[EMAIL PROTECTED] wrote:
Hi all,
I had a student ask me a question in class the other night regarding
split-brain patients. Does visual information go to both hemispheres? From pictures, it looks as though information coming into your right
visual field splits and goes to both the right and left hemisphere and
vice versa for the information coming into your left visual field. I
understand that the information still crosses by way of the optic nerve,
but it seems as though from pictures that the visual information goes to
both hemispheres, although that is not the way it is explained.
Thank you, Nina
As others have written, left visual field information crosses over to the right at the optic chiasm, while right visual field information crosses over to the left. However visual information from the eye does follow at least two other tracts back into the brain--one to the superchiasmatic nucleus, and another to the superior colliculi. I'm not sure that either or both of these paths cross over from one hemisphere to the next. Perhaps they do. But since the fiber paths are below the corpus callosum, they remain intact in split brain patients--which might be one reason why the right hand can "know" and therefore reach out and touch what the left brain cannot say.
--Kathy Morgan
Wheaton College
Norton, MA
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