raine et al (1997) brain abnormalities in murderers brain abnormalities in murderers indicated by...
TRANSCRIPT
Raine et al (1997) Brain abnormalities in murderers
Brain abnormalities in murderers indicated by positron emission tomography
Biological Psychiatry 42 495-508
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in
murderers
Introduction • is there a biological basis for criminality? • PET scans • radioactive labels on: • blood/blood sugars • dopamine (neuro-transmitter) gamma ray signals • 7-8M ps • also MRI and fMRI
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
PET scans showing ‘hot spots’ for cognitive activities
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
introduction: problems • colourisation v complex errors • 'hot spots' same for 'on & 'off' brain actions• practiced brain activity declines in that area 'hottest spots' = only for newest tasks? • "it seems we should not let the quality of
evidence get in the way of a good story" Banyard and Grayson 2000
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
PET scan of a subject whilst practicing a new language skill
A scan of the same subject demonstrating
this skill after it had become familiar
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
the study: subjects
• 41 people: 39M 2F
• charged with murder
• pleading not guilty by reason of insanity (NGRI)
• all referred for PET for legal reasons
• average age 34.3
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
the study: subjects’ medical histories • schizophrenia 6 • head injury/organic brain damage 23 • drug abuse 3 • affective disorder 2 • epilepsy 2 • hyperactivity or learning disorder 3 • personality disorder 2
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
the study: controls
• 1 for each subject
• matched for age / sex
• schizophrenics with non-murderer schizophrenics
• all controls screened for mental/physical health
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
the study: the PET process • injection with glucose tracer • 32 mins on target recognition task • NRGI/controls compared re 14 L&R brain areas • 6 cortical: • inc prefrontal; parietal; temporal; occipital • 8 sub cortical: • inc corpus callosum; amygdala; hippocampus
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
the study: ANOVA
• statistical comparison
• ANalysis Of VAriance
• compares a range of factors
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
results: cortical areas
• differences in activity in lobes of cerebral cortex cf controls;
• parietal & pre-fontal: less activity =?
• occipital: more activity =?
• temporal: same =?
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
results: sub cortical areas
• less activity in corpus callosum cf controls
• a sub-cortical area =?
• cf Sperry
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
results: sub cortical areas • imbalance between hemispheres cf controls in;• amygdala; hippocampus – less activity L /
more R• thalamus - more activity R / same L• handedness made no difference • ethnicity made no difference • head injury patients’ corpus callosum only
difference
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: authors (1)• supports previous findings; 1. amygdala (part of limbic system)
differences (linked to emotions; lack of fear)
2. corpus callosum differences linked to lack of long term perspective?
• cautious about implications
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: authors (2) • results; • do not show violence is only biological in origin • do not show NGRIs not responsible for their
own actions • do no say anything about causes of differences • cannot be generalised from NGRIs to other
violent offenders • cannot be generalised to other types of crime
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: other issues • imaging methods still being developed • pre-scan task no bearing on violent
behaviour • NGRIs not necessarily charged with
violent act • cause effect of brain differences
unclear
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: practical applications
• diagnosis of criminality?
• no clear evidence to support this
• treatment of criminality
• no clear evidence to support this
Mark
Sou
ter
psy
chlo
tron
.org
.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: summary
• data unclear
• differences small
• cause-effect unknown
• meaning of differences unknown
Mark
Sou
ter
psy
chlo
tron
.org
.uk