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Abstract:
Abstract: Although increased activity in the hippocampus and
related structures of the medial temporal lobe (MTL) has been
reliably observed with fMRI during memory encoding tasks, increased
activity during retrieval has been less commonly reported. Reliable
increases in activation at retrieval during a recognition memory
task (targets versus foils) have been reported when pictures of
objects were used at study, and words that named or did not name
studied objects were used at test, i.e., when recognition involved
making a comparison between two different stimulus types (Gabrieli,
Brewer, Desmond, & Glover, 1997; Stark & Squire, 1999). In
three fMRI experiments, we addressed the role of stimulus type on
activity in the hippocampus during recognition memory testing, and
we also asked whether hippocampal activity requires making a
comparison between different stimulus types. In Experiment 1,
pictures of objects were used at study and words that either named
or did not name the objects were used at test. In Experiment 2,
pictures of objects were used both at study and at test. Finally,
in Experiment 3, words were used both at study and at test. In all
three experiments, reliable increases in activity for targets
versus foils were observed in the hippocampus (left or bilateral).
Hippocampal activity during recognition memory testing does not
require a comparison between different stimulus types.
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