localisation of function

Question 1

what is holistic theory

Answer 1

The view of the early 19th century that all parts of the brain were involved in processing thought and action

Question 2

what is localisation theory

Answer 2

The theory that different areas of the brain are responsible for different physical and psychological functions.
If an area of the brain is damaged through illness or injury, the function associated with that area is also affected.

Question 3

what is lateralisation

Answer 3

the brain is divided in two hemispheres and lateralised meaning some physical and psychological functions are controlled by a particular hemisphere.
Generally, the left side of the body is controlled by the right hemisphere and the right side of the body controlled by the left hemisphere.

Question 4

what is the outer layer of the brain

Answer 4

the cerebral cortex - 3mm thick and is what separates humans from lower animals as it is highly developed.

Question 5

what are the four lobes of the cerebral cortex

Answer 5

frontal, parietal, occipital, temporal

Question 6

what is the motor area and where is it located

Answer 6

the motor area is located at the back of the frontal lobe. It controls voluntary movement. Damage may result in the loss of fine motor movements.

Question 7

what is the somatosensory area and where is it located

Answer 7

located at the front of the parietal lobes. It processes sensory information from the skin (eg touch, heat, pressure). The amount of somatosensory area dedicated to a particular body part indicates its sensitivity.

Question 8

what is the visual area and where is it

Answer 8

the visual area is located in the occipital lobe at the back of the brain. Each eye sends visual information from the right visual field to the left visual cortex and from the left visual field to the right visual cortex.

Question 9

what is the auditory area and where is it

Answer 9

auditory area is located in the temporal lobe. It analyses speech based information. Damage may produce partial hearing loss - more extensive damage = more hearing loss

Question 10

The Two Language Centres:
describe Broca’s area

Answer 10

Broca’s area - responsible for speech production. Located in the left frontal lobe.
Damage to this area causes Broca’s aphasia which is characterised by speech that is slow and lacks fluency. Difficulty finding words and naming objects

Question 11

describe Wernicke’s area

Answer 11

Wernicke’s area - responsible for language comprehension. Located in the left temporal lobe.
People with Wernicke’s aphasia produce language but have problems with understanding it, so they produce fluent but meaningless.
Will often produce nonsense words.

Question 12

what is aphasia

Answer 12

an inability to produce or understand speech as a result of brain damage

Question 13

Strength of localisation:
Case study of aphasiac

Answer 13

Case study of Tan by Broca.
Tan had brain damage and could only say the word ‘tan’.
A post mortem examination found damage to an area in the frontal lobe.
Broca then studied 8 other patients with brain damage to the left frontal hemisphere who also had language deficits. Found that patients with damage to these areas in the right hemisphere did not have the same language problems.

This supports localisation of function as it shows a specific area of the brain is linked to language as damage to the left frontal hemisphere caused speech problems, but the same area on the right hem. did not have the same effect when damaged.

Question 14

supporting evidence for localisation of function - Phineas Gage.

Answer 14

Phineas Gage experienced an accident in which a piece of iron went through his prefrontal cortex. He survived and experienced a change in personality such as a loss of inhibition and anger.
This change proves evidence to support localisation of function as it was believed that the prefrontal cortex was responsible for personality.

Question 15

weakness of localisation of function: plasticity

Answer 15

when the brain has become damaged (eg. illness or accident) and a particular function has been compromised or lost, the rest of the brain appears to reorganise itself in an attempt to recover the lost function (plasticity).
There are several cases of stroke victims being able to recover their lost abilities as a result of the illness.
This suggests that functioning may be more holistic rather than localised as different areas of the brain are able to recover the lost function of one particular area.

Question 16

brain scan evidence to support localisation of function

Answer 16

Petersen et al. used brain scans to show activity in Wernicke’s area during a listening task and activity in Broca’s area during a reading task.
Also a study of long term memory by Tulving et al. revealed semantic and episodic memories are located in different parts of the prefrontal cortex.
These studies suggest that different areas of the brain have different functions, supporting localisation theory.

Question 17

what is Lashley’s undermining evidence

Answer 17

Lashley removed areas of the cortex (10-50%) in rats who were learning a maze. No area was proven to be more important than any other in the rats ability to learn the maze.
The process of learning appeared to require all of the cortex rather than being confined to a particular area.
This suggests that higher cognitive processes (eg learning) are not localised but distributed in a more holistic way in the brain.
However, we should be cautious in drawing conclusions related to human learning from this study as pps were rats and therefore may learn and have different brains than humans.