Investigation of the stability of the potentials of the dorsal surface evoked by single and paired stimulations of the afferent nerve

In spinal and anesthetized cats in the region of the lumbosacral thickening we have recorded the potentials of the dorsal surface (PDS) in response to single or paired stimulation of the peripheral nerves. The intervals between the stimuli were 400, 100, and 20 msec. The recording was made once every 15 sec. We have constructed the histograms of the changes in the N₁-component recorded on conditioning and single stimulation. After conversion of the histograms for single responses we established agreement of the newly obtained histograms with those constructed for the conditioned responses. The coefficients of variance for both cases proved to be practically identical. In applying single stimulation of different strengths the coefficient of variance increased if the amplitude of the responses fell. The coefficient of variance for the low amplitude responses did not change on conditioning unlike that for the responses evoked by weak single stimulation. It has been shown that the confidence limits of change in the coefficient of variance for a confidence probability of 0.99 and 0.95 obtained in experiments with conditioning practically concur with the intervals for the single stimulation. It is concluded that presynaptic inhibition has no appreciable antifluctuation influences on the N₁-component of the PDS.Dnepropetrovsk State University. Translated from Neirofiziologiya, Vol. 2, No. 1, pp. 10–16, January–February, 1970.