The influence of stimulus taste and chemesthesis on tongue movement timing in swallowing.

Purpose: 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.

Method: 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.

Results: 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.

Conclusions: 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.