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Dense encoding of natural odorants by ensembles of sparsely activated neurons in the olfactory bulb

Published inScientific reports, vol. 6, 36514
Publication date2016
Abstract

Sensory information undergoes substantial transformation along sensory pathways, usually encompassing sparsening of activity. In the olfactory bulb, though natural odorants evoke dense glomerular input maps, mitral and tufted (M/T) cells tuning is considered to be sparse because of highly odor-specific firing rate change. However, experiments used to draw this conclusion were either based on recordings performed in anesthetized preparations or used monomolecular odorants presented at arbitrary concentrations. In this study, we evaluated the lifetime and population sparseness evoked by natural odorants by capturing spike temporal patterning of neuronal assemblies instead of individual M/T tonic activity. Using functional imaging and tetrode recordings in awake mice, we show that natural odorants at their native concentrations are encoded by broad assemblies of M/T cells. While reducing odorant concentrations, we observed a reduced number of activated glomeruli representations and consequently a narrowing of M/T tuning curves. We conclude that natural odorants at their native concentrations recruit M/T cells with phasic rather than tonic activity. When encoding odorants in assemblies, M/T cells carry information about a vast number of odorants (lifetime sparseness). In addition, each natural odorant activates a broad M/T cell assembly (population sparseness).

Keywords
  • Coding
  • Olfactory bulb
  • Cell assembly
Funding
  • Swiss National Science Foundation - grant numbers: 31003A_153410 to A.C., CR33I13_143723 to A.C. and I.R. and 31003A_170114 to I.R.
  • European Commission - From neurons to behavior: analysis of the mechanisms underlying sensory coding and plasticity in chemical senses [243344]
Citation (ISO format)
GSCHWEND, Olivier et al. Dense encoding of natural odorants by ensembles of sparsely activated neurons in the olfactory bulb. In: Scientific reports, 2016, vol. 6, p. 36514. doi: 10.1038/srep36514
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Article (Published version)
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ISSN of the journal2045-2322
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