Conclusions
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1.
Decreases in the frequency and increases in the regularity of the bursts of type I–II cells of the medial septal nucleus-diagonal band nucleus (MS-DB) occur to various extents during surgical (transection of the medial forebrain bundle) and pharmacological (Nembutal) shut-offs of ascending afferentations; however, phase-frequency drives of theta cycles to a low-frequency stimulus differ substantially under these conditions.
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2.
Nembutal sharply restricts the upper boundary for overall (up to 8 Hz) and precise (up to 5 Hz) driving of the background theta cycles to a stimulus. When basal undercutting of the septum is done, the upper boundary of overall (10 Hz) and precise (8 Hz) driving differ insignificantly from the corresponding control parameters (12 and 9 Hz).
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3.
Nembutal significantly increases the duration of the initial pause in cells with driving “by pause” (from 55.1±2.7 to 95.2±6.7 msec). This does not occur with basal undercutting.
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4.
Under both conditions, there is significant improvement in comparison with normal driving to low frequencies of stimulation near the background frequency of the theta cycles.
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5.
MS-DB cells with weak rhythmic modulation (type III) can react to stimulation with two types of responses: the driving of background bursts and the following of single spikes. These responses differ with respect to latent periods, frequency optima, and pharmacological sensitivities.
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Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti imeni I. P. Pavlova, Vol. 38, No. 2, pp. 323–332, March–April, 1988.
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Brazhnik, E.S., Vinogradova, O.S. Frequency modulation of the neuronal theta bursts in the rabbit's septum deprived of ascending afferent input. Neurosci Behav Physiol 19, 26–33 (1989). https://doi.org/10.1007/BF01148407
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DOI: https://doi.org/10.1007/BF01148407