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BioMed Research International
Volume 2013 (2013), Article ID 592426, 9 pages
Research Article

Topography of Striate-Extrastriate Connections in Neonatally Enucleated Rats

1Department of Psychology, and Behavior and Neuroscience Program, University of Washington, P.O. Box 351525, Seattle, WA 98195-1525, USA
2Laboratory for Motor Neuron Disease, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-Shi, Saitama Prefecture 351-0198, Japan

Received 29 April 2013; Revised 15 August 2013; Accepted 29 August 2013

Academic Editor: Eduardo Puelles

Copyright © 2013 Robyn J. Laing et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


It is known that retinal input is necessary for the normal development of striate cortex and its corticocortical connections, but there is little information on the role that retinal input plays in the development of retinotopically organized connections between V1 and surrounding visual areas. In nearly all lateral extrastriate areas, the anatomical and physiological representation of the nasotemporal axis of the visual field mirrors the representation of this axis in V1. To determine whether the mediolateral topography of striate-extrastriate projections is preserved in neonatally enucleated rats, we analyzed the patterns of projections resulting from tracer injections placed at different sites along the mediolateral axis of V1. We found that the correlation between the distance from injection sites to the lateral border of V1 and the distance of the labeling patterns in area 18a was strong in controls and much weaker in enucleates. Data from pairs of injections in the same animal revealed that the separation of area 18a projection fields for a given separation of injection sites was more variable in enucleated than in control rats. Our analysis of single and double tracer injections suggests that neonatal bilateral enucleation weakens, but not completely abolishes, the mediolateral topography in area 18a.