Suprathreshold gustatory stimuli cause biphasic respiratory responses during resting respiration in humans.

Abstract

Until now there has been no standardized and internationally accepted method available to objectify taste perception. Such a method would be useful for expert opinions in the assessment of gustatory disorders. The aim of our study was to develop and evaluate an analogous method for the gustatory sense. Nonrandomized, controlled clinical trial. A continuous flow of water was presented to the tongues of 34 healthy adult subjects (15 men, 19 women). In this stream, suprathreshold gustatory stimuli were applied during regular resting respiration. Nasal respiration was measured unilaterally with a differential pressure transducer. No significant differences were measured between the different tastants but were between tastants and blanks. Gustatory-evoked changes in the breathing pattern resulted frequently in a prolongation of the first poststimulatory breath. The second and third breath became frequently shorter. The observed gustatory-evoked respiratory responses are probably orienting reflex (OR) reactions. The deceleration of the first breath could be related to attention toward any chemosensory input. The acceleration of the second and third breath could reflect the subject's intention to recognize the four taste qualities. The measurement of respiratory OR evoked by gustatory stimuli can be used as a simple, inexpensive, and reliable objectifying clinical tool to prove intact central gustatory processing.