Characterizing SEPs from Pacinian-targeted vibrations.

Abstract

This study characterizes short- and long-latency somatosensory evoked potentials (SEPs) elicited by high-frequency vibrotactile stimuli. Unlike conventional electrical stimulation, such vibrations selectively recruit Pacinian corpuscles while sparing other mechanoreceptors, motor, proprioceptive, and nociceptive fibers, thereby offering a more ecologically valid proxy for natural touch. We first show that SEP components P45, P100, N140, P200 and P300 scaled systematically with vibration amplitude, and quantify the increase in SEP voltage per increase in peak-to-peak vibration amplitude for suprathreshold stimuli. We then compare vibrotactile SEPs to those produced by perceptually matched electrical stimulations given at the same finger location. The overall morphology of vibrotactile SEPs at contralateral electrode CP3 appeared similar to electrical SEPs from the P45 and onward. However, short-latency components P45 and N70 revealed distinct scalp topographies, indicating different cortical sources for the two stimulation modalities. Source analysis revealed greater early activation (~45 ms) of contralateral primary somatosensory regions while posterior parietal areas and SII showed differential activation for vibrations and electrical stimulations. Later processing and integration of sensory information recruited similar neural sources for both modalities. These findings offer a comprehensive reference for SEP responses to Pacinian-targeted vibrations and highlight the use of naturalistic stimuli in human somatosensory electrophysiology.