Localisation of function + hemispheric lateralisation Flashcards
What is meant by localisation of function
Certain functions have certain locations within the brain
What is meant by hemispheric lateralisation
The two halves of the brain are functionally different + each hemisphere has functional specialisation
Motor area
Location
Function
Right, left or both hemispheres
Location- frontal lobe
Function - controls voluntary movement in opposite side of body
Right, left or both hemispheres -both, left controls right side of the body + vice versa
somatosensory area
Location
Function
Right, left or both hemispheres
Location - parietal lobe
Function - receive incoming sensory information from skin to produce sensations related to pressure, pain, temperature, ect
Right, left or both hemispheres - both, somatosensory area on one side of the brain receives sensory info from the other side of the body
Visual area
Location
Function
Right, left or both hemispheres
Location - occipital lobe
Function - receives + processes visual info. Contains parts that process different types of information including colour shape or movement
Right, left or both hemispheres - both, information to the right hand side in Visual field is processed in the left hemisphere and, vice versa
Auditory Area
Location
Function
Right, left or both hemispheres
Location - temporal lobe
Function - responsible for analysing and processing acoustic info
Right, left or both hemispheres - both info from the left ear goes primarily to the right hemisphere, Vice versa
Broca’s area
Location
Function
Right, left or both hemispheres
Location - left frontal lobe
Function - involved in speech production, damage leads to Broca’s aphasia
Right, left or both hemispheres - left
Wernicke’s Area
Location
Function
Right, left or both hemispheres
Location - left frontal lobe
Function - involved in language comprehension. Damage needs to Wernicke’s aphasia
Right, left or both hemispheres - left
Research related to Broca’s + Wernicke’s area
CASE STUDY (TAN): could understand spoken language but unable to produce coherent words, + could only say ‘Tan’. After Tan’s death, BROCA conducted a post-mortem his brain + found a lesion in the left frontal lobe. ∴ concluded this area was responsible for speech production. People w/ damage to this area experience Broca’s aphasia, → slow and inaccurate speech. BUT DRONKERS: conducted MRI scan on Tan’s brain, to confirm Broca’s original work. Although there was a lesion found in Broca’s area, they also found evidence to suggest that other areas may have also contributed to the failure in speech production. ∴ it is likely not just Broca’s area responsible for speech production PETERSON: brain scans to show how Wernicke’s area was active during a listening task (understanding) + Broca’s area was active during a reading task (speech). TS LoF +also supports lateralisation as showed language centres are in the left hemisphere. BUT LASHLEY: removed areas of the cortex in rats that were learning a maze. No area was proven to be any more important than the other in terms of learning, which seemed to require every part of the cortex TDNS localisation but suggests cognitive functions are holistically distributed. TIFB SAGIN: some patients showed symptoms of Wernicke’s aphasia w/o damage to this area. TS language comprehension is more complex than originally thought.
ISSUES W/ CASE STUDIES: cant generalise 1 pts experience to everyone else
Limitations of localisation of function
Plasticity- LASHLEY: Equipotentiality Theory → intact areas of cortex can take over responsibility for specific cognitive functions following brain injury. ∴ casts doubt on theories about the LoF. TS functions are not localised to just one region, as other regions can take over specific functions following brain injury.
Limitations of hemispheric lateralisation
TIFB DANELLI: (case study EB) 2.5 y/o who lost almost all of L. hemisphere after tumour removal. At the time all of his linguistic abilities disappeared but after intensive rehab, tested him against controls + found his R. hemisphere compensated for the loss of his left.
localisation of function + hemispheric lateralisation IDA
REDUCTIONISM vs HOLISM:
biologically reductionist in nature and try to reduce very complex human behaviours + cognitive processes to one specific brain region. Such critics suggest that a more thorough understanding of the brain is required to truly understand complex cognitive processes like language.
GENDER BIAS:
fails to take into account individual differences. HERASTY: found women have proportionally larger Broca’s + Wernicke’s areas than men, perhaps explains the greater ease of language use amongst women. BUT, TS a level of beta bias in the theory: the diffs between men + woman are ignored, + variations in the pattern of activation and the size of areas observed during various language activities are not considered.
