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Abstract:
Using event-related fMRI, the neural correlates of memory
encoding can be studied by contrasting the item-related activity
elicited in a study task according to whether the items are
remembered or forgotten in a subsequent memory test. Previous
studies have implicated the left prefrontal cortex in the
successful encoding of verbal material into episodic memory when
the study task is semantic in nature. Here, we ask whether the
neural correlates of episodic encoding differ depending on type of
study task. 17 subjects participated in an event-related fMRI
experiment in which at study, participants were cued to make either
animacy or syllable judgements about words. A recognition memory
test followed after a delay of about 15 min. For the animacy task,
words that were subsequently remembered showed greater activation
in left and medial prefrontal regions. For the syllable task, by
contrast, successful memory for words was associated with
activations in bilateral intraparietal sulcus, bilateral fusiform
gyrus, right prefrontal cortex, and medial posterior occipital
gyrus. No evidence was found for greater activation in left
prefrontal cortex for subsequently remembered words in the syllable
task. These findings suggest that the brain networks supporting
effective encoding into episodic memory differ according to study
task.
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