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Abstract:
This project investigated the neurological substrates that
underlie conceptual implicit memory and recognition-based
familiarity in amnesic patients and controls to examine the
possibility that a common conceptual fluency mechanism supports
both processes. Evidence for a common mechanism would contradict
current theories that assume implicit and explicit memory tasks
reflect distinct retrieval processes supported by separate neural
systems. Previous studies examining conceptual priming or
familiarity in amnesia have led to mixed results, with no study
directly comparing these two processes in the same group of
patients. Two measures of conceptual priming were used in this
study: category exemplar generation and semantic decision.
Participants were also given a Remember/Know recognition memory
test to obtain estimates of familiarity. Further comparisons were
made between amnesic patients with selective lesions of the
hippocampus and patients with lesions including both the
hippocampus and parahippocampus to determine if the parahippocampus
supports familiarity. If a common neurological substrate underlies
conceptual implicit memory performance and familiarity judgments,
then amnesic patients should perform similarly on both of these
tasks. However, if amnesics show impaired performance on one type
of test but spared performance on the other, then this would
suggest that these tasks do not rely on the same conceptual fluency
mechanism.
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