Neural and Hormonal Influences in Aggression

Question 1

What system is involved in aggression

Answer 1

The limbic system

Question 2

What are the two key structures in the limbic system

Answer 2

The amygdala and the hippocampus

Question 3

What does the amygdala do in relation to aggressive behaviour

Answer 3

It is responsible for quickly evaluating the importance of sensory information and prompting an appropriate response

Question 4

What shows that the amygdala relates to aggression

Answer 4

If certain areas of the amygdala are stimulated electronically, an animal responds with aggression, such as snarling. If the same areas are surgically removed, the animal no longer responds to things that they would have responded to with rage. Kluver and Bucy removed the amygdala of a monkey who was dominant in his social group and he lost his dominant place in the group

Question 5

Who destroyed a monkeys amygdala to remove it’s dominance

Answer 5

Kluver and Bucy

Question 6

How is the hippocampus related to aggressive behaviour

Answer 6

It helps in the formation of long term memories, and so allows an animal to compare the conditions of a current threat withsimilar past experiences. Impariered hippocampal function prevents the nervous system from putting things into relevant context, and so the amygdala may respond inappropriately to stimuli, resulting in aggressive behaviour. Boccardi found habitually violent offenders exhibited abnormalities of hippocampal functioning

Question 7

Who found habitually violent offenders have abnormal hippocampi

Answer 7

Boccardi

Question 8

How does serotonin link to aggression

Answer 8

In normal levels it has a claming effect, typically inhibiting firing of the amygdala. Low levels of serotonin remove this effect, and the consequence is that individuals are more impulsive and and display more aggressive behaviour

Question 9

What can deplete serotonin levels

Answer 9

Some drugs. Studies giving participants dexenfluramine, known to deplete serotonin, found that it was associated with an increase in aggression and hostility scores. Only in men though

Question 10

What hormone may influence aggression

Answer 10

Testosterone. It is thought to control aggression, and Sapolsky summarised research by describing how removing the source of testosterone from different species typically resulted in much lower levels of aggression

Question 11

Who said that removing the balls from different species lowered aggression levels

Answer 11

Sapolsky

Question 12

What is evidence of testosterone being an element in aggression

Answer 12

Dabbs measured salivary testosterone in violent and non-violent criminals and those with the highest testosterone had a history of primarily violent crimes while the those with the lowest levels had mainly non-violent crimes

Question 13

Who measured criminal saliva

Answer 13

Dabbs

Question 14

What is evidence for the role of the amygdala in aggression (eval)

Answer 14

Pardini et al found that reduced amygdala volume can predict the development of severe and persistent aggression in a longitudinal study of male participants from childhood to adulthood. Some of the 56 participants with carying histories were subject to an MRI at 26, and the results showed that lower amygdala volumes exibited higher levels of aggression.

Question 15

Who did a longitudinal study and found small amygdala meant more aggression

Answer 15

Pardini

Question 16

What evidence from non humans supports the role of serotonin (eval)

Answer 16

Raleigh et al founnd that vervet monkeys fed experimental diets high in trytophan exhibited decreased levels of aggression, and those fed diets low in trytophan exhibited more aggressson. Similar studies into dogs administered to vetinary hospitals for aggression found higher levels of serotonin in non-aggressive doggos.

Question 17

Who studied monkeys high on serotonin removal drugs

Answer 17

Raleigh

Question 18

Why is evidence into hormonal influences inconsistent (eval)

Answer 18

Some studies show a positive relationship and others find no such connection. Positive correlations have been found between testosterone levels and self-reported aggression levels in prison inmates, but no correlation was found between testosterone levels and acual violent behaviour among inmates in prison

Question 19

Why might aggression actually be dominance behaviour (eval)

Answer 19

Mazur suggests that we should distinguish between aggression and dominance. Individuals act aggressively when they intend to harm, but act dominantly if they wish to achieve or maintain status over another. Mazur claims that aggression is just one dominance behaviour, and that the influence of testosterone on dominance is likely more varied. Some studies have even found that testosterone can make women act nicer depending on the situation, promoting the view that testosterone promotes status-seeking behaviour rather, and aggression is just one type

Question 20

Who suggested that testosterone causes dominance

Answer 20

Mazur