title: Odor discrimination requires proper olfactory fast oscillations in awake mice.
abstract: Gamma oscillations are commonly observed in sensory brain structures, notably in the olfactory bulb. The mechanism by which gamma is generated in the awake rodent and its functional significance are still unclear. We combined pharmacological and genetic approaches in the awake mouse olfactory bulb to show that gamma oscillations required the synaptic interplay between excitatory output neurons and inhibitory interneurons. Gamma oscillations were amplified, or abolished, after optogenetic activation or selective lesions to the bulbar output neurons. In response to a moderate increase of the excitation/inhibition ratio in output neurons, long-range gamma synchronization was selectively enhanced while the mean firing activity and the amplitude of inhibitory inputs both remained unchanged in output neurons. This excitation/inhibition imbalance also impaired odor discrimination in an olfactory learning task, suggesting that proper fast neuronal synchronization may be critical for the correct discrimination of similar sensory stimuli.
authors.affiliation: Laboratory for Perception and Memory, Institut Pasteur, F-75015 Paris, France; CNRS UMR 3571, F-75015 Paris, France. Electronic address: gabriel.lepousez@pasteur.fr.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lepousez
authors.forename: Pierre-Marie
authors.initials: PM
authors.lastname: Lledo
mesh_terms: D000818:Animals; D004192:Discrimination, Psychological / Q000502:physiology*; D004569:Electroencephalography; D058407:Electroencephalography Phase Synchronization / Q000502:physiology; D005583:Fourier Analysis; D018756:GABA Antagonists / Q000494:pharmacology; D007858:Learning / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000502:physiology; D009812:Odorants; D009830:Olfactory Bulb / Q000502:physiology*; D062308:Optogenetics; D011963:Receptors, GABA-A / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D012903:Smell / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology
chemical_list: D018756:GABA Antagonists; D011963:Receptors, GABA-A; D016194:Receptors, N-Methyl-D-Aspartate