Interocular suppression weakens binocular disparity integration in the dorsal visual stream

Abstract

A unified percept depends on the coordinated interplay of sensory integration and suppression, yet how this interaction is implemented across cortical representations remains unclear. Using binocular vision as a tractable model system, we combined fMRI with multivariate analyses to test how interocular suppression reshapes binocular disparity integration across human visual pathways. Local binocular rivalry weakened near-far disparity decoding, with disruption increasing along the dorsal pathway from V1 to V3A and intraparietal sulcus (IPS), but no reliable loss in ventral regions. In V3A, anticorrelated random-dot stereograms showed an inverted representational relationship relative to correlated stimuli, and this structure was abolished under suppression, indicating disrupted non-canonical disparity integration. Informational connectivity further revealed that suppression selectively weakened V3A-centered coordination while largely sparing coupling among early visual areas. Together, these findings identify higher-level dorsal regions as a key substrate for coordinating integrative and suppressive computations during unified percept formation.