Abstract
Experience can result in multiple forms of neural plasticity, including modifications of bottom-up or top-down inputs to an area. Loss of central vision has been shown to result in unexplained BOLD activity in the projection of the scotoma on primary visual cortex (Masuda et al., 2005; Masuda et. al, 2021). Given that bottom-up inputs from LGN enter mainly in the middle layers of V1, whereas top-down inputs are preferentially in superior and inferior layers, investigating the layer-specific modulation of these inputs in the deafferented area will be important to clarify our understanding of neural plasticity after vision loss. Studies in healthy controls have shown that attention can strongly modulate activity in superficial and inferior layers of V1, and less-so in middle layers, consistent with a top-down signal (vanKerkoerle et al, 2017). Some studies suggest that this modulation may come from frontal regions, including parts of the Fronto-Parietal Network (FPN) (Hopfinger et al, 2000; Giesbrecht et al., 2003). This suggests that superior and inferior layers will have stronger functional connections to fronto-parietal network regions than middle layers. We tested this hypothesis in participants with healthy vision by examining functional connectivity during rest at high resolution using 7T resting state MRI. Superior and inferior layers of V1 were more strongly correlated to FPN regions, and middle layers were less correlated, consistent with top-down control from fronto-parietal regions. In order to test how these top-down signals are modulated by experience, we collected high-resolution resting state data from 5 patients with MD and 5 controls. All MD participants underwent Macular Integrity Assessment to precisely map their scotoma on the cortex. Our data, showing layer-specific patterns of functional connectivity consistent with fronto-parietal top down control of V1, are a proof of concept for examining how these patterns differ in central vision loss.