Showing papers in "Chemical Senses in 1984"

Temporal integration of pungency

Abstract: Four experiments explored possible temporal summation in olfaction and the common chemical sense. In one experiment, participants judged the perceived magnitude of various concentrations and durations (1.25 - 3.75 s) of the pungent odorant ammonia and the nonpungent odorant isoamyl butyrate. The perceived magnitude of ammonia increased during an inhalation whereas the magnitude of isoamyl butyrate did not. Time-intensity trading relations for ammonia indicated nearly perfect temporal summation. In another experiment, modulation of the concentration of ammonia during an inhalation led to assessments of perceived magnitude that confirmed the high degree of temporal summation seen in the first experiment. That is, approximately equal time-integrated mass of inhaled ammonia led to approximately equal perceived intensity. A third experiment indicated that temporal summation for ammonia arose from its pungency rather than from its odor, a fourth that trigeminally-mediated reflex apnea in response to ammonia also exhibits temporal summation. The degree of temporal summation measured with the reflex came very close to that assessed psychophysically. When stimulated with ammonia, the common chemical sense behaves more like a total mass detector than a concentration detector. The investigation raises the possibility that the short-term sensory reaction to most pungent stimuli may follow this simple rule.

Influence of stimulus intensity on odour discrimination by olfactory bulb neurons as compared with receptor cells

Abstract: Previously reported electrophysiological responses recorded from individual neurons in the olfactory bulb of frogs stimulated with odorous compounds were further analyzed using statistical methods. Five of the odorants were delivered at two concentrations. The pattern of discriminatio n among these odorants was investigated with the aid of the Pearson's correlation test and Benzecri's 'analyse des correspondances'. Special attention was paid to the incidence of odour concentration on this discrimination pattern. The results were compared with those of a similar study performed on receptor cells in the same experimental conditions. The comparison indicated that the information processing in the olfactory bulb seems to improve discrimination between chemically different stimuli, especially those poorly discriminated by receptor cell responses, whereas it protects this discrimination against a massive influence of the intensity of the stimuli.

Effects of gymnemic acid on sweet taste perception in primates

Abstract: Application of gymnemic acid (GA) on the tongue depresses the taste of sucrose in man. This effect, as indicated by electrophysiological responses, has been found to be absent in three nonhuman primate species. In the present behavioral study the effect of GA on taste responses in 22 primate species, with two subspecies, and 12 human subjects has been investigated. In all the nonhuman primates studied, including the Pongidae which are closely related to man, GA did not suppress the response to sucrose, only in man did GA have a depressing effect

The validity of the equiratio taste mixture model investigated with sorbitol-sucrose mixtures

Abstract: Le modele developpe applicable aux melanges binaires glucose-fructose est teste sur 3 melanges sorbitol-saccharose equiproportionnels. Les fonctions psychophysiques montrent une legere deviation par rapport au modele et on en presente les causes possibles