So is there an auditory chiasm and do the visual field tests done with split
brain patients work similarly with the left and right auditory fields?
Nathalie Cote
> -----Original Message-----
> From: Stephen Black [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, September 14, 2000 8:54 AM
> To: TIPS
> Subject: Corpus callosum question
>
>
> 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]
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> J1M 1Z7
> Canada Department web page at
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