Resources
Authors & Affiliations
Yujie Hou, Wang Mingli, Loic Magrou, Kenneth Knoblauch, David Van Essen, Takuya Hayashi, Zoltan Toroczkai, Szabolc Horvát, Maria Ercsey-Ravasz, Zhiming Shen, Henry Kennedy
Abstract
The spatial embedding of the cortical connectome ensures that inter-areal connection strength is largely determined by distance. A flat map of macaque area V1 show that the areal neighborhoods of the far periphery upper and lower visual field representations are highly distinct from each other and from that of the fovea, predicting that they exhibit distinct connectivity profiles. Tracer injections in upper and lower visual fields in areas V1 and V2 revealed different connectivity profiles at different eccentricities. Connection strengths of most projections differ significantly with eccentricity with respect to distance and origin, i.e., projections to central and upper visual field representations are significantly stronger from ventral stream areas, projections to peripheral lower field are stronger from dorsal stream areas. These differences in the feedback to area V1 and V2 are echoed by differences in their feedforward projections. The Voronoi portioning and the shortest pathlength analysis revealed that trees rooted in the peripheral lower and upper field as well as the fovea representations of V1 reach different cortical areas and make distinct clusters. Projection differences in upper and lower fields of V1 and V2 are discussed with respect to their cognitive and perceptual roles. Area V1 is unique in having a highly distinctive cytoarchitecture and sharply defined border and yet it is imperative to consider the retinotopic subdivisions. Our results argue in favor of connectomes being not based on Broadman areas and instead future connectomes and large-scale models need to be grounded in a more fine-grained cortical parcellation.