VIBRATION-EVOKED SENSORY NERVE ACTION-POTENTIALS DERIVED FROM PACINIAN CORPUSCLES

To evaluate sensory response to natural stimuli, we developed a method to record sensory nerve action potentials evoked by high-frequency vibratory stimulation. Trains of 250 Hz sinusoidal indentations with a duration of 100 msec were applied to the finger tip at a rate of 3 Hz. The responses were obtained with surface electrodes placed over the median and ulnar nerves at the wrist. Averaged wave forms consisted of two components: an initial diphasic or triphasic potential and the following low amplitude trains of discharges phase-locked to vibratory stimuli. Anesthesia of the skin at the stimulation site or tourniquet-induced ischemia of the limb eventually diminished both components. Neither of them therefore represented artifacts from electrode movement or electromagnetic field intrinsic to the stimulator. Various kinds of mechanoreceptors may contribute to the first component. Pacinian corpuscles probably give rise to the second component as the only skin receptors that can respond to high-frequency vibratory stimuli of 250 Hz. This method helps examine neural coding of the receptor and the peripheral nerve fiber mediating vibration sense.