Discuss the role of Neural and/or hormonal mechanisms in aggression:
The neural mechanisms that are most associated with aggressive behaviour are neurotransmitters. Neurotransmitters are chemicals that allow impulses in one area of the brain to be transmitted to another area. Two neurotransmitters are believed to be important in the control of aggressive behaviour; serotonin and dopamine. It is thought that Low levels of serotonin and high levels of dopamine are associated with aggressive behaviour.
Serotonin is a neurotransmitter that, when it is at a normal level in the body, exerts a calming, inhibitory effect on neural firing in the brain. However, when levels of serotonin are low, particularly in the pre-frontal cortex, this inhibitory effect is removed, with the consequence that individuals are less able to control their impulsive aggressive behaviour. Serotonin works in the frontal parts of the brain to inhibit the firing of the amygdala, the part of the brain that controls fear anger and other emotional responses. However if there is less serotonin in these areas, there is less inhibition of the amygdala. As a result, when the amygdala is stimulated by external events, it becomes more active, causing the person to act on their impulses and making aggression more likely.
Although not as well established as the link with serotonin, there is some evidence that dopamine does have some influence on aggressive behaviour, with increases in dopamine being associated with increases in aggressive behaviour. Recent evidence with mice (Couppis et al 2008) suggests that the brain appears to see aggression as a reward. According to this view, whenever we perform an activity that we find rewarding the brain releases higher level of dopamine. When this dopamine attaches to receptors in the brain, it creates a pleasure circuit, which the individual finds reinforcing. The person is thus motivated to repeat the actions that led to the dopamine increase, which may then make aggressive behaviour more frequent.