BIOPSYCHOLOGY - localisation of function and hemispheric lateralisation Flashcards
what is localisation of function?
belief that specific areas of the brain are associated with specific functions (e.g. language, memory etc)
- also referred to as cortical specialisation
what is hemispheric lateralisation?
- 2 halves of the brain are not entirely alike
- each hemisphere has functional specialisations
- some mental processes are mainly specialised to left or right hemisphere (lateralisation)
- left = dominant for speech/language, right = dominant for visual motor tasks
what are the areas of cortical specialisation?
- motor cortex
- somatosensory cortex
- auditory centres - auditory cortex
- visual centres - visual cortex
what is the motor cortex?
- responsible for voluntary movements
- located in frontal lobe along precentral gyrus
- both hemispheres have a motor cortex
- controls muscles on opposite side of body
- regions controlling different parts of the body are logically next to one another (region controlling foot is next to leg)
what is the somatosensory cortex?
- processes input from sensory receptors in the body that are sensitive to touch
- detects sensory events
- located in parietal lobe along postcentral gyrus
- sensory info on skin produces sensations of touch, localised to parts of the body
- both hemispheres have somatosensory cortex
- cortex on one side receives sensory info from opposite side
what is the visual cortex?
- located in occipital lobe
- processing begins in retina
- nerve impulses from retina transmit to brain via optical nerve
- is in both hemispheres
- right receives input from left field of view
- different areas process different visual info
what is the auditory cortex?
- concerned with hearing
- located in temporal lobes of both sides of the brain
- pathway begins in cochlea in inner ear, then to thalamus, then travels to auditory cortex in brain via auditory nerve
what are the 2 language centres?
- Wernicke’s area
- Broca’s area
what is Wernicke’s area?
- important for comprehension of language
- located in posterior part of left temporal lobe
- neural loop (aracuate fasciculus) runs between Broca’s and Wernicke’s area
what is Broca’s area?
- critical for speech production
- located in posterior part of frontal lobe of left hemisphere
what support is there for localisation of function?
- brain scan evidence
- neurosurgical evidence
- support for language centres for aphasia studies
what limitations are there for localisation of funciton?
- plasticity and equipotentiality
- individual differences
how does brain scan evidence support localisation of function?
- Wernicke’s area lit up - listening task
- Broca’s area lit up - reading task
- shows many neurological functions are localised
how does neurosurgical evidence support localisation of function?
- 44 OCD patients had to undergo neurosurgical procedure of cingulate gyrus
- post-surgical follow up 32 weeks later: 1/3 met criteria for successful response to surgery, 14% for partial response
- shows symptoms/behaviours associated with merntal disorders are localised
what is aphasia?
inability or impaired ability to understand or produce speech as a result of brain damage
- broca’s aphasia = impaired ability to produce language
- wernicke’s aphasia = impaired ability to understand language
how do aphasia studies support localisation of funtion?
- broca’s aphasia = impaired ability to produce language
- wernicke’s aphasia = impaired ability to understand language
- shows how different parts of the brain are localised to specific functions
how is individual differences a limitation of localisation of function?
- study of silent reading: large variability in individual patterns of activation across individuals
- observed activity in temporal, left frontal and occipital lobes
- other studies have found gender differences in size of brain areas involves in language e.g. women have larger brocas area so greater use of language
how is plasticity and equipotentiality theory a limitation of localisation of function?
- theory = basic motor and sensory functions were localised but higher mental processes weren’t (Lashley)
- intact areas of the cortex could take over responsibility for specific cognitive functionsfollowing injury to the area allow normal functioning
- effects of damage to the brain are due to the extent, not the location
