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Responses of nucleus centrum medianum of thalamus to stimulation of deep somatic nerves in cats

Lo Fusun, Yuan Chunsu, Yang Shanlu, Zhang Xiangtong

Shanghai Brain Research Institute, Academia Sinica. Shnaghai, China

Abstract

In the centromedian nucleus of the thalamus of waking but immobilized cats, repetitive stimulation of the deep peroneal nerve or the deep radial nerve at a frequency of 8 Hz resulted in a sustained increase in unit discharge rate in the centromedian nucleus so long as the stimulation was maintained, i. e. the centromedian neurones did not adapt to low frequency stimuli. Within half a minute following the cessation of stimulation, the discharge rate of most neurones remained high, then subsided to control level. Repetitive stimulation of the deep nerve at a frequency of 4 Hz could also bring about a sustained increase in the discharge rate, which was sometimes not so prominant as that in the former case and did not outlast the period of stimulation. After continuous high frequency stimulation (60 Hz), there was an initial increase in discharge rate but it tapered off within about half a minute. Therefore, only low frequency (4-8 Hz) stimulation of the deep somatic nerves can effectively activate the centromedian neurones and be closely correlated in time with peripheral stimulation. Taking all the available evidences into consideration, we may conclude that there is a parallel relationship between the discharge rate of the centromedian neurones and the inhibition of the nociceptive discharges in the parafascicular nucleus. This suggests that the centromedian nucleus plays an important role in the process of acupuncture analgesia.

Key words: Thalamus;Nucleus centrum medianum;Deep somatic nerve;Evoked discharges

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Citing This Article：

Lo Fusun, Yuan Chunsu, Yang Shanlu, Zhang Xiangtong. Responses of nucleus centrum medianum of thalamus to stimulation of deep somatic nerves in cats. Acta Physiol Sin 1985; 37 (2): (in Chinese with English abstract).