Response properties of the glossopharyngeal taste system of the mud puppy (Necturus maculosus)

Abstract

The general properties of the glossopharyngeal taste system of the mud puppy,Necturus maculosus, were determined using standard electrophysiological recording techniques. Electrical activity from the whole nerve was quantified by an electronic integrator. The tongue was stimulated with diverse stimuli over an extended range of concentrations: the electrolytes, NaCl, KCl, CaCl2, CsCl, LiCl, and NH4C1; the amino acids, L-alanine, DL-alanine, and glycine; and stimuli representing the four basic taste qualities in humans, HCl (sour), quinine hydrochloride (bitter), sucrose (sweet), and NaCl (salty). The response pattern to all stimuli was identical: a phasic increase in activity which adapted nearly to baseline within 10 s (Fig. 4A), a response which was directly related to stimulus concentration (Fig. 4B). HCl was the most effective stimulus tested, whereas CsCl and sucrose were the least (Figs. 4, 6), However, the stimulus-response (SR) function for L-alanine suggested that saturation was reached and that threshold was far below 0.001 mol/l, the lowest concentration tested (Fig. 5B).