Localisation of Function in the brain and Hemispheric Lateralisation

Question 1

Localisation of function (2)

Answer 1

This is where specific areas of the brain are special for certain functions e.g. the motor cortex is responsible for voluntary movements. Only this area of the brain is responsible for this job.

Question 2

Hemispheric lateralisation (2)

Answer 2

The brain is split into two symmetrical halves called the left and right hemisphere. This is the idea that the two hemispheres are responsible for different mental processes e.g. the right hemisphere is responsible for recognition and creativity and the left hemisphere is responsible for language

Question 3

Holistic theory (2)

Answer 3

Before investigations into lateralisation and localisation scientists believed that all parts of the brain worked together for processing information.

Question 4

What are the language areas of the brain?

Answer 4

1) Broca’s area
2) Wernicke’s area

Question 5

What are the different areas of the brain?

Answer 5

1) Broca’s area
2) Wernicke’s area
3) Motor cortex
4) Auditory cortex
5) Somatosensory cortex
6) Visual cortex

Question 6

AO1: Broca’s area

Answer 6

• Left Hemisphere
• Involved in production of written and spoken language
• Damages involved Broca’s aphasia which is slow speech including lack of fluency or complete absence of speech. They might produces short meaningful speech that requires great effort.

Question 7

AO1: Wernicke’s area

Answer 7

• Left hemisphere
• Involved in the understanding of spoken language
• Damage results in Wernicke’s aphasia where individuals can’t understand spoken language. They may produce nonsense speech.

Question 8

AO1: Motor cortex

Answer 8

• Both hemispheres
• Involved in the creation of voluntary motor movements. Each hemisphere controls the movement of opposite sides of the body.
• Damage includes loss of control over small and fine movements on the opposite sides of the body (contralateral wiring e.g picking up small objects)

Question 9

AO1: Visual cortex

Answer 9

• Both hemispheres
• Involved in receiving information from the eye. RH controls LVF and LH controls RVF. It also processes colour and shape.
• Damage produces blindness, hallucinations and inability to recognise colour or motion

Question 10

AO1: Somatosensory

Answer 10

• Both hemispheres
• Processes information from senses in skin. Including touch, pressure, pain and temperature from all areas in the body
• Damage includes problems perching touch, failure to recognise object by touch

Question 11

What are the evaluations (3)

Answer 11

1) RTS Broca
2) RTC Patient EB
3) Discussion

Question 12

AO3: RTS Broca

Answer 12

Research to support localisation of function in the brain was conducted by Broca. He reported the case study of man who lost the ability to speak, except for one word ‘Tan’, even though he could still understand language. Post-mortems showed damage in one area in the left hemisphere, which is now named Broca’s area. This supports the idea of localisation because the function of Broca’s area is specifically to produce language. Therefore, increasing the validity of research into localisation of function in the brain.

Question 13

AO3: RTC - Patient EB

Answer 13

In addition, research to contradict localisation of function comes from a case study on a patient named EB. EB suffered from brain damage that resulted in the removal of his left hemisphere and therefore his language centres. Despite this, after some time EB managed to regain some of his language ability that would not be possible if the language centres were completely localised to the left hemisphere. This shows that language must be in more areas than just the left hemisphere suggesting a holistic explanation of brain functioning is more appropriate. Therefore, reducing the validity of research into localisation of function in the brain.

Question 14

AO3: Discussion

Answer 14

However, both case studies lack population validity. It may not be appropriate to generalise the findings on the localisation of function to the typical population, as these are unique case studies where brain damage may have affected the way in which the brain functions and some individuals may be able to process language in other areas of the brain. (A* only For example, some research has suggested that Broca’s area is not solely located in the left hemisphere but is found in the dominant cerebral hemisphere which is commonly found to be opposite to the dominant handedness). Therefore, suggesting that more research is needed with more diverse samples before firm conclusions on the localisation of language areas are possible.