Localisation Of Function Flashcards
What is localisation of function?
Specific functions (physical and psychological) have specific locations in the brain
What are the 4 lobes which make up the brain?
Occipital, temporal, parietal, frontal
What are the 6 specialised areas in the brain?
Motor, somatosensory, visual, auditory, Broca’s, Wernicke’s
Describe the case study which shows support for localisation of the brain?
Phineas Gage was working on a rail road when an iron rod entered his head and causes severe damage to his frontal lobe. He went from being calm and reserved to quick-tempered. The change in his temperament suggests the frontal lobe is responsible for regulating personality.
What is the role of the motor cortex and where is it found?
Controls voluntary movement in the opposite side of the body.
Found in the back of the frontal lobe
What is the role of the somatosensory cortex and where is it found?
Processes sensory information related to touch, pressure, pain and temperature which it then localises to specific body regions.
Found in the parietal lobe.
What is the role of the visual cortex and where is it found?
Each eye sends information from the right visual field to the left visual cortex and the left visual field to the right visual cortex.
Found in the occipital lobe.
What is the role of the auditory cortex and where is it found?
Analyses speech-based information.
Found in temporal lobe
What is the role of Broca’s and Wernicke’s area?
Broca’s area= speech production. Found in frontal lobe, left hemisphere
Wernicke’s area= speech comprehension. Found in temporal lobe, left hemisphere
3 strengths for localisation of the brain
Brain scan evidence of localisation:
Petersen et al. (1988) used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task, suggesting that these areas of the brain have different functions.
Case study of Phineas Gage
There has been evidence which has revealed that damage to either Broca’s or Wernicke’s area has led to different types of language difficulty.
Expressive aphasia (Broca’s aphasia)= an impaired ability to produce language. In most cases caused by brain damage in Broca’s area. E.g. Patient Tan could understand speech but couldn’t produce any coherent words (could only say the word ‘Tan’). When he died a post-mortem revealed that Tan had a lesion in the left frontal lobe.
Receptive aphasia (Wernicke’s aphasia)= an impaired ability to understand language= usually the result of damage in Wernicke’s area. This suggests that the role of speech production and speech comprehension is localised in the brain.
2 limitations for localisation of the brain
Law of equipotentiality:
It has been found that when the brain is damaged and a function is lost, the rest of the brain can reorganise itself in an attempt to recover the lost function.
Lashley described this as the law of equipotentiality= surviving brain circuits ‘chip in’ so the same neurological action can be achieved.
Eg. stroke victims recovering functions
Evidence for holistic theory:
Lashley (1950)- suggested that higher cognitive functions are not localised but distributed in a more holistic way in the brain.
He removed areas of the cortex (between 10 and 50%) in rats that were learning a maze. No area was proven to be more important than any other area in terms of the rats’ ability to learn the maze. The process of learning appeared to require every part of the cortex, rather than being confined to a particular area.
This evidence seems to suggest that learning is too complex to be localised and requires the involvement of the whole brain.
