Robust coupling between the C-tactile afferent and the hair follicle in humans

C-low-threshold-mechanoreceptors (C-LTMR) were first discovered in the cat over 80 years ago and were subsequently documented in multiple mammalian species, including humans. Although their intimate association with hair follicles has been documented in mouse skin innervated by spinal ganglia, the functional anatomy in human skin is not known. The present study aimed to establish whether human C-LTMRs, also referred to as C-tactile (CT) afferents, have a functional association with hair follicles by determining their response to hair deflection using microneurography. Recordings from 15 consecutive CT afferents where the response to hair deflection was investigated showed that individual CT afferents respond to selective hair deflection. Mechanical hair plucking evoked after-discharge in CT afferents in the order of seconds following the stimulus. The results provide electrophysiological evidence that human CT afferents, similar to C-LTMRs in mice, have a functionally relevant anatomical relationship to hair follicles. KEY POINTS: In humans, recordings from 15 C-tactile afferents where the response to hair deflection was investigated, showed that individual C-tactile afferents respond to selective hair deflection. Mechanical hair plucking evoked after-discharge in C-tactile afferents in the order of seconds following the stimulus. The results provide electrophysiological evidence that human C-tactile afferents, similar to previously reported C-tactile afferents in mice, have a functionally relevant anatomical relationship to hair follicles.