Making Sense of Taste : Psychophysical, molecular biological and neurophysiological studies of umami taste processing in humans

Abstract

Monosodium glutamate elicits a specific umami taste and increases palatability of food. In order to comprehensively study the mechanisms of the taste perception of glutamate, this work compiles results from several research fields namely, psychophysics, molecular biology and neurophysiology.<br> At the perception level, the aim of the study was to explore individual variation in the perception of glutamate in the healthy population. At the cellular level, the question referred to the role of single nucleotide polymorphisms (SNPs) present in the umami taste genes, on taste transduction of glutamate. At the neurophysiological level, the aim was to determine the topographical differences in cortical processing of umami and salt taste by using gustatory event related potentials (ERP). Finally, the laterality of the gustatory pathway was elucidated by using functional brain imaging (fMRI) in humans.<br> Psychophysical screening in the German and Norwegian population verified the existence of “taste-blindness” for umami taste. Through functional assays our results demonstrated that some of the SNPs present in the umami receptor, impaired the function of the receptor. Gustatory ERP recordings showed that there is segregation of brain areas related to umami and salt taste processing. fMRI analysis revealed that salt and umami taste follow different pathways from the taste receptor cells to the gustatory cortex.