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
