brain mechanism of emotion

Question 1

S.M case study - amygdala atrophy

Answer 1

Amygdala plays role in recognising facial expressions of fear
Selective impairment in recognition of one emotion with spared recognition of other emotions suggests distributed nature of emotion processing in the brain

Question 2

MacLean’s limbic system theory (1949/52)

Answer 2

Amygdala, orbitofrontal cortex, portions of basal ganglia
Popularised the term limbic system

Question 3

Kluver-Bucy syndrome (1939)

Answer 3

First observed when bilateral removal of temporal lobes in monkeys caused dramatic change in emotional behaviour

Question 4

Anatomy of amygdala

Answer 4

Medial temporal lobes is where you find amygdala
One in each hemisphere

Question 5

Amygdala and emotional processing

Answer 5

Change in emotional behaviour in Kluver-Bucy syndrome linked to amygdala
Electrical stimulation of amygdala in humans lead to anxiety and fear

Question 6

Amygdala and fearful facial expression

Answer 6

When fearful expressions viewed in PET scanner, amygdala region had clear linear increase in brain activity

Question 7

Fear conditioning

Answer 7

Form of classical conditioning where repeated pairings of neutral stimulus with aversive stimulus result in fear response to neutral stimulus alone

Question 8

Amygdala and fear conditioning

Answer 8

Amygdala lesioned mice do not show fear learning
If animal is lesioned after learning association then the association is lost
Amygdala is important for learning and storing conditioned fear response, but not necessary to exhibit fear response

Question 9

Fear pathways in the brain - low road

Answer 9

Quick, subcortical pathway

Question 10

Fear pathways in the brain - high road

Answer 10

Slower, cortical pathway
More conscious route

Question 11

Fear pathways in the brain

Answer 11

Two pathways allow for a quick response but also a thoughtful process of assessing danger

Question 12

Amygdala and emotional learning

Answer 12

Double disassociation suggests that amygdala is necessary for implicit emotional learning and hippocampus necessary for explicit emotional learning

Question 13

Amygdala and emotional memory

Answer 13

Amygdala plays an important role in memory enhancement through arousal
Recall on emotional video correlated with amygdala activity

Question 14

Huntington’s disease

Answer 14

Genetic disorder with symptoms like excessive movements and cognitive decline arising in mid-adulthood

Question 15

Insula

Answer 15

Region of cortex lying beneath temporal lobes bilaterally
Located close to primary gustatory cortex involved in early processing of taste

Question 16

Huntington’s disease and insula

Answer 16

Degree of disgust related impairment is correlated with amount of insula damage

Question 17

Disgust and the insula

Answer 17

Greater the level of disgust in the expression, the more activity in the insula in neurotypical patients
patient with insula damage selectively impaired in recognition of disgust across modalities, despite understanding concept of disgust

Question 18

Distaste vs canonical disgust facial expressions

Answer 18

Canonical disgust activates the insula more than distaste
Less likely to react to distaste as that isn’t affecting the observer

Question 19

Canonical disgust

Answer 19

Lip curl
Related to environment

Question 20

Distaste

Answer 20

Stick tongue out
Related to bad taste

Question 21

Insula - beyond disgust

Answer 21

Viewing others in pain also elicits insula activation but modulated by interpersonal relationship between observer and expresser

Question 22

Anger and orbitofrontal cortex

Answer 22

More anger in a facial expression, the more activity in orbitofrontal cortex

Question 23

Lesions on orbitofrontal cortex

Answer 23

Causes difficulties in reversal learning and socially inappropriate behaviour

Question 24

Anger and dopamine

Answer 24

Non human studies have demonstrated altered dopamine activity during aggressive encounter

Question 25

MAOA

Answer 25

Genetic basis for individual differences in aggression
More pronounced in men
Low activity variant carriers show changes in grey matter volume in amygdala, leading to increased activity in angry faces

Question 26

Anger in the brain

Answer 26

Facial expressions of anger illicit increased activation in orbitofrontal cortex
Patients with VS lesions impaired in recognition of anger
Administration of dopamine receptor D2 antagonist shows reduction in participants recognition of angry facial expressions

Question 27

MacLean’s single system model - Specialised group of structures working collectively to form unitary emotion system

Answer 27

Little support for unitary system localised in one specific circuit
If amygdala damaged in a single circuit model then all emotions should be affected but that is NOT the case, essentially disproving the single circuit model