Topographic maps are fundamental to sensory processing

In all mammals, much of the neocortex consists of orderly representations or maps of receptor surfaces that are typically topographic at a global level, while being modular at the local level. These representations appear to emerge in development as a result of a few interacting factors, and different aspects of brain maps may be developmentally linked, As a result, evolutionary selection for some map features may require other features that may not be adaptive. Yet, an overall adaptiveness of brain maps seems likely. Most notably, topographic representations permit interconnections between appropriate sets of neurons to be made in a highly efficient manner. Topographic maps provide an especially suitable substrate for the common spatiotemporal computations for neural circuits. Finally, aspects of perception suggest the functional importance of topographic maps, (C) 1997 Elsevier Science Inc.