Neural

• Limbic system- connects the brain stem to the cortex.

  One of its functions is to control a range of emotional behaviours including aggression.
• Amygdala - important structure in the limbic system associated with aggression.
• Function of amygdala - quickly evaluating the emotional importance of sensory information and prompting an appropriate response including aggression.
• If the amygdala malfunctions in any way due to a tumour, damage or atypical development then aggression may be more likely
• AO3 - Pardini

  Found that participants who had smaller amygdala's than normal showed higher levels of aggression and violence. This supports the idea that if the amygdala isn't working properly - malfunctions lead to aggression.
• AO3 - Kluver and Bucy

  Destroyed the amygdala in aggressive monkeys, resulting in less aggressive behaviour supporting the role of the amygdala in aggression, however this tells us little about human aggression.
• AO3 - against

  The amygdala does not operate in isolation. The orbitofrontal cortex regulates emotional responses driven by the amygdala and damage to the orbitofrontal cortex results in impulsivitity and loss of control. Suggests the limbic system is not the only area of the brain involved in aggression.
• 2 neural explanations:

  • Limbic system
  • Serotonin
• Serotonin is a neurotransmitter involved in the communication of impulses between neurone.

  It has a widespread inhibitory effect on the brain.
• Normal levels of serotonin are associated with greater behavioural control as it typically inhibits the firing of the amygdala
• Normal levels of serotonin in the orbitofrontal cortex are linked with reducing firing of neurons and this is associated with a greater degree of behavioural self control.
• Low levels of serotonin are associated with low behavioural control, impulsivity and aggression.
• AO3 - Virkkunen

  Compared levels of waste product of serotonin in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders.

  The levels were significantly lower in the impulsive offenders and they suffered sleep irregularities. Serotonin affects sleep patterns.

  Disturbance of sleep patterns strongly implies some disruption of serotonin supporting its role in reactive aggression.
• AO3 - Baleigh

  Gave different diets to vervet monkeys.

  Tryptophan increases serotonin levels in the brain and the monkeys whose diets was high in tryptophan showed decreased levels of aggression. Those whose diets was low in tryptophan exhibited increase aggressive behaviour.