localisation of function in the brain- biopsychology Flashcards
what is localisation versus holistic theory
19th century discovered specific areas of brain associated with physical and psychological functions, before investigations generally supported holistic theory of the brain that all parts of the brain were involved in processing of thought and action
broca and wernicke argued localisation of function- idea that different parts of brain perform different tasks and are involved with different parts of the body, follows then that if certain area of brain becomes damaged the function associated with that area will be affected
what are the hemispheres of the brain
main part of the brain divided into two symmetrical halves called left and right hemisphere
some physical and psychological functions are controlled or dominated by particular hemisphere called lateralisation
general rule activity on left hand side of body controlled by right hemisphere and activity on right hand side controlled by left hemisphere
what is the cerebral cortex
outer layer of both hemispheres, cortex of both hemispheres subdivided into four centres called lobes of brain frontal lobe and pariteral lob occupational lobe and temporal lobe
lobe part of organ seperate in some way from the rest
each lobe in the brain associated with different functions
what is the motor area
controls voluntary movement in opposite sie of the body
damage to this area of the brain may result in a loss of control over fine movements
what is the somatosensory area
seperated from the motor area by a valley called central sulcus
sensory info from skin is represented
amount of somatosensory area devoted to particular body part denotes sensivitivity
what is occipital lobe
back of the brain visual area
each eye sends info from the right visual field to the left visual cortex and from the left visual field to the right visual cortex
means damage to the left hemisphere can produce blindness in part of the right visual field of both eyes
what is the temporal lobe
house of auditory area analyses speech based information
damage may produce partial hearing loss
more extneisve damage the more extensive loss
damage to specific area may affect ability to comprehend language
what is the language centres of the brain
language restrictred to left side of the brain
1880s Broca identified small area in left frontal lobe responsible for speech production
damage to Brocas area causes Brocas aphasia which is characterised by speech that is slow laborious and lacking in fluency
brocas mist famous patient was tan because that was the only word he could say, people with brocas aphasia have difficulty with prepositions and conjunctions
broca wernicke descibing people who had no problem producing language but severe difficulties understanding it such that the speech they produced was fluent but meaningless
wernicke identified a region in the left temporal lobe as being responsible for language understanding, results in wenickes aphasia when damaged
people who have wernickes aphasia will often produce nonsene words as part of the content of their speech
what is evidence from neurosurgery
strength- localisation damage to areas of the brain has been linked to mental disorders
neurosurgery last resort method for treating some mental disorders targeting specific areas of the brain which may be involved
cingulotomy involves isolating region called the cingulate gyrus which has been implicated in OCD
dougherty reported on 44 people with PCD who had undergone cingulotomy, post surgical follow up after 32 weeks about 30% had met the criteria for successful response to the surgery and 14% partial response
success of procedures suggests that behaviours associated with serious mental disorders may be localised
what is evidence from brain scans
strength- brain scans that supports idea that many everyday brain functions localised
peterson used brain scans to demonstrate how wernickes area active during listening task and brocas area active during reading task
review of long term memory studies by buckner and peterson revealed semantic and episodc memories reside in different parts of prefrontal cortex
studies confirm localised areas for everyday behaviour
objective methods for mesauring brain activity have provided sound scientific evidence that many brain fucntions localised
weakness- challenge comes from lashley removed areas of cortex in rats that were learning the route through a mazeno area was proven to be more important than any other area in terms of the rats ability to learn the route
the process of learning seemed to require every part of the cortex rather than being confined to particular area
suggests that higher cognitive prcesses such as learning are not localised but distributed in more holistic way in the brain
what is the language localisation questioned
weakness- lanaguage may not be localised just to brocas and wernickes areas
dick and tremblay found only 2% modern researchers think language in the brain completely controlled by brocas and wernickes areas
advances in brain imagine techniques such as fMRI mean that neural processes in brainc an be studied with more clarity than ever before
seems than language function distributed fa more holistically in the brain than first thought
so called language streams have identified across cortex including brain regions in right hemisphere as well as subcortical regions such as thalamus
suggests that rather than being confined to couple of key areas language may be organised more holistically in the brain which contradicts localisation theory
what is case study evidence
unique cases of neurological damage support localisation theory such as case of phineas gage
problems with case studies
difficult to make meaningful generalisations from findings of single individual
conclusions drawn may depend on subjective interpretation of researcher
what is the case of phineas gage
whilst working in railroad 1848 25 year old gage preparing to blast section of rock with explosives to create new railway line
during process gage dropped his tamping iron onto rock causing explosve ignite
explosion hurled the metre length pole through gages left cheekc passing behind left eye and exitig his skull from top of his head taking portion of brain with it most of his frontal lobe
gage survived but damage to his brain left a mark on [ersonality
turned from someone who was calm and reserved to someone who was wuick tempered rude and no longer gage
seen as landmark case in science as change in his temperment followig accident suggested frontal lobe may be responsible for regulating mood
