FACE-SENSITIVE REGIONS IN HUMAN EXTRASTRIATE CORTEX STUDIED BY FUNCTIONAL
MRI.
PUCE, AINA, TRUETT ALLISON, JOHN C. GORE, and GREGORY McCARTHY.
Neuropsychology Laboratory, Veterans Administration Medical Center, West
Haven CT 06516, Departments of Surgery (Neurosurgery), Neurology, and
Diagnostic Radiology, Yale University School of Medicine, New Haven CT
06510.
APStracts 2:0135N, 1995.
SUMMARY AND CONCLUSIONS
1. We have previously identified face-selective areas in the mid-fusiform and
inferior temporal gyri in electrophysiological recordings made from
chronically implanted subdural electrodes in epilepsy patients (Allison et al.
1994a). In this study, functional magnetic resonance imaging (fMRI) was used
to study the anatomical extent of face-sensitive brain regions and to assess
hemispheric laterality. 2. A time series of 128 gradient echo echoplanar
images was acquired while subjects continuously viewed an alternating series
of 10 unfamiliar faces followed by 10 equiluminant scrambled faces. Each cycle
of this alternating sequence lasted 12 s and each experimental run consisted
of 14 cycles. The time series for each voxel was transformed into the
frequency domain using Fourier analysis. Activated voxels were defined by
significant peaks in their power spectra at the frequency of stimulus
alternation and by a 180 phase shift which followed changes in stimulus
alternation order. 3. Activated voxels to faces were obtained in the fusiform
and inferior temporal gyri in 9 of 12 subjects and were approximately
coextensive with previously identified face-selective regions (Allison et al.
1994a). Nine subjects also showed activation in the left or right middle
occipital gyri, or in the superior temporal or lateral occipital sulci.
Cortical volumes activated in the left and right hemispheres were not
significantly different. Activated voxels to scrambled faces were observed in
6 subjects at locations mainly in the lingual gyri and collateral sulci,
medial to the regions activated by faces. 4. Face stimuli activated portions
of the mid-fusiform and inferior temporal gyri, including adjacent cortex
within occipitotemporal sulci. This region of extrastriate cortex is face-
sensitive as assessed by fMRI, but the degree to which it is face-selective
remains to be determined.
Received 27 December 1994; accepted in final form 25 April 1995.
APS Manuscript Number J808-4.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.