Eye Blink Responses to the Four Basic Taste Stimuli in Healthy Young Humans

Taste stimuli can elicit facial responses, and the facial responses may be useful indexes of taste sensations. In this study, we propose that eye blinking is also elicited by taste stimuli and we examined eye blink responses in six healthy young adults. Low and high concentration solutions of the four basic taste qualities (sweetness, saltiness, sourness, and bitterness) and distilled water were delivered via a silicone tube. Facial responses were recorded by a video camera and eye blink responses were identified. The number of eye blinks in the 5 s following stimulation, and the latency and duration of the first eye blink, were quantified. High concentrations of sour and bitter solutions increased the number of eye blinks (195% and 227%, respectively; P < 0.01), and shortened the latency (68% and 62%; P < 0.05) and prolonged the duration (188% and 184%; P < 0.05) of the first eye blink compared to distilled water. Eye blink responses may be due to a gustofacial reflex and/or a myotatic reflex within the facial muscles. These results suggest that the eye blink response can be used as an index of gustofacial response.