The structure of the brain and different brain areas as an explanation of aggression

Question 1

Describe the case of Phineas Gage

Answer 1

1848, he suffered an accident an accident when an explosion made an iron rod up through Gages head and out the top of his head
For the remaining 11 years of his life after the accident, his personality had a fundamental change, he became aggressive.

Question 2

What did the doctor conclude about Phineas Gage?

Answer 2

Concluded that the damage to his brain, which included severing the prefrontal cortex which led to a change in his character
Shows damage to the frontal lobe seemed to cause an increase in aggression

Question 3

The midbrain?

Answer 3

Contains an area called the periaqueductal grey matter, which links the amygdala and hypothalamus with the prefrontal cortex

Question 4

What do lesions in the midbrain show?

Answer 4

Lesions in the PAG in rats have recently given birth show an increase in aggression when the rats are confronted with potential threat in the form of an unfamiliar male rats

Question 5

The amygdala?

Answer 5

Responsible for emotions, behaviour and motivation

Question 6

Amygdala human research

Answer 6

Raine (1997)
Significant brain differences found between the brains of murderers and non-murderers.
Murderers had low glucose metabolism in the left brain and greater in the right amygdala activity
Abnormalities in their functioning may relate to the failure to learn from experience displayed by criminal violent offenders, which could explain fearlessness in offenders

Question 7

Amygdala animal research

Answer 7

Dawner (1961)
Removed part of the amygdala in monkeys and cut out the optic nerve
If the monkeys had visual input that connected to the intact amygdala, they reacted in their normal way towards humans, aggressive
If their visual input had no amygdala to reach then the monkeys were much calmer and placid.
Provides evidence for the amygdala being involved in aggression.

Question 8

The hypothalamus?

Answer 8

Responsible for maintaining control of the body through release of hormones

Question 9

Hypothalamus human research

Answer 9

Alpers (1937)
Studied a well-liked, mild-mannered, middle-aged lawyer who was later shown to have a tumour in the medical hypothalamus, began to display uncharacteristic outbursts of aggressive behaviour.
This localised tumour was said to be the cause of the uncharacterised aggression

Question 10

Hypothalamus animal research

Answer 10

Hess (1928)
Demostrated an ability to induce aggressive behaviour in cats by electrical stimulation of the hypothalamus.

Question 11

The prefronal cortex?

Answer 11

Situated just behind the forehead responsible for the decision making and planning

Question 12

Prefrontal Cortex human research

Answer 12

Raine (1997)
Found that murderers had lower levels of glucose metabolism in the left and right pre frontal cortex
Damage to this area of the brain can result in impulsively, loss of self control, immaturity and the inability to modify behaviour which can all turn into aggression

Question 13

Strengths

Answer 13

• Animal experimentation has greatly improved our knowledge of aggression and the underlying neurobiology
• There are similarities between animals and humans in terms of brain structure making generalisation possible

Question 14

Weaknesses

Answer 14

• Many researchers have concerns using brain imaging in the legal system to determine criminal responsibility. Imaging cannot tell what a person was thinking at the time of a violent act
• There is an assumption with case study evidence that damage to an area of the brain results in the impairment we see in the individual