hemispheric lateralisation and split brain research

Question 1

what is localisation and lateralisation?

Answer 1

localisation-> funtions (like vision) governmed by specific areas
Lateralised-> two sides called hemispheres, thus hemispheric lateralisation

some functions= both hemispheres. vision= L + R occipital lobe.

Question 2

talk about the left and right hemispheres

Answer 2

LANGUAGE
LH -> Broca’s area in left frontal lobe, Wernicke’s in left temporal lobe.
language=lateralised, performed in 1 hemisphere.

RH
produces rudimentary words + phrases, contribute to emotional context of what is said.
lead to suggestion LH=analyser RH=synthesiser

some functions X lateralised (vision in LH + RH)
BUT motor area, cross wired, RH controls left side, LH controls right side.

MORE COMPLICATED- vision.
eye recieves light from LVF and RVF.
LVF connected to RH, RVF connected to LH.
enables area to compare diff perspectives, aids perception.

Question 3

Split brain research , and the research of Sperry

Answer 3

connection between RH and LH severed. Reduces epilepsy. during seizure, brain experiences excessive electrical activity, travels from one H to the next. Reduce fits, connection cut.

SPERRY
11 people who had split brain surgery studied.
Image projected to RVF (processed by LH)
same/diff image projected to LVF (processed by RH)
normal brain-> corpus callosum immediately share info, giving complete pic of world
However X be conveyed from one H to the other

FINDINGS
picture shown to RVF, ppt described what was seen. X for LVF (RH)
X do this if object was shown to LVF, ‘nothing there’
connected brain- messages go from RH to language centre in LH
BUT, although X give verbal labels, could select matching object out of site with left hand.
If pinup was shown to LVF, emotional reaction (giggle) but ppt reported seeing nothing or just flash of light.

Conclusion- show lateralisation, support LH=verbal, RH=silent but emotional

Question 4

Split brain research evaluation

Answer 4

+ve recent research
Gazzaniga showed split brain ppt perform better than control on some tasks
example= faster @ spotting odd one out in array of shapes.
in normal brain, LH cognitive strategies watered down by inferior RH
support L and R distinct

-ve generalisation issues
causal relationship= hard to establish. B of split brain ppt compared to neurotypical C group.
issue= X ppts in C group had epilepsy.
confounding variable
differences due to epilepsy, X split brain.
FUTHERMORE
split brain oversimplify hemispheric lateralisation, ignore plasticity, and how this allows compensation across hemispheres.
question V

Question 5

hemispheric lateralisation evaluation

Answer 5

+ve lateralisation in connected brain
research shows 2 hemispheres process info diff.

FINK
PET scan, identify 2 active brain areas during visual processing task. ppt w connected brain asked to attend
global element (all of forest) RH more active
finer detail (individual tree) LH more active
suggests ( as far as visual processing is concerned) HL is feature of connected brain, and split brain.

-ve, idea of LH as analyser + synthesiser WRONG
diff functions in LH + RH, research suggests people X have dominant side, which creates diff personality
Nielsen et al, analysed brain of 1000 people aged 7-29
found people used certain hemispheres used for certain tasks (lateralisation) X evidence for dominant side.
Notion of left brained and right brained is XXXXXXXXXXXXXX