Taste qualities elicited by electric stimulation of single human tongue papillae

Single human taste papillae in 5 young test subjects were electrically stimulated 84 times each with a silver wire (0.4 mm tip diameter) versus a 5 x 3.5 cm2 reference electrode on the left wrist of the subject. The electrical pulses were positive (54 papillae) or negative (45 papillae) of 0.5 msec duration and had a frequency of 50, 100, 200, 400, 600 or 800 Hertz. For control 45 papillae were merely touched by the electrode without current stimulation. Significant gustatory and tactile results (x2-test, P less than or equal to 0.05) signaled by the subjects were: a) on anodic stimulation 50 +/- 5% of the touched papillae gave overall taste responses, namely 22.2% sour, 3.8% bitter and 1.8% salty; the rest were mixed sensations. Sweet was not reported in these final experiments; b) on cathodic stimulation 42.2 +/- 5% of the papillae responded with taste, which again were reported as 22.2% sour, 2.2% salty, the rest mixed; c) on mere touching there were hardly any gustatory sensations reported. - These results indicate only a relative specifity for each single human taste papilla and its taste fibres.