Hemispheric Lateralisation and split brain research Flashcards
what is localisation
some functions such as vision and language are governed by specific areas in the brain
what is hemispheric lateralisation
idea that two halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rater than the other
why is language lateralised
because the Broca area is in the left frontal lobe and the Wernickes area is in the left temporal lobe so shows how it is being performed in one hemisphere than the other
what suggests that the Lh is the analyser and the RH is the synthesizer
RH can only produce rudimentary words and phrases but contributes emotional context to what is being said
what functions are not lateralised
vision because the somatosensory appears in both hemispheres
what does the Right hemisphere control
controls movement on the left side of the body
what does the left hemisphere control
controls movement of the right side of the body
what happens in the case of vision
it is both contralateral and ipsilateral (opposite and same sided)
where does each eye receive light from
from left visual field and right visual field
what is left visual field of both eyes connected to
Right hemisphere
what is the right visual field of both eyes connected to
left hemisphere
what does the contralateral functon of eye help with
enables visual area to compare the slightly different perspective from each eye and aids depth perception
what does split-brain surgery involve
severing connections between RH and LH mainly the corpus collosum
why is the split brain surgery use
to reduce epilepsy. During an epileptic seizure the brain experience excessive activity which travels from one hemisphere to another. To reduce fits these connections are cut
what did Sperry research
devised a system to study how two different hemispheres deal with for example speech and vision
what was the procedure of Sperry research
11 people studied who had split brain surgery image was projected to patients RVF (processed by LH) same or differnt image is projected at the LVF
In the normal brain the corpus callosum would immediately share the information between both hemisphere share giving a full picture of the visual world
However, presenting the image to one hemisphere of a split brain participant meant that information cannot be conveyed to one hemisphere to the other
what were the findings of the research
when picture of an object the patients RVF could describe what was shown but could not do this if shown to the LVF
this is because the message from RH cannot relay to language centre
Although could not give verbal description to objects shown in the LVF
they could select a matching object out of sight using left hand (link to RH).Left hand was able to select an that was most closely associated with the object shown with object presented in LVF
what was the conclusion of the research
these observations show how certain functions are lateralised in the brain support the view that the LH is verbal and RH is silent but emotional
What is STRENGTH
PET scans show when normal participants attend to global elements of an image the RH is more active
When required to focus on finer detail the specific areas of the LH tend to to dominate
This suggests that hemispheric lateralisation is a feature of the normal brain as well as the split brain
what is a Limitation
maybe different functions in the RH and LH but reseqarch suggests people dont have dominant side
Nielson et al analysed 1000 bran scans. Finding people did use certain hemisphere for certain tasks but no dominance
This suggests that the notion of right- or - left brained people is wrong (e,g artist brain)
