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- Investigate whether violent criminals had brain dysfunction in areas of the brain.
- Compare a group of murderers with a control group of non-murderers using brain scans.
- Murderers plead not guilty by reasons of insanity.
- Hypthosesised that no dysfunction would be found in caudate, putamen, globus pallidus, midbrain, cerbellum.
- Would not have dysfunction in areas implicated in mental illnesses, not previously related to violence.
- Scans may help us identify indviduals before they commit a crime.
- Previously thought by Lombosso that criminals have distinguishable facial features - discredited.
- First study to use brain scans.
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- Quasi-experiment - matched pair designs. Opportunity sampling.
- Participants - 41 murderers, 39 men, 2 women. Mean age - 34.3 years.
- IV - NGRI, DV - brain differences. All charged with murder/manslaughter.
- University of California examined, obtained proof of diminished capacity.
- Schizophrenia - 6, head injury/organic damage - 23, psychoactive drug abuse - 3, epilepsy - 2, hyperactivity/learning disorders - 3, personality disorder - 2, affective disorder - 2.
- Participants - medication free, checked with urine sample 2 weeks prior.
- Control group - matched each murderer with normal individual - same sex. 6 schiozphrenics matched with 6 from mental hospital. other controls no history of psychiatric illness or in any relations.
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- PET Scans - Positron Emission Tomography
- FDG - radioactive glucose tracer injected 30 seconds into procedure. Chance to practice before injection.
- Scans performed 32 minutes into CPT.
- Brain uses glucose for energy - more active parts use more glucose.
- All participants asked to do a continuous performance task specifically aimed to activate target areas of brain.
- Horizontal slices of brain recorder using cortical peel and box technique. 10 slices.
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- Both groups performed similarly. Any differences in activity not due to performance on test.
- Murderers - significantly lower glucose metabolism in prefrontal cortex - both hemispheres.
- Reduced activity in left angular gyrus and corpus callosum. Reduced activity in amygdala, thalamus, hippocampus - only in lefy hemisphere. - Areas previously linked to violence.
- Cerebellum and occipital lobe - higher glucose metabolism - more activity.
- No significant differences for amount of midbrain, caudate, putamen, globus pallidus, cerebellum activity between murderers and controls. Parts of brain not involved in violence.
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