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Abstract:
Abstract: Previous studies have suggested that the basal
ganglia may play an important role in category learning, since
patients with Parkinson's Disease were impaired on a probabilistic
categorization task. However, Parkinson's patients were not
impaired at other types of category learning tasks, suggesting that
under some conditions category learning can be sustained despite
basal ganglia dysfunciton, perhaps by other brain systems. One
problem with these findings may be that the original task on which
Parkinson's patients were impaired used a category structure that
was very hard to discriminate, leading to poor performance even
among control subjects. The goal of the present study was to
clarify the nature of the category learning deficits in Parkinson's
using a probabilistic categorization task which was formally
similar to the earlier task, but which was easier to learn and
which was trained repeatedly for three days. Under these
conditions, we found that Parkinson's patients performed
consistently worse than age matched controls across three days of
training. However, we also found that Parkinson's patients improved
significantly across training, eventually reaching performance
levels that were similar to those obtained by control subjects
after a single day. The results suggest that Parkinson's Disease
may lead to changes in learning rate which can be overcome with
extensive training.
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