Neural and Hormonal Mechanisms in Aggression

Biological psychology proposes that aggression has physiological underpinnings involving specific brain structures, neurotransmitters, and hormones. This lesson examines the roles of the limbic system (particularly the amygdala and hypothalamus), the neurotransmitter serotonin, and the hormone testosterone in explaining aggressive behaviour. Throughout, we consider the strengths and limitations of biological explanations.

Key Definition: Aggression is behaviour directed towards another individual with the intention of causing harm. It may be hostile (driven by anger, aimed at causing pain) or instrumental (goal-directed, a means to achieve an objective).

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The Limbic System

The limbic system is a group of interconnected brain structures located deep within the temporal lobes and beneath the cortex. It plays a central role in emotional processing, motivation, and behaviour — including aggression.

The two structures most strongly implicated in aggression are the amygdala and the hypothalamus.

The Amygdala

The amygdala is an almond-shaped structure in the temporal lobe. It is involved in processing emotions — particularly fear and aggression — and in the formation of emotional memories.

Evidence from animal studies: