Temporal coding of pheromone pulses and trains in Manduca sexta.
We investigated the ability of pheromone-sensitive olfactory receptors of male Manduca sexta to respond to 20-ms pulses of bombykal, the major component of the conspecific pheromonal blend. Isolated pulses of bombykal elicited a burst of activity which decreased exponentially with a time constant of 160-250 ms. Trains of pulses delivered at increasing frequencies (0.5-10 Hz) elicited temporally modulated responses at up to 3 Hz. Concentration of the stimulus (1, 10, 100 ng per odor source) had a marginal effect on the temporal resolution of the receptors. Within a train, the responses to individual pulses remained constant, except for 10-Hz trains (short-term adaptation). A dose-dependent decline of responsiveness was observed during experiments (long-term adaptation). Although individual neurons may not respond faithfully to each pulse of a train, the population of receptors sampled in this study appears to be capable of encoding the onset of odor pulses at frequencies of up to at least 3 Hz.
Marion-Poll
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INRA, Station de Phytopharmacie, route de Saint Cry, Versailles, France.
Tobin
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D000222:Adaptation, Physiological / Q000502:physiology; D000466:Alkadienes / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D008297:Male; D009036:Moths / Q000502:physiology*; D010675:Pheromones / Q000494:pharmacology*; D012903:Smell / Q000502:physiology*; D013268:Stimulation, Chemical
D000466:Alkadienes; D010675:Pheromones; C066482:bombykal