amygdala

• what is the amygdala responsible for?

  basic emotions like happiness, fear, anxiety, aggression.

  • when exposed to threatening stimuli our fight of flight is activated by our amygdala.
• what would happen with an abnormal amygdala?

  • low levels of anxiety/ fear = risk taking behaviour which can result in a criminal act.
  • low levels of amygdala activation = sudden outbursts of unprovoked anger
• case study for amygdala?

  Charles Whitman (1966), Uni of Texas shot Wife and mother, killed 14 people and injured 32 in a mass shooting.

  • autopsy reported a cancerous brain tumour was located in the area of the amygdala
• brain scanning for amygdala?

  Raine (1997), wanted to investigate brain dysfunctions in areas of the brain associated with violence in murderers pleading NGRI

  • 2 groups with 41 participants. did continuous performance task involving Ps staring at a screen and pressing a button when various symbols came up. radioactive glucose tracer injected
  • found decrease in activity of certain areas of brain (PFC) with abnormal asymmetries of activity in structure of limbic system that could predispose a person toward violent behaviour
• results of Raines study?

  • cortical: decrease in brain activity in both hemispheres of the PFC. also decrease in brain activity of parietal cortex.
  • subcortical: decrease in activity of both hemispheres of corpus callosum, abnormal asymmetry of limbic system in thalamus amygdala and hippocampus
• recent research linking amygdala to criminal behaviour?

  • Yang (2009), 27 psychopathic people compared to structural MRI scanner. Found people with psychopathy had lower volumes on both amygdala compared to controls, 17.1% less volume on left amygdala and 18.9% less volume in right amygdala.
  • Pardini (2014), neuroimaging scans on group of 26- year old men. 2 groups of normal/ smaller sized amygdala, found that reduced size was more likely to be aggressive.
• strengths of amygdala?

  • supported by evidence (Raine, Whitman, Yang, Pardini)
  • use of neuroimaging, objective and easy to analyse scams (inter-rater reliability increased)
• weaknesses of amygdala?

  • no direct cause and effect conclusions can be drawn, amygdala doesn't operate alone and is heavily influenced by frontal cortex.
  • studies like Yang, found correlations between amygdala size but no direct links
  • reductionist, only looks into amygdala when other parts of brain may be involved (overlooks complexities of behaviour)