Biological Psych: Classic Study - Raine et al (1997)

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  • Raine et al (1997)
    • Aim
      • to find out which brain areas were dysfunctional in violent offenders
        • using PET scans
    • Sample
      • 41 criminals with murder/manslaughter convictions
        • 10 had schizophrenia
        • 23 had brain damage/head injury
      • all tested to gain evidence to support NGRI
      • Control group
        • matched pairs
          • age
          • gender
          • psychiatric illness
    • Lab experiment
      • IV
        • whether they had committed murder/manslaughter or not
      • DV
        • results of PET scans
    • Procedure
      • 1. P's performed continuous  performance task (CPT)
        • stare at screen, blurred symbols appear
        • press button when certain symbol appears
        • constant attention (10 mins)
      • 2. Radioactove glucose traker injected
        • flurodeoxyglucose
      • 3. Brains PET scanned
        • After 32 mins of task
        • to look at glucose metabolic rate in brain
        • to look at level of activity in brain areas
    • Results
      • NGRI group had brain dysfunction in areas previously related to violent behaviour
      • Lower levels of brain activity compared to control group in
        • Cortical brain areas
          • Prefrontal Cortex
            • lateral prefrontal
            • medial prefrontal
        • Subcortical brain areas
          • in both hemispheres in corpus callosum
      • abnormal asymmetrical levels of limbic system activity compared to controls in
        • Thalamus
          • right hemisphere higher than controls, left hemisphere same
        • Amygdala
          • right higher, left lower
        • medial temporal lobe
          • right higher, left lower
        • no overall diff in level of activity in amygdala, temporal lobe and thalamus
    • Conclusions
      • lack of functioning in PFC results in reduced ability to regulate the activity of limbic system
        • so less able to control impulsive and aggressive responses to threatening stimuli
      • abnormal functioning of amygdala results in murderers being fearless
        • increased chance of acting violently
      • hippocampus and thalamus related to learning.
        • abnormal functioning - criminals unable to modify own behaviour by learning from actions
      • right hemisphere could negative mood.
        • normally regulated by left hemisphere
          • corpus callosum not as active in murderers compared to controls
            • unable to regulate negative mood and could become more violent

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