Abstract
Incompatible stimuli presented to two eyes compete for representation and awareness. This phenomenon is referred to as binocular rivalry. To date, the neural mechanisms of binocular rivalry remains elusive. Here, we used an fMRI encoding model to reconstruct the responses of hypothetical orientation-selective channels while subjects viewed two orthogonally gratings presented dichoptically. Subjects participated in one training session for weight estimation and two to four binocular rivalry/replay sessions for reconstruction. In the training session, contrast-reversing sinusoidal gratings at six possible orientations (15°, 45°, 75°, 105°, 135°, and 175°) were presented. In the binocular rivalry/replay sessions, for each rivalry run, 15° and 105° oriented gratings were presented dichoptically for 90s and subjects pressed one of three buttons to report their perception. Each rivalry run was immediately followed by a replay run which mimicked the subject's perception in the preceding rivalry run. Using the estimated weights from the training session, for each visual area, we decomposed the spatial pattern of fMRI activation into responses of orientation-tuned channels. We compared the channel responses between the rivalry and replay conditions, and found that, in the rivalry condition, the channel response to the dominant orientation was weaker than that in the replay condition. In contrast, the channel responses to the suppressed orientation in the two conditions showed the opposite pattern. These effects were most pronounced in V1 and attenuated in V2 and V3. In V4, the channel response patterns in the rivalry and replay conditions became indistinguishable. These results revealed how binocular rivalry affected the neural representations of dominant and suppressed orientations in the visual hierarchy of human brain and suggest that substantial suppressed information during binocular rivalry is still represented in early and intermediate visual areas.
Meeting abstract presented at VSS 2016