The Influence of Stimulus Taste and Chemesthesis on Tongue Movement Timing in Swallowing

Abstract

To explore the influence of taste and trigeminal irritation (chemesthesis) on durational aspects of tongue movement in liquid swallowing, controlling for the influence of perceived taste intensity. Electromagnetic midsagittal articulography was used to trace tongue movements during discrete liquid swallowing with 5 liquids: water, 3 moderate concentration tastants without odor (sweet, sour, sweet-sour), and a high concentration of citric acid (sour taste plus chemesthesis). Participants were 33 healthy adults in 2 gender-balanced, age-stratified groups (under/over 50). Perceived taste intensity was measured using the Generalized Labeled Magnitude Scale (Bartoshuk, 2000; Bartoshuk et al., 2004). Tongue movement sequencing and durations of the composite tongue movement envelope and component events (rise phase, location of first movement peak, release phase) were calculated. No obligate sequence of tongue segment movement was observed. Overall durations and the timing of the first movement peak were significantly longer with water than with the moderate concentration of sweet-sour liquid. Perceived taste intensity did not modulate stimulus effects in a significant way. The expected pattern of shorter movement durations with the high concentration of citric acid was not seen. A chemesthetic-taste stimulus of high citric acid did not influence the durations of tongue movements compared with those seen during the swallowing of moderate concentration tastants and water.