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Abstract:
Abstract: Findings from neuropsychology, neuroimaging, and
electrophysiology converge to suggest that prefrontal cortex (PFC)
contributes to performance on episodic memory tests, but the
precise functional roles of different prefrontal regions remain
unclear. Evidence from prior ERP and fMRI studies is consistent
with the view that PFC is engaged more on memory tasks that require
specific episodic information (e.g., Nolde et al., 1998; Ranganath
& Paller,,1999; in press). In the present study, we used
event-related fMRI to further investigate the response properties
of different prefrontal regions during episodic retrieval. Subjects
were scanned while performing two tests of recognition memory for
objects with different demands on the specificity of information to
be retrieved. Both tests included size-changed versions of studied
objects and previously unstudied objects. In the "general test,"
subjects discriminated between studied and unstudied objects,
whereas in the "specific test," subjects additionally determined
whether old objects were larger or smaller than at study.
Preliminary analyses revealed that activation in dorsolateral PFC
(areas 9 and 46) was greater during specific than during general
test trials for both old and new objects. Such changes were not
reliably observed in inferior (areas 44, 45, and 47) or anterior
PFC (area 10). Implications of these results for characterizing the
differing roles of PFC sub-regions during episodic remembering will
be discussed.
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