hem lateralisation and split brain research Flashcards
what can the RH produce
-rudimentary words and phrases but contributes emotional context
what is the role of LH and RH
-LH = analyser
-RH= synthesiser
how do we know some functions are not lateralised
-vision, motor , somatosensory areas appear in both hemispheres
what is the case of the motor area
-it’s cross wired
-RH controls left side
-LH controls movement on the right
what is the case of the vision
- it’s contralateral and ipsilateral
- each eye receives light from LVF and RVF
-LVF of both eyes is connected to the RH and the RVF of both eyes is connected to LH
what does the visual area allow for
-compares the slightly different perspective from each eye and aids depth perception
-similar to auditory (disparity from two inputs helps us locate source of sounds)
what is the split brain research
-operation severing the connections between RH and LH mainly the corpus callosum
-reduces epilepsy
-in epilepsy the brain experiences excessive elec activity which travels from one hem to another
-to reduce these the connections are cut
- it studies function of both hems when they can’t communication w eachother (the 2 hems )
what is the procedure of sperrys research
-11 ppl who had split brain op were studied using special set up
-image projected to RVF (processed by the LH)
-same or diff image could be projected to LVF(processed by RH)
-in normal world the corpus collosum would immediately share info between both hems for complete pic
-but in a split brain particpant the image could not be conveyed from one hem to another
what were the findings of sperrys research
-when a picture was shown to Ps rvf the Ps could describe what was seen but could not if shown to LVF
-bc in connected brain msgs are sent from RH to language centres in the LH
-but not possible in split brain
-could not give verbal labels to images projected at LVF
-but could select matching object with left hand (linked to RH)
-left hand could select an object of close association with an object presented to LVF
-if pic shown to LVF there was emotional reaction e,g giggle but reported seeing nothing or flash of light
what were the conclusion of sperrys research
-certain functions are lateralised in the brain and support the view that LH is verbal and RH is silent but emotional
strength for hemispheric lat?
(lateralisation in the connected brain)
-fink et al used PET scans to identify which brain areas were active visual processing task
-when they looked at global elements e.g a whole forest regions of the RH were active
-when focusing on finer details the specific areas of LH were more dominate
-so hemispheric lateralisation is also in split brain and connected brain
weaknesses for hemispheric lat?
(one brain)
-LH as analyser and RH as synthesiser may be wrong
-recent research suggests people do not have a dominant side of their brain that creates diff personalities
-Nielsen et al analysed certain hems for certain tasks but there was no evidence of a dominant side
strenghs for split brain research?
(research support)
-gazzingna showed split brain participants perform better than connected controls on certain tasks
-faster at identifying odd one out in similar objects than normal controls
-sperrys earlier findings find the left brain and right brain are distinct
weaknesses of split brain research?
(generalisation issues)
-casual rs hard to establish
behaviour of those in sherry split brain Ps compared to neurotypical control grp
-no participant in the control grp had epilepsy
-major confounding variable
- any differences may have been due to epilepsy rather than split brain
(ethics)
-trauama of operation means Ps wouldn’t fully understand implications of what they agreed too
repeated testing overtime may have been stressful
