Odor discrimination requires proper olfactory fast oscillations in awake mice

Neuron. 2013 Nov 20;80(4):1010-24. doi: 10.1016/j.neuron.2013.07.025. Epub 2013 Oct 17.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Discrimination, Psychological / physiology*
  • Electroencephalography
  • Electroencephalography Phase Synchronization / physiology
  • Fourier Analysis
  • GABA Antagonists / pharmacology
  • Learning / physiology
  • Mice
  • Neurons / physiology
  • Odorants*
  • Olfactory Bulb / physiology*
  • Optogenetics
  • Receptors, GABA-A / physiology
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Smell / physiology*
  • Wakefulness / physiology


  • GABA Antagonists
  • Receptors, GABA-A
  • Receptors, N-Methyl-D-Aspartate