15.1.1 Neural & Hormonal Mechanisms in Aggression

Aggression:

Aggression: A physical or non-physical behaviour that is threatening or to harm other people or objects

Neural and hormonal mechanisms in aggression

The Limbic system:

The Limbic system is made up of the hypothalamus, amygdala and hippocampus

These three brain regions work together to produce aggression

Limbic system structures that are implicated in aggressive behaviour.

The role of the hypothalamus in aggression:

Hypothalamus: Produces aggression

Amygdala: Decides whether an event in the environment is good or bad

The amygdala helps the hypothalamus to detect danger by determining the emotional meaning of events in the environment (whether an event is good or bad).

• If an event is perceived as dangerous, the amygdala sends nerve impulses to the hypothalamus, causing it to produce aggressive behaviour

Evaluation - the Amygdala:

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The role of the hippocampus in aggression:

Hippocampus: Accesses memories to decide whether an event is threatening

The hippocampus stores long-term memories. When something happens nearby in our environment, the hippocampus sends information about relevant memories via nerve impulses to the amygdala.

This information helps the amygdala decide the emotional meaning of the event.

• If an event is perceived as dangerous, the amygdala sends nerve impulses to the hypothalamus, causing it to produce aggressive behaviour

The role of the frontal cortex in aggression:

Frontal cortex: Stops aggression in inappropriate situations

It does this by sending electrical signals that inhibit neurons in the amygdala, causing them to generate fewer nerve impulses, which stops the amygdala from sending nerve impulses to the hypothalamus, preventing aggressive behaviour.

E.g. If someone's frontal cortex is damaged, neurons in their amygdala will not be inhibited, so will continue sending signals to the hypothalamus. Thus, they are more likely to be aggressive.

The role of neurotransmitters in aggression - Serotonin:

Serotonin: A neurotransmitter that reduces aggression

Serotonin inhibits neurons in the amygdala, so it reduces nerve impulses sent to the hypothalamus. Thus, serotonin reduces aggressive behaviour

E.g.

• The more serotonin we have, the less likely we are to be aggressive
• The less serotonin we have, the more likely we are to be aggressive

Evaluation – Serotonin:

The role of hormones in aggression - Testosterone:

Testosterone: A hormone that increases our tendency to be aggressive

Hormones are chemical messengers released by glands into the bloodstream.

E.g. The more testosterone that is released, the more aggressive you are.

• Testosterone is released by the adrenal glands and sex glands (testes and ovaries)
• Men produce more testosterone than women so they are more likely to display aggression than women

Evaluation – Testosterone:

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Evaluation – Neural and hormonal explanation