Characterizing SEPs from Pacinian-targeted vibrations

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 whereas 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.<b>NEW & NOTEWORTHY</b> Somatosensory-evoked potentials (SEPs) are commonly studied using transcutaneous nerve stimulation, which does not reflect the selective engagement of mechanoreceptors in natural touch. Here, we use naturalistic vibrotactile stimuli to selectively target Pacinian mechanoreceptors. We quantify the scaling of short- and long-latency SEPs with vibration amplitude and uncover key differences from electrically evoked responses. This work enhances the ecological validity of SEP research and provides a framework for studying neural responses to real-world touch.