Explanations of aggression: Brain structure and functioning

What is the main structure of the brain?

The brain is decided into 2 hemispheres, joined by the corpus callosum. The left hemisphere controls the right side of our body whilst the right side controls the left side of our body.

What is the cerebral cortex divided into?

4 lobes - each responsible for specific functions and behaviours

What is the frontal lobe?

The location for awareness, rational thinking and impulse control.

What is the parietal lobe?

The area of sensory perception and integration. Awareness of somatic sensation and processing. Involved in cognition, speech and writing.

What is the occipital lobe?

The area responsible for visual perception, including colour, form and motion of objects. Involved in distance and depth perception as well as voluntary muscle movement.

What is the temporal lobe?

The area associated with auditory ability and memory acquisition as well as object and facial recognition, language and understanding expression, emotional processing and reaction.

What is the broca’s area?

Involved in speech production. Damage causes aphasia - slow, influent speech

What is the wernicke’s area?

Area involved in understanding of language. Damage causes fluent but meaningless speech.

What is aggression?

Behaviour intended to cause psychological or physical harm.

What happened to Phineas Gage?

He had a large iron rod driven through his head, damaging his left frontal lobe. Fundamental changes were noted to his personality, for example, he became more aggressive.

What is the prefrontal cortex?

An area of the brain that sits right behind the forehead. It is influential in governing social interaction and regulation of behaviour. The ability to delay gratification of an impulse is associated with this area as well as learning from consequence. Damage to this area (resulting in less activity) often leads to problems with anger management, irritability, and impulse control. This can lead to increased aggression as the individual will have a lack of self control and an inability to recognise the negative consequences that aggression will cause.

What is the hypothalamus?

The role of the hypothalamus is the maintain homeostasis through the regulation of hormones, including those that regulate sexual function. This is linked to aggressive behaviour via the production of testosterone - increased testosterone can increase the levels of aggression seen in an individual, The amygdala will also stimulate the hypothalamus if a threat is perceived, which triggers the body’s flight-or-fight response.

What is the amygdala?

The centre for emotional behaviour and motivation. It plays a central role in how an organism assesses and responds to threats and challenges as a part of the fight or flight response. If there is a perceived threat this may lead to the expression of aggression to protect yourself. However, if there is dysfunction in this area then harmless events may be interpreted as a threat, producing aggressive responses.

Strength of the theory?

There is supportive evidence for the idea that brain structure links to aggression. Raine (1997) found that the brains of murderers and non-murderers looked different.

Weakness of the theory?

Research on this area is mainly correlations, as ethically we cannot conduct experiments on humans to aggravate their aggression levels or damage parts of their brain to investigate the effects. This is a weakness heavyset it is therefore not possible to include that it is specifically brain structure which is the cause when aggressive behaviour observed. Therefore, we cannot establish a cause and effect relationship, other factors (eg- the environment) may have an influence on aggression.