neural and hormonal mechanisms in aggression

Question 1

Reactivity of what system predicts aggressive behaviour?

Answer 1

limbic cystem

Question 2

what is the limbic system?

Answer 2

subcortical structures in the brain including the hypothalamus and amygdala

Question 3

what is the most important structure in the limbic system?

Answer 3

amygdala

Question 4

why is the amygdala the most important structure in limbic system?

Answer 4

plays a key role in how humans and non-human animals assess and respond to environmental threats and challenges

Question 5

the reactivity of the _______ in humans has proven to be an important predictor of aggressive behaviour

Answer 5

amygdala

Question 6

who conducted a study that shows a strong association between aggression and amygdala activity?

Answer 6

Gospic et al

Question 7

how did Gospic et al show a strong association between aggression and amygdala activity?

Answer 7

• Gospic carried out brain scans (fMRI) on participants in a lab-based game designed to provoke aggression- the Ultimatum game
• scans revealed that aggressive reactions were associated with a fast and heightened response by amygdala
• a benzodiazepine drug which reduces arousal of the autonomic nervous system taken before the game halved the number of aggressive reactions and decreased amygdala activity
• showing a strong association between aggression and amygdala activity

Question 8

apart from limbic system, what is the other neural mechanism in aggression?

Answer 8

low levels of serotonin results in reduced self-control and increased aggression

Question 9

normal levels of serotonin in the orbitofrontal cortex have ________ effects

Answer 9

inhibitory (they are linked with reduced firing of neurones which is associated with greater behavioural self-control; decreases serotonin may disturb this mechanism, reducing self-control, increasing impulsive behaviours)

Question 10

who conducted research into the comparison of levels of serotonin metabolite (breakdown by-product) called 5-HIAA in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders?

Answer 10

Virkkunen et al

Question 11

what did Virkkunen et al find?

Answer 11

levels of serotonin metabolite significantly lower in impulsive offenders, who also suffered more sleep irregularities; this is relevant because serotonin regulates sleepy patterns. Disturbance of this pattern strongly implies disruption of serotonin functioning, supporting its role in reactive aggression

Question 12

what is the hormonal mechanism involved in aggression?

Answer 12

testosterone

Question 13

testosterone is a hormone responsible for

Answer 13

the development of masculine features and also helps to regulate social behaviour via its influence on areas of the brain involved in aggression

Question 14

evidence for an association between testosterone and aggression in humans comes from studies of prison populations e.g. violent offenders such as

Answer 14

Dolan et al

Question 15

what did Dolan et al find?

Answer 15

a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 male offenders in UK maximum security prisons; these men mostly suffered from personality disorders e.g. psychopathy and had histories of impulsively violent behaviour

Question 16

animal studies such as _____ et al show experimental increases in testosterone are related to greater aggressive behaviour in several species. The converse is also true as testosterone decrease leads to reduction in aggression in castration studies

Answer 16

Giammanco et al

Question 17

what are the evaluation points for neural and hormonal mechanisms in aggression?

Answer 17

• majority of research based upon correlations
• animal studies
• limitation of the role of testosterone is that evidence in humans is mixed
• heavy androcentric research

Question 18

explain how a limitation of the role of testosterone is that evidence in humans is mixed

Answer 18

• this is because research shows that other hormones other than testosterone are significantly involved in aggression
• dual-hormone hypothesis for example claims that high levels of testosterone lead to aggressive behaviour only when levels of cortisol are low (hormone produce by adrenal cortex); so when cortisol is high, the influence of testosterone on aggression is blocked
• the combined activity of testosterone and cortisol may be a better prediction of human aggression than testosterone alone