Abstract
The role of long-range integration mechanisms underlying visual perceptual binding and their link to interhemispheric functional connectivity, as measured by fMRI, remains elusive. Only inferences on anatomical organization from resting state data paradigms not requiring coherent binding have been achieved. Here, we used a paradigm that allowed us to study such relation between perceptual interpretation and functional connectivity under bistable interhemispheric binding vs. non-binding of visual surfaces. Binding occurs by long-range perceptual integration of motion into a single object across hemifields and non-binding reflects opponent segregation of distinct moving surfaces into each hemifield. We hypothesized that perceptual integration vs. segregation of surface motion, which is achieved in visual area hMT+, is modulated by changes in interhemispheric connectivity in this region. Using 7T fMRI, we found that perceptual long-range integration of bistable motion can be tracked by changes in interhemispheric functional connectivity between left/right hMT+. Increased connectivity was tightly related with long-range perceptual integration. Our results indicate that hMT+ interhemispheric functional connectivity reflects perceptual decision, suggesting its pivotal role on long-range disambiguation of bistable physically constant surface motion. We reveal for the first time, at the scale of fMRI, a relation between interhemispheric functional connectivity and decision based perceptual binding.
Highlights
The visual system segments and binds local stimulus’ features to produce globally coherent percepts
We set to investigate with high-resolution (7T) functional magnetic resonance imaging, the role of interhemispheric functional connectivity across hMT+ in both hemispheres as a modulator of perceptual integration vs. segregation of multiple physically constant moving surfaces separated across hemifields
We tested whether interhemispheric functional connectivity in visual area hMT+ reflects long-range perceptual binding and decision
Summary
The visual system segments and binds local stimulus’ features to produce globally coherent percepts. As plaids’ components overlap, these stimuli mainly recruit mechanisms that require local integration of motion in relatively small receptive fields They cannot be used to study interhemispheric binding of visual motion features at a larger spatial scale. We used a previously described bistable non-overlapping moving stimulus[16,17] composed of a 1D component moving in each visual hemifield, which requires interhemispheric integration (1D components are interhemispherically integrated into a single 2D surface comprehending both hemifields) or segmentation (1D components are perceptually parsed into different objects) This allows us to investigate the role of the hMT+ interhemispheric functional connectivity in the modulation of surface segregation vs integration as a probe to investigate the role long-range interactions in decision. We set to investigate with high-resolution (7T) functional magnetic resonance imaging (fMRI), the role of interhemispheric functional connectivity across hMT+ in both hemispheres as a modulator of perceptual integration vs. segregation of multiple physically constant moving surfaces separated across hemifields
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