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Abstract:
Abstract: The effect of test delay on implicit and explicit
memory for images of novel visual objects was examined in
Parkinson's and Huntington's patients. Participants studied the
objects for 5-second exposures and indicated whether each faced
predominantly to the left or to the right. Performance on both
implicit object decision and explicit (old-new) recognition tasks
was observed immediately following study and after several
study-to-test delays. The Parkinson's patients exhibited a decline
in performance over delay in the explicit object recognition task
compared to age-matched controls. This trend contrasted markedly
with their performance on the implicit object decision task, which
was similar to that of the age-matched group. Huntington's patients
showed impaired performance over delay on the object decision task
relative to their age-matched controls, but did not differ in the
recognition test. Priming was intact when assessed immediately, but
was not present at any of the delayed tests. Thus both basal
ganglia diseases were associated with diminished memory
performance, but Huntington's patients showed this deficit on an
implicit memory task while Parkinson's patients manifested
defective explicit recognition. The difference in the pattern of
results may be due to the different cortical-basal ganglia circuits
affected in the two diseases.
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