week 8 language and lateralisation

Question 1

cerebral lateralisation of function

Answer 1

we have left and right brains, legit like two seperate brains connected and communicate through commisures, of which the corpus callosum is the biggest.

Question 2

tests of cerebral lateralisation

Answer 2

Sodium anatal
dichotomus listening
FMIRI, PET
TMS

Question 3

sodium amytal test.

Answer 3

sodium amytal test. They mke an injection into cateroid artery to make one hemisphere stop working, and see if they can speak.

Question 4

Aphasia: deficit in language comprehension or production due to brain damage

Answer 4

Deficit in language comprehension or production. LH damage

Question 5

Apraxia

Answer 5

Difficulty performing movements when asked. LH damage

Question 6

which hemisphere controls most of speech

Answer 6

left hemisphere

Question 7

is lateralisation absolute?

Answer 7

No. Lateralisation is more of a statistical phenominon than a practical one; the hemispheres closely communicate and specalise.

Question 8

tell me about split brain cat studies.

Answer 8

Each hemisphere can learn independently. Intact cats, learning transfers between hemispheres, when have eye patch put on their results didn’t change, still did task well. Split brain cats (with one eye patched) learn task as well as controls, no memory or savings demonstrated when the patch was transferred to other eye. This is seen also in monkeys and humans.

Question 9

What is cross-cueing

Answer 9

When these hemispheres in split brain individuals try and cheat to communicate even without the corpus callosum, through facial expressions, snatching things from other hand etc.

Question 10

tell me about brocas work

Answer 10

In 1860s, broca described 8 cases with language disturbance, all of whom had damage to left hemisphere. Other patients with right frontal damage had NO language disturbance. Brocas aphasia is when you can understand language, but cannot ‘find’ the words to communicate.

Question 11

tell me about wernickes area

Answer 11

Wernickes area (1870), area distinct from brocas area, as was the difficulties in language. 
Known as receptive aphasia, speech is totally fluent but nonsensical, poor comprehension.  Lesion site is in superior temporal lobe, adjacent to auditory cortex.

Question 12

what are the 7 areas in the wernicke-gershwind model?

Answer 12

Involves 7 key areas
Brocas area (speech production)
Wernickes areas (speech comprehension
Arcuate fasciculus (how broca and wernicke communicate). 
Left angular gyrus 
Primary auditory,
Visual
Motor cortexes.

Question 13

flaws in the wernicke-gershwind model?

Answer 13

Written words don’t need to be transformed into a ‘pseudo-auditory signal in wenickes area)
Importance of brocas and wernickes area can be overstated. Severiy of brocas/wernickes aphasia depends on extent of damage surronding this areas. No patient with aphasic patients have damage ONLY to brocas or wenickes areas, a PURE aphasia is RARE, most people have issues with both.
Other areas outside 7 components effect language processing

Question 14

relationship between laterality and handedness

Answer 14

Left hemisphere -speech dominant in almost all dextrals(right-handers) & most sinestrals(left-handers), but more in right handers.

Question 15

Left hemisphere vs right hemisphere in split brain patients

Answer 15

Left hemisphere can saywhat it has seen; right hemisphere can only point to it. So, if you show them a picture to right visual field (LH), right hand can show you what it was and you can tell them. But if you show them on the LVH (RH), they can’t say what it was but can only point with the left hand.