Bio - Lateralisation & split-brain research.

Question 1

What is hemispheric lateralisation?

Answer 1

Refers to the fact that some mental processes in the brain are mainly specialised to either the left or right hemisphere.

Question 2

What is split-brain research?

Answer 2

Research that studies individuals who have been subjected to the surgical separation of the two hemispheres of the brain as a result of severing the corpus callosum.

Question 3

What is the left hemisphere dominant for?

Answer 3

Language and speech.

Question 4

What does the right hemisphere excel at?

Answer 4

Visual-motor tasks.

Question 5

If language is located in the left hemisphere, how can we talk about things that are experienced in the right hemisphere e.g. face recognition?

Answer 5

The two hemispheres are connected allowing information received by one hemisphere to be sent to the other hemisphere through connecting bundles of nerve fibres such as the corpus callosum.

Question 6

How are the two hemispheres of the brain connected?

Answer 6

By the corpus callosum.

Question 7

What is the corpus callosum?

Answer 7

A bundle of nerve fibres connecting the two brain hemispheres which allows information received by one hemisphere to be sent to the other hemisphere.

Question 8

What does the corpus callosum do?

Answer 8

Connect the two brain hemispheres and allows information received by one hemisphere to be sent to the other hemisphere.

Question 9

When did the chance to investigate the different abilities of the two hemispheres come about?

Answer 9

When, in a treatment for epilepsy, surgeons cut the bundle of nerve fibres that formed the corpus callosum.

Question 10

What was the aim of the procedure done by surgeons to cut the corpus callosum as a means of treating epilepsy?

Answer 10

To prevent the violent electrical activity that accompanies epileptic seizures crossing from one hemisphere to the other.

Question 11

What are patients that underwent the surgical cutting of the corpus callosum often referred to as?

Answer 11

‘Split-brain’ patients.

Question 12

Who (that we need to know about) carried out split-brain research?

Answer 12

Sperry (and Gazzaniga) (1967).

Question 13

What was Sperry able to do to test the capabilities of the separated hemispheres in split-brain research?

Answer 13

They were able to send visual information to just one hemisphere at a time in order to study what is known as hemispheric lateralisation.

Question 14

What did Sperry aim to study?

Answer 14

Hemispheric lateralisation.

Question 15

Describe the procedure of the study done by Sperry which was carried out on split-brain patients

Answer 15

The split-brain patient would fixate on a dot in the centre of a screen while information was presented to either the left or right visual field. They would then be asked to make responses with either their left hand (controlled by the right hemisphere) or their right hand (controlled by the left hemisphere), or verbally (which is controlled by the left hemisphere), without being able to see what their hands were doing.

Question 16

What were the findings of the study done by Sperry on split-brain patients?

Answer 16

When things were presented to the right visual field, they responded with what they had seen e.g. a dog. However, when things were presented to their left visual field the patient said that they could see nothing.

Question 17

Explain the findings of the study done by Sperry on split-brain patients

Answer 17

When things were presented to the right visual field, they responded with what they had seen e.g. a dog. However, when things were presented to their left visual field the patient said that they could see nothing.

This happens because the information from the left visual field is processed by the right hemisphere, but as it has no language centre, they cannot respond verbally. The left hemisphere, which does have a language centre, does not receive information about seeing the picture presented to them, and therefore, cannot say that it has seen it.

Question 18

What have we learnt from split-brain research?

Answer 18

There are a number of differences between the two hemispheres, for example:

• The left hemisphere is responsible for speech and language.
• The right hemisphere specialises in visual-spatial processing and facial recognition.

However, split-brain research has not shown that the brain is organised into discrete regions with specific sections responsible for specific tasks. It has instead suggested that the connectivity between the different regions of the brain is as important as the operation of the different parts.

Question 19

What hasn’t split-brain research shown?

Answer 19

That the brain is organised into discrete regions with specific sections responsible for specific tasks. It has instead suggested that the connectivity between the different regions of the brain is as important as the operation of the different parts.