scholarly journals Paradoxically sparse chemosensory tuning in broadly-integrating external granule cells in the mouse accessory olfactory bulb

2019 ◽  
Author(s):  
Xingjian Zhang ◽  
Julian P. Meeks
Keyword(s):  
Patch Clamp ◽  
Olfactory Bulb ◽  
Olfactory System ◽  
Granule Cells ◽  
Ex Vivo ◽  
Accessory Olfactory Bulb ◽  
Main Olfactory Bulb ◽  
Patch Clamp Electrophysiology ◽  
Accessory Olfactory System ◽  
Critical Circuit

AbstractThe accessory olfactory bulb (AOB) is a critical circuit in the mouse accessory olfactory system (AOS), but AOB processing is poorly understood compared to the main olfactory bulb (MOB). We used 2-photon GCaMP6f Ca2+ imaging in an ex vivo preparation to study the chemosensory tuning of AOB external granule cells (EGCs), an interneuron population hypothesized to broadly integrate from mitral cells (MCs). We measured MC and EGC tuning to natural chemosignal blends and monomolecular ligands, finding that EGC tuning was far sparser than MC tuning. Simultaneous patch-clamp electrophysiology and Ca2+ imaging indicated that this was only partially explained by lower GCaMP6f-to-spiking ratios in EGCs compared to MCs. Ex vivo patch-clamp recordings revealed that EGC subthreshold responsivity was broad, but monomolecular ligand responses were insufficient to elicit spiking. These results indicate that EGC spiking is selectively engaged by chemosensory blends, suggesting different roles for EGCs than analogous interneurons in the MOB.

Ultrastructural morphology and synaptic plasticity of granule cells in accessory olfactory bulb

2011 ◽  
Vol 71 ◽  
pp. e356
Author(s):  
Keiko Moriya-Ito ◽  
Endoh Kentaroh ◽  
Yoko Tsukamoto ◽  
Masumi Ichikawa
Keyword(s):  
Synaptic Plasticity ◽  
Olfactory Bulb ◽  
Granule Cells ◽  
Accessory Olfactory Bulb ◽  
Ultrastructural Morphology

scholarly journals Noradrenergic Regulation of GABAergic Inhibition of Main Olfactory Bulb Mitral Cells Varies as a Function of Concentration and Receptor Subtype

2009 ◽  
Vol 101 (5) ◽  
pp. 2472-2484 ◽  
Author(s):  
Qiang Nai ◽  
Hong-Wei Dong ◽  
Abdallah Hayar ◽  
Christiane Linster ◽  
Matthew Ennis
Keyword(s):  
Olfactory Bulb ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Gabaergic Inhibition ◽  
Mitral Cells ◽  
Main Olfactory Bulb ◽  
Pontine Nucleus ◽  
Patch Clamp Electrophysiology ◽  
Α1 Receptors

The main olfactory bulb (MOB) receives a rich noradrenergic innervation from the pontine nucleus locus coeruleus (LC). Previous studies indicate that norepinephrine (NE) modulates the strength of GABAergic inhibition in MOB. However, the nature of this modulation and the NE receptors involved remain controversial. The goal of this study was to investigate the role of NE receptor subtypes in modulating the GABAergic inhibition of mitral cells using patch-clamp electrophysiology in rat MOB slices. NE concentration dependently and bi-directionally modulated GABAA receptor–mediated spontaneous and miniature inhibitory postsynaptic currents (sIPSCs/mIPSCs) recorded in mitral cells. Low doses of NE suppressed sIPSCs and mIPSCs because of activation of α2 receptors. Intermediate concentrations of NE increased sIPSCs and mIPSCs primarily because of activation of α1 receptors. In contrast, activation of β receptors increased sIPSCs but not mIPSCs. These results indicate that NE release regulates the strength of GABAergic inhibition of mitral cells depending on the NE receptor subtype activated. Functionally, the differing affinity of noradrenergic receptor subtypes seems to allow for dynamic modulation of GABAergic inhibition in MOB as function of the extracellular NE concentration, which in turn, is regulated by behavioral state.

scholarly journals Zonal organization of the mammalian main and accessory olfactory systems

2000 ◽  
Vol 355 (1404) ◽  
pp. 1801-1812 ◽  
Author(s):  
Kensaku Mori ◽  
Harald von Campenhausen ◽  
Yoshihiro Yoshihara
Keyword(s):  
Olfactory Bulb ◽  
Sensory Neurons ◽  
Olfactory System ◽  
Expression Patterns ◽  
Odorant Receptors ◽  
Accessory Olfactory Bulb ◽  
Basal Zone ◽  
Olfactory Systems ◽  
Tufted Cells ◽  
Zonal Organization

Zonal organization is one of the characteristic features observed in both main and accessory olfactory systems. In the main olfactory system, most of the odorant receptors are classified into four groups according to their zonal expression patterns in the olfactory epithelium. Each group of odorant receptors is expressed by sensory neurons distributed within one of four circumscribed zones. Olfactory sensory neurons in a given zone of the epithelium project their axons to the glomeruli in a corresponding zone of the main olfactory bulb. Glomeruli in the same zone tend to represent similar odorant receptors having similar tuning specificity to odorants. Vomeronasal receptors (or pheromone receptors) are classified into two groups in the accessory olfactory system. Each group of receptors is expressed by vomeronasal sensory neurons in either the apical or basal zone of the vomeronasal epithelium. Sensory neurons in the apical zone project their axons to the rostral zone of the accessory olfactory bulb and form synaptic connections with mitral–tufted cells belonging to the rostral zone. Signals originated from basal zone sensory neurons are sent to mitral–tufted cells in the caudal zone of the accessory olfactory bulb. We discuss functional implications of the zonal organization in both main and accessory olfactory systems.

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