Classical evidence: Rain et al Brain abnormalities in murderers indicated by PET scans Flashcards
What did rain want to do?
-Look at weather there was physical differences between criminals and non criminals
Lombroso on criminals?
Criminals had narrow sloping forehead with large ears and protruding chin
Aims of study?
-Look at direct measures of both cortical and subcortical brain function with PET scans
-Looked at a group of murders who pled not guilty by insanity
-Was thought that murders would show evidence of brain dysfunction in prefrontal cortex as well as other areas linked to violence
What is cortical?
On the cortex e.g. lobes, motor cortex and Broca’s area
What is subcortical?
Below the cortex, e.g. limbic system, thalamus and hypothalamus
Expectations of raine?
Dysfunctions expected in the prefrontal cortex, angular gyrus, amydyla, hippocampus, thalamus and the corpus callosum
-Not in caudate, putamen, globus pallidus, midbrain, cerebellum
Methodology- research methods?
Quasi- naturally occurring iv (iv NGRI murders)
PET scans- radioactive racer and glucose showing brain activity, brain scanning technique to identify areas of brain
Methodology- Experimental technique?
Matched pairs
2 people in control group matched on age sex or mental health
Methodology- Sampling method?
Opportunity sampling
Murders referred to the university of california to prove mental impairment
Methodology- sample
82 p’s
mean age 34.3
Methodology- sample detail?
6 schizophrenics
23 head injury’s or organic brain damage
3 with substance abuse
2 affective disorder
2 epilepsy
3 hyperactivity and learning disorders
2 passive aggressive or paranoid disorder
Methodology- sample iv?
41 murders
39 men
2 women
Methodology- control group?
41 ‘normal adults’ matched on age, sex and mental health
Procedure- step 1?
CPT practice trials given for 10 mins (click when u see a dot)
Procedure- step 2?
30 secs later radiocative tracer (FDG) injected
Delay intended to avoid task novelty effect
Procedure- step 3?
Each PET was conducted after 32 minutes from the injection
producing 10 horizontal, cross sectional images of the brain
The scan analysed 6 cortical areas and 8 subcortical areas
Procedure- step 5?
PET scan of murders compared to control group
Findings-
Prefrontal cortex, what is this, the activity and findings?
-Regulayion of thoughts, actions, emotions
-Lower activity
-Lower glucose metobalism to controlls in later and mmedial prefrontal areas
-Supporting conclusion
Findings- Angular gyrus?
Reduced in left hemesphere
-Explains low iq and poor preformance in school
-Supports hypothesis but didnt expect asymetry
Findings- Hippocampus (limbic system)?
Hemerspheric aysmetry
-Reduced in left increased in right
-Explains lack of inibition of agression
-Partialy supports conclusion
Findings- Corpus collosum?
This is the tissue connecting the hemespjeres meaning hemespheres not connecting effectivly
-Reduced actibity
Findings-
Amydgala (limbic system), what is this, the activity and findings?
Processing centre for emotions
-Lower and higher activity
-Reduced activity in left amygdala and greater activity in right amygdala compared to to controls (Hemispheric asymmetry)
-Supports conclusion
Findings-
Thalamus (limbic system), what is this, the activity and findings?
Information relay station from sence, explaining failure to learn from experiences
-Higher activity in right
-Less activity in left
-Supports conclusion
Findings- cerebellum?
Increased activity not supporting hypothesis
Findings-
Caudate, putamen, globus pallidus, midbrain what is this, the activity and findings?
Learning and memory’s
same activity
Slightly higher than controls but all non significant
-Supports hypothesis
3 conclusions?
-Reduced activity in areas of the brain associated with violence
-Biology should not be used alone to explain violent predispositions
-Findings are specific to NGRI murderes only
Conclusion- -Reduced activity in areas of the brain associated with violence?
Murdered pleading NCRI have statistically difference in glucose metabolism in specific areas of the brain supporting evidence that areas or brain linked to violence
However they don’t conclusively demonstrate brown activity in NGDD murder in areas linked to violence
-Abnormal symmetry, amygdala, thalamus, M+L, hippocampus (However replication further research retinm and less selective sample needed)
Conclusion- biology should not be used alone to explain violent predisposition?
Social external factors also play a part
Even they we have findings, it shouldn’t be used as evidence to not punish them
-Findings establish a casual link, Correlation not causation between brain, dysfunction and criminality
Conclusion- findings are specific to NGRI murdered only?
Cant be generalised as only focusing on brain of NGRI murdered not people
who own up to crime other types of violence (lacks population validity)
-Specificity to violence as oppose to crime, can’t be applied to all crime, variable been established in the inclusion of the non violent criminal group
