Neural and Hormonal Mechanisms in Aggression

Question 1

How is the amygdala related to aggression?

Answer 1

• The amygdala is thought to be particularly important in regulating emotional behaviour.
• Research by Gospic et al (2011) found that when participants rejected an unfair reward, there was a sudden increase in amygdala activity, suggesting a link between amygdala activity and aggression.

Question 2

What is the limbic system and its role in aggression?

Answer 2

• The limbic system is responsible for regulating emotions and emotional behaviour.
• It consists of the fornix, cingulate gyrus, thalamus, hippocampus, hypothalamus, and amygdala.
• The amygdala, in particular, plays an important role in regulating emotional behavior and has been linked to aggression.

Question 3

What role does serotonin play in aggression?

Answer 3

• Serotonin is an inhibitory neurotransmitter that reduces the action potential in the postsynaptic membrane.
• It is associated with the regulation of impulsive behaviour when present in normal concentrations in the orbitofrontal cortex.
• Increasing serotonin levels have been correlated with decreased aggression.
• Berman et al found that participants who were given the serotonin agonist ‘paroxetine’ behaved less aggressively compared to a control group.

Question 4

How is serotonin related to sleeping patterns and aggression?

Answer 4

• Lower levels of serotonin have been proposed to be involved in controlling sleeping patterns, as serotonin is found in lower levels in non-violent offenders (Virkkunen et al, 1994).
• Additionally, due to the link between serotonin and the regulation of emotional/impulsive behaviour, it has been suggested that serotonin plays a role in aggression.

Question 5

What is the relationship between testosterone and aggression?

Answer 5

• Testosterone, a male sex hormone, is present in significantly larger concentrations in men compared to women.
• It is responsible for the production of male facial characteristics and reproductive organs.
• Decreased testosterone levels have been linked to decreased levels of aggressive behavior, as shown in castration studies.
• However, Dolan et al (2001) found that violent prisoners in maximum security prisons displayed higher levels of testosterone than their non-violent counterparts.

Question 6

What is the role of the orbitofrontal cortex in aggression?

Answer 6

• The orbitofrontal cortex (OFC) may also play a significant role in aggression. It is connected to serotonin and has been shown to regulate impulsive behaviour.
• Therefore, the neural connections between the OFC and the limbic system could be important in understanding aggression, instead of focusing on these areas in isolation.

Question 7

How does cortisol influence the relationship between testosterone and aggression?

Answer 7

• Carre and Mehta (2011) propose the dual-hormone hypothesis, suggesting that testosterone does not work alone in determining aggression.
• It has an antagonistic relationship with the stress hormone cortisol. Increased levels of aggression are associated with increased testosterone levels, but this relationship is observed only when cortisol levels are low.
• Different hormones have different predictive values for aggression and are part of a system when developing aggressive behaviour.