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ABSTRACT: Recent studies have applied optical imaging of intrinsic signals to the rodent olfactory system, providing a unique view of how odorous molecules are represented in the central nervous system.
Current Biology 10/2001; 11(17):R687-90. · 9.65 Impact Factor
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ABSTRACT: The mechanisms that underlie a wine lover's ability to identify a favorite vintage and a dog's ability to track the scent of a lost child are still deep mysteries. Our understanding of these olfactory phenomena is confounded by the difficulty encountered when attempting to identify the parameters that define odor stimuli, by the broad tuning and variability of neurons in the olfactory pathway,and by the distributed nature of olfactory encoding. These issues pertain to both biological systems and to newly developed 'artificial noses' that seek to mimic these natural processes. Information theory, which quantifies explicitly the extent to which the state of one system (for example, the universe of all odors) relates to the state of another (for example, the responses of an odor-sensing device),can serve as a basis for analysing both natural and engineered odor sensors. This analytical approach can be used to explore the problems of defining stimulus dimensions, assessing strategies of neuronal processing, and examining the properties of biological systems that emerge from interactions among their complex components. It can also serve to optimize the design of artificial olfactory devices for a variety of applications, which include process control, medical diagnostics and the detection of explosives.
Trends in Neurosciences 04/1999; 22(3):102-8. · 14.23 Impact Factor
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ABSTRACT: Information about odorant stimuli is thought to be represented in spatial and temporal patterns of activity across neurons in the olfactory epithelium and the olfactory bulb (OB). Previous studies suggest that olfactory receptor neurons (ORNs) distributed in the nasal cavity project to localized regions in the glomerular layer of the OB. However, the functional significance of this convergence is not yet known, and in no studies have the odorant response properties of individual ORNs projecting to defined OB regions been measured directly. We have retrogradely labeled mouse ORNs connecting to different glomeruli in the dorsal OB and tested single cells for responses to odorants using fura-2 calcium imaging. ORNs that project to clusters of dorsomedial (DM) glomeruli exhibit different odorant response profiles from those that project to dorsolateral (DL) glomeruli. DL-projecting ORNs showed responses to compounds with widely different structures, including carvone, eugenol, cinnamaldehyde, and acetophenone. In contrast, DM-projecting neurons exhibited responses to a more structurally restricted set of compounds and responded preferentially to organic acids. These data demonstrate that ORN afferents segregate by odorant responsiveness and that the homogeneity of ORN and glomerular input varies with different OB regions. The data also demonstrate that a subpopulation of ORNs projecting to DM glomeruli is functionally similar.
Journal of Neuroscience 07/1998; 18(12):4560-9. · 7.11 Impact Factor
