Brain Lat.

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Published on 17 Dec 2010
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Brain Lateralization: Chapter 4 Lecture 9
-refers to the fact that brain function does not happen bilaterally, different structures serve
different purposes
Historical Perspectives:
- began in testing of WII brain injuries, each patient exhibited different speech
Brain damage observed in left hemisphere:
-100% showed some form of aphasia (problems in language)
-30% showed some recovery in varying degrees, it was found that most left/ambidextrous
peopled recovered
-the least amount of recovery was reported in right handed people
Brain damage observed in right hemisphere:
-very few language problems and rarely lead to language problems
-those who did show aphasia were left/ambidextrous
-it was concluded that because right hemisphere damage did not result in language
problems and right handed people also did not show symptoms, language is attributed to
left hemisphere functioning
-in left handed people, language is bilateral, both hemispheres deal with language
-If damage is done to the RH and you are RIGHT handed then NO aphasia
-but if damage is done to LH and you are RIGHT handed then aphasia
-if LEFT handed, damage in either LH or RH can effect language but the other H not
damage can compensate
Children (below age 5) and Brain Damage
-at this age language is still bilateral. Therefore any damage to either lobe can effect
-100% of patient s will show recovery, this is because the other NOT damaged H will
-at this age the brain is very plastic and some will have damage H removed (because
scarred tissue can result in seizure late on in life)
-during development brain becomes lateralized
Acolosual patients (born without corpus collusom)
-those with no CC have language on both side
-therefore it seems that during development in ‘normal’ person both H are capable of
language acquisition but LH seems to suppress RH and become dominant and more
LH differences:
- plantum temperale: area of primary language. When taken out it was shown to be more
heavy and convoluted and larger by 1/3.
-therefore the autonomy might be better equipped to handle language
-this automical difference can even be see in birds and results in there vocalisation
-also noted in 10-31 weeks of gestation
Sodium Amytal Test
-used in patients who qualify for hippocampus removal(to much scar tissue from damage
and therefore increase chance of siezures , this is only done in sever cases when
barbiturates are not working and are debilitating
-used to identify what part of the brain is effected because you cannot just cut into
temperal lobe (critical for language)
-injected into one side R-side will put to sleep RH: l lay down, arms out, and count
-if right hand drops: LH if left hand drops : bilateral
Test in Colllage kids
- revealled that right handed kids, where info is presented(verbal) to the LH it is
processed faster than non verbal hemp.
-this suggest that when presented to the RH it attempts to decode it and when unable to
will give to LH to process
Split Brain Patients
- used to stop seizures from spreading to other side of the brain ie) Jasonian marche can
create a grand Mall seizure (recall JM refers to seizure that begins in a specific locale
then begins to spread and cross over to other H)
-CC is cut (note: it is not the only neurofiburlary connection between H
-are normal in every day life
Research of Gazzaniga & Sperry:
-used students and presented an image to one H or the other
-they would present either a verbal image (word) or a pictoral image (non verbal)
-precede to ask student what the A. saw (verbal response) or B. pick out what they saw by
feeling object (motor response)
A. presenting object visually (non verbal) to non-verbal hemp. (RH)
i. When asked what it was were unable to verbally respond/describe it
-language is in LH; received in LH and respond through LH
Ii. Tell them to feel and pick out object with right hand they are unable
-Right hand is communicating with LH and LH did not see anything
Iii. Tell them to feel and pick out object with Left hand the can show you
-Left hand is communicating with RH (who did see it)
B. presenting a word visually
i. cannot verbally tell you what they say
-word presented to non verbal hemp (RH)
Ii. Asked to pick out obeject with right hand
-unable to because right hand communicates with LH who did not see it
Iii. Cannot pick out verbal info in non-speaking hemp. Except for small words that were
learned early in life, suggesting that the RH might have language from when development
still held it bilaterally)
RIGHT HEMP abilities:
1. Musical abilities: -music presented to left ear (RH) will be more remembered
- damage in RH=problems with music abilities
2. Geographical and Spatial abiliites