L16 - Brain mechanisms pt 2 Flashcards
1
Q
What is Huntington’s disease?
A
- Genetic disorder with symptoms arising in mid-adulthood
- Symp: excessive movements, cog decline and severe atrophy of regions like basal ganglia and insula
2
Q
What is the Insula?
A
- Means Island
- Found bilaterally: region of cortex lying beneath temporal lobe
- Located close to primary gustatory cortex involved in processing of taste
3
Q
What is the relationship between Huntingtons and insula? (With study)
A
- Huntingon’s: Selective impairments in recognising facial expressions of disgust and impairments in vocal expressions of disgust
- Degree of disgust-related impairment is correlated with amount of insula damage
STUDY: - Looked at regional variations in grey matter volume and correlated this with insula/basal ganglia changes in pre-clinical patients
- Patients who have clinical Huntington’s have reduction in grey matter volume in the insula despite being pre-clinical AND degree of the insula volume has decreased is associated with their disgust recog scores
4
Q
What is the relationship between disgust and the insula? (3 studies)
A
- STUDY: Put people in a scanner and looking at reactions to differing intensities of disgust
- Greater response in insula to stronger expressions of disgust
- STUDY: ppts in the scanner observed actors smelling and reacting to disgusting, pleasant and neutral odours
- Then ppts in scanner had to smell disgusting/pleasant/neutral smell themselves
- Insula is activated by smelling the disgusting smell as well as viewing others expression of disgust AND shows an overlap of experience and recognition = same part of cortex = suggests understanding emotions in others is from simulating emotions to self = empathy
- STUDY: Patient with insula damage selectively impaired in recognition of disgust across modalities
- Patient tested facial expression recognition, non-verbal emotional sounds, emotional prosody = understood concept of disgust BUT disgust sensitivity score was lower
- Insula is important for recognition and experience of disgust
5
Q
What are other aspects of disgust? (Types)
A
- Disgust: bad taste & evolved to prevent contamination and disease through ingestion
- Moral disgust: Refers to social behaviour that is unacceptable or violates moral conventions
6
Q
What are facial expressions of disgust?
A
- Sticking tongue out in babies: to expel things from mouth
- Can be distaste expression = not seen in moral disgust
- Can be canonical disgust = typically used to convey disgust/moral disgust
7
Q
What are the components of disgust expression
A
- Upper lip curl = disgust in expanded form and indicates offense external to the body = recruits more action from observer
- Mouth gape = informs something in mouth = elicits less action from observer
8
Q
Evidence for distaste vs canonical disgust expressions
A
- Presented ppts with both expressions and neutral ones
- When comparing canon vs distaste = engages regions that are involved in theory of mind = people more likely to wonder what the person is disgusted about as it is less clear
- Insula is engaged in response to facial expressions of disgust with greater personal/interpersonal value to observer
9
Q
What is the relationship between moral disgust and the insula
A
- Moral disgust also activates the insula
- Ppts read statements in scanner related to pure/moral disgust and neutral
- No evidence of pure disgust statements eliciting activity in insula
10
Q
What is the role of the insula beyond disgust?
A
- Involved in self-awareness inc bodily states inc pain/empathy
- Viewing others in pain elicits insula activating but modulated by interpersonal relationship between observer and expresser
11
Q
What is anger?
A
- Show people facial expressions of anger in the scanner = more anger = greater response in orbital frontal cortex
- Orbitofrontal cortex has a lot of other riles e.g computing current emotional value of stimulus
- Also integrates info from ventral striatum and amygdala with context, allows for flexible changes in behaviour to stimuli that have become devalued
- Lesions in OFC cause difficulties in reversal learning and socially inappropriate behaviour - but can still recognise anger
12
Q
What was a study looking at anger as a neural substrate in the ventral striatum?
A
- Patients with focal lesions affecting VS have impairments in recognsiing anger from diff modalities
- Tested across diff emotion recognising tasks against controls with patients with lesions affecting dorsal striatum
- VS group have impairment in recognising anger across modalities
13
Q
What is the role of dopamine in anger?
A
- VS is part of reward-processing region with dopamine channel
- Non-human studies show altered dopamine activity during aggressive encounters
- STUDY: administered ppts with dopamine receptor blocks so dopamine cannot act = found transient reduction in ability to recognise angry facial expressions
14
Q
What is the MAOA gene risk factor in aggression?
A
- Genetic basis for individual diff in aggression
- Dutch family with strong history of violence = because of MAOA gene = codes for enzyme to metabolise dopamine
- Coded on x chromosome = larger effect on men
- Low activity variant (L)= less enzymes = more neurotransmitters in synapse to metabolise the synapse
L-carriers have smaller grey matter volume in anger processing = increased activity in amygdala in angry faces
15
Q
What about other emotions in the brain?
A
- Most research concerned with 6 basic emotions
- Basic emotions should have their specific neural basis
- Emotions are much more complex than the 6 basic ones e.g shame
