neural mechanisms of aggression

• neural explanation?

  • how brain can affect aggression
  • caused by abnormalities in brain structure/neurochemistry
• limbic system?

  • central part of brain involved in processing emotional responses & made up of multiple components
• which part of limbic system is linked to aggression?

  amygdala
• what happens when amygdala is stimulated?

  causes an aggressive response
• role of pre frontal cortex?

  • mediate limbic system
  • if damaged/communcation between 2 is lost - pfc cannot inhibit amygdala - increases aggression
• abnormality in amygdala?

  • raises level of testosterone making aggressive behaviour more likely
• research into limbic system?

  1. summer 2007
  2. kluver & bucy 1930s
• summer 2007?

  • reported case study of 14 year old girl who had mri scan due to highly aggressive behaviour & epileptic seizures
  • tumour detected in limbic system
  • tumour treated with drugs girl returned to normal levels of aggression
  • shows abnormalities in amygdala do influence aggression levels to increase
  • theory is accurate
  • neural mechanisms do play role in aggression
• kluver & bucy 1930s?

  • removed part of temporal lobes of rhesus monkeys destroying amygdala
  • behaviour changed - kluver bucy syndrome
  • included loss of fear & lower levels of aggression
  • shows limbic system has important influence on aggression
  • amygdala is responsible for aggression as when removed aggression decreases
  • neural mechanisms do play role in aggression
• serotonin?

  • mood regulatory neurotransmitter
  • inhibitory effect on brain
  • imbalance of serotonin impacts levels of aggression
  • debate whether low levels of serotonin increase aggression levels/vice versa
• serotonin & prefrontal cortex?

  • serotonin known to be main form of communication between pfc & amygdala
  • if serotonin levels low means pfc unable to inhibit amygdala leading to aggressive behaviour
• research into serotonin?

  1. cherek 1996
• cherek 1996?

  • found that when men take ssri drugs which increases serotonin levels they displayed low levels of aggression
  • shows neural mechanisms do play role in aggression
  • high levels of serotonin reduce aggression/lower levels increase aggression
  • furthering argument that imbalance of neurotransmitter can alter behaviour
  • aggression has physical cause
• 2 * of neural mechanisms?

  1. evidence to support from delgado
  2. empirical evidence from charles whitman case study
• 2 X of neural mechanisms?

  1. contradictory theory that it has social psychological cause
  2. biologically deterministic
• * evidence to support from delgado?

  • stimulated hypothalamus (part of limbic system) of monkeys with mild electric cuurents & found they attacked other monkeys
  • shows limbic system as whole plays role in aggression
  • works holistically to govern our emotions
  • when stimulated leads to increase in aggression
• * charles whitman case study?

  • 1/8/66 former US marine killed 16 & wounded 32 pople - fired rifles/shot gun/handguns from 28th floor observation deck of tower of uni of texas & later shot by police
  • autopsy - brain tumour in region of amygdala
  • bouts of intense rage before & admitted to overwhelming periods of hostility with minimum provocation
  • supports role of neural mechanisms
  • shows when damage present within l.s unable to regulate emotional responses - results in aggression/violent acts
  • was rage alone sufficient - systematically planned violence first on fam members & random members of public
• X contradictory theory of social psychological cause?

  • slt suggests instead of being down to innate biological factors aggression explained in terms of environmental exposure
  • beleives its a learnt behaviour developed through observation & imitation of aggressive role models - vicariously reinforced
  • ignores role of environment
  • may be best to look at aggression from more holisitic pov & take into account environmental factors - learning
  • interactionist apprach more appropriate
• X biologically deterministic?

  • pro: cause & effect so empirical & used to develop practical applications to treat aggression
  • allows us predict & prevent future behaviour eg identify whos at risk look at levels of nt & meds to prevent imbalance
  • con: implies that aggression caused by brain chem/physical structure - out of our control/not in free will
  • potential socially sensitive - criminals being absolved - less responsible for crimes due to brain structure/chem
  • may upset/offend victims/families
  • feel removal of blame minimises significance of trauma
  • excuse/normalise aggression in others