Neural mechanisms

Question 1

Who spoke about the limbic system?

Answer 1

Papez and Maclean

Question 2

What is involved in the Limbic system?

Answer 2

The hypothalamus
Amygdala
Parts of the hippocampus

Question 3

What does the amygdala do?

Answer 3

Reactivity of it in humans and other mammals is an important predictor of aggressive behaviour
The more responsive the amygdala the more aggressive the person is
Amygdala has key role in how mammals assess and respond to environmental threats

Question 4

Who asses amygdala activity?

Answer 4

Gospic et al

Question 5

What did Gospic et al study?

Answer 5

Some participants subjected to mild provocation
When participants reacted aggressively FMRI cans showed a fast heightened response by amygdala
Benzodiazepine drug (reduced arousal of autonomic nervous system) taken before provocation led to two effects
. decrearsed activity of the amygdala
. halved number of rejections (reduced aggression)
Illustrating again role of amygdala

Question 6

What is serotonin?

Answer 6

Neurotransmitter
Widespread inhibitory effects in the brain

Question 7

What are levels of serotonin linked with?

Answer 7

Normal levels in orbitofrontal cortex - reduced firing of neurones in turn associated with greater behavioural self control
Decreased - disrupts this mechanism, reducing self control, leading to increase in impulsive behaviour eg aggression

Question 8

What did Virkkunen et al do?

Answer 8

Compared levels of a serotonin breakdown product in cerebrospinal fluid of violet impulsive and violent non impulsive offenders
Levels were significantly lower in the impulsive offenders

Question 9

What is a limitation of the limbic explanation?

Answer 9

Recent research showing that non limbic brain structures are also involved in aggression
Limbic structures function together with the orbitofrontal cortex (OFC) - not part of the limbic system
OFC is involved in impulse regulation and inhabitation of aggressive behaviour
Coccaro et al
OFC activity is reduced in those psychiatric disorders that feature aggression
Reduced activity disrupts the oFCs impulse control function - causes aggressive behaviour

Question 10

What is a strength of serotonin explanation?

Answer 10

Research into the effects on drugs
Drugs that increase serotonin have been found to reduce levels of aggressive behaviour
Berman et al
Gave participants placebo or dose of paroxetine
Took part in lab based game that involved giving and receiving electric shocks in response to provocation (insults)
Paratoxine group consistently gave fewer and less intense shocks than placebo group
Evidence of a casual link between serotonin function and aggression