Biological theory of aggression – brain structure and brain functioning

What areas of the brain have been found to be involved with aggression?

Prefrontal cortex

Hypothalamus

Amygdala

(Serotonin & dopamine)

1) Brain structure – prefrontal cortex

Where is it?

This part of the Cerebral cortex right at the front of the frontal lobe

What does it do?

Regulates behaviour and governs social interactions. Gives us ability to delay gratification of an impulse by inhibiting (suppressing) messages from the amygdala

Link with aggression

Raine

• Prefrontal cortex has connections to amygdala and the hypothalamus

• Damage to this area often needs to problems with anger Management, irritability and impulse control

What is the evidence to support this?

(Can use raine)

Case study of Phineas Gage

Railway worker – iron rod exploded and blue straight through face and out top of head. People said his personality changed. Damage to prefrontal cortex which caused this.

Problem with this case study

No medical records, Case studies are individual may not be able to use the wider population

2) Brain structure – hypothalamus

Where is it?

Hypothalamus is part of the limbic system

What does it do?

Maintains homeostasis through regulation of hormones, including those regulate sexual function

What is the link with aggression?

In males via the production of testosterone

What is the evidence for this?

Animal experiments using cats – electrical stimulation of the hypothalamus and cats produces an aggressive response including hissing and growling. Stimulation of different parts results in different types of aggression e.g. stimulation to the dorsal hypothalamus (at the back) produce defensive behaviour which is shown by the animal in response to threat or attack.

3) Brain structure – amygdala

Where is it?

Part of the limbic system

What does it do?

Centre of emotions, emotional behaviour and motivation. Integrates internal and external stimuli and every sense of modality has an input, which when combined gives us an addictive feeling or reaction to environment.

What is the link to aggression?

Has central role in how an organism assesses and response to environmental threats and challenges.

Reactivity of a amygdala in humans is proven to be important prediction of aggressive behaviour.

What is the evidence to show this?

Case study of Charles Whitman – Texas shooter a student and ex-marine, fired down from the clocktower killing 14 people and wounding 31. Earlier that day killed wife and Mother.

Suffer suffering feelings of rage, confusion, and violent impulses

He had a tumour which may have pushed against a amygdala

4) Brain function – role of serotonin and dopamine

What does it do?

Normal levels of serotonin in the OFC are associated with a reasonable degree of behaviour self control

Link with aggression

Decreased Serotonin disturbs this and reduces self control which can lead to impulsive behaviours.

Levels of serotonin breakdown lower in violent impulsive offenders.

Serotonin and activity stimulates dopamine overacting and both of these are linked with impulsivity and aggression