Patterns of Ocular Dominance Domains and Cytochrome Oxidase Blobs in Striate Cortex of The Prosimian Primate Galago

Previous anatomical studies of ocular dominance columns (ODCs) in V1 of galagos did not investigate the overall tangential arrangement of eye-specific input in different cortical layers of V1. Likewise, studies using optical imaging of intrinsic signals have not provided information on the pattern of ODCs in layer 4 and deeper layers because this technique detects mostly activity patterns of neurons in the superficial layers. Here we demonstrate the patterns of ODCs across the cortical layers following intraocular injections of the transneuronal tracer WGA-HRP, and correlate these patterns with the array of CO blobs in tangential sections of the flattened cortex. In sections through supragranular V1, the WGA-HRP labeling appears as an array of distinct patches that most likely represent the patchy koniocellular input to layer 3 shown by previous studies. In layer 4, WGA-HRP labeling forms interconnected bands whose overall arrangement resembles the pattern of ODCs in cats. Comparison of the HRP and CO labeling patterns revealed that in supragranular layers, virtually all CO blobs overlap with WGA-HRP labeled patches. Since only one eye was injected with WGA-HRP, these data suggest that CO blobs receive input from both eyes. Moreover, in layer 4, CO blobs are not necessarily centered on ODCs, but often span the borders between left and right columns. Our results provide new information on the distribution and correlation of eye specific input across cortical layers in galago V1, and support the view that the alignment between ODCs and CO blobs seen in macaques is not a general feature of primate V1.