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Abstract:
Abstract: It has been suggested that the basal ganglia are
involved in incremental learning of stimulus-response associations,
while the hippocampal region is involved in more complex learning,
such as stimulus-stimulus associations. These ideas have been
supported by data showing impairement in stimulus- response
learning in individuals with Parkinson's disease, and in
stimulus-stimulus learning in individuals with hippocampal-region
damage. The goal of the present study was to look for evidence of
this dissociation in a single task which involved both
stimulus-response and stimulus-stimulus association. In this task,
subjects first learned a series of concurrent discriminations of
visual stimuli, and then were tested for transfer to novel
recombinations of familiar stimuli. Parkinson's patients showed
slower initial learning, particularly as memory load increased, but
those patients who were able to learn the original task showed good
transfer in the second phase. In contrast, individuals with
hippocampal atrophy showed the opposite pattern: little or no
impairment in acquisition, but devastated transfer, as reported
previously (Schnirman, Myers, Gluck, Kluger, Ferris and DeLeon,
1999). These results are consistent with the idea that the basal
ganglia are involved in incremental learning, while the hippocampus
is needed for stimulus-stimulus association.
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