Orientation-selective chromatic mechanisms in human visual cortex.
We used functional magnetic resonance imaging (fMRI) at 3T in human participants to trace the chromatic selectivity of orientation processing through functionally defined regions of visual cortex. Our aim was to identify mechanisms that respond to chromatically defined orientation and to establish whether they are tuned specifically to color or operate in an essentially cue-invariant manner. Using an annular test region surrounded inside and out by an inducing stimulus, we found evidence of sensitivity to orientation defined by red-green (L-M) or blue-yellow (S-cone isolating) chromatic modulations across retinotopic visual cortex and of joint selectivity for color and orientation. The likely mechanisms underlying this selectivity are discussed in terms of orientation-specific lateral interactions and spatial summation within the receptive field.
School of Psychology, University of New South Wales, Sydney, NSW, Australia.
James S
JS
McDonald
Damien J
DJ
Mannion
Erin
E
Goddard
Colin W G
CW
Clifford
D001931:Brain Mapping / Q000379:methods; D003118:Color Perception / Q000502:physiology*; D055253:Color Vision / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012160:Retina / Q000502:physiology; D013028:Space Perception / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*