and negative faces
Increased comfortable proximity to others
What is a weakness of Patient SM as a case study of bilateral amygdala lesion?
Had facial disfigurement - may have caused decreased fear response
How did Urbach-Wiethe disease affect South African patients and what does this suggest?
Decreased basolateral amygdala volume
Increased fear
BLA may inhibit fear behaviour
What is the effect of an amygdala lesion in macaques and what does this suggest the role of the amygdala may be?
Social disinhibition Increased approach behaviour Increased likeability Decreased aggression Decreased social hierarchy ranking
What do amygdala neurons respond to in macaques when shown photos of other macaques?
Some respond to identity of macaque
Some respond to specific facial responses
What do individual amygdala neurons respond to in humans?
Some to selective part of face
Some to whole face
Some differentiate between happy and fearful expressions
What is the overall role of the amygdala and the purpose of its function?
Value coding - positive and negative values
Updates values
Name the areas of the amygdala olfactory system
Olfactory input - cortico-medial nuclei - hypothalamus
Where does the main olfactory bulb project to and what is the role of the next projection in the pathway?
Cortical nucleus
Hypothalamus - coordinating responses about odour-driven innate aversive/appetitive behaviours
Where does the accessory olfactory bulb project to and what is the role of the next projection in the pathway?
Medial nucleus
Hypothalamus - affiliative/defensive behaviours
Name the areas of the amygdala fronto-temporal system
Neocortex - basolateral nuclei - dorsomedial thalamic nucleus - PFC
Name the areas of the amygdala autonomic system
Visceral input - central nucleus - hypothalamus/brainstem
