INFORMATION-PROCESSING IN MAMMALIAN OLFACTORY SYSTEM

In recent years, considerable progress has been made in understanding how the olfactory system uses neural space to encode sensory informati on. In this review, we focus on recent studies aimed at understanding the organizational strategies used by the mammalian olfactory system t o encode information, The odorant receptor gene family is discussed in the contest of its genomic organization as well as the specificity of olfactory sensory neurons. These data have important consequences for the mechanisms of odorant receptor gene choice by a given sensory neu ron, Division of the olfactory epithelium into zones that express diff erent sets of odorant receptors is the first level of input organizati on, The topographical relationship between periphery and olfactory bul b represents a further level of processing of information and results in the formation of a highly organized spatial map of information in t he olfactory bulb, There, local circuitry refines the sensory input th rough various lateral interactions, Finally, the factors that may driv e the development of such a spatial map are discussed, The onset of ex pression and the establishment of the zonal organization of odorant re ceptor genes in the epithelium are not dependent upon the presence of the olfactory bulb, suggesting that the functional identity of olfacto ry sensory neurons is determined independently of target selection. (C ) 1996 John Wiley & Sons, Inc.