Feasibility of modulating taste perception using subthreshold electrical stimulation

Subthreshold electrical noise can enhance sensory processing via stochastic resonance; however, its effect on taste remains unclear. This study investigated whether subthreshold white-noise electrical stimulation, applied to the skin surface along the mandibular margin, modulates taste perception. Young, healthy adults participated in psychophysical experiments using sodium chloride solutions for salty tastes and sucrose solutions for sweet tastes. For each taste, participants evaluated salty or sweet samples under randomized no-stimulation and stimulation conditions at 0.4, 0.6, and 0.8 times their sensory threshold using a nine-point taste intensity scale. The minimum perceptible concentrations were determined based on taste evaluation values. Additionally, stimulation to no-stimulation ratios were calculated as normalized minimum concentrations. For saltiness, the minimum concentration was significantly lower with stimulation under the 0.8 times condition than with no-stimulation (median, 0.15% vs. 0.20%; Holm-adjusted p = 0.012), and normalized minimum concentrations differed across stimulation intensities ( p = 0.004). No significant effects were observed for sweetness at any stimulation intensity. Additionally, exploratory within-participant selection of the best-performing intensity was conducted separately for saltiness and sweetness, which yielded descriptively low minimum concentrations. These findings suggest feasibility of modulating taste perception with subthreshold electrical noise, particularly for saltiness, with no significant enhancement for sweetness.