Blind World


Wake Forest Study targets vision coordination area of brain.





June 26, 2003.

By Tim Whitmire,
The Associated Press.




CHARLOTTE, N.C.


Researchers from the Wake Forest University School of Medicine think they have isolated cells in the brain that are responsible for coordinating the way humans see their world.


Their research may offer hope for people suffering from "visual neglect," frequently found in patients who have suffered strokes or traumatic brain injuries.


People suffering visual neglect not only don't see things, as in cases of blindness, but are not even conscious that they not are seeing things.


"It is as if that part of space does not exist," John McHaffie, the neurobiology professor who headed the research team, said in a telephone interview Wednesday.


"It's distinguishable from blindness in the sense that a person who is blind acknowledges that half the world is invisible to him and will recognize it as a lack of vision.


"People that have neglect go so far as to deny the existence of half the world," he said.


A man with visual neglect might stop shaving half his face. Often, people who suffer from the condition have trouble dressing, walking and caring for themselves.


According to the Wake Forest researchers' report, published Wednesday in the journal Nature, signals from the basal ganglia, a large collection of nuclei inside the brain that are known to control voluntary movements, may help regulate visual activity in the brain.


"We discovered a push-pull system in the basal ganglia that regulates activity on the two sides of the brain," McHaffie said.


When damage to the visual cortex occurs in a stroke or other brain injury, the researchers theorized, the carefully balanced system goes haywire and visual neglect results.


Researchers think by suppressing signals from the basal ganglia cells identified as responsible for coordinating visual activity, they may be able to restore function to the visual brain.


McHaffie said research showed that lesions in the brain's cortex that caused visual neglect in cats could be "undone" by creating a second lesion in the basal ganglia.


Still not clear, McHaffie said, is whether manipulating the basal ganglia would have unforeseen repercussions.


He also said because strokes and severe brain injuries often affect many different parts of the brain, solving the problem of visual neglect is not necessarily a cure-all.






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