Lesson 6 - Localisation Of Function

Question 1

What is Localisation of Function?

Answer 1

This refers to the principle / theory that specific functions have different locations within the brain e.g. memory, hearing, sight etc;

Question 2

What are the brain’s 4 lobes? What is the brain divided into?

Answer 2

Frontal lobe
Temporal lobe
Parietal lobe
Occipital lobe 
Right and Left hemisphere

Question 3

Where is the location of the visual centre? What is the visual cortex’s function?

Answer 3

The visual cortex is located in the occipital lobe in both hemispheres.

The visual cortex is an essential part of processing visual information.

Question 4

Describe the visual pathway:

Answer 4

Visual processing begins in the retina - this is where light enters and strikes the photoreceptors. Nerve impulses are then transmitted to the brain via the optic nerve. The majority will terminate in the thalamus which relays the information to the visual cortex.

Question 5

Where is the location of the auditory centre? What is the auditory cortex’s function?

Answer 5

The auditory cortex is located in the temporal lobe of both hemispheres.

The auditory cortex is an essential part of processing auditory information.

Question 6

Describe the auditory pathway:

Answer 6

The auditory pathway begins at the cochlea which is in the inner ear. This is where sound waves are converted into nerve impulses which travel to the auditory cortex via the auditory nerve.

Basic decoding of sound occurs in the brain stem but more detailed processing occurs in the thalamus BEFORE impulses reach the auditory cortex.

Question 7

Where is the location of the motor cortex?

Answer 7

The motor cortex is located in the frontal lobe in both hemispheres.

Question 8

Describe the motor cortex’s function:

How does it identify itself with the localisation of function?

Answer 8

The motor cortex is responsible for voluntary motor movements.

Different parts of the motor cortex control different parts off the body (different functions have different locations).

Question 9

What is the location of the somatosensory cortex?

Answer 9

It is located in the parietal lobe of both hemispheres.

Question 10

What is the function of the somatosensory cortex?

Answer 10

This area detects sensory events arising in different regions of the body and produces sensations (touch, pain, etc;) which it then localises to specific parts of the body.

Question 11

Where is the Broca’s area?

Answer 11

The frontal lobe on the LEFT hemisphere.

Question 12

What is the Broca’s area?

Answer 12

Paul Broca discovered that patients who had lesions to the left hemisphere of the frontal lobe had trouble with language production but NOT understanding where patients lack fluency.

Question 13

Which Aphasia is caused by damage to the Broca’s area?

Answer 13

Expressive aphasia.

Question 14

Where is the Wernicke’s area?

Answer 14

The temporal lobe on the LEFT hemisphere.

Question 15

What is the Wernicke’s area?

Answer 15

Carl Wernicke discovered that patients who had lesions to the left hemisphere of the temporal lobe had trouble with language understanding but NOT production.

Question 16

Which Aphasia is caused by damage to the Wernicke’s area?

Answer 16

Receptive aphasia

Question 17

Where is each lobe on the brain?

Answer 17

Frontal lobe - left (top and bottom)
Parietal lobe - top middle
Occipital - right
Temporal lobe - bottom (middle and right)

SEE NOTES FOR MORE DETAIL

Question 18

What are 5 weaknesses of localisation of function? (1,2,3)

Answer 18

• Some functions are more localised than others. For example, motor and somatosensory functions are highly localised to specific areas of the cortex compared to functions like personality which are not specifically localised but instead are more widely distributed.
• Lashley (1930) invented the Equipotentiality Theory which suggested that higher mental functions are NOT localised, where if damaged, other intact areas of the cortex can take over responsibility for that specific function.
• Dronkers (2007) re-examined the brains of two of Paul Broca’s patients where MRI scans revealed that many areas of the brain were damaged, NOT just the Broca’s Area. Lesions to the Broca’s area cause temporary speech disruption but does not result in severe disruption of language. This revealed that language is not as highly localised as originally thought but it is instead more widely distributed.

Question 19

What are 5 weaknesses of localisation of function? (4,5)

Answer 19

• Bavelier (1997) discovered that there are individual differences when observing which brain areas are activated when a person is reading silently proving that not all specific functions are highly localised-they observed activity in the right temporal lobe, the left frontal lobe and occipital lobe.
• Dejerine (1892) discovered that a patient could not read because of damage BETWEEN the visual cortex and the Wernicke’s area - it may be how brain areas communicate which is more important than specific brain regions.