The human taste code
Wed-P2-058
Presented by: Göran Hellekant
Objectives: To reveal the human taste code
Introduction: Since antiquity human taste has been divided into 4-5 taste qualities. However, responses in taste fibers of other animal species have only partly clustered according to human qualities. We realized taste qualities vary according to phylogeny, where species closer to humans show higher fidelity to human taste qualities. Methods/results: We compared psychophysical data and taste nerve recording from humans to behavioral tests and single taste fiber recordings in chimpanzee, rhesus and marmoset. Our data show how, with phylogenetic closeness to humans, taste fibers responded more exclusively to tastants within each human taste quality. We then used the sweet taste modifiers, miraculin (Mir) and gymnemic acid (GA). In human, Mir adds sweet to sour taste and doubles nerve responses to acids. After Mir, nonhuman primates also doubled acid intake while both acid-specific and sweet-specific single taste fibers responded to acids. In human GA eliminates sweet quality. In chimpanzee GA abolished taste fiber responses to sweet without affecting responses to other tastes. Conclusions: Information from each type of taste receptor cell reaches a specific cortical taste area where it gives rise to taste qualities; taste is created in the cortical region where taste fibers deliver action potentials, thus satisfying the criteria of labelled-line coding which follows Mueller’s law of specific nerve energy for pain, touch, and temperature where sensation is created in the cortex after conveyance by sensory fibers. In humans these cortical areas give rise to the taste qualities, sweet, sour, bitter, salt and umami.This principle has not been detected in other species due to species differences in taste receptor structure and cortical taste areas.
Introduction: Since antiquity human taste has been divided into 4-5 taste qualities. However, responses in taste fibers of other animal species have only partly clustered according to human qualities. We realized taste qualities vary according to phylogeny, where species closer to humans show higher fidelity to human taste qualities. Methods/results: We compared psychophysical data and taste nerve recording from humans to behavioral tests and single taste fiber recordings in chimpanzee, rhesus and marmoset. Our data show how, with phylogenetic closeness to humans, taste fibers responded more exclusively to tastants within each human taste quality. We then used the sweet taste modifiers, miraculin (Mir) and gymnemic acid (GA). In human, Mir adds sweet to sour taste and doubles nerve responses to acids. After Mir, nonhuman primates also doubled acid intake while both acid-specific and sweet-specific single taste fibers responded to acids. In human GA eliminates sweet quality. In chimpanzee GA abolished taste fiber responses to sweet without affecting responses to other tastes. Conclusions: Information from each type of taste receptor cell reaches a specific cortical taste area where it gives rise to taste qualities; taste is created in the cortical region where taste fibers deliver action potentials, thus satisfying the criteria of labelled-line coding which follows Mueller’s law of specific nerve energy for pain, touch, and temperature where sensation is created in the cortex after conveyance by sensory fibers. In humans these cortical areas give rise to the taste qualities, sweet, sour, bitter, salt and umami.This principle has not been detected in other species due to species differences in taste receptor structure and cortical taste areas.