neural and hormonal explanation of aggression

• Aggression is any physical or non-physical behaviour that is threatening or intends to harm humans or objects.
• The hypothalamus is involved in producing aggressive behaviour.
• The amygdala determines the emotional meaning of events in the environment and decides whether an event is good or bad.
• If the events are bad or dangerous, then the amygdala sends nerve impulses to the hypothalamus, causing it to produce  aggressive behaviour.
• The hippocampus accesses memories to decide whether an event is threatening.
• The limbic system consists of the amygdala, hypothalamus and hippocampus. The limbic system produces aggressive behaviour.
• The frontal cortex stops aggression by inhibiting neurons in the amygdala. This causes neurons in the amygdala to stop generating nerve impulses being sent to the hypothalamus which prevents the production of aggressive behaviour.
• If a person’s frontal cortex can’t generate electrical signals then they are more likely to be aggressive as their amygdala will not be inhibited and signals will continue to be sent to the hypothalamus.
• Serotonin reduces aggressive behaviour by inhibiting neurons in the amygdala and reducing nerve impulses sent to the hypothalamus.
• Testosterone is a hormone that increases our tendency to be aggressive. Men produce and release more testosterone than women, so are more likely to be aggressive.
• Testosterone is produced and released by the adrenal glands and the sex glands.
• Support for the role of the amygdala in aggression. Sumer et al 2007 conducted a case study into a girl with excessive aggression and found a tumour pressing onto her amygdala causing increased activity in the amygdala and more nerve impulses to be sent to the hypothalamus. This is positive as it supports the neural explanation of aggression.
• Support for role of amygdala in aggression. Mpakopoulou conducted a review of 13 studies where patients with excessive activity in their amygdala and high levels of aggression had an amygdalotomy and found after surgery, patients aggressive behaviour reduced 33 - 100% as the amygdala could no longer send nerve impulses to the hypothalamus. This is positive as it supports the neural explanation of aggression.
• Inconsistency between studies investigating the role of amygdala in aggression. Some studies have found that a damaged amygdala is associated with a decrease in aggression, others have reported an increase in aggression suggesting the role of the amygdala might differ depending on the sub-region of the amygdala. This is problematic as the role of the amygdala may be more complicated than first thought.
• Support for role of serotonin in aggression. Crockett used a social decision-making game to investigate the role of serotonin in aggression and found participants with increased serotonin behaved less aggressively. This is positive as it supports the neural explanation of aggression.
• Support for role of testosterone in aggression. Dabbs et al 1987 conducted a correlational study looking at the relationship between testosterone and violence in prisoners and found a positive correlation between testosterone levels and violence. This is positive as it supports the hormonal explanation of aggression. However, a limitation of this is that it is not possible to establish a cause and effect relationship in correlational studies.
• Neural and hormonal explanations ignore non-biological factors which contribute to aggression. Neural and hormonal explanations ignore environmental and social factors which could consequently lead to increased or reduced aggression. This is problematic because it is a reductionist explanation.