6 - Localisation of Function Flashcards
What is the term ‘localisation of function’ about?
The principle that specific functions have specific locations within the brain
Where is the visual cortex located?
Occipital lobe
How does the visual cortex work? How does it get information?
Visual processing starts at the retina where light enters and strikes the photoreceptors.
Nerve impulses from the retina are transmitted to the brain via the optic nerve.
Most impulses terminate at the thalamus ( acts as a relay station ) where information is passed onto the visual cortex.
Where is the auditory cortex located?
Temporal lobe
How does the auditory cortex work?
The auditory pathway begins in the cochlea in the inner ear, where sound waves are converted to nerve impulses.
These travel down the auditory nerve to the auditory cortex.
The brain stem does basic decoding. Then it goes to the thalamus for further processing of the stimulus before relaying the nerve impulse to the auditory cortex.
Where is the motor cortex located?
Frontal lobe, in the precentral gyrus
What is the motor cortex responsible for?
Generation of voluntary motor movements
Where is the somatosensory cortex located?
Parietal lobe in the postcentral gyrus
What is the somatosensory cortex responsible for?
Detects sensory events arising in different parts of the body
Using sensory information from the skin, the somatosensory cortex produces sensations of touch, pressure, pain and temperature, which it then localises to specific parts of the body.
What are the two language centres?
Broca’s area
Wernicke’s region
What is the function of Broca’s area and where is it located?
Speech production
Left frontal lobe.
Later discovered two regions of the Broca’s area, one involved in language, the other involved in responding to demanding cognitive tasks.
What is the function of Wernicke’s region and where is it located?
Speech perception and processing
Temporal lobe
What connects the Broca’s area to Wernicke’s region?
Neural loop known as the arcuate fasciculus.
What are the advantages to localisation of function?
Expressive aphasia is an impaired ability to produce language (caused by damage to the Broca’s area) whereas receptive aphasia is an impaired ability to understand language (this is usually a result of damage to the Wernicke’s area).
What are the negatives to localisation of function?
Some functions are more localised than others. Motor and somatosensory functions are highly localised to specific areas of the cortex. Other functions (e.g. personality) are more widely distributed.
Equipoteniality theory states 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 for that function.
Preserved brains of two of Broca’s patients re-examined. MRI scans revealed that several areas of the brain had been damaged. Lesions to the Broca’s area cause temporary speech disruption they do not usually result in severe disruption of language. Language is more a more widely distributed skill than originally thought.
It was found that there are individual differences in which brain areas are activated when a person is engaged in silent reading. They observed activity in the right temporal lobe, left frontal lobe and occipital lobe.
It may be that how brain areas communicate with each other is more important than specific brain regions. A patient who could not read because of damage between the visual cortex and Wernicke’s area was found.
