localisation of function + hemispheric lateralisation Flashcards
What is localisation of function?
- specific areas of the brain
- specialised for certain functions
- e.g. motor cortex responsible for voluntary movement
What is hemispheric lateralisation?
- the brain is split into two symmetrical halves
- the left and right hemisphere
- different hemispheres responsible for different mental processes
- e.g. left = language and
right = recognition and creativity
What is the holistic theory?
- all parts of the brain work together
- when processing information
Broca’s area
- left hemisphere
- involved in production of spoken and written language
- damage can cause Broca’s aphasia
- slow speech that lacks fluency
- or complete absence of speech
- or produce short meaningful speech requires great deal of effort
Motor cortex
- both hemispheres
- involved in creation of voluntary movements
- each hemisphere controls movement of opposite side of body
- damage cause loss of control
- over fine movements on opposite side of body (contralateral wiring)
-or cause paralysis
Somatosensory cortex
-both hemispheres
- processes information from senses in the skin
- includes touch, pressure, pain
- damage can produce problems in perceiving touch
- or failure to recognise objects by touch
Visual cortex
- both hemispheres
- receives information directly from eyes
- right visual field = left hemisphere
- left visual field = right hemisphere
- damage can cause blindness
- or hallucinations
- or inability to see colour/motion
Wernicke’s area
- left hemisphere
- involved in understanding of language
- damage can cause Wernicke’s aphasia
- canning understand spoken language
- or produce nonsense words
Auditory cortex
- both hemispheres
- analysing speech based information
- e.g. hearing pitch and volume
- damage cause partial hearing loss
- through to full hearing loss
AO3 for Localisation of function: RTS by Broca
P - RTS LOF in brain by Broca
E - case study - man who lost ability to speak - expect word ‘Tan’ - he could understand language
E - post mortem showed damage one area in LH - now named Broca’s area
L - shows language production localised one specific brain area as theory predicts
AO3 for Localisation of function: RTC from patient EB
P - RTC LOF - case study - patient EB
E - EB suffered brain damage - resulted in removal LH therefore language centres
E - however, after some time regained some language ability - not possible if language centres completely localised to LH
L - demonstrates language must be in more areas than LH - suggest holistic explanation of brain function more appropriate than LOF
AO3 for Localisation of function: Discuss for EB and Tan
P - case study of EB and Tan - lacks population validity - not appropriate generalise findings on LOF to typical population
E - these are unique case studies - brain damaged may have affected way brain functions - some ppl can process language in RH
E - for example - some research suggest language not solely lateralised to LH - found in dominant cerebral hemisphere - commonly found be opposite dominant handedness
L - so suggest more research needed - more diverse samples before firm conclusions on LOF/language centres possible
AO3 for localisation of function: RTC by Lashley
P - RTS LOF by Lashley
E - removed areas of cortex in rats - between 10-50% - were learning a maze - found no area was more important than any other areas in terms of ability to learn maze
E - process of learning required all areas of cortex than one specific localised area
L - so suggests holistic explanation of brain may be more appropriate than LOF in brain
What is the difference between both hemispheres?
- each have different functions and roles
Role of the left hemisphere
- responsible for language
- two main language centre in LH:
- Broca’s area = speech production
- Wernicke’s area = understand lang
