DescriptionThe human visual system masks the perceptual consequences of retinal or cortical lesion-induced scotomas by predicting what is missing from nearby regions of the visual field. To reveal the neural mechanisms underlying this remarkable capacity, which we refer to as predictive masking (PM; but also known as “filling-in”), we used fMRI and neural modeling to track changes in cortical population receptive fields (pRFs) and connectivity (connective fields) in response to the introduction of an artificial scotoma (AS). Consistent with predictive masking, we found that extrastriate areas increased their sampling of the V1 region outside the AS projection zone. Moreover, throughout the visual field and hierarchy, pRFs shifted their preferred position towards the AS border. A gain field model, centered at this border, accounted for these shifts, especially for extrastriate areas. Overall, these shifts are inconsistent with PM suggesting these primarily reflect how the visual system focuses neural resources on potentially informative regions in visual space. Overall, we conclude that the system-wide reconfiguration of neural populations in response to a change in visual input is guided by extrastriate signals and underlies the predictive masking of scotomas. Our work provides the first evidence of such a system wide reconfiguration of connectivity in response to a sustained change in visual stimulation, such as due to an (artificial) lesion. Moreover, it extends previous work by showing that RF shifts are not confined to the AS projection zone and thus are insufficient to explain PM. I will discuss the basic and clinical implications of our findings, and highlight some of the analytical innovations in fMRI analysis that were driven by this project.
|Gehouden op||Stockholm University, Sweden|
|Mate van erkenning||International|