Rubrospinal synaptic influences on the lumbar motoneurons of the rat

Gurevich, N.; Belozerova, T. V.

doi:10.1007/bf01065493

Cited by 1 publication

(1 citation statement)

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“…The fact that the number of propriospinal fibers is much greater than the number of fibers of the specialized descending systems [7] agrees with such a supposition. The excitatory pattern of the effects induced in flexor motoneurons by cortical stimulation under our experimental conditions is an additional proof for the involvement of rubro-spinal fibers in the formation of the response to cortical stimulation [7,14,17]. It should be taken into account that we recorded VR responses at the L 4 level, and motoneurons of the flexor muscles dominate in this segment [18].…”

Section: Discussionmentioning

confidence: 95%

Extrapyramidal descending influences on neurons of the spinal cord in a superreflexia state

Makii

Rodinskii

2006

Neurophysiology

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The spinal superreflexia state was modeled in experiments on rats using preliminary transection of the spinal cord and injection (in the course of the acute experiment) of 4-aminopyridine. An extremely high (reaching 15-20 mV) amplitude of monosynaptic reflex discharges (MRs) evoked by stimulation of the dorsal root and recorded from the ventral root (VR) L 4 and the presence of an additional component in the above discharges were phenomena indicative of the development of the above state. Under such conditions, the amplitudes of the discharges evoked in the VR by electrical stimulation of the round window of the labyrinth (vestibular stimulation) and of the discharges elicited by stimulation of the motor cortex under conditions of bilateral transection of the pyramids increased several times. Thresholds of the VR responses to vestibular and cortical stimulations demonstrated an about threefold drop; latencies of the mass responses and responses of single spinal moto-and interneurons decreased about twofold, on average. The pattern of vestibular conditioning effects on the VR MRs changed: in intact animals vestibular stimulation induced inhibition of the VR MRs, while in animals with superreflexia such stimulation led to facilitation of the MRs. Cortical stimulation under conditions of pyramidotomy in both intact animals and animals with superreflexia resulted in facilitation of the VR MRs of a nearly the same intensity. The levels of convergence of the segmental and supraspinal effects on interneurons and motoneurons of the rat spinal cord dramatically increased under superreflexia conditions. The possible mechanisms of augmentation of the descending influences on spinal neuronal systems under the above conditions are discussed.

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Section: Discussionmentioning

confidence: 95%