Response properties of macaque monkey chorda tympani fibers

Abstract

Many of the chorda tympani fibers of crab-eating monkeys respond to more than one of the four basic stimuli (NaCl, sucrose, HC1, and quinine hydrochloride) as well as cooling or warming of the tongue. Fibers could be classified into four categories depending on their best sensitivity to any one of the four basic stimuli. Sucrose-best and quinine-best fibers are rather specifically sensitive to sucrose and quinine, respectively, while salt-best and acid-best fibers respond relatively well to HC1 and NaCl, respectively. Saccharin, dulcin, and Pb acetate produce a good response in sucrose-best fibers, but quinine-best and salt-best fibers also respond to saccharin. Highly significant positive correlations exist between amounts of responses to sucrose and those to saccharin, dulcin, and Pb acetate, indicating that these substances produce in the monkey a taste quality similar to that produced by sucrose. Co npared with chorda tympani fibers of rats, hamsters, and squirrel monkeys, macaque monkey taste fibers are more narrowly tuned to one of the four basic taste stimuli and more highly developed in sensitivity to various sweet-tasting substances. Also LiCl and NaCl are more effective stimuli for gustatory receptors in macaque monkeys than NH4CI and KC1. This contrasts with a higher sensitivity to KC1 and NH4CI than to NaCl in chorda tympani fibers of squirrel monkeys. © 1975, Rockefeller University Press., All rights reserved.