Basics:
4 lobes (frontal, temerpal, parietal & Occipital) 2 Hemispheres (left, right)
Prefrontal cortex:
-Responsible for personality expression, planning complex cog behaviours, controls social inhibitions, input to emotional responses and emotional regulation. They are the breaks to aggression as they control social rules.
-Raine: Pre-frontal cortex, murders deemed NGRI had low levels of glucose metabolism compared to control group. Low levels or damage to PFC leads to impulsive, immature behaviour, lack of self-control, altered emotions and behaviour (aggression)
-Phineas Gage- Iron rod driven through his head damaging his PFC altering his personality making him become impulsive, rude, obscene.
-Domasio- suggested damage to this area leads to aggression
Amygdala:
-Controls mostly our fear telling us what is dangerous, responsible for perception of emotions (anger, sadness, fear) Controls aggression too
-Raine: Found in murders NGRI higher glucose levels in right hemisphere of the brain (0.88) while the controls are lower. Higher stimulus to this area leads to aggression and inability to display appropriate emotional responses.
-Bear: stripping amygdala supresses fear in animals and triggers automatic arousal, reducing this leads to fearlessness & lack of emotional response.
-Dainer: Studied Monkeys removing parts of amygdala. Monkeys had reduced visual signals, this meant that they were calm when if they had increased visual signals it meant they were aggressive.
Hypothalamus:
-Responsible for producing body essential hormones which control cells and organs. Hormones govern physiological functions (mood, temperature regulation, thirst, hunger, sex drive)
-Alpers: Studied well liked, mild mannered, middle aged lawyer who developed tumour in his hypothalamus, producing uncharacterised outbursts of aggression.
-Hess: Increased aggression in cats by electrically stimulating hypothalamus, this stimulated hypothalamus attack area (HAA) in cats triggering ‘biting attacks’ Stimulating HAA overrides PFC social rules creating aggression.
| Strengths | Weaknesses |
| Raine – scans on 41 murders NGRI found lower activity on right (0.94) than controls (0.97)– lower glucose region of amygdala lead to it being damage causing aggression
Bear: stripping amygdala supresses fear in animals and triggers automatic arousal, reducing this leads to fearlessness & lack of emotional response. – Abnormalities lead to fearlessness, not restricting aggression. Scientific status – Raine uses pet scan to see regions of the brain which were using glucose correctly – objective data more scientific rigor. Application – research found damage to the PFC can lead to aggression behaviour of impulse, altered emotions & loss of self-control – shows bio reasons for aggression & help develop bio treatment. |
Low generalisability – Raine only used 41 murders pleading NGRI, (39 men, 3 women) so not cover wide range of criminals – only generalise to this group.
Social learning theory – suggests that aggressive behaviour is from watching role models performing such behaviour and individual imitating – looks at nurture aspects of aggression which theory ignores. Reductionist – theory doesn’t look at other factors such as NT, hormones or nurture theories & reduces aggression to brain function – more holistic theory needed. |