I'll pass on the teeth-grinding one, but for this one:
On Thu, 14 Sep 2000 [EMAIL PROTECTED] wrote:
>
> 2) In a split-brain patient, does the cutting of the Corpus Callosum involve
> cutting any part of the tract that crosses the optic chiasm? If it does sever
> the optic tract at this point, how does that affect perception and cognition
> in the patient?
The optic chiasma is never split in a patient undergoing a
split-brain operation. Not only would this be a difficult and
dangerous thing to do, given its location at the base of the
brain, but it would have no therapeutic value. The reason the
corpus callosum is split in patients with epilepsy which can't be
controlled by drugs is to stop an epileptic focus of abnormal
activity spreading across the corpus callosum to the mirror focus
in the opposite hemisphere. The optic chiasma isn't responsible.
This is why split-brain patients are tested by flashing stimuli
to the right or left visual fields. This delivers the stimulus to
one side of the brain only, despite an intact optic chiasma. If
they didn't flash, the subject would be able to fixate the
stimulus, which would deliver it to both hemispheres.
However, in animal research, the optic chiasma may be split.
-Stephen
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Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470
Department of Psychology fax: (819) 822-9661
Bishop's University e-mail: [EMAIL PROTECTED]
Lennoxville, QC
J1M 1Z7
Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy
Check out TIPS listserv for teachers of psychology at:
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