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J Neurophysiol

Title:		Chemical factors determine olfactory system beta oscillations in waking rats
Author(s):		Lowry CA; Kay LM;
Address:		"Committee on Neurobiology, Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, USA"
Journal Title:		J Neurophysiol
Year:		2007
Volume:		20070418
Issue:		1
Page Number:		394 - 404
DOI:		10.1152/jn.00124.2007
ISSN/ISBN:		0022-3077 (Print) 0022-3077 (Linking)
Abstract:		"Recent studies have pointed to olfactory system beta oscillations of the local field potential (15-30 Hz) and their roles both in learning and as specific responses to predator odors. To describe odorant physical properties, resultant behavioral responses and changes in the central olfactory system that may induce these oscillations without associative learning, we tested rats with 26 monomolecular odorants spanning 6 log units of theoretical vapor pressure (estimate of relative vapor phase concentration) and 10 different odor mixtures. We found odorant vapor phase concentration to be inversely correlated with investigation time on the first presentation, after which investigation times were brief and not different across odorants. Analysis of local field potentials from the olfactory bulb and anterior piriform cortex shows that beta oscillations in waking rats occur specifically in response to the class of volatile organic compounds with vapor pressures of 1-120 mmHg. Beta oscillations develop over the first three to four presentations and are weakly present for some odorants in anesthetized rats. Gamma oscillations show a smaller effect that is not restricted to the same range of odorants. Olfactory bulb theta oscillations were also examined as a measure of effective afferent input strength, and the power of these oscillations did not vary systematically with vapor pressure, suggesting that it is not olfactory bulb drive strength that determines the presence of beta oscillations. Theta band coherence analysis shows that coupling strength between the olfactory bulb and piriform cortex increases linearly with vapor phase concentration, which may facilitate beta oscillations above a threshold"
Keywords:		"Analysis of Variance Animals *Beta Rhythm Electrophysiology Male *Odorants Olfactory Pathways/*physiology Rats Rats, Sprague-Dawley Smell/*physiology Spectrum Analysis Stimulation, Chemical Time Factors *Wakefulness;"
Notes:		"MedlineLowry, Catherine A Kay, Leslie M eng R01 DC007995/DC/NIDCD NIH HHS/ T32 GM07839/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2007/04/20 J Neurophysiol. 2007 Jul; 98(1):394-404. doi: 10.1152/jn.00124.2007. Epub 2007 Apr 18"