PMID- 32503886
OWN - NLM
STAT- MEDLINE
DCOM- 20201123
LR  - 20240329
IS  - 1529-2401 (Electronic)
IS  - 0270-6474 (Print)
IS  - 0270-6474 (Linking)
VI  - 40
IP  - 27
DP  - 2020 Jul 1
TI  - Paradoxically Sparse Chemosensory Tuning in Broadly Integrating External Granule 
      Cells in the Mouse Accessory Olfactory Bulb.
PG  - 5247-5263
LID - 10.1523/JNEUROSCI.2238-19.2020 [doi]
AB  - The accessory olfactory bulb (AOB), the first neural circuit in the mouse 
      accessory olfactory system, is critical for interpreting social chemosignals. 
      Despite its importance, AOB information processing is poorly understood compared 
      with the main olfactory bulb (MOB). Here, we sought to fill gaps in the 
      understanding of AOB interneuron function. We used 2-photon GCaMP6f Ca(2+) 
      imaging in an ex vivo preparation to study chemosensory tuning in AOB external 
      granule cells (EGCs), interneurons hypothesized to broadly inhibit activity in 
      excitatory mitral cells (MCs). In ex vivo preparations from mice of both sexes, 
      we measured MC and EGC tuning to natural chemosignal blends and monomolecular 
      ligands, finding that EGC tuning was sparser, not broader, than upstream MCs. 
      Simultaneous electrophysiological recording and Ca(2+) imaging showed no 
      differences in GCaMP6f-to-spiking relationships in these cell types during 
      simulated sensory stimulation, suggesting that measured EGC sparseness was not 
      due to cell type-dependent variability in GCaMP6f performance. Ex vivo 
      patch-clamp recordings revealed that EGC subthreshold responsivity was far 
      broader than indicated by GCaMP6f Ca(2+) imaging, and that monomolecular ligands 
      rarely elicited EGC spiking. These results indicate that EGCs are selectively 
      engaged by chemosensory blends, suggesting different roles for EGCs than 
      analogous interneurons in the MOB.SIGNIFICANCE STATEMENT The mouse accessory 
      olfactory system (AOS) interprets social chemosignals, but we poorly understand 
      AOS information processing. Here, we investigate the functional properties of 
      external granule cells (EGCs), a major class of interneurons in the accessory 
      olfactory bulb (AOB). We hypothesized that EGCs, which are densely innervated by 
      excitatory mitral cells (MCs), would show broad chemosensory tuning, suggesting a 
      role in divisive normalization. Using ex vivo GCaMP6f imaging, we found that EGCs 
      were instead more sparsely tuned than MCs. This was not due to weaker GCaMP6f 
      signaling in EGCs than in MCs. Instead, we found that many MC-activating 
      chemosignals caused only subthreshold EGC responses. This indicates a different 
      role for AOB EGCs compared with analogous cells in the main olfactory bulb.
CI  - Copyright (c) 2020 Zhang and Meeks.
FAU - Zhang, Xingjian
AU  - Zhang X
AD  - University of Texas Southwestern Medical Center, Dallas, Texas 75390.
FAU - Meeks, Julian P
AU  - Meeks JP
AUID- ORCID: 0000-0002-7537-4491
AD  - University of Texas Southwestern Medical Center, Dallas, Texas 75390 
      Julian_Meeks@urmc.rochester.edu.
AD  - University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642.
LA  - eng
GR  - R01 DC015784/DC/NIDCD NIH HHS/United States
GR  - R01 DC017985/DC/NIDCD NIH HHS/United States
GR  - R21 NS104826/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
DEP - 20200605
PL  - United States
TA  - J Neurosci
JT  - The Journal of neuroscience : the official journal of the Society for 
      Neuroscience
JID - 8102140
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Calcium/physiology
MH  - Cytoplasmic Granules
MH  - Electrophysiological Phenomena/physiology
MH  - Female
MH  - Interneurons/physiology
MH  - Male
MH  - Mice
MH  - Mice, Inbred C57BL
MH  - Neuroimaging
MH  - Odorants
MH  - Olfactory Bulb/*cytology/*physiology
MH  - Patch-Clamp Techniques
MH  - Smell/*physiology
MH  - Vomeronasal Organ/cytology/physiology
PMC - PMC7329303
OTO - NOTNLM
OT  - accessory olfactory system
OT  - chemical senses
OT  - interneuron
OT  - olfaction
OT  - sensory processing
OT  - vomeronasal system
EDAT- 2020/06/07 06:00
MHDA- 2020/11/24 06:00
PMCR- 2020/07/01
CRDT- 2020/06/07 06:00
PHST- 2019/09/16 00:00 [received]
PHST- 2020/04/20 00:00 [revised]
PHST- 2020/04/23 00:00 [accepted]
PHST- 2020/06/07 06:00 [pubmed]
PHST- 2020/11/24 06:00 [medline]
PHST- 2020/06/07 06:00 [entrez]
PHST- 2020/07/01 00:00 [pmc-release]
AID - JNEUROSCI.2238-19.2020 [pii]
AID - JN-RM-2238-19 [pii]
AID - 10.1523/JNEUROSCI.2238-19.2020 [doi]
PST - ppublish
SO  - J Neurosci. 2020 Jul 1;40(27):5247-5263. doi: 10.1523/JNEUROSCI.2238-19.2020. 
      Epub 2020 Jun 5.