stereopsis preserved

[P3D <gosfield@xxxxxxxxxxxxxxxxx>]

more on the importance of stereopsis in evolutionary terms--

In my medical work i have done quite a few brain scans (studies of the 
metabolic activity and/or blood flow in living brains in humans) of folks 
in advanced stages of degenerative diseases (alzheimer's, pick's disease, 
the increasingly popular Jacob Kreutzfelt) and depression, as well as 
those who are severely injured from traumatic impact, as well as the 
changes of normal aging.

The two areas of the cortex of the brain which are most consistently 
preserved through all the ills that flesh is heir to are: 

1) the cerebellum, which functions importantly as a switchboard responsible 
for coordinating information from many areas of the brain (sorry for the
oversimplification) and

2)the visual cortex (in the occiptial region). In the visual cortex, 
specifically the calcarine cortex, where there is an area in each 
hemisphere which receives input from both eyes.

i have met quite a few people who are barely functioning mentally, from 
globally effective diseases or severe diffuse brain trauma, yet 
the metabolic function of the visual portion of the brain is quite 
normal.  I don't know what the specific effect on stereopsis has been in 
these cases.

there are specific lesions in the brain which affect specifically
stereopsis, although at this point i haven't located much material on the
subject. 

Any visual neurologists in the group?

ted
gosfield@xxxxxxxxxxxxxxxxx


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