e left of the video screen. When they saw a stimulus, they reached toward the video screen and touched it on the side where the stimulus appeared.
Slowness to respond to stimuli appearing on the left side of the video screen, she theorized, would mean the patient had spatial neglect and was having trouble noticing the stimuli. Patients who promptly noticed left-side stimuli could report that perception by reaching to their unimpaired right side.
Of 29 patients tested, six were able to respond promptly to left-side stimuli, suggesting they had motor neglect. When Sapir compared high-resolution magnetic resonance imaging brain scans from the two groups, she found a starkly consistent pattern: all the patients identified as having motor neglect had damage to the putamen, while those who still responded slowly to left-side stimuli did not.
Although the putamen isn't damaged in Parkinson's disease, scientists have identified it as a brain region that processes dopamine, the neurotransmitter that drops to low levels in Parkinson's patients.
Scientists plan further study of how other types of neglect may be connected to damage to different brain areas. As an example, Sapir notes that when clinicians give recovering stroke patients a simple drawing to copy, some will leave out the left side of the drawing, while others will copy objects from all over the drawing, but leave out the left sides of individual objects. Whether this represents different kinds of neglect stemming from damage to different brain areas is not yet clear.
"Another possible kind of neglect has to do with putting a patient's good hand on their bad side," Sapir says. "When you do this to some patients, their ability to respond with their good hand decreases. It's like a postural deficit."
Sapir and her colleagues hope to eventually develop a battery of tests that will allow clinicians to dissociate the different kinds of neglecPage: 1 2 3 4 Related medicine news :1
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