Neural factors into aggressive behaviour: neuronal mechanisms

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Psychology unit 3 aggression
Neural factors into aggressive behaviour- neuronal mechanisms
Description- The Pepez-Maclean limbic theory
Pepez named specific brain structures thought to be involved in aggression. Whilst
some of these have been disproved, animal research suggests that a collection of
brains structures including the amygdala, the hypothalamus and the periaqueductal
grey structure in the brains tem are all connected into a circuit of neurones
influencing aggression. The system is arranged hierarchically so that activity in
the PAG is required for activity in the hypothalamus. The prefrontal cortex
appears to control how we act on our aggressive urges.
/ Potegal found that the amygdala was also involved in aggressive
behaviour in a hamster. During aggressive acts, neurones in the medial
nucleus of the amygdala were more active (no other parts of the brain had
higher activity). This suggests that aggression is linked to activity in the
amygdala. However Potegal suggests that the underlying brain structures of
the amygdala and hypothalamus are similar enough to allow generalisations
between humans and animals. But there is one large difference of the role
of the frontal cortex which is involved in all social behaviour and this may
mediate the aggressive influences of the amygdala and the hypothalamus in
humans. This idea is supported by humans with frontal lobe damage such as
Phineas Gage, who are impulsive and aggressive. Phineas Gage had an
accident which left him being aggressive and impulsive whereas before the
accident he was caring and hardworking.
Flynn used electrodes to stimulate the hypothalamus in cats. When the
lateral hypothalamus was stimulated the predatorial aggression was present
but when the medial hypothalamus was stimulated vicious aggression was
present. This shows that the hypothalamus is involved in different types of
/ Research has found that humans can have the amygdala removed in
order to reduce aggression. However, it also means no emotion is felt after
removal either. This shows that the amygdala is involved in aggression in
humans but may also be involved in other emotions as well.


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