Heterogeneity and convergence of olfactory first-order neurons account for the high speed and sensitivity of second-order neuronsReportar como inadecuado

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* Corresponding author 1 UMR 1392 Institut d-Ecologie et des Sciences de l-Environnement de Paris 2 IRHS - Institut de Recherche en Horticulture et Semences 3 CSGA - Centre des Sciences du Goût et de l-Alimentation Dijon 4 Institut de la Vision 5 RCIM - Laboratoire Récepteurs et Canaux Ioniques Membranaires

Abstract : In the olfactory system of male moths, a specialized subset of neurons detects and processes the main component of the sex pheromone emitted by females. It is composed of several thousand first-order olfactory receptor neurons ORNs, all expressing the same pheromone receptor, that contact synaptically a few tens of second-order projection neurons PNs within a single restricted brain area. The functional simplicity of this system makes it a favorable model for studying the factors that contribute to its exquisite sensitivity and speed. Sensory information—primarily the identity and intensity of the stimulus—is encoded as the firing rate of the action potentials, and possibly as the latency of the neuron response. We found that over all their dynamic range, PNs respond with a shorter latency and a higher firing rate than most ORNs. Modelling showed that the increased sensitivity of PNs can be explained by the ORN-to-PN convergent architecture alone, whereas their faster response also requires cell-to-cell heterogeneity of the ORN population. So, far from being detrimental to signal detection, the ORN heterogeneity is exploited by PNs, and results in two different schemes of population coding based either on the response of a few extreme neurons latency or on the average response of many firing rate. Moreover, ORN-to-PN transformations are linear for latency and nonlinear for firing rate, suggesting that latency could be involved in concentration-invariant coding of the pheromone blend and that sensitivity at low concentrations is achieved at the expense of precise encoding at high concentrations.

Keywords : moths and butterflies olfactory receptor neurons coding mechanisms transfer functions distribution curves curve fitting pheromones neurons

Autor: Jean-Pierre Rospars - Alexandre Gremiaux - David Jarriault - Antoine Chaffiol - Christelle Monsempes - Nina Deisig - Sylvia Anton

Fuente: https://hal.archives-ouvertes.fr/


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