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Abstract:
Several functional MRI studies have highlighted the role of
the inferotemporal cortex (IT) and fusiform gyrus in the processing
of faces in normal subjects. What has not been determined, is the
pattern of cortical activation associated with face processing in
patients with a lesion to the fusiform gyrus. Two individuals, SM
and CR, who sustained damage to their right temporal lobe, were
scanned, along with a group of intact control subjects. While both
SM and CR have face perception difficulties, SM is the more
impaired of the two. fMRI imaging was performed on a 3.0T Signa
whole body scanner, with resonant gradient echo planar
capabilities. Fourteen 3mm thick adjacent axial planes were imaged
(TR=3.0s, TE=25ms, matrix size=128x64) while subjects passively
viewed faces, objects, greebles, a fixation cross and jumbled
images and while they performed a same/different judgement task on
pairs of faces (or objects). While the normal subjects and CR
showed similar areas of activation in right IT and fusiform gyrus,
this was not the case with SM. In SM, more posterior areas of IT,
in the right hemisphere, were activated. In addition, a much more
anterior area of activation in the left hemisphere was also
activated. The current results indicate that two other areas in
SM's brain appear to have been recruited for the purpose of
processing faces. The recruitment of these areas is not enough,
however, to improve SM's performance to CR's level, whose cortical
activation appears to mirror the normal pattern.
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