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Abstract:
Abstract: Using event-related fMRI, we previously
demonstrated that dorsolateral PFC and not ventrolateral PFC,
exhibits greater recruitment during conditions requiring
manipulation of information held in working memory compared to
passive maintenance of the same amount of information (D'Esposito
et al., 1999, Postle et al, 1999). Our current aim was to explore
further the types of cognitive processes that lead to differential
recruitment of dorsal vs. ventral PFC. During fMRI, participants
performed a working memory task in which each trial consisted of
three 3 X 3 grids, presented sequentially, each containing a
different object in a different location. On different blocks of
trials, subjects studied, and were tested after a brief delay, on
either object, location, or combined object+location information.
We found that (1) memory for bound information, and not memory for
features, showed greater dorsal, as compared to ventral PFC
activation at the time of test (and not during the study, or delay
period) and (2) increases in reaction times (across trial types)
were associated with increases in dorsal PFC activation at the time
of test. These results provide additional evidence that the PFC is
functionally subdivided in a dorsal/ventral fashion according the
type of processing demands. Also, further evidence is provided for
possible neural correlates of processing efficiency.
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