In this collaborative paper with our German colleagues, we validated a low‐intensity sinusoidal electrical stimulation paradigm to preferentially activate C‐fibers in rodent skin.
We used in vivo GCaMP6s imaging of L4 dorsal root ganglia in anesthetized mice and verified the recruitment of small‐diameter neurons during transcutaneous 4 Hz stimulation of the hindpaw (0.4 mA). Our German colleagues, applied similar paradigms in humans and pigs: "Sinusoidal transcutaneous stimulation (4 Hz) was assessed psychophysically in healthy volunteers (n = 14) and neuropathic pain patients (n = 9). Pursuing laser Doppler imaging and single nociceptor recordings in vivo in humans (microneurography) and pigs confirmed the activation of “silent” C‐nociceptors. Synchronized C‐fiber compound action potentials were evoked in isolated human nerve fascicles in vitro."