title: Signaling between periglomerular cells reveals a bimodal role for GABA in modulating glomerular microcircuitry in the olfactory bulb.
abstract: In the mouse olfactory bulb glomerulus, the GABAergic periglomerular (PG) cells provide a major inhibitory drive within the microcircuit. Here we examine GABAergic synapses between these interneurons. At these synapses, GABA is depolarizing and exerts a bimodal control on excitability. In quiescent cells, activation of GABAA receptors can induce the cells to fire, thereby providing a means for amplification of GABA release in the glomerular microcircuit via GABA-induced GABA release. In contrast, GABA is inhibitory in neurons that are induced to fire tonically. PG-PG interactions are modulated by nicotinic acetylcholine receptors (nAChRs), and our data suggest that changes in intracellular calcium concentrations triggered by nAChR activation can be amplified by GABA release. Our results suggest that bidirectional control of inhibition in PG neurons can allow for modulatory inputs, like the cholinergic inputs from the basal forebrain, to determine threshold set points for filtering out weak olfactory inputs in the glomerular layer of the olfactory bulb via the activation of nAChRs.
authors.affiliation: Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045 Neuroscience Program, University of Colorado School of Medicine, Aurora, CO 80045.
authors.forename: Pirooz Victor
authors.initials: PV
authors.lastname: Parsa
authors.affiliation: Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045 Neuroscience Program, University of Colorado School of Medicine, Aurora, CO 80045.
authors.forename: Rinaldo David
authors.initials: RD
authors.lastname: D'Souza
authors.affiliation: Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045 Neuroscience Program, University of Colorado School of Medicine, Aurora, CO 80045 sukumar.v@ucdenver.edu.
authors.forename: Sukumar
authors.initials: S
authors.lastname: Vijayaraghavan
mesh_terms: D000109:Acetylcholine / Q000502:physiology; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal; D002118:Calcium / Q000737:chemistry; D007395:Interneurons / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009830:Olfactory Bulb / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011950:Receptors, Cholinergic / Q000502:physiology; D011978:Receptors, Nicotinic / Q000502:physiology; D015398:Signal Transduction; D013569:Synapses / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine; D002118:Calcium
keywords: cholinergic; excitatory GABA; interneurons; nicotinic; normalization