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Abstract:
Abstract: Neuroimaging studies suggest that within-modality
priming is associated with reduced regional cerebral blood flow
(rCBF) in the extrastriate area whereas cross-modality priming is
associated with increased rCBF in prefrontal cortex. To
characterize the nature of rCBF changes in within- and
cross-modality priming, we conducted two neuroimaging studies using
positron emission tomography (PET). In experiment 1, rCBF changes
in within-modality auditory priming on a word stem completion task
were observed under same- and different-voice conditions. Both
conditions were associated with decreased rCBF in extrastriate
cortex. In the different voice condition there were additional rCBF
changes in the middle temporal gyrus and prefrontal cortex. Results
suggest that the extrastriate involvement in within-modality
priming is sensitive to a change in sensory modality of target
stimuli between study and test, but not to a change in the feature
of a stimulus within the same sensory modality. In experiment 2, we
studied cross-modality priming on a visual stem completion test
after encoding in full- and divided-attention conditions. Increased
rCBF in prefrontal cortex was observed in the full but not in the
divided-attention condition. Because explicit retrieval is
compromised after encoding under divided attention, prefrontal
involvement in cross-modality priming following the full-attention
encoding condition may be associated with the recruitment of
explicit retrieval.
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