CONSTRUCTION AND ANALYSIS OF A DATABASE REPRESENTING A NEURAL MAP

We describe the development and analysis of a quantitative database re presenting the global structural and functional organization of an ent ire sensory map. The database was derived from measurements of anatomi cal characteristics of a statistical sample of typical mechanosensory afferents in the cricket cereal sensory system, Anatomical characteris tics of the neurons were measured quantitatively in three dimensions u sing a computer reconstruction system. The reconstructions of all neur ons were aligned and scaled to a common standard set of dimensions, ac cording to a highly reproducible set of intrinsic fiducial marks. The database therefore preserves accurate information about spatial relati onships between the neurons within the ensemble. Algorithms were imple mented to allow the integration of electrophysiological data about the stimulus/response characteristics of the reconstructed neurons into t he database. The algorithms essentially map a physiological function o nto a ''field'' representing the continuous distribution of synaptic t erminals throughout the neural structure. Subsequent analysis allowed quantitative predictions of several important functional characteristi cs of the sensory map that emerge from its global organization. First, quantitative and testable predictions were made about ensemble respon se patterns within the map. The predicted patterns are presented as gr aphical images, similar to images that might be observed with activity -dependent dyes in the real neural system. Second, the synaptic innerv ation patterns from the sensory afferent map onto the dendrites of a p ostsynaptic target interneuron were predicted by calculating the overl ap between the interneuron's dendrites with the afferent map. By doing so, several aspects of the stimulus/response properties of the intern euron were accurately predicted. (C) 1994 Wiley-Liss, Inc.