Gustatory effects of miraculin, monellin and thaumatin in the Saguinus midas tamarin monkey studied with electrophysiological and behavioural techniques.

A comparative electrophysiological and behavioural study has been made in 17 closely related monkeys of the new world species, Saguinus midas tamarin. The electrical activity in the chorda tympani proper nerve of two of the monkeys was recorded during the application to the tongues of 0.02% monellin and thaumatin, 0.5% miraculin and stimuli representing the four taste qualities. It was observed that monellin and thaumatin gave no or little response and that miraculin enhanced the response to the sour stimulus, but not that to any other taste quality. Behavioural studies were then made with a two-bottle preference test in 15 monkeys. It was found that the animals did not discriminate or discriminated poorly between water and thaumatin or monellin. After miraculin they changed their strong rejection of 0.02 M citric acid, in a choice between water and acid, into a strong preference for the acid. These results show a close relation between the electrophysiological and the behavioural data.