(brain) hemispheric lateralisation & split-brain research AO1

Question 1

hemispheric lateralisation

Answer 1

idea that 2 halves of the brain are functionally different & certain mental processes/behaviours mainly controlled by 1 hemisphere rather than the other

Question 2

split-brain research

Answer 2

series of studies which began in 1960s involving those with epilepsy who had experienced surgical separation of the hemispheres to reduce severity of epilepsy
- enabled researchers to test lateral functions of the brain in isolation

Question 3

where are 2 main language centres found & describe them

Answer 3

• only in LH
  1) broca’s area = left frontal lobe
  2) wernicke’s area = left temporal lobe

Question 4

examples of functions which aren’t lateralised

Answer 4

vision, somatosensory & motor exist in both hemispheres

Question 5

motor cortex - cross wired (contralateral wing)

Answer 5

RH controls movement of left side of body & vice versa

Question 6

which cortex is both contralateral & ipsilateral

Answer 6

vision cortex

Question 7

contralateral

Answer 7

opposite sides

Question 8

ipsilateral

Answer 8

same-sided

Question 9

explain how the vision cortex is both contralateral & ipsilateral

Answer 9

• each eye receives light from left visual field (LVF) & right visual field (RVF)
• LVF of both eyes connected to RH
• RVF of both eyes connected to LH

Question 10

why is the vision cortex both contralateral & ipsilateral

Answer 10

enables visual areas to compare slightly different perspectives from each eye & aids depth perception

Question 11

what system did roger sperry (1968) devise

Answer 11

to study how 2 separated hemispheres deal with, for example, light & vision

Question 12

procedure of sperry (1968)

Answer 12

• 11 people who’d had split-brain surgery were studied
• used special set up: image could be projected in RVF (LH) & same/different image into LFV (RH)
• ‘normal’ brain = corpus callosum would share info between hemispheres giving complete picture of visual world
• split-brain patient = info cannot be conveyed from 1 hemisphere to the other

Question 13

findings of sperry (1968)

Answer 13

• if pic of object shown to RVF (LH) = ppt could describe what they see
• couldn’t do this if shown to LVF (RH) = said ‘nothing there’
  = due to normally messages from RH relayed to language centres in LH
• even though couldn’t give labels to images seen by LVF (RH), they could select matching object from sight using left hand
• if pinup pic shown to LVF, there was emotional reaction (eg. laugh) but usually reported seeing nothing/flash of light

Question 14

conlcusions of sperry (1968)

Answer 14

show how certain functions are lateralised in the brain & support view that LH is verbal & RH is ‘silent’ but emotional