brain abnormalities in murderers indicated by positron emission tomography
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Brain Abnormalities in Murderers Indicated by Positron Emission Tomography . Adrian Raine, Monte Buchsbaum, and Lori LaCasse 1997. Adrian Raine. Typical Criminals?. Physiological Psychology . The central question is: - PowerPoint PPT PresentationTRANSCRIPT
Brain Abnormalities in Murderers Indicated by Positron Emission Tomography.
Adrian Raine, Monte Buchsbaum, and Lori LaCasse
1997
Adrian Raine
Typical Criminals?
Physiological Psychology
The central question is:
Can we link physiological process or structure directly to human behaviour?
Physiological Psychology
Research suggests that brain dysfunction may PREDISPOSE a person to being violent
The FRONTAL brain region may be associated with violent behaviour
Some violent offenders plead NGRI (not guilty by reason of insanity) to murder charges
Physiological Psychology - Raine The Raine hypothesis is that some
seriously violent individuals have localised brain damage in certain areas of the brain including
the prefrontal cortex; the amygdala;the prefrontal cortex; the amygdala; the thalamus; the hippocampus; and the the thalamus; the hippocampus; and the
corpuscallosum.corpuscallosum.
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Physiological Psychology - Raine
The frontal lobe It is important for voluntary and planned
motor behaviours - such things as voluntary movement of eyes, trunk, limbs and the many muscles used for speech
The motor speech area (Broca's area) is usually in the frontal lobe of the left hemisphere regardless of which hemisphere is dominant for handedness (i.e. the left hemisphere for right handers).
Frontal Lobes
Frontal Lobes
Raine suggests three reasons why prefrontal prefrontal deficits may cause antisocial personality:•First, the region appears to be critical for self-restraint and deliberate foresight. "One thing we know about antisocials is that they do not think ahead," said Raine.•Second, it’s crucial for learning conditioned responses — essential, for example, to a child’s linking the thought of a misdeed with anxiety over punishment. "Unconscious mental-emotional associations such as these lie at the core of what we call conscience," Raine said.•Third, if prefrontal deficits underlie the Antisocial Personality Disorder (APD) group’s low levels of autonomic arousal, these people may unconsciously be trying to compensate through stimulation-seeking. "For some kids," said Raine, "one way of getting an arousal-jag is by robbing stores or beating people up."
parietal lobe (pa rye' it ul) It is important for aspects of somesthetic
sensation (i.e. touch, kinesthesia, pain), taste, and other sophisticated perceptive abilities.
An example of the latter would be the receptive speech area (Wernicke's area) which is in the inferior part of the parietal lobe on the left side regardless of which hemisphere is dominant for handedness.
The parietal lobe of the right hemisphere appears to be especially important for perceiving spatial relationships.
Parietal Lobe
corpus callosum (cull low' sum)
It is an enormous bundle of axons which interconnects (joins) the left and right cerebral hemispheres.
It disseminates information from the cerebral cortex on one side of the brain to the same region on the other side – it is a communication bridge .
Corpus Callosum
thalamus (thal' uh mus)A large mass of grey matter deeply situated in the forebrain. There is one on either side of the midline. It relays to the cerebral cortex information received from diverse brain regions. Sort of a requisite 'last pit stop' for information going to cortex. Axons from every sensory system (except olfaction) synapse here as the last relay site before the information reaches the cerebral cortex. There are other thalamic nuclei that receive input from cerebellar-, basal ganglia- and limbic-related brain regions.
Thalamus
temporal lobe (temp' or ul)
Various parts of it are important for the sense of hearing, for certain aspects of memory, and for emotional/affective behaviour.
Physiological Psychology - Raine
The participants:41 murderers (39 males 2 females)Charged with murder/manslaughter in
California/USAAll pled NGRIAll were referred for physiological
examination
Physiological Psychology - Raine
The ‘histories’head injury/brain damage(23)drug abuse (3)affective disorder (2)epilepsy (2)hyperactivity & learning impairment (3)personality disorder (2)
Physiological Psychology - Raine
CONTROL GROUP41 normal individuals (non murderers)matched for sex and ageincluding 6 ‘murdering’ schizophrenics
who were matched with 6 ‘ non murdering’ schizophrenics
Physiological Psychology - Raine
The methodA ‘natural’ experiment (quasi) using
independent measures design where participants were matched on key criteria.
The procedurePET Scans were used to examine the
brain
Physiological Psychology - Raine
What is a PET SCAN?Positron Emission TomographyThis method assesses the amount of
metabolic activity in various parts of the brain
A scanning machine detects positrons emitted through the head with high amounts being associated with a higher level of metabolic activity.
Physiological Psychology - Raine
THE PET SCAN process Patients are injected with fluorodeoxyglucose
tracer (radioactive glucose)For about 30 minutes before the PET SCAN
the participants are engaged in a ‘continuous activity’
This activity aimed to activate the FRONTAL LOBES, and the RIGHT TEMPORAL and PARIETAL LOBES
Diagrams from Raine’s research
A typical PET scan
Raine found some significant results
He suggested there was evidence for DIFFERENCES in the brains of the murderers
He found amongst other things LOWER ACTIVITY in some
CORTICAL REGIONS of the brain
SUMMARY OF DIFFERENCES in the brains of the murderers
Reduced activity in prefrontal cortex, parietal region & corpus callosum
Left hemisphere less activity than right
Abnormal asymmetries in amygdala & thalamus
Both groups performed similarly on performance task
There were certain characteristics that were NOT CONTROLLED..i.e
6 murderers were left handed14 murderers were non white23 murderers had history of head injury
Physiological Psychology - Raine
DISCUSSION POINTSPre Frontal deficit - associated with
impulsivityHippocampus & amygdala - associated with
aggressive behaviour & with conditioned emotional responses
Amygdala - reduced activity associated with fearlessness
Corpus Callosum - dysfunction associated with predisposition to violence
Physiological Psychology - Raine
CONCLUSIONUnlikely that violence is due to a single
brain mechanismEvidence that - murderers pleading
NGRI may have different brain functions to ‘normal’ people
Evidence that - murderers have different brain functions to psychiatric patients
Physiological Psychology - Raine
Validity & reliability of the research? Large sampleSignificant results (non trivial)Two tailed testsAreas of brain selected based on
previous researchCould IQ differences be a factor?
Physiological Psychology - Raine
WHAT these findings DO NOT demonstrate
That violent behaviour is ‘caused’ by biology
That murderers are NOT RESPONSIBLE for their actions
That brain dysfunction causes violent behaviour
Physiological Psychology - Raine
WHAT these findings DO demonstrate
That there MAY BE a link between brain activity and a predisposition towards violence which should be investigated further
Physiological Psychology - Raine
Ethics - how might you criticise this study?
Generalisation - can the findings of this study be generalised to all murderers?
Why or why not?
Raine’s findings raise important ethical questions about culpability and free will. "To what extent," he asked, "should we take disordered brain functioning into account as part of the reason for certain types of crime?
Assuming these people are not responsible for their own brain damage, should we hold them fully responsible for their criminal acts?"
Ethics
Physiological Psychology - Raine
Questions Suggest one thing that cannot be
concluded from this study
The conclusions suggest that murderers who plead NGRI are different to 2 groups - which 2 groups?
Physiological Psychology - Raine
Questions Describe the strengths &
weaknesses of the NATURAL experimental method?
What do you think might be the main difficulty in drawing conclusions from PET observed ‘brain activity’?
Physiological Psychology - Raine
Application - how is this study useful?
InterventionsRaine suggested a number of interventions that could
be applied.Cognitive and behavioural therapy and drug therapy
have potential. Biofeedback – training children or adults to control
their own arousal levels – could be a useful tool. And children could be channelled into safe activities
that might satisfy their natural stimulation-seeking and aggressive proclivities.
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