Taste effects resulting from intermittent electrical stimulation of the tongue.

Abstract

Use of intermittent electrical stimulation on the tongue makes it possible to examine relationships between frequency and intensity of stimulation and the so-called "critical fusion frequency" of taste. Experiments were conducted in which the tongue of an intact human subject was stimulated by square wave currents at frequencies between 20 and 1000 cps. Two types of limen to anodal stimulation were found employing the method of limits. Thresholds were obtained from the anterior dorsal surface of the tongue and from the lip mucosa. It was found that as the stimulus intensity increased on the tongue the subject first detected stimulation as a sour or metallic steady taste. This threshold was termed the electric taste limen. With further increases in intensity a point was reached at which intermittence abruptly appeared. This was called the critical fusion or pulse threshold. Taste and pulse thresholds were expressed as a function of frequency. For 2 of 3 subjects the taste and pulse threshold curves were significantly different in form. No electric taste could be elicited from the lip. Pulse thresholds could be determined. The form of the pulse curves for tongue and lip is similar. In all experiments the threshold tended to rise with increase in frequency. From these data it was concluded that similar intermittent threshold curves can be obtained from regions with and without taste receptors. It was also concluded that the so-called critical fusion frequency of taste can not be used as an indicator of receptor mechanisms of taste.