Neural + Hormonal Mechanisms

• neural


  brain
• hormonal


  regulation + production of chemicals in the body
• limbic system


  Amygdala handles emotions -> linked to aggression Studies have reveal the removal of the amygdala results in a reduction of aggression whereas damage to amygdala leads to increased testosterone levels & heightened aggressive behaviour
• hypothalamus


  Responsible for the regulation of the autonomic nervous system which helps us determine our emotional responses to situations/perceived threats

  Damage to hypothalamus is one reason why someone may become aggressive
• serotonin


  Neurotransmitters help to maintain our mood -> when levels are too low, this prevents someone controlling their aggressive behaviour + impulsivity

  When levels are normal in OFC, it leads to decreased neural activity + increased self-control in behaviour

  Decrease or lack of serotonin disrupts this mechanism leads to an increase in impulsivity + aggression - Denson et al

  Virkkunen et al - compared levels of a serotonin breakdown product (5-HIAA) in cerebrospinal fluid of violent impulsive + non-impulsive offenders

  Levels were significantly lower in impulsive offenders
• testosterone


  Men are generally more aggressive than women

  Dolan et al found a positive correlation between testosterone levels + aggressive behaviours in a sample in 60 male offenders in UK maximum security hospitals

  these men most had personality disorders e.g. psychopathy, and histories of impulsive violent behaviour
• progesterone


  evidence suggesting progesterone plays important role in women

  levels of progesterone vary during ovulation cycle + lowest during and just after menstruation

  Ziomkiewicz et al found a negative correlation between progesterone levels + self-reported aggression

  Suggests low levels of progesterone are linked to increased aggression in women
• Strength - research support for role of the brain

  Kluver and Bucy removed parts of the limbic system in rhesus monkeys. They found the monkeys started to demonstrate an absence of emotion and fear, even in response to stimuli they would normally fear. Some of the monkeys also appeared to lose understanding of group hierarchies and were aggressive towards more dominant monkeys in group

  suggests that the limbic system is important in regulating our aggressive impulses and behaviours, and that impairment may be the reason why some people are aggressive
• Strength - able to investigate aggression that's compatible with the aims of science

  For example, Wong et al used MRI scans to investigate neural structures such as the amygdala and found that violent male criminals in Broadmoor hospital had a smaller amygdala than a control group

  This suggests that the brain is influential in aggression and demonstrates the objective and testable way this explanations researches the link between the brain and aggression
• Weakness - could be considered gender bias

  Many of the studies used to support it are only conducted on male samples. This is beta bias and assumes the findings from male samples can also be used to explain female aggression and behaviours.

  This is a limitation because it minimises the differences between men and women and fails to acknowledge differences that would matter. For example, women have higher levels of hormone oxytocin which means they respond to stress & threats in a very different way to males. Just this one hormonal difference along, suggests that men can't represent women in aggression research
• Weakness - criticised for being biologically deterministic

  This means that the explanation assumes that aggression is the result of biological factors that are beyond an individual's control

  This is a limitation since it doesn't acknowledge the role of free will and choice that people have in how they behave. A deterministic view like this suggests people who are aggressive aren't responsible for their behaviour and this could create problems for society and justice