OBJECTIVE EVALUATION OF THE GUSTATORY SENSITIVENESS OF PATIENTS BY THE ELECTROPHYSIOLOGICAL RECORDING OF THE RESPONSE OF BUD CELLS TO TASTE STIMULI.

Practical and reliable methods for the objective measure of taste function are critically important for studies aimed at evaluating eating behavior and taste function impairment. Here we present direct measures of the peripheral gustatory system activation, by means of a new, highly reliable and yet non-invasive technique for the electrophysiological recording from the human tongue in response to taste stimuli. Firstly, we validated the efficacy of method based on comparing the bioelectric activity recorded in response to the paradigmatic gustatory stimulus, 6-n-propylthiouracil (PROP), with parameters defining PROP genotype and phenotype of forty-three subjects. The main results were: 1) PROP stimulation evoked negative monophasic potentials characterized by a fast initial rise followed by a slow decline, which represent the measure of the summated voltage change resulting from the response of stimulated taste cells; 2) direct associations were found between parameters describing the waveform of signals (depolarization amplitude and depolarization rate) and TAS2R38 genotype, fungiform papilla density and PROP phenotype of subjects. Secondly, we developed an automated learning approach capable of discriminating among subjects belonging to three PROP taster categories (super-tasters, medium taster and non-taster), by exploiting features extracted by electrophysiological recordings from the tongue of thirty-nine subjects. Results showed that it is possible to automatically achieve objective PROP taster status identification with a high accuracy (80 ± 18%), which reaches 94 ± 15% when only super-tasters and non-tasters are considered. Finally, preliminary results of the electrophysiological recording in response to sucrose, NaCl, citric acid, caffeine, umami and oleic acid showed the feasibility of the method also for other gustatory stimuli, thus providing a first proof of its general applicability.The proposed approach, representing the first objective and automatic method to directly measure human gustatory responses, may represent a milestone for physiology studies on taste, with applications ranging from basic science and medicine to food tasting evaluations.