Natural scenes contain a variety of visual cues that facilitate
boundary perception (e.g., luminance, contrast, and texture). Here we
explore whether single neurons in early visual cortex can process both
contrast and texture cues. We recorded neural responses in cat A18 to both
illusory contours formed by abutting gratings (ICs, texture-defined) and
contrast-modulated gratings (CMs, contrast-defined). We found that if a
neuron responded to one of the two stimuli, it also responded to the
other. These neurons signaled similar contour orientation, spatial
frequency, and movement direction of the two stimuli. A given neuron also
exhibited similar selectivity for spatial frequency of the fine,
stationary grating components (carriers) of the stimuli. These results
suggest that the cue-invariance of early cortical neurons extends to
different kinds of texture or contrast cues, and might arise from a common
nonlinear mechanism.