Amygdala and sz Flashcards
What is the amydala?
a structure in the brain
What is the amgdala made up of?
- ‘grey matter’- a collection of neuron cell bodies densely packed together into a cluster of 13 nuclei
Where is the amygdala located?
- medial temporal lobe
What system is the amygdala part of?
- the limbic system
How many amygdalae are there in the brain?
- 2- one in each hemisphere
Who first implicated the amygdala in emotional behaviour?
- James Papez (1937) later Paul Maclean (1952)
What is the amygdala neurally linked to?
- the hypothalamus, hippocampus, and prefrontal cortex
What does the amygdala have an influence on?
brain functioning + behaviours associated with emotion, motivation, and social interaction in both humans and non-human animals
it also plays a major role in how we assess and respond to environmental threats, hence its importance in determining aggressive behaviour
Coccaro et al (2007)
studied people with IED (a symptom of which is outbursts of reactive aggression)
each participant viewed pictures of faces whilst having an fMRI scan of their brain
there was a key difference between these participants and non-IED controls
the IED participants showed high levels of amygdala activity when they viewed angry faces, showing an association between amygdala activity + processing of aggressive emotions + the study had high realism as an angry facial expression is an everyday signal of threat
How can a dysfunction of the amygdala affect fear conditioning?
as children we learn to inhibit our aggressive and antisocial behaviours through fear conditioning- we learn that aggressive behaviour leads to punishment or other negative outcomes
the amygdala is involved in fear conditioning and processing fear information, so a dysfunction of the amygdala means the child can’t identify the social cues that indicate threat + therefore doesn’t link punishment to their aggressive behaviour
fear conditioning is disrupted, so the outcome is that individual with the amygdala dysfunction seems fearless, overly aggressive, and antisocial
Gao and colleagues (2010)
longitudinal study of 1,795 participants, tested for fear conditioning at the age of 3 years
used physiological arousal (indicated by sweating) in response to a painful noise
20 years later, the researchers found out which participants were involved in criminal behaviour + those who had committed crimes at 23 years had shown no fear conditioning when they were 3
How does amygdala dysfunction cause psychopathy?
it responds to signals of distress in other people, so normal amygdala activity inhibits antisocial behaviour
once we realise that someone is distressed, this usually stops us from behaving aggressively towards them
however, the amygdala dysfunction in psychopaths means this inhibitory mechanism is disrupted, so they are able to make impulsive decisions, behave aggressively, and become involved in criminal behaviour without guilt or remorse
Glenn et al (2009)
found that reduced size of the amygdala were found in psychotic individuals and saw a reduction in moral decision making
How does Gospic et al (2011) support evidence for the role of the amygdala? -
used the ultimatum game where two players (Proposer and Responder) have a sum of money, and the proposer offers to split the money fairly or unfairly
the unfair offer is suppose to be a social provocation
if the responder accepts the fair offer, the money is split fairly, but if they accept the unfair offer neither player receives the money
a rejection of an offer is deemed aggressive behaviour
responders all underwent fMRI scans whilst playing, an it was found that amygdala activity was heightened + quicker when responders rejected unfair offers
a sedative drug was also given before the study that reduced aggression + reduced amygdala activity
How does the longitudinal Pardini (2014) study support evidence for the role of the amygdala?
high levels of aggression over the 20-year time period were associated with lower amygdala volumes + continued in a follow-up study 3 years later
all confounding variables were controlled in this study
evidence of predictive validity of the explanation
How can other brain areas be seen as important?
- the amygdala doesn’t operate on its own to determine aggressive criminal behaviour
it functions together with the orbitofrontal cortex which is thought to influence self-control
How does Raine et al (1997) prove that other brain areas are important?
murderers who had used used an overwhelming degree of reactive aggression in their crimes had a greater glucose metabolism in their amygdala, but abnormally low metabolism in the prefrontal cortex (which includes the OFC)
this shows how complex the regulation of aggressive criminal behaviour is, as it involves at least 3 important brain structures: the amygdala, the OFC, and the neural connection between them
How are the effects of the amygdala indirect?
it has a role in regulating fear and anxiety–related behaviours, e.g. the physiological arousal that accompanies the fight-or -flight response
damage to the amygdala affects the ability to process fear + anxiety related information normally, which in turn affects social functioning . This makes aggressive behaviour more likely but not inevitable
therefore, amygdala dysfunction is rather a risk factor for criminal behaviour than a direct cause of it + it is dependent on environmental and other biological factors
How does Gesch (2002) show that diet can cure amygdala dysfunction?
some prisoners were given capsules containing nutrients like vitamins, minerals, and omega-3 fatty acids
the other participants received a placebo
after 2 weeks, the active intervention group committed 35% fewer disciplinary offences on average than they had before the trial began + committed 26% fewer offences on average than the placebo control group
