Lamellar Schwann cells in the Pacinian corpuscle potentiate vibration perception.

Pacinian corpuscles are among the most sensitive mechanoreceptors found in vertebrates, and they are tuned to vibrations in the highest perceptible frequency range (100 to 2000 Hz). One of their anatomical hallmarks is the onion-like cell layers surrounding the central axon. The innermost layers consist of ~60 densely packed lamellar Schwann cells (LSCs), whose function remains largely unknown. Using high-resolution three-dimensional electron microscopy, we found that LSCs do not form concentric rings, but complex, multilayered, and intertwining assemblies that are connected via a high density of desmosomes and gap junctions. LSCs make multiple converging contacts with the afferent axon via desmosomes. Using optogenetic manipulations of LSCs, we demonstrate not only that their activation drives reliable time-locked spiking in the axon but also that their inactivation significantly elevates the thresholds in situ and increases perceptual thresholds behaviorally. Together, these findings provide evidence that LSCs are a key element of somatosensory processing, actively potentiating mechanosensitivity in Pacinian corpuscles.