biological theory of aggression: brain structure

Question 1

prefrontal cortex
where is it?

Answer 1

• it is the part of the cerebral cortex right at the front of the frontal lobe.

Question 2

what does the prefrontal cortex do?

Answer 2

• regulates behaviour and governs social interaction.

Question 3

PFC link with aggression

Answer 3

• it has connections to the amygdala and hypothalamus.
• damage to this area often leads to problems with anger management, irritability and impulse control.

Question 4

evidence PFC: case study of Phineas gage

Answer 4

• railway worker in usa in 1848
• he suffered an accident when an iron rod set off an explosive and it blew straight through his face and out the top of his head.
• for the last years of his life, people say his personality changed as he became aggressive and irresponsible.
• it was the damage to his pfc which caused this.

problem with case study like this:
we can’t generalise

Question 5

amygdala - where is it? what does it do?

Answer 5

• part of the limbic system
• centre for emotions, emotional behaviour and motivation

Question 6

amygdala link with aggression

Answer 6

• it integrates internal and external stimuli and every sensory modality has an input, which when combined gives us an instinctive feeling or reaction to the environment that includes aggression.
• the prefrontal cortex connects to the amygdala and the connection may lead to expression of aggression

Question 7

evidence for amygdala: case study of Charles Whitman

Answer 7

• texas tower shooting 1966
• Charles fired down from the clock tower on the campus of uni of Texas, killing 14 and wounding 31. on same day he killed wife and mother.
• he was suffering from feeling of rage, confusion and violent impulses - he journaled it.
• he had tumour which may have been pushed against the regions of the amygdala.

Question 8

hypothalamus - where is it, what does it do?

Answer 8

• part of limbic system
• maintains homeostasis ( stability of the body)

Question 9

hypothalamus - link with aggression

Answer 9

• it maintains the regulation of hormones including those of sexual function, such as testosterone, which is implicated in aggression
• it has been shown to cause aggressive behaviour when electrically stimulated but more importantly has receptors that help determine aggression levels based on their interactions with the neurotransmitter serotonin and vasopressin.

Question 10

evidence for hypothalamus: animal experiments using cats

Answer 10

• electrical stimulation of hypothalamus in cats produces an aggressive response including hissing and growling.
• stimulation of different parts results in different types of aggression eg stimulation to the dorsal hypothalamus produced defensive behaviour which is shown by the animal in response to threat or attack.

Question 11

small evaluation points

Answer 11

alternative - the theory does not take into account the role of nurture- eg social learning theory would suggest that…
this suggests that this theory of aggression is somewhat incomplete.

Question 12

brain function: role of serotonin and dopamine

Answer 12

• essentially low levels of serotonin or high levels of dopamine are linked with aggression
• normal levels of serotonin in the OFC are associated with a reasonable degree of behaviour self control
  decreased serotonin may disturb this and reduce self control leading to more impulsive behaviours
• serotonin underactivity stimulates dopamine overactivity and both are linked with impulsivity and aggression.

Question 13

evidence : serotonin

Answer 13

• research has shown levels of serotonin breakdown product were lower in violent and impulsive offenders compared to non violent offenders.