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Abstract:
Abstract: Pleasant and unpleasant episodic memories
differentially influence adaptive behavior. To explore their neural
substrates, eleven healthy male subjects were studied with PET and
15-O-water under 12 conditions in a 3 (pleasant, unpleasant or
neutral) x 2 (familiar or unfamiliar pictures) x 2 (presence or
absence of retrieval effort) factorial design. International
Affective Picture System pictures were used as stimuli to be
recalled during subsequent PET imaging. Prior to each scan subjects
viewed 20 pictures of one emotion type. During scans subjects
viewed pictures of the same emotion type for 6 seconds each. Data
were analyzed in SPM. We examined the 3-way interaction (emotion1 -
emotion2) x (familiar-unfamiliar) x (retrieval - nonretrieval).
Relative to matched unpleasant conditions, retrieval of familiar
pleasant pictures was associated with blood flow increases in right
superior temporal, left inferior frontal, bilateral superior
prefrontal cortices, left cuneus and left lingual gyrus (all
z>3.09, p<.001, uncorrected). Relative to matched
pleasant conditions, retrieval of familiar unpleasant pictures was
associated with increases in left inferior and mid-frontal,
bilateral temporal, right parahippocampal and right
occipito-temporal cortices (all z>3.09, p<.001, uncorrected).
Thus, different distributed sets of structures are uniquely
activated during pleasant or unpleasant episodic memory retrieval.
These findings provide neuroanatomical support for behavioral
findings indicating that episodic memories are differentially
organized according to their emotional significance.
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