a1 Cambridge Computational Biology Institute, Department for Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
Most types of retinal neurons are spatially positioned in non-random patterns, termed retinal mosaics. Several developmental mechanisms are thought to be important in the formation of these mosaics. Most evidence to date suggests that homotypic constraints within a type of neuron are dominant, and that heterotypic interactions between different types of neuron are rare. In an analysis of macaque H1 and H2 horizontal cell mosaics, Wässle et al. (2000) suggested that the high regularity index of the combined H1 and H2 mosaic might be caused by heterotypic interactions during development. Here we use computer modeling to suggest that the high regularity index of the combined H1 and H2 mosaic is a by-product of the basic constraint that two neurons cannot occupy the same space. The spatial arrangement of type A and type B horizontal cells in cat retina also follow this same principle.
(Received December 05 2007)
(Accepted December 31 2007)
c1 Address correspondence and reprint requests to: Stephen J. Eglen, Cambridge Computational Biology Institute, Department for Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom. E-mail: email@example.com