Abstract
A stochastic stimulus on Gp I fibers was used to establish a tonic reflex discharge in spinal motoneurons in spinal (decapitate) cats. Using this technique, a frequency transfer characteristic describing the dependence of the discharge rate on afferent frequency was measured. The significance of this characteristic, and its limitations, were discussed. The tendency towards periodicity in the motoneuron discharge as the discharge rate is increased was measured. A transition from an approximately random discharge to an approximately periodic discharge occurs between 5 and 10 impulses/ sec. The contributions to this transition of after-hyperpolarization, spontaneous post-synaptic potentials, and the nature of the stimulus are discussed. An optimal stimulus frequency for depolarizing the motoneuron was defined and found to occur in the range of 65-85 impulses/sec.

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