Neurophysiological & Neurochemical Explanations

• what is localisation of brain function?

  the idea that certain area of the brain have specific functions e.g. frontal lobe associated with decision making and reasoning
• what behaviours would be seen in someone with antisocial personality disorder (ATP)?

  • lack of empathy
  • reduced emotional responses
  • criminal/offending behaviour
• what did Adrian Raine identify in studies of the APD brain?

  • many brain-imaging studies that demonstrated individuals with APD have reduced activity in the prefrontal cortex, which regulates emotional behaviour
  • Raine et al (2000) also found 11% reduction in volume of grey matter in prefrontal cortex of people with APD compared to controls
• what is the amygdala responsible for in relation to criminal behaviour?

  • the amygdala is part of the limbic system, which is seen to have some sort of survival benefit
  • the amygdala in particular has been identified as a structure with links to emotion regulation and aggression
  • this suggests higher activation in amygdala can result in more aggressive behaviour and inappropriate actions, due to increased fear response
• why are mirror neurones unique?

  mirror neurones are unique because they fire both in response to a personal action and in response to the actions of others

  • these special neurones may be involved in social cognition, allowing us to interpret the intention and emotions of others
  • criminals may have low activity of mirror neurones or a lack of them, causing them to be unable to feel empathy e.g.
• what does research suggest about offenders with APD?

  that they can experience empathy but more sporadically, arguing therefore that those with APD are not completely without empathy, but may have a neural 'switch' that can be turned on and off, in contrast with a 'normal' brain which has empathy switch permanently on
• what was the aim of Raine et al (1997)?

  To identify brain regions specific to offenders charged with murder or manslaughter, who had pleaded not guilty by reason of insanity
• what was Raine et al (1997) method?

  • The participants were 41 murderers (2 female) who had been charged with murder or manslaughter and had pleaded not guilty by reason of insanity.
  • The researchers used a (positron emission tomography) PET scanning method to highlight areas of brain activity and these results were compared to an age and gender matched control group.
• what were the results of Raine et al (1997)?

  • They found reduced activity for the offender group in areas such as the prefrontal cortex and corpus callosum (the nerve fibres responsible for swift communication between the hemispheres).
  • Additionally, there were abnormalities in the activity of the limbic system, including the amygdala and thalamus.
• what were the conclusions of Raine et al (1997)?

  • indication that offenders (specifically violent offenders) have abnormal brain function when compared to normal controls.
  • As there is largely reduced activity, it would suggest that the brains of offenders are slowed and perhaps unable to make the swift decisions to react appropriately in certain situations.
  • e.g. the frontal lobes are linked to planning behaviour; therefore, perhaps the decreased prefrontal cortex activity indicates that offenders are unable to consider the consequences of their actions and control their behaviour.
• what evidence is there to contradict the idea of low amygdala activation causing aggressive behaviour?

  • Potegal et al (1996) found that the stimulation of the amygdala in hamsters led to pronounced aggressive behaviour.​
• what are some evaluation points about Raines study?

  • proportionally small and uneven ratio of females to males in sample, so can't generalise
  • objective, scientific methods for measuring brain activity (PET scanning) gives study high internal validity
  • use of matched control group gives high validity as comparison and causation can be clearly seen
• what is some other evidence for neurophysiological explanations?

  • Evidence for the link between crime and the frontal lobe.
  • Kandel and Freed (1989) found that people with damage to the frontal lobe including the prefrontal cortex (associated with planning behaviour) tended to display antisocial behaviour such as: Impulsive behaviour, Emotional instability, Inability to learn from mistakes.
  • This supports the idea that brain damage may be a causal factor in offending behaviour.
• what is a neurotransmitter?

  chemical messengers in the body, transmitting signals from nerve cells to target cells helping to regulate bodily functions e.g. heart rate
• what studies are about serotonin being linked to mood and impulsivness?

  •  Moir and Jessel (1995) cite a number of human and animal studies which suggest a link between low levels of serotonin and aggression, which is linked to criminal behaviour
  • Scerbo and Raine (1993) conducted a meta-analysis on 29 pieces of research into anti-social adults and children, finding in all cases, low levels of serotonin.
• what is dopamine related to?

  Dopamine has been identified as it is linked to pleasure, which is a rewarding feeling and a desire to repeat certain behaviours.