Club-like receptors respond to light touch but not to whisking.

Abstract

Rodents explore their environment by actively whisking and contacting objects with their whiskers. Each whisker follicle contains hundreds of mechanoreceptors, but how specific afferents distinguish between self-motion and touch remains unclear. Here, using artificial whisking in male rats, intra-axonal recordings, and morphological reconstruction, we identify a distinct mechanoreceptor subtype-club-like endings-that respond exclusively to touch and remain silent during whisking. In contrast, Merkel and lanceolate endings exhibit mixed selectivity. Club-like endings are arranged in a single-layer circular array near the center of mass of the whisker-follicle unit, embedded in a collagen-rich structure called the ringwulst. Using scanning electron microscopy, we show that these endings are tightly anchored to the glassy membrane and collagen fibers, forming a mechanically isolated zone. This configuration minimizes activation during whisking while preserving sensitivity to touch. We propose that these features evolved to enhance tactile precision in whisking species, as supported by the absence of such specializations in non-whisking animals such as cats.