Oscillations or cycling discharges of neurons provide a clock or impose a """"""""tempo"""""""" for various kinds of information processing. We recently found that olfactory bulb ET cells are endowed with spontaneous rhythmic bursting that persists and becomes more regular in the presence of fast synaptic blockers. Using simultaneous whole-cell recording from pairs of juxtaglomerular (JG) neurons, we were the first to discover that membrane potential oscillations and spontaneous bursting activity are highly correlated in external tufted (ET) cells associated with the same glomeruli. This synchronous activity occurs at theta frequency (1-8 Hz), the same frequency that characterizes investigative sniffing in rodents. Therefore, synchronous ET cell bursting may play an important role in olfactory coding and in regulating the induction of synaptic plasticity at the first input stage of the main olfactory bulb. In this proposal, we hypothesize that ET cells coordinate the activity of other olfactory bulb neurons and may play a role of a pattern generator of the olfactory bulb network. In particular, this project will assess the functional roles of synaptic and non-synaptic interactions in establishing correlated activity between ET cells and other neurons including interneurons and output neurons. We will use dual patch clamp and extracellular recording techniques and cross-correlation analysis to test the following hypotheses: (i) ET cell bursting activity is shaped by feedback dendrodendritic inhibition from PG cells, (ii) ET cells in neighboring glomeruli have correlated activity that is mediated by short axon cells, (iii) ET cells coordinate the activity of other output neurons, tufted and mitral cells, via chemical and electrical synapses. Taken together, the experiments proposed in this study will provide important, new insights into the intrinsic synaptic organization of the glomeruli and the role of glomerular circuitry in olfactory coding.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
7R01DC007123-02
Application #
7192980
Study Section
Somatosensory and Chemosensory Systems Study Section (SCS)
Program Officer
Davis, Barry
Project Start
2005-07-01
Project End
2010-06-30
Budget Start
2006-01-01
Budget End
2006-06-30
Support Year
2
Fiscal Year
2005
Total Cost
$266,241
Indirect Cost
Name
University of Arkansas for Medical Sciences
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
122452563
City
Little Rock
State
AR
Country
United States
Zip Code
72205
Hayar, Abdallah; Charlesworth, Amanda; Garcia-Rill, Edgar (2010) Oocyte triplet pairing for electrophysiological investigation of gap junctional coupling. J Neurosci Methods 188:280-6
Ye, Meijun; Hayar, Abdallah; Garcia-Rill, Edgar (2009) Cholinergic responses and intrinsic membrane properties of developing thalamic parafascicular neurons. J Neurophysiol 102:774-85
Nai, Qiang; Dong, Hong-Wei; Hayar, Abdallah et al. (2009) Noradrenergic regulation of GABAergic inhibition of main olfactory bulb mitral cells varies as a function of concentration and receptor subtype. J Neurophysiol 101:2472-84
Heister, David S; Hayar, Abdallah; Garcia-Rill, Edgar (2009) Cholinergic modulation of GABAergic and glutamatergic transmission in the dorsal subcoeruleus: mechanisms for REM sleep control. Sleep 32:1135-47
Dong, Hong-Wei; Heinbockel, Thomas; Hamilton, Kathryn A et al. (2009) Metabotropic glutamate receptors and dendrodendritic synapses in the main olfactory bulb. Ann N Y Acad Sci 1170:224-38
Dong, Hong-Wei; Hayar, Abdallah; Callaway, Joseph et al. (2009) Group I mGluR activation enhances Ca(2+)-dependent nonselective cation currents and rhythmic bursting in main olfactory bulb external tufted cells. J Neurosci 29:11943-53
Hayar, Abdallah; Gu, Chunping; Al-Chaer, Elie D (2008) An improved method for patch clamp recording and calcium imaging of neurons in the intact dorsal root ganglion in rats. J Neurosci Methods 173:74-82
Karpuk, Nikolay; Hayar, Abdallah (2008) Activation of postsynaptic GABAB receptors modulates the bursting pattern and synaptic activity of olfactory bulb juxtaglomerular neurons. J Neurophysiol 99:308-19
Hayar, Abdallah; Ennis, Matthew (2007) Endogenous GABA and glutamate finely tune the bursting of olfactory bulb external tufted cells. J Neurophysiol 98:1052-6
Heister, David S; Hayar, Abdallah; Charlesworth, Amanda et al. (2007) Evidence for Electrical Coupling in the SubCoeruleus (SubC) Nucleus. J Neurophysiol 97:3142-7

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