Separate coding of different gaze directions in the superior temporal sulcus and inferior parietal lobule.
Electrophysiological recording in the anterior superior temporal sulcus (STS) of monkeys has demonstrated separate cell populations responsive to direct and averted gaze. Human functional imaging has demonstrated posterior STS activation in gaze processing, particularly in coding the intentions conveyed by gaze, but to date has provided no evidence of dissociable coding of different gaze directions. Because the spatial resolution typical of group-based fMRI studies (approximately 6-10 mm) exceeds the size of cellular patches sensitive to different facial characteristics (1-4 mm in monkeys), a more sensitive technique may be required. We therefore used fMRI adaptation, which is considered to offer superior resolution, to investigate whether the human anterior STS contains representations of different gaze directions, as suggested by non-human primate research. Subjects viewed probe faces gazing left, directly ahead, or right. Adapting to leftward gaze produced a reduction in BOLD response to left relative to right (and direct) gaze probes in the anterior STS and inferior parietal cortex; rightward gaze adaptation produced a corresponding reduction to right gaze probes. Consistent with these findings, averted gaze in the adapted direction was misidentified as direct. Our study provides the first human evidence of dissociable neural systems for left and right gaze.
Calder
Andrew J
AJ
Medical Research Council, Cognition and Brain Sciences Unit, 15 Chaucer Road, CB2 7EF Cambridge, United Kingdom. andy.calder@mrc-cbu.cam.ac.uk
Beaver
John D
JD
Winston
Joel S
JS
Dolan
Ray J
RJ
Jenkins
Rob
R
Eger
Evelyn
E
Henson
Richard N A
RN
D000222:Adaptation, Physiological; D001519:Behavior; D005149:Facial Expression; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*