Neural Mechanisms - The Brain

Question 1

What is the limbic system?

Answer 1

A network of structures deep in the brain.

Question 2

What are the main structures that make up the limbic system?

Answer 2

Hypothalamus, thalamus, hippocampus, amygdala.

Question 3

What did Papez (1937) and Maclean (1952) identify?

Answer 3

Identified the limbic system as comprising of the:

Hypothalamus.
Amygdala.
Parts of the hippocampus.
Thalamus.
(As well as other structures).

In terms of aggression, the most important is the amygdala.

Question 4

Outline how the amygdala plays a key role in human and non-human animals.

Answer 4

Amygdala controls how human and non-human animals assess and respond to environmental threats and challenges.

Question 5

What has the reactivity of the amygdala shown in humans?

Answer 5

An important predictor for aggressive behaviour.

Question 6

What did Gospic et al do in 2011?

Answer 6

Used a well-established lab method of assessing aggressive behaviour called the Ultimatum Game.

Question 7

Outline the procedure of Gospic et al’s study from 2011.

Answer 7

Two players, a Proposer and a Responder.

A Proposer offers to split money in a certain way with the a Responder.

If the Responder accepts, the money is split as proposed.

If the Responder rejects the offer, both receive nothing.

Question 8

What happened to the PPs of Gospic’s study, during the game?

Answer 8

PPs in this study (Responders) had an fMRI during the game.

Question 9

What did researchers find from Gospic’s study from 2011?

Answer 9

Found that when Responders rejected unfair offers (an aggressive reaction to a social provocation), scans revealed a fast and heightened response by the amygdala.

Question 10

What affect did benzodiazepines (BZs) have on responses to unfair offers? (taken before the game).

Answer 10

Halved the number of rejections (i.e reduced aggression) and decreased activity of the amygdala.

This provides us with strong evidence of an association between reactive aggression and amygdala activity.

Question 11

What does the stimulation of the amygdala in cats cause? What is this called?

Answer 11

Causes a fearful or anger response to occur.

This is called piloerection.

Question 12

Outline the study completed by Bushman in 2017.

Answer 12

Rat lesion studies suggest that different types of aggression may be controlled by different subsets of brain structures.

Question 13

Outline the study completed by Raine et al, in 1997?

(Supports the idea that the limbic system is involved in aggression)

Answer 13

Supports the idea that the limbic system is involved in aggression.

This is because when PET scans looked at 41 murderer’s brains and 41 controls, they found abnormalities in the functioning of the limbic system implicated in aggression.

This suggests that the structures within the limbic system may influence aggressive behaviour in humans.

Question 14

Outline the study completed by Raine et al, in 2000

(Challenges the idea that the limbic system is involved in aggression)

Answer 14

Challenges the idea that the limbic system is involved in aggression.

This is because they found that the prefrontal cortex (which inhibits aggressive behaviour), was 14% less active than normal in non-abused murderers and 15% smaller in antisocial males.

This suggests that it may be that a different brain regions codes for aggression.

Question 15

Is Raine et al’s research from both 1997 and 2000 objective?

Answer 15

No, this is correlational so this does not mean brain anomaly caused aggressive behaviour.

Correlation does not equal causation.

Question 16

Outline the case study of Charles Whitman.

(Supports the idea that the limbic system is involved in aggression)

Answer 16

Supports the idea that the limbic system is involved in aggression.

This is because, after murdering his family and a dozen strangers and taking his own life, it was found that he had a tumour pressing on his amygdala.

This suggests that the brain area was responsible for his aggressive behaviour.

Question 17

Outline the case study completed by Sumer et al in 2007.

(Supports the idea that the limbic system is involved in aggression)

Answer 17

Supports the idea that the limbic system is involved in aggression.

This is because they cited an epileptic and violent 14 year old girl who was diagnosed with a tumour in the limbic system (following an MRI). After drug therapy she became less aggressive with more “normal” levels of behaviour.

This suggests that the high levels of aggression could have been prompted by the tumour in the limbic system.

Question 18

Outline the case study of Phineas Gage.

(Challenges the idea that the limbic system is involved in aggression)

Answer 18

Challenges the idea that the limbic system is involved in aggression.

This is because a tamping pole severed his prefrontal cortex, leading him to develop a more aggressive and violent personality, from what was originally very social and pleasing.

This suggests that there are other brain areas involved in aggression.

Moreover, it also lends support for Raine (2000), and their findings of prefrontal cortex aggression.

Question 19

How could the explanation of aggression through the limbic system be seen as reductionist?

Answer 19

The role of the limbic system in aggressive behaviour is not clear cut:

The system is made up of many components, and the extent to which the different structures are involved is not fully understood.

Equally, it could be an interaction of the various components.

Question 20

What is the role of the orbital frontal cortex (OFC)?

Answer 20

Self-control

Impulse regulation.

Inhibition of aggressive behaviour.

Question 21

Other than the limbic system, what is thought to be implicated in aggression?

Answer 21

The orbital frontal cortex.

Question 22

Are all limbic abnormalities associated with aggression?

Answer 22

Not all people who have limbic system abnormalities display aggressive behaviour.

We cannot therefore ascertain cause and effect.

Question 23

Outline Coccaro et al’s study from 2007.

Answer 23

Supports the idea that the orbital frontal cortex is involved in aggression.

This is because they found that patients with psychiatric disorders where aggression is a prominent behaviour, activity in the orbital frontal cortex is reduced.

This suggests that the orbital frontal cortex may be involved with aggressive behaviour.