Distinct rich and diverse clubs regulate coarse and fine binocular disparity processing: Evidence from stereoscopic task-based fMRI

While cortical regions involved in processing binocular disparities have been studied extensively, little is known on how the human visual system adapts to changing disparity magnitudes. Even though there is an established correlation of BOLD signal with disparity magnitudes, this correlation is not inherent and instead arises from specific causal interactions within an integrated network. Here, we investigate causal mechanisms of coarse and fine binocular disparity processing using fMRI with a clinically validated, custom anaglyph-based stimulus. Therefore, we use degree (D) and participation coefficient (PC) metrics representing rich and diverse properties of the brain network, respectively. Twenty-six healthy participants were asked to indicate hidden 3D shapes through anaglyph filters at four disparity magnitudes. Our findings reveal significant changes at different disparity magnitudes in terms of D and PC of Middle Temporal (MT), V2, V3 and Superior Parietal Lobule (SPL) across both hemispheres. Of these, MT exhibited overlapping rich and diverse club characteristics among other brain regions. Further, diverse clubs outperform rich clubs in decoding disparity magnitudes irrespective of the hemisphere, thereby reinforcing their integrative network properties. These findings imply that distinct rich and diverse clubs exist and provide functional evidence for the variability in human stereopsis.