Neural And Hormonal Mechanisms

Question 1

What is the limbic system

Answer 1

Part of the brain that includes the:
- amygdala
- hypothalamus
- hippocampus

Question 2

What is the role of the limbic system

Answer 2

It plays a key role in the way that an organism responds to environmental threats and challenges
- key factor in whether we respond aggressively or not

Question 3

The amygdala

Answer 3

Centre for emotions, emotional behaviour and motivation
- involved with instinctive feelings and reactions to environmental stimuli, which includes aggression

Question 4

Research support for the role of the amygdala in aggression

Answer 4

Gospic et al
-Ultimatum study

Question 5

Gospic et al

Answer 5

• lab method, assessing aggressive behaviour using a game ‘the Ultimatum game’
• 2 players, the proposer and the responder
  Proposer offers to split money in a certain way w the responder
• if responder agrees, money is split how stated, if rejected, no one gets money
• ppts had their brains scanned w fMRI’s while playing
• found heightened response in the amygdala when responders rejected unfair offers

Question 6

Gospic additional findings

Answer 6

when benzodiazepine was taken before playing (drug that reduces arousal of ANS):
1. Number of rejections were halved (reduced aggression)
2. Decreased activity in amygdala
- strong evidence of an association between reactive aggression and amygdala activity

Question 7

Serotonin

Answer 7

key hormone that stabilises our mood, feelings of well-being and happiness
- has widely inhibitory effects in the brain, slows and dampens neuronal activity

Question 8

Findings about serotonin

Answer 8

1. Denson - found when S was present at normal concentration in orb frontal cortex, it was associated w reduced firing of neurons = greater behavioural self control
2. Virkkunen compared levels of S in cerebrospinal fluid of violent impulsive and violent non-impulsive offenders
   - found levels were lower in impulsive, they also suffered more sleep irregularities

Question 9

Hormones

Answer 9

Chemical messengers in the body which scan change behaviour and cause physical changes in the body

Question 10

Hormones involved in aggression

Answer 10

• oxytocin
• testosterone

Question 11

pre natal exposure to testosterone

Answer 11

has an organising effect on the developing brain
- increased spatial ability + competitive aggression
- immediately after birth, T cells stimulate growth in areas on the hypothalamus and amygdala

Question 12

Testosterone research

Answer 12

1. Giammanco
2. Dolan

Question 13

Giammanco

Answer 13

Animal study
- showed increases in T have produced aggressive behaviour in several species
- and vice versa, less T = decreased aggressive behaviour

Question 14

Dolan

Answer 14

Found positive correlation between T and aggressive behaviour
- sample of 60 male offenders in max security hospitals
- most suffered from personality disorders, and had history of impulsively violent behaviour

Question 14

Supporting evaluation for neural and hormonal mechanisms

Answer 14

1. Berman et al study (placebo or no)
2. Mazurs MBoS and Mehta and Joseph

Question 15

Berman et al

Answer 15

Gave pots a placebo or a dose of paoxetine (serotonin booster)
- lab study where they could give shocks of varying intensity as a response to provocation
- ppts w drug gave fewer and less intense shocks
CA - only true for those who had a history of aggression

Question 16

Mazurs MBoS, Mehta and Joseph

Answer 16

Mazurs model suggests that human T levels change rapidly throughout the day esp in response to social interactions related to status
- eg. falling from 1st to 2nd = change in T and affects post-comp aggression

Mehta and Joseph, study w competitive game and measured changes in T before and after comp, given choice to re-challenge, or complete an unrelated test
- found 73% of the losers (whose T rose) decided to re-challenge their opponent but only 22% of the losers (whose T fell) decided to do so
- supports Mazurs theory that T changes based on status, improves validity

Question 17

Opposing evaluation for neural and hormonal mechanisms

Answer 17

1. Mixed evidence for T
   -Carre and Mehta, high levels of T only produce aggression when cortisol levels are low
   - when cortisol levels are high, T fuelled aggression is blocked

Popma, confirmed this belief in a study of direct physical aggression in adolescent males
- C and T may be a better predictor of aggression