Enhancement of Tongue Tactile Sensitivity via Stochastic Resonance.

The sensory function of the tongue is crucial for chewing and swallowing. A decline in this function due to aging or disability increases the risk of aspiration, choking, and aspiration pneumonia. The objective of this study was to determine whether stochastic resonance, in which the application of noise vibrations enhances the tactile sensitivity of fingers and other body parts, also occurs in the tongue and to determine its effects. To do so, we evaluated the effects of noise vibration applied to the submental region on tongue sensitivity during both passive and active touch. This was assessed in 15 young men (mean age ± standard deviation, 22.7 ± 1.0 years) and 12 older men (73.9 ± 5.2 years) with no tongue-related disorders or relevant medical history. The Semmes-Weinstein perception test was used to measure tactile thresholds, while the Roughness Discrimination Test was used to assess the accuracy rates of roughness discrimination. The tactile threshold for passive touch decreased in 96% of participants, with improved sensitivity observed in both the young and older groups. Furthermore, the accuracy rate for roughness discrimination during active touch improved in 59% of participants, with enhanced sensitivity noted in both groups. No participants failed to show an effect of stochastic resonance on either passive or active touch. These findings indicate that noise vibration applied to the submental region immediately enhances the sensory function of the tongue, suggesting potential applications in new dietary support devices.