The nature of spinal shock communication IV. Atony of the motor neuron in spinal shock

Summary

The condition of motorneurons was studied during spinal shock in experiments on frogs. The myotatic reflex of the gastrocnemius muscle was recorded by electromyograms in the first series of experiments. The disappearance of the initial impulses or an increase of the anelectrotonic “silence period” was noted in the monosynaptic and polysynaptic impulses in spinal shock. In the second series of experiments, the authors recorded the potentials of the IXth anterior root during electric stimulation of the corresponding posterior root. The disappearance or reduction of the intial monosynaptic potential following chordotomy, and its restoration after recovery from spinal shock, pointed to the fact that the motorneurons cells are the site of the spinal shock development. The anelectrotonic condition of the motorneuron during the shock period is an atonia provoked by the exclusion of the supraspinal impulses.