Visual System Organization and Development

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DESCRIPTION (provided by applicant): In our working model of visual information processing, we hypothesize that there are three segregated parallel pathways [magnocellular (M), parvocellular (P), and koniocelIular (K)] from the lateral genicuIate nucleus (LGN) to primary visual cortex (V1), forming both dedicated and multi-functional systems and networks. Within this scheme, separate output layers and compartments of V1 have distinct modes for utilizing signals from all three input pathways and generating output signals that contribute to the dynamics and functional maps of extrastriate areas. In light of this model, the major effort of our project is to understand how parallel LGN pathways in primates contributes to the properties of V1 and its extrastriate targets. This proposal focuses on all three LGN relays and how their inputs affect V1 and higher visual centers, but places added emphasis on the K pathway considering the fact that it has been, until recently, largely ignored. Our specific aims are designed to test hypotheses generated by our working model. In Aim I, we will determine the number of physiologically distinct K channels and the classes of retinal ganglion ceils that project to K LGN layers. In Aim II, we will determine the relationship between LGN relay cells and the dynamics and functional maps found within V1. In Aim III, we will apply the same techniques utilized in Aim II to determine how LGN relays contribute to the dynamics and functional maps found within extrastriate areas V2, V3, and DM/V3a. The results of our proposed studies will contribute important new information to our understanding of the fundamentals of how the brain processes visual information and of brain architecture in general.