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Aaron Seitz, Stephen Grossberg; How do laminar circuits coordinate their development in the visual cortex? The role of the cortical subplate.. Journal of Vision 2002;2(7):100. doi: 10.1167/2.7.100.
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© ARVO (1962-2015); The Authors (2016-present)
How is the development of cortical maps in V1 coordinated across the cortical layers? Many neural models propose how maps of visually important properties like orientation (OR), ocular dominance (OD), and spatial frequency develop. These models show how spontaneous activity, before eye opening, combined with correlation learning, can generate map structures similar to those found in vivo. Most of these models do not discuss the ubiquitous organization of cortical cells into layers or how cells coordinate their development across these layers. This is an especially important problem given anatomical evidence that clusters of horizontal connections develop in layer 2/3 between iso-oriented regions before being innervated by layer 4 afferents, and that that the initial orientation preference of these connections is maintained after layer 4 afferents reach them. How is orientation preference coordinated across layers despite the fact that thalamic afferents wait in the subplate for weeks before the cortical plate? These problems are addressed within a model of how the cortical subplate develops its own OR and OD maps which then entrain those of the other lamina. Other evidence shows that subplate ablation interferes with the development of OD columns and OR tuning. We demonstrate that the same types of mechanisms which have been proposed to develop OR and OD maps in earlier models of the cortical plate can drive their development in the subplate. The model demonstrates how these maps may then be transferred to layer 4 by a known transient subplate-layer 4 circuit. The model also demonstrates how the subplate guides the early clustering of horizontal connections in Layers 2/3 and 5. Finally the model discusses how vertical correlations from the subplate guide the formation of interlaminar circuitry.
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