Central Processing of Odor Signals: Lessons from Adult and Neonatal Olfactory Tract Lesions

  • Marshall Devor


It is plain why we know so little about the neural processing of odor signals. Beginning at the receptor level there appear to operate a number of different mechanisms for stimulus separation and transduction (Beidler, 1971). But even if there were a single simple process, say an orderly array of specific receptor types or a spatiotemporal map (Davies, 1971), we would need take only one step further centrally before order was chaos once again. From receptor sheet to olfactory bulb there is only the faintest hint of a topographic mapping (Clark, 1951). Then we face the convergence of 26,000 receptor cells, on the average, into a single glomerulus and thence to second order neurons in the bulb, each participating in many glomeruli (Allison and Warwick, 1949). Finally, most every region of the bulb distributes axons to the whole of the olfactory cortex (see Fig.1; White, 1965; Lohman and Mentink, 1969; Price, 1973; Broadwell, 1975; Devor, 1976a). This looks like a structure specifically designed to scramble the message received by single receptors. Nor is there much evidence of specificity in electrophysiological recordings from single cells at receptor, bulbar or cortical levels (e.g. Gesteland, 1971; Mathews, 1972; Haberly, 1969). If we accept the premise that nature is not perverse, then there may well be a mechanism operating here that is different from that of most other sensory systems in which feature extraction and topographic mapping and remapping play such a prominent role.


Olfactory Bulb Odor Signal Olfactory Tubercle Olfactory Cortex Main Olfactory Bulb 
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Copyright information

© Plenum Press, New York 1977

Authors and Affiliations

  • Marshall Devor
    • 1
  1. 1.Neurobiology Unit, Russian Compound, Life Sciences InstituteThe Hebrew UniversityJerusalemIsrael

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