Presentation on theme: "Brain Abnormalities in Murderers Indicated by Positron Emission Tomography. Adrian Raine, Monte Buchsbaum, and Lori LaCasse 1997."— Presentation transcript:
Brain Abnormalities in Murderers Indicated by Positron Emission Tomography. Adrian Raine, Monte Buchsbaum, and Lori LaCasse 1997
Physiological Psychology The central question: 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 §Discussion points §What are the advantages to the physiological explanation of behaviour? §What are the disadvantages? §Why is this approach described as determinist? §How else can violent behaviour be explained?
Physiological Psychology - Raine § The Raine hypothesis §That the seriously violent individuals have localised brain damage in the prefrontal cortex; the amygdala; the thalamus; the hippocampus;
Physiological Psychology - Raine
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).
Raine suggests three reasons why 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.
corpus callosum (cull low' sum) It is an enormous bundle of axons which interconnects the left and right cerebral hemispheres. Therefore, it is a commissure. It disseminates information from the cerebral cortex on one side of the brain to the same region on the other side.
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.
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/USA §All pled NGRI §All were referred for physiological examination
Physiological Psychology - Raine §CONTROL GROUP §41 normal individuals (non murderers) §matched for sex and age §including 6 ‘murdering’ schizophrenics who were matched with 6 ‘ non murdering’ schizophrenics
Physiological Psychology - Raine §The method §A ‘natural’ experiment §The procedure §PET Scans to examine the brain
Physiological Psychology - Raine §What is a PET SCAN? §Positron Emission Tomography §This 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
A typical PET scan
Physiological Psychology - Raine §THE RESULTS §DIFFERENCES in the brains of the murderers §CORTICAL REGIONS §LOWER ACTIVITY
Physiological Psychology - Raine §THE RESULTS §DIFFERENCES in the brains of the murderers §SUBCORTICAL REGIONS §LOWER ACTIVITY
Physiological Psychology - Raine §THE RESULTS §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
Physiological Psychology - Raine §THE RESULTS §Both groups performed similarly on performance task §NOT CONTROLLED §6 murderers were left handed §14 murderers were non white §23 murderers had history of head injury
Physiological Psychology - Raine §DISCUSSION POINTS §Pre Frontal deficit - associated with impulsivity §Hippocampus & 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 §CONCLUSION §Unlikely that violence is due to a single brain mechanism §Evidence 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 sample §Significant results (non trivial) §Two tailed tests §Areas of brain selected based on previous research §Could 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?
Interventions §Raine 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.