Sensations Evoked by Microstimulation of Single Mechanoreceptive Afferents Innervating the Human Face and Mouth

The study examined the sensations evoked by microstimulation of mechanoreceptive afferents in the human face and mouth, involving 10 healthy volunteers and 35 single afferents. It found that fast adapting type I (FA I), FA hair, and slowly adapting type I (SA I) afferents, which terminated superficially, often evoked sensations matching their receptive fields, with FA afferents producing vibratory sensations and SA I afferents producing constant pressure sensations. In contrast, periodontal, slowly adapting type II (SA II), and deep tongue afferents, which terminated more deeply, did not evoke matching sensations, suggesting they required multiple afferents to be stimulated for perceptual access. The study indicated that SA II and periodontal afferents might help monitor the mechanical state of soft tissues, contributing to the body's representation in the central somatosensory system.