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Abstract:
Abstract: Episodic encoding occurs as a byproduct of certain
forms of information processing independent of whether there is any
intent to memorize. We explored a paradoxical form of incidental
encoding using rapid-presentation event-related functional MRI in
14 subjects. The incidental encoding task was an episodic memory
retrieval task. Subjects viewed words and indicated whether or not
they remembered them. Relevant to encoding, the fate of the new
items presented during the recognition test was examined using a
second, surprise test of recognition. New words presented during
recognition were remembered well suggesting the initial recognition
test was an effective incidental encoding procedure. More
critically, event-related analysis of those new items that were
later remembered revealed greater activity in left frontal regions
(along inferior frontal gyrus) than those that were later forgotten
-- the same pattern of results as previously observed for
traditional incidental and intentional episodic encoding tasks
(e.g., Wagner et al., 1998 Science). This finding may offer a
partial explanation for why repeated testing improves memory
performance. Furthermore, the observation of correlates of episodic
memory encoding during retrieval tasks challenges some
interpretations that arise from direct comparisons between
"encoding tasks" and "retrieval tasks." Encoding processes and
their neural correlates may arise in many forms of task, even those
nominally labeled as retrieval tasks by the experimenter.
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