Studying human gustation: A multidisciplinary approach

Abstract

The sense of taste, per se, signals caloric (sweet), proteins and amino acids (umami), osmolytes (salt), freshness of food (sour), and toxic or hazardous (bitter) compounds. Taste was one of the first senses to develop and carries evident evolutionary advantage. However, in our daily life, the way we experience food is not limited to taste. The total perception of eating is a combination of these primary taste characteristics (detected by the gustatory system) with the addition of ortho-and retro-nasal perception of volatile compounds (flavors) together with oral, thermal, and mechano-sensory sensations. In concert, all these factors contribute to build the final sensation that we commonly attribute to the degustation of food.When studying taste, one must take into consideration multiple disciplines, including anatomy, neuroscience, sensory science, and nutrition, but one must also understand how psychology-the characteristic patterns of thoughts, feeling, and behaviors that influence taste perception-contributes to degustation. This clarifies how complex the investigation of the sense of taste in humans in a laboratory environment can be and how easily an incorrect paradigm can lead to misinterpretations.In this In Focus issue, we bring together contributions from across several areas of human gustation by means of varied methodologies and analyses including electrophysiology, psychophysics, and brain imaging. Each paper brings forth evidence that needs to be considered when studying gustation in humans. We begin with a brief update of what we know about the human gustatory pathway before providing new indication for quantitative measurements of gustatory functions. Then, we explore how different sensory modalities, including audition and olfaction, influence the gustatory system. Finally, we discuss how personality traits have to be considered when studying gustatory preference.In our first article, Iannilli and Gudziol (2019) review human anatomy of the sense of taste and its ascending signal transmission. This article refers to the experimental evidence about taste laterality and the gustatory neuronal path in humans observed in anatomical and clinical studies. We summarize the current state of understanding of the pathways and identify six gustatory pathway models, schematically drawn in the paper, that consider signal transduction along the ascending fibers through the tongue, medulla, pons, midbrain, the thalamus, the primary gustatory cortex, and the secondary gustatory cortex. The review also critically discusses noninvasive neuroimaging studies, including paradigms and methodologies commonly used to investigate human gustation with functional magnetic resonance for imaging (fMRI), magnetoencephalography, and electroencephalography (EEG). The second article by Andersen et al. (2019) focuses on a specific analysis of the gustatory EEG signal. They examined the detection of subconsciously and near consciously distinguishable taste differences using the time-resolved multivariate pattern analysis of a128-ch...

Olfaction as a Marker for Dystonia: Background, Current State and Directions

“…As the olfactory and the gustatory system interact in daily life, both systems need to be considered to fully understand the chemical senses [ 47 , 126 ]. The architecture of the gustatory system is very different from that of the olfactory system [ 42 , 43 , 127 ]. While parts of the olfactory system are considered an evagination of the brain, parts of the gustatory system are derivatives of the skin [ 42 , 43 ].…”

“…Theses taste receptor cells are connected with the cranial nerves VII, IX, and X [ 42 , 43 , 129 ]. The axons of these cranial nerves, which are involved in taste, reach the brain stem and synapse with neurons of the solitary tract [ 42 , 43 , 127 , 130 ]. The axons of these neurons in turn ascend either through the central tegmental tract to the ipsilateral ventral posterior medial nucleus of the thalamus, or with the medial lemniscus to the contralateral thalamic counterpart [ 127 , 131 , 132 ].…”

“…The axons of these cranial nerves, which are involved in taste, reach the brain stem and synapse with neurons of the solitary tract [ 42 , 43 , 127 , 130 ]. The axons of these neurons in turn ascend either through the central tegmental tract to the ipsilateral ventral posterior medial nucleus of the thalamus, or with the medial lemniscus to the contralateral thalamic counterpart [ 127 , 131 , 132 ]. From these thalamic nuclei the gustatory signals reach the insula cortex and the sensorimotor cortex [ 132 , 133 , 134 , 135 , 136 , 137 ].…”

Rapid quantitative detection of glucose using biological sensor system as combined with electrochemical data treatment

“…Gustation is important for animals due to its guidance of nutrition and safety, and it has become a hot research topic during the past decade. [1] There are four widely accepted types of gestation: sweet, bitter, sour, and salty. Cells with gustation receptors (CGRs) and related gustation transmission elements have been proposed in oral cavity and tongue surface.…”