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Abstract:
As faces are known to be processed more holistically than
other visual objects (Tanaka & Farah, 1993), we hypothetised
that activity in face-specific regions in the fusiform gyrus of
human subjects should be modulated by processing either parts in
whole faces, or whole stimuli. During 12 PET sessions (H215O, SPM
analysis methods), subjects had to decide whether a particular
feature in a probe face or house was identical or different than
the same feature in the target stimulus, or whether the whole
target stimulus was identical or different than the probe stimulus.
Comparing face conditions with object conditions revealed bilateral
activation in the anterior fusiform gyrus (BA37) and in the right
posterior fusiform region (BA19). Within these well-defined
face-specific regions, the right anterior fusiform gyrus was found
to be more activated when matching whole faces than face parts
while this pattern of activity was reversed in the left homologous
region. The right fusiform posterior region was found to be
face-specific only when part based processing on objects was used
as baseline condition. These results suggest that activity within
category specific regions in the human visual brain can be
modulated by different task demands. Grant support: FRSM
3.4520.98.
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