Stem Cell Reports
Volume 15, Issue 6, 8 December 2020, Pages 1333-1346
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Article
Unique Functional Properties of Mature Adult-Born Neurons in the Mouse Olfactory Bulb

https://doi.org/10.1016/j.stemcr.2020.10.010Get rights and content
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Highlights

  • In awake mice mature adult-born neurons differ from resident GABAergic cells

  • 24% of neurons belong to a strongly active cell cluster, absent among resident cells

  • Serotonergic inputs target adult-born but not resident GABAergic cells

Summary

The rodent olfactory bulb (OB) is continuously supplied with adult-born cells maturing into GABAergic neurons. Using in vivo ratiometric Ca2+ imaging to readout ongoing and sensory-driven activity, we asked whether mature adult-born cells (mABCs) in the glomerular layer of the bulb become functionally identical to resident GABAergic (ResGABA) neurons. In awake head-restrained mice the two cell populations differed significantly in terms of ongoing spontaneous activity, with 24% of mABCs contributing to a strongly active cell cluster, absent among ResGABA cells. Odor-evoked responses of mABCs were sparse, less reliable, and had smaller amplitudes compared with ResGABA cells. The opposite was seen under anesthesia, with response reliability increasing and response size of mABCs becoming larger than that of ResGABA cells. Furthermore, ongoing activity of mABCs showed increased sensitivity to ketamine/xylazine and was selectively blocked by the antagonist of serotonin receptors methysergide. These functional features of mABCs clearly distinguish them from other OB interneurons.

Keywords

awake mice
in vivo calcium imaging
adult-born cells
serotonin
5-hydroxytryptamin
noradrenaline
acetylcholine
olfactory bulb
GABAergic cells
odor responses

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