Response of the Spinal Tract and Nucleus of the Trigeminal Nerve to Two Stimuli

(Summary) 1. An attempt was made to separate pre- and post-synaptic action potentials on the basis of recovery of spike height to the second of two supramaximal stimuli.

2. Two distinct groups of action potentials were recorded from the spinal tract of the trigeminal nerve.

3. A series of recovery-cycles of the spike potentials of the sciatic nerve was plotted for comparison with the spike potential of the spinal tract of the fifth nerve.

4. A 2 channel stimulator and a 5 unit synchronizer circuit were designed and constructed for use in these experiments. The utilization of a Schmitt circuit to achieve time delay is believed to be a new application of that circuit.

5. From the date presented here, it may not be certain that the second peak of the potential wave recorded from the spinal tract and nucleus of the fifth nerve is from second or higher order fibers, but it gives strong support to the belief that it is actually post-synaptic.

6. The methods used in these experiments are not necessarily restricted to use in trigeminal pathways but should be applicable to any synaptic region.