L6 - Localisation Of Function

Question 1

What is Localisation of Function?

Answer 1

• refers to principle that functions have specific locations in the brain

Question 2

Where are the visual centres?

Answer 2

• Visual Cortex is in the Occipital lobe of BOTH hemispheres.
• Processing starts in the retina where light enters and strikes photoreceptors.
• Nerve impulses from the retina go to the brain through the optic nerve.
• The majority of nerves terminate in the thalamus which passes the info to the visual cortex

Question 3

Where are the Auditory centres?

Answer 3

• Auditory cortex is in the temporal lobe in BOTH hemispheres
• Starts in the cochlea in the inner ear where sound waves are converted into nerve impulses
• These travel through the auditory nerve to the auditory cortex
• Decoding happens in the brain stem, and the thalamus carries out further processing before impulses reach the auditory cortex

Question 4

What is the Motor Cortex?

Answer 4

• Responsible for generation of voluntary motor movements
• Located in frontal lobe of BOTH hemispheres
• Different parts of the motor cortex control different parts of the body.
• Damage to this area can cause a load of muscle function/paralysis in one or both sides of the body

Question 5

What is the Somatosensory Cortex?

Answer 5

• Detects sensory events from different regions of the body
• Located in Parietal lobe of BOTH hemispheres
• Uses sensory info from skin + produces sensations of touch, pressure, pain + temp, which is then localised

Question 6

What is Broca’s Area?

Answer 6

• Patients who have difficulty PRODUCING speech.
• Lesions to LEFT hemisphere of frontal lobe
• EXPRESSIVE aphasia is language/speech problems + affects production not understanding
• Speech will lack fluency

Question 7

What is Wernicke’s Area?

Answer 7

• LEFT hemisphere of TEMPORAL lobe
• Lesions to this area could speak but could not understand language
• Area is responsible for processing spoken language
• Connected to Broca’s Area by a neural loop.
• RECEPTIVE aphasia is an impaired ability to understand language

Question 8

Evaluation (-)

Answer 8

• Some functions are more localised than others e.g motor functions are highly localised to specific areas of the cortex but other functions like personality are distributed
• Equipoteniality theory holds that higher mental functions are not localised and that intact areas of the cortex take over responsibility for a specific cognitive function following injury to the area normally responsible
• A psychologist re-examined the preserved brains of Broca’s patients and MRI Scans revealed that several areas of the brain had been damaged. Lesions to the Broca’s area cause temp speech disruption and usually do not result in severe disruption. Language is a more widely distributed skill
• A psychologist found that there are individual differences in which brain areas are activated when reading silently. Observed activity in Right Temp Lobe, Left Frontal lobe and Occipital lobe
• How brain areas communicate may be more important than specific brain regions. A patient could not read because of damage between the visual cortex and Wernicke’s area