HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 101/4/1988    most recent 91116.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Shao, Z. Articles by Shipley, M. T. Search for Related Content PubMed PubMed Citation Articles by Shao, Z. Articles by Shipley, M. T.

Two GABAergic Intraglomerular Circuits Differentially Regulate Tonic and Phasic Presynaptic Inhibition of Olfactory Nerve Terminals

¹Department of Anatomy and Neurobiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland; and ²Department of Gene Technology and Developmental Neurobiology, Institute of Experimental Medicine, Budapest, Hungary

Submitted 6 October 2008; accepted in final form 10 February 2009

Olfactory nerve axons terminate in olfactory bulb glomeruli forming excitatory synapses onto the dendrites of mitral/tufted (M/T) and juxtaglomerular cells, including external tufted (ET) and periglomerular (PG) cells. PG cells are heterogeneous in neurochemical expression and synaptic organization. We used a line of mice expressing green fluorescent protein under the control of the glutamic acid decarboxylase 65-kDa gene (GAD65+) promoter to characterize a neurochemically identified subpopulation of PG cells by whole cell recording and subsequent morphological reconstruction. GAD65+ GABAergic PG cells form two functionally distinct populations: 33% are driven by monosynaptic olfactory nerve (ON) input (ON-driven PG cells), the remaining 67% receive their strongest drive from an ONETPG circuit with no or weak monosynaptic ON input (ET-driven PG cells). In response to ON stimulation, ON-driven PG cells exhibit paired-pulse depression (PPD), which is partially reversed by GABA_B receptor antagonists. The ONETPG circuit exhibits phasic GABA_B-R-independent PPD. ON input to both circuits is under tonic GABA_B-R-dependent inhibition. We hypothesize that this tonic GABA_BR-dependent presynaptic inhibition of olfactory nerve terminals is due to autonomous bursting of ET cells in the ONETPG circuit, which drives tonic spontaneous GABA release from ET-driven PG cells. Both circuits likely produce tonic and phasic postsynaptic inhibition of other intraglomerular targets. Thus olfactory bulb glomeruli contain at least two functionally distinct GABAergic circuits that may play different roles in olfactory coding.

This article has been cited by other articles:

				Q. Yuan Theta bursts in the olfactory nerve paired with {beta}-adrenoceptor activation induce calcium elevation in mitral cells: A mechanism for odor preference learning in the neonate rat Learn. Mem., October 26, 2009; 16(11): 676 - 681. [Abstract] [Full Text] [PDF]