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task 6 Split brain (Commissurotomy (Split brain)
--> severing corpus…
task 6 Split brain
Commissurotomy (Split brain)
--> severing corpus callosum + anterior commissure
--> done to prevent epilepsy , by keeping disruptive firing of neurons contained in just one hemisphere
--> allows to study what each hemisphere individually can do , processes or is responsible for :3 !!
Studies
--> important to test each hemisphere independently (unilateral testing) too see effects of each hemisphere
--> lol kind of unfair and not true to life conditions but whatver :P ?
monkey visual discrimination
--> if left hemisphere trained for certain object recognition (left parietal) eg. choosing triangle over circle,
--> right hemisphere didnt have access to this information #
--> apart from that completely normal functioning of monkeys!
Limitations:
- Brains not representative cause afflicted by epilepsy
- low number of split brain patients
- high variability within split brain patients
- e.g. some have active right hemisphere , some dont
- or neuroplasticity / synaptic rearrangement leads to left/right hemisphere to learn things that were lateralized in teh other hemisphere / the other hemisphere was responsible for e.g. language in righ themisphere
- if hemispheres can learn independently (through neuroplasticity) these brains are already different through plasticity changes than before the surgery thus not representative as much anymore
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T-scope test
--> set up so that stimulus appeared only in either the left or right visual field (so would only fall on the left or right side of both retinas) by having them focus on a dot in the middle of a screen
--> the stimulus woul dbe shortly flashed on the right side or the left side of their visual field form that dot
----> this guaranteed they couldn't move their eyes to perceive the dot on the right visual field with their left one by shifting their eyes to it :3 !!
Naming objects
if flashed in right visual field (left hemisphere responsible)
--> they could name it
----> because language lateralized in left hemisphere
if flashed on left visual field (right hemisphere responsible)
--> they could not name it! (becasue no acces to language speaking capabilities)
----->BUT they could pick the right object by feeling ut with their left hand (still right hemisphere) (Cross modal matching)
the left hemisphere can name what it sees but doesnt know it
the right hemisphere Knows what it sees but cant name it
Visuospatial superiority of right hemisphere
---> visuospatial task easy to perform with left hand (right hemisphere) because it involves right parietal cortex which is specialized for spatial perception --> hard to perform with right hand (left hemisphere) thus left parietal, which is important for naming objects --> gazzaniga argued only superior if objects need to be manipulated one way or another :3 !! (manipulo-spatial superiority) #
Face recognition
---> highly lateralized in right hemisphere (even in left handed people)
---> fusiform face area usually more lateralized in right hemisphere (in left handed people slightly left lateralized BUT was small sample size so careful with interpretation :3 !!)
Chimeric figures
--> composite of two faces shown via T-scope test
--> later either asked to either point to face they saw or to verbally say which face they saw based on the whole pictures of the composite pictures
if asked to point (visual spatial right hemisphere)
---> they pointed at the face they saw in their left visual field (which corresponds to right hemisphere)
---> right hemisphere = higher accuracy of picking right corresponding face more often :3 !! shows right side superior !
LINK WITH OTHER EREADER OF RECOGNIZING ONESELF !!!
if asked to verbally say which picture it was (speech lateralized in left hemisphere)
---> they picked the face they saw in their right visual field (which corresponds to left hemisphere)
History
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Second: full split brain (Vogel+ Bogen)
--> corpus callosum + anterior commissure
--> great effect on reducing eppilepsy (fully contains disruptive neural firing to one hemisphere)
--> normal functioning in daily life
if language bilateralizes also onto the right hemisphere some time after operation the right hemisphere can also speak basic nouns etc :3 !!
Duality mind problem
--> evidence shows both hemispheres might work independently in split brain patients
--> so does each hemisphere have its own consciousness?
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Limitation:
--> Nobody know what consciousness really is(definition)
--> No empirical evidence of consciousness or what it is!
verbal report ughghh not again lol
example in course manual
Brain areas
parietal lobe
left parietal
-->important for naming objects
--> short term memory for verbal info (eg. name of object)
right parietal
--> spacial perception
--> short term memory for nonverbal info (eg.location of objects )
temporal lobe
left hemisphere (temporal lobe)
--> lateralisation of language (brockkers / wernickens area)
--> damage can cause aphasia
--> often called dominant hemisphere
perception
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commissures
--> allow for almost instant information exchange between left and right hemisphere (especially since homotopic mostly)
--> if both cut information cannot be transmitted directly thus instantly anymore
Corpus callosum
homotopic connections (mostly)
--> connects one point of left hemisphere with exactly same point in right hemisphere and vice versa :3 !!
connects:
--> frontal, parietal, occipital + (partly) temporal lobe of both hemispheres with each other
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anterior commissure
--> connects frontal temporal lobe + parts of amygdala of hemispheres with each other
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