Marianna E. Schmidt^1,2, Iman Aganj^3,4, Jason Stockmann^3,4, Berkin Bilgic^3,4,5, Yulin Chang⁶, W. Scott Hoge⁷, Evgeniya Kirilina¹, Nikolaus Weiskopf^1,8,9, Shahin Nasr^3,4; ¹Max Planck Institute for Human Cognitive and Brain Sciences, ²Max Planck School of Cognition, Leipzig, Germany, ³Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, ⁴Harvard Medical School, ⁵Harvard/MIT Health Sciences and Technology, ⁶Siemens Medical Solutions USA Inc., Malvern, PA, USA, ⁷Imaginostics, Inc., Orlando, FL, USA, ⁸Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth System Sciences, Leipzig University, Leipzig, Germany, ⁹Wellcome Center for Human Neuroimaging, Institute of Neurology, University College London

Despite their importance in shaping visual perception, functional connectivity between ocular dominance columns (ODCs), the building blocks of neuronal processing within the human primary visual cortex (V1), remains mostly unknown. In this study, we used high-resolution fMRI (7T; voxel size = 1mm isotropic) to localize ODCs and assess their resting-state (eyes closed) functional connectivity (rs-FC) in 11 individuals (3 females) with intact vision (age=30.9±5.9 years). Consistent with studies in animals, we found stronger rs-FC between ODCs with alike rather than unalike ocular preference (p<0.01). The level of rs-FC was generally higher at mid-cortical depths, while selectivity was more pronounced at superficial and deep cortical depths. Surpassing expectations from anatomical studies of ODC connectivity, we found the following. First, the selective rs-FC between ODCs was preserved for distances of up to 4cm, indicating that connectivity between ODCs remains selective across multiple synapses. Second, rs-FC selectivity was significantly higher between ODCs that exhibited stronger (compared to weaker) ocular preference (p<10-3), even though ODC mapping and rs-FC measurements were conducted in separate scan sessions. Third, the extent of selectivity appeared to vary between foveal vs. peripheral and to a lesser extent between dorsal vs. ventral regions, suggesting a heterogeneity in the distribution of rs-FC within V1. We further tested whether the ODC map was predictable from the rs-FC pattern. Our preliminary results showed a significant correlation between rs-FC and ODC maps (p<10-5). The level of this correlation declined when the size of regions of interest increased from 20.21mm2 (r=0.20) to 286.47mm2 (r=0.08). This result indicates a promising opportunity for ODC mapping in individuals with disrupted binocular vision (e.g., monocular blindness). In conclusion, our results demonstrate the utility of high-resolution fMRI for studying mesoscale rs-FC within V1, successfully replicating the findings based on animal models and highlighting promising new opportunities for future exploration.