Sensory inputs to neurones in Clarke's column from muscle, cutaneous and joint receptors

Abstract

SUMMARY1. Discharge of neurones at the region of Clarke's column of the cat was recorded intracellularly or extracellularly in response to electrical stimulation of various hind limb nerves or to adequate stimuli applied to a variety of sensory receptors.2. According to the type of excitatory sensory input, the neurones were classified into four groups. Their relative proportions were: muscle group, 55-65 %; cutaneous group, 15-25 %; joint group, 5-15 %; convergent group, 10-20%.3. The location of the neurone cell bodies was examined by marking the site of extracellular recording with fast green. The neurones of the muscle or cutaneous group were found to be within Clarke's column. One out of four neurones tested for the joint group and two out of six cells examined for the convergent group were found to be located outside the column.4. There was no difference in axonal conduction velocity among the neurones of different groups.5. The neurones of different groups could be distinguished in terms of the pattern of discharges recorded under 'resting' conditions and during activation of sensory receptors. It is suggested that information carried by dorsal spinocerebellar tract neurones to the cerebellum has a lower signal-to-noise ratio for cutaneous inputs than for muscle or joint inputs.

Sensory input to cells of origin of uncrossed spinocerebellar tract located below Clarke's column in the cat.

“…This appears to be in contrast to monosynaptic excitation from group I fibres of Clarke's column neurones, the majority of which have been considered to be activated primarily from a single muscle or a few synergists (Holmqvist, Lundberg & Oscarsson, 1956;Eccles, et al 1961 b;Mann, 1971;Kuno et al 1973; Knox et al 1977); Mann (1971) and Knox et al (1977) reported convergence of monosynaptic actions from more than one muscle or muscle group in about 20 % of DSCT axons, but the sampled axons in these studies could originate not only from Clarke's column but also from more caudal levels. For comparing the degree of convergence in the caudal spinocerebellar neurones now under study with that in Clarke's column neurones, only some of the previously reported observations can be used, because some studies used only intra-252 SENSORY INPUT TO NON-CLARKE DSCT CELLS axonal recording from DSCT fibres which discloses only supraliminal effect (Holmqvist et al 1956) and other studies used a much smaller number of peripheral nerves for testing (Kuno et al 1973;Knox et al 1977). In the intracellular study of Clarke's column neurones by Eccles et al (1961 b) in which various nerves of the hindlimb were extensively tested, convergence of afferents from different mascles was found in 36 % (twenty-one out of fifty-eight) of neurones.…”

“…The same holds true for the neurones with cutaneous input. Clarke's column neurones were reported to respond to stimulation of only one cutaneous nerve (Kuno et al 1973), while 38 % of the present spinocerebellar neurones with skin input were excited by cutaneous afferents from two or three nerves.…”

“…Only a small proportion of neurones (6 %, Kuno et al 1973) were found to be activated by both muscle and cutaneous afferents. Mann (1971) gave the value of 8 %, but axons originating below Clarke's column could have been also included.…”

“…Some spinocerebellar neurones with uncrossed axons, on the other hand, have been found outside Clarke's column: ventral or lateral to the column (Kuno et al 1973) or below the caudal level of the column (Hungo, Okada & Sato, 1967; Aoyama, Hongo & Kudo, 1973; Tapper, Mann, Brown & Codgell, 1975). Recent anatomical investigations using retrograde transport of horseradish peroxidase (HRP) revealed that there exist a few groups of spinocerebellar tract neurones with ipsilaterally ascending axons in the lumbar cord caudal to Clarke's column (Matsushita, Hosoya & Ikeda, 1979).…”

Spontaneous Discharge and Peripherally Evoked Orofacial Responses of Trigemino–Thalamic Tract Neurons during Wakefulness and Sleep

“…The spontaneous firing rate of DSCT neurons as a population decreases during AS relative to W and QS. This difference may be attributable in part to the different types of afferent information conveyed by TGT (Sessle and Greenwood, 1976;Azerad et al, 1982;Sessle et al, 1986;Ro and Capra, 1994) as opposed to DSCT neurons (Kuno et al, 1973;Mann, 1973;Walmsley, 1991) and/or different central regulatory mechanisms (Cairns et al, , 1996Soja et al, 1996a).…”