Purpose: The purpose of this study was to determine whether gustatory-evoked potentials are useful or not for an objective evaluation of taste.
Methods: Fifteen healthy subjects were selected. Electrical stimulation was delivered to the taste buds area of the tongue (chorda tympani, glossopharyngeal nerve area) and the soft palate (greater petrosal nerve area). Electric taste threshold and quality of judgment were measured under 7 conditions of stimulus duration (1,000, 500, 300, 200, 120, 100, and 70 msec). Electroencephalogram (EEG) was recorded at 19 sites of the 10-20 International System standard. The results from 40 presentations were averaged.
Results: Electric taste threshold was significantly higher when below 100 msec (chorda tympani nerve area), 120 msec (glossopharyngeal nerve area), and 200 msec (greater petrosal nerve area). In taste quality judgment, the number of subjects in whom taste was induced decreased in the stimulus duration condition of less than 100 msec (chorda tympani, glossapharyngeal), and decreased in all of the stimulus duration conditions (greater petrosal nerve area). In the cerebral-evoked potentials noted at 9 sites, three peaks (P1, N1, P2) were observed when taste was induced in the subjects. On the other hand, P2 wave was indistinct when only touch was induced. As stimulus intensity increased, peak latencies could not be seen to change significantly, but N1-P2 amplitude increased significantly. The latencies in these peaks were similar to typical potentials in the literature (K-H Plattig, 1971).
Conclusion: P2 was considered to be a gustatory-evoked potential. Investigation of this response has shown it to be a useful method for objective examination of taste.