Neural Mechanisms in Aggression

Question 1

what are the main mechanisms involved in aggression?

Answer 1

• limbic system
• orbitofrontal cortex and serotonin

Question 2

what researchers are involved in the limbic system?

Answer 2

Papez and Maclean linked the limbic system to emotional behaviours, aggression

Question 3

what was the limbic system defined as?

Answer 3

hypothalamus, amygdala and parts of the hippocampus

Question 4

what is the important predictor of aggressive behaviour in humans and other mammals?

Answer 4

the reactivity of the amygdala

Question 5

what is the role of the amygdala?

Answer 5

has a key role in how mammals access and respond to environmental threats

Question 6

who investigated amygdala activity?

Answer 6

Gospic et al

Question 7

what did Gospic et al do?

Answer 7

• participants were subjected to mild provaction
• when participants reacted aggressively fMRI scans showed a fast and heightened response by the amygdala
• a benzodiazepine drug (reduces arousal of ANS) taken before provocation led to two effect:
  = decreased activity of amygdala
  = halved the number of rejections(reduced aggression)

Question 8

what is serotonin?

Answer 8

a neurotransmitter that has widespread inhibitory effects in the brain (slows down and calms neuronal activity)

Question 9

what are normal levels of serotonin in the orbitofrontal cortex linked with?

Answer 9

• reduced firing of neurons which in turn is associated with greater behavioural self-control

Question 10

what does decreased serotonin cause?

Answer 10

decreased serotonin leads to reduced self-control and leading to an increase in impulsive behaviour including aggression

Question 11

what researcher was involved with orbitofrontal cortex and serotonin?

Answer 11

• Virkkunen et al

Question 12

what did Virkkunen et al do?

Answer 12

• compared levels of serotonin breakdown (5-HIAA) in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders
• levels were significantly lower in impulsive offenders

Question 13

what are the evaluations of the neural and hormonal mechanisms in aggression?

Answer 13

• limitation = more recent research shows that non-limbic brain structures are also involved in aggression
• strength = serotonin explanation has helped with research into the effects of drugs

Question 14

what is the limitation of the neural mechanisms in aggression?

Answer 14

• more recent research shows that non-limbic brain structures are involved in aggression
• limbic structures function together with OFC which is not part of the limbic system
• OFC = involved in impulse regulation and inhibition of aggressive behaviour
• Coccaro et al = OFC activity is reduced in psychiatric disorders that feature aggression, this reduced activity disrupts OFC ‘s impulse control function which in turn causes aggressive behaviour
  = neural regulation of aggression is more complex

Question 15

what is a strength of the neural mechanisms in aggression?

Answer 15

• serotonin explanation is research into the effects of drugs
• drugs which increase serotonin have been found to reduce levels of aggressive behaviour
• Berman et al = gave ppts either a placebo or a dose of paroxetine, then ppts took part in lab-based game which involved giving and receiving electric shocks in response to provocation
• paroxetine group consistently gave fewer and less intense shock than placebo group
  = evidence of causal link between serotonin function and aggression