Posted by alexandra_k on July 29, 2013, at 0:21:55
In reply to How therapy works, posted by Twinleaf on July 28, 2013, at 10:59:54
Thanks for posting it, Twinleaf, it does look interesting.
There are better and worse claims for hemispheric specialization. One of the first discoveries was that people who acquired lesion to Werneke or Broca's (left hemisphere) regions simultaneously acquired an inability to comprehend or produce speech in their native language.
And blood flows to those regions when people engage in linguistic tasks (compared to I forget what other control tasks) in the MRI scanner (aka: those regions 'light up').
Not ALL people have language localized to these regions... They found that people who know more than one language have a different (more distributed, less localized) set-up. Their second language in particular is more resilient to being knocked out of them via localized tumor or localized stroke (insofar as those things have localized effects) or surgery... They found that some people have their language production / comprehension processing in comperable regions of the right (rather than left hemisphere). That was more common in left handers, but was still rare (even for left handers).
(This matters because neurosurgeons want to leave alone areas that are needed like that).
There is also hemispheric specialization for motor production. The left hemisphere controlling the limbs and much of the right side of the body and vice versa. You can see that quite clearly when those regions are stimulated for neurosurgery (the surgeon 'tests' a bit before removing it. E.g., if you stimulate a bit and the hand jumps then if you remove that bit the hand will probably jump no more). I think that is the thought. Whether it is actually true I do not know. I do know that they test before removal and don't remove bits the surgeon judges to be needed (usually this is about motor production, removing tumors from near the motor production region of the cortex, I think).
There is some stuff on how the left side is more specialized for reason because of the links to language processing... I forget... Maybe I make stuff up... Temporal lobe lesion to I forget which hemisphere... Right? f's up spatio-temporal processing... perhaps also math... temporal lobe epilepsy is associated with lesion or tumor to right hemisphere not left. Or maybe I'm making stuff up now... The face displays basic emotions not symetrically... Since the right side of the motor cortex controls the left side of the face (mostly)... They have found that the left side of the face is more emotionally expressive, apparently. thus the claim that the right hemisphere is more specialized for emotional expression and other non-verbal stuff.
The crude picture of one half of the brain working while the other doesn't work is of course false. There is always a base rate of neural firing... It isn't THAT they fire it is more the RATE of firing. Like the idea of we only use 20% of our brains is crappy... You can remove 80% of the rat cortex before you totally f up rat maze running is the thought there. But of course rats don't tell the experimentor to quit already. Not after... But also not before...
poster:alexandra_k
thread:1047925
URL: http://www.dr-bob.org/babble/psycho/20130309/msgs/1047967.html