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Abstract:
Using fMRI, we tested the hypothesis that learning
associations between pairs from different stimulus categories
(faces and houses) would result in greater retrieval-related
activation of fusiform and parahippocampal face and house
responsive regions than viewing unassociated stimuli. Participants
(n = 7) memorized house-house, house-face, face-house, and
face-face pairs before scanning. Blocked scans of novel faces,
houses, and fixation crosses were used to localize fusiform regions
preferentially responsive to faces (face ROIs) and
parahippocampal/fusiform regions preferentially responsive to
houses (house ROIs) in each subject. During event-related
incidental retrieval scans, participants were shown fixation
crosses; faces previously unpaired, paired with houses, or paired
with faces; and houses previously unpaired, paired with faces, or
paired with houses; and were required to make perceptual judgements
about the displayed stimuli (houses: shutters/no shutters, faces:
blonde hair/ non-blonde hair). ROI analyses in bilateral
parahippocampal/fusiform house ROIs revealed that viewing faces
previously paired with houses lead to greater signal decreases than
viewing unpaired faces. The right fusiform face ROI revealed a
greater response to houses previously paired with faces than to
unpaired houses. These results support our prediction that during
retrieval of associated pairs, there is activation of fusiform and
parahippocampal regions. These results suggest that incidental
retrieval of associations is sufficient to drive the same cortical
regions that can be driven by perceptual stimulus
characteristics.
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