Abstract
The detection of Glass patterns requires long-range or global integration of local orientation signals across the visual field. The sites involved in this integration process are not yet known. We used functional MRI (fMRI) to identify human cortical areas that respond preferentially to Glass patterns alternating with random patterns comprised of the same local elements. The stimuli were designed to be compatible with both fMRI and VEP recording techniques. Using phase-encoded retinotopic mapping and functional localizer scans, we located the most significant Glass pattern fMRI activations with respect to known visual areas.
Consistent with a previous report, we find activations to the presentation of Glass patterns in both dorsal and ventral regions of occipital cortex, but little signal in striate cortex or early extrastriate visual areas. The strongest activations comprise two distinct foci: one anterior to V4 on the ventral surface, and one sited in or close to the V3A/B complex on the dorso-lateral surface.