title: Responses of single neurons and neuronal ensembles in frog first- and second-order olfactory neurons.
abstract: A major challenge in sensory neuroscience is to elucidate the coding and processing of stimulus representations in successive populations of neurons. Here we recorded the spiking activity of receptor neurons (RNs) and mitral/tufted cells (MCs) in the frog olfactory epithelium and olfactory bulb respectively, in response to four odorants applied at precisely controlled concentrations. We compared how RN responses are translated in MCs. We examined the time course of the instantaneous firing frequency before and after stimulation in neuron ensembles and the dependency on odorant concentration of the number of action potentials fired in a preselected 5-s time window (dose-response curves) in both single neurons and neuron ensembles. In RNs and MCs, the dose-response curves typically increase then decrease and are well described by alpha functions. We established the main quantitative properties of these curves, including the distributions of concentrations at threshold and maximum responses. We showed that the main transformations occurring in the transition from RNs to MCs is the lowering of the firing threshold and a large decrease in the total number of spikes fired. We also found that the number of action potentials fired by recorded neurons and hence their energy consumption is independent of odorant concentration, and that this is a consequence of their time- and concentration-dependent activities. This article is part of a Special Issue entitled Neural Coding 2012.
authors.affiliation: UMR 1272 Physiologie de l'Insecte: Signalisation et Communication & Unité Mathématiques et Informatique Appliquées, INRA, F-78000 Versailles, France. Electronic address: jean-pierre.rospars@versailles.inra.fr.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Rospars
authors.forename: Pavel
authors.initials: P
authors.lastname: Sanda
authors.forename: Petr
authors.initials: P
authors.lastname: Lansky
authors.forename: Patricia
authors.initials: P
authors.lastname: Duchamp-Viret
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D009474:Neurons / Q000502:physiology*; D009812:Odorants; D009833:Olfactory Pathways / Q000502:physiology; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D011895:Rana ridibunda
keywords: Dose–response curve; Intensity coding; Mitral cell; Olfactory receptor neuron; Population coding