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Centrifugal regulation of neuronal activity in the olfactory bulb of the waking rabbit as revealed by reversible cryogenic blockade

Centrifugal regulation of neuronal activity in the olfactory bulb of the waking rabbit as... 221 69 69 2 2 C. M. Gray J. E. Skinner Section of Neurophysiology, Department of Neurology, and the Neuroscience Program Baylor College of Medicine 77030 Houston TX USA Max-Planck-Institute for Brain Research Deutschordenstraße 46 D-6000 Frankfurt a.M. 71 Fed. Rep. Germany Summary The influences of centrifugal projections to the olfactory bulb were examined on the bulbar EEG and mitral-tufted cell activity in waking rabbits. Each of 6 rabbits was implanted, under surgical anesthesia, with fine wire electrodes for recording of the EEG and mitral-tufted cell unit activity and for stimulating the lateral olfactory tract. Two cooling probes, for reversible cryogenic blockade, were implanted on either side of the left olfactory peduncle. Records of EEG and unit activity were taken for 200 s before, during and after cooling of the probes to 3 degrees centigrade. Antidromic evoked potentials were used to assess the efficacy of the blockade. During the cryogenic blockade bursts of EEG activity, evoked in the bulb by inspiration through the nose, were augmented in amplitude and reduced in frequency. Mitral-tufted cell unit activity was reduced in rate but was more highly correlated with the phase and amplitude of the EEG bursts. Analysis of individual EEG bursts revealed that the variance in frequency of bulbar activity was significantly reduced in the isolated state. The data demonstrate that oscillatory bursting activity in the olfactory bulb is intrinsically maintained within a relatively fixed frequency range during receptor input and does not depend on centrifugal projections for its electrogenesis. Changes in EEG frequency, amplitude and correlation with unit activity support the hypothesis that centrifugal projections act in part to inhibit mitral-tufted cell output by direct excitation of granule cells. These findings are supported by a theoretical model in which distributed feedback to the granule cells from more central olfactory structures acts to regulate the coherency of bulbar activity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experimental Brain Research Springer Journals

Centrifugal regulation of neuronal activity in the olfactory bulb of the waking rabbit as revealed by reversible cryogenic blockade

Gray, C.; Skinner, J.
Experimental Brain Research , Volume 69 (2) – Jan 1, 1988
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References (43)

Publisher
Springer Journals
Copyright
Copyright © 1988 by Springer-Verlag
Subject
Biomedicine; Neurosciences; Neurology
ISSN
0014-4819
eISSN
1432-1106
DOI
10.1007/BF00247583
Publisher site
See Article on Publisher Site

Abstract

221 69 69 2 2 C. M. Gray J. E. Skinner Section of Neurophysiology, Department of Neurology, and the Neuroscience Program Baylor College of Medicine 77030 Houston TX USA Max-Planck-Institute for Brain Research Deutschordenstraße 46 D-6000 Frankfurt a.M. 71 Fed. Rep. Germany Summary The influences of centrifugal projections to the olfactory bulb were examined on the bulbar EEG and mitral-tufted cell activity in waking rabbits. Each of 6 rabbits was implanted, under surgical anesthesia, with fine wire electrodes for recording of the EEG and mitral-tufted cell unit activity and for stimulating the lateral olfactory tract. Two cooling probes, for reversible cryogenic blockade, were implanted on either side of the left olfactory peduncle. Records of EEG and unit activity were taken for 200 s before, during and after cooling of the probes to 3 degrees centigrade. Antidromic evoked potentials were used to assess the efficacy of the blockade. During the cryogenic blockade bursts of EEG activity, evoked in the bulb by inspiration through the nose, were augmented in amplitude and reduced in frequency. Mitral-tufted cell unit activity was reduced in rate but was more highly correlated with the phase and amplitude of the EEG bursts. Analysis of individual EEG bursts revealed that the variance in frequency of bulbar activity was significantly reduced in the isolated state. The data demonstrate that oscillatory bursting activity in the olfactory bulb is intrinsically maintained within a relatively fixed frequency range during receptor input and does not depend on centrifugal projections for its electrogenesis. Changes in EEG frequency, amplitude and correlation with unit activity support the hypothesis that centrifugal projections act in part to inhibit mitral-tufted cell output by direct excitation of granule cells. These findings are supported by a theoretical model in which distributed feedback to the granule cells from more central olfactory structures acts to regulate the coherency of bulbar activity.

Journal

Experimental Brain Research – Springer Journals

Published: Jan 1, 1988

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