Gap junctional communication and the development of local circuits in neocortex

In the neocortex, as well as in many other brain regions, neurons responding to similar stimulus features are usually found close to one another. Here we examine the possible role of gap junctional communication in forming and defining these local neuronal groupings, examples of which may be the columns found in the neocortex of virtually all mammalian species. We have approached this question experimentally in cortical brain slices using calcium imaging to visualize multicellular activity patterns, and tracer injections to identify the anatomical pattern of gap junction coupling in the developing neocortex. Our results suggest that dendrodendritic gap junctional communication may be involved in the formation of local connectivity, most likely by synchronizing electrical or biochemical activity among neighboring neurons.