Taste Stimulation Research Articles

Sensory studies on the taste and flavor perception of food products by anodal transcutaneous electrical stimulation.

Electrical taste technologies designed to modify the taste of foods have recently garnered increasing recognition as a viable strategy to regulate excessive salt intake. Transcutaneous electrical stimulation (TES) is a method used in non-invasive electrical taste stimulation, which involves the placement of electrodes near the mouth (not inside the mouth) to avoid disruption of natural eating behavior. Previous studies have demonstrated the taste-enhancing effect of anodal TES (aTES) applied to the anterior part of the jaw. However, there has been no detailed examination of TES-mediated alteration of the taste characteristics of different types of food products with complex flavors. In this study involving 27 human participants, we used the Quantitative Descriptive Profile method to conduct a sensory evaluation investigation of aTES-mediated changes in taste characteristics of six processed food products: cold potato potage, chicken broth soup, rice porridge with pickled plums (umeboshi), Chinese pork stir fry, stir-fried pork and radish, and fried dumplings. The application of aTES significantly increased both the intensity of saltiness and overall taste in all six foods. Furthermore, aTES significantly enhanced and suppressed some of the flavor attributes of these foods. An aTES-mediated increase in palatability was only observed in fried dumplings, indicating that further investigation of the relationship between flavor characteristics and palatability is needed.

The Contribution of the Corpus Callosum to the Symmetrical Representation of Taste in the Human Brain: An fMRI Study of Callosotomized Patients

The present study was designed to establish the contribution of the corpus callosum (CC) to the cortical representation of unilateral taste stimuli in the human primary gustatory area (GI). Unilateral taste stimulation of the tongue was applied to eight patients with partial or total callosal resection by placing a small cotton pad soaked in a salty solution on either side of the tongue. Functional images were acquired with a 1.5 Tesla machine. Diffusion tensor imaging and tractography were also performed. Unilateral taste stimuli evoked bilateral activation of the GI area in all patients, including those with total resection of the CC, with a prevalence in the ipsilateral hemisphere to the stimulated tongue side. Bilateral activation was also observed in the primary somatic sensory cortex (SI) in most patients, which was more intense in the contralateral SI. This report confirms previous functional studies carried out in control subjects and neuropsychological findings in callosotomized patients, showing that gustatory pathways from tongue to cortex are bilaterally distributed, with an ipsilateral predominance. It has been shown that the CC does play a role, although not an exclusive one, in the bilateral symmetrical representation of gustatory sensitivity in the GI area, at least for afferents from one side of the tongue.

Variable physical functions in individuals in response to sensory stimuli

PurposeSensory stimulation affects physical function; however, the type and range of physical function change remain unclear. This study aimed to evaluate the type and extent of changes in simple physical functions resulting from exposure to color and taste stimuli.MethodsFive basic colors (red, blue, yellow, green, and black) and foods representative of the five basic tastes (sweet, sour, salty, bitter, and umami) were used as stimuli. Three different physical function tests on muscle strength (grip strength), flexibility (bending length), and balance (stabilometer trajectory area) were performed while wearing color-tinted goggles or after tasting food stimuli. All the stimuli tests were performed in 1 day and repeated for 6 successive days each for color and taste stimuli.ResultsEach stimulus had a different effect on the participants. For color stimulation, the median change ratio between the minimum and maximum effects was 5.68% (4.14–8.07%) for muscle strength, 8.52% (5.11–13.39%) for flexibility, and 30.60% (26.81–36.18%) for balance. The corresponding values for taste stimulation were 4.96% (3.67–7.89%), 6.11% (4.37–8.86%), and 28.92% (21.38–34.01%). The rate of change in balance was the highest among the three physical tests and was significantly different from the rate of change in other physical functions (balance vs. muscle power, P < 0.001; balance vs. flexibility, P < 0.001).ConclusionColor and taste stimuli have different effects on physical function, with individual-level differences in sensitivity to stimuli. Sensory stimuli may affect individual physical functions.

TastePeptides-EEG: An Ensemble Model for Umami Taste Evaluation Based on Electroencephalogram and Machine Learning.

In the field of food, the sensory evaluation of food still relies on the results of manual sensory evaluation, but the results of human sensory evaluation are not universal, and there is a problem of speech fraud. This work proposed an electroencephalography (EEG)-based analysis method that effectively enables the identification of umami/non-umami substances. First, the key features were extracted using percentage conversion, standardization, and significance screening, and based on these features, the top four models were selected from 19 common binary classification algorithms as submodels. Then, the support vector machine (SVM) algorithm was used to fit the outputs of these four submodels to establish TastePeptides-EEG. The validation set of the model achieved a judgment accuracy of 90.2%, and the test set achieved a judgment accuracy of 77.8%. This study discovered the frequency change of α wave in umami taste perception and found the frequency response delay phenomenon of the F/RT/C area under umami taste stimulation for the first time. The model is published at www.tastepeptides-meta.com/TastePeptides-EEG, which is convenient for relevant researchers to speed up the analysis of umami perception and provide help for the development of the next generation of brain-computer interfaces for flavor perception.

Contribution of TRPC3-mediated Ca2+ entry to taste transduction.

The current concept of taste transduction implicates the TASR/PLCβ2/IP3R3/TRPM5 axis in mediating chemo-electrical coupling in taste cells of the type II. While generation of IP3 has been verified as an obligatory step, DAG appears to be a byproduct of PIP2 cleavage by PLCβ2. Here, we provide evidence that DAG-signaling could play a significant and not yet recognized role in taste transduction. In particular, we found that DAG-gated channels are functional in type II cells but not in type I and type III cells. The DAG-gated current presumably constitutes a fraction of the generator current triggered by taste stimulation in type II cells. Bitter stimuli and DAG analogs produced Ca2+ transients in type II cells, which were greatly decreased at low bath Ca2+, indicating their dependence on Ca2+ influx. Among DAG-gated channels, transcripts solely for TRPC3 were detected in the taste tissue, thus implicating this channel in mediating DAG-regulated Ca2+ entry. Release of the afferent neurotransmitter ATP from CV papillae was monitored online by using the luciferin/luciferase method and Ussing-like chamber. It was shown that ATP secretion initiated by bitter stimuli and DAG analogs strongly depended on mucosal Ca2+. Based on the overall findings, we speculate that in taste transduction, IP3-driven Ca2+ release is transient and mainly responsible for rapid activation of Ca2+-gated TRPM5 channels, thus forming the initial phase of receptor potential. DAG-regulated Ca2+ entry through apically situated TRPC3 channels extends the primary Ca2+ signal and preserves TRPM5 activity, providing a needful prolongation of the receptor potential.

Comparing Taste Perception Across Modalities in Healthy Adults: Liquids Versus Dissolvable Taste Strips.

Taste stimulation has rehabilitative value in dysphagia management, as it activates salient underlying afferent pathways to swallowing which may evoke feedforward effects on swallow biomechanics. Despite its potential beneficial effects on swallow physiology, taste stimulation's clinical application is limited for persons unsafe to orally consume food/liquid. This study aimed to create edible, dissolvable taste strips matched to flavor profiles previously used in research assessing taste's effects on swallowing physiology and brain activity, and to evaluate how similar their perceived intensity and hedonic, or palatability, ratings were between their liquid counterparts. Plain, sour, sweet-sour, lemon, and orange flavor profiles were custom-made in taste strips and liquid modalities. The generalized Labeled Magnitude Scale and hedonic generalized Labeled Magnitude Scale were used to assess intensity and palatability ratings for flavor profiles in each modality. Healthy participants were recruited and stratified across age and sex. Liquids were rated as more intense than taste strips; however, there was no difference in palatability ratings between the modalities. There were significant differences across flavor profiles in intensity and palatability ratings. Collapsed across liquid and taste strip modalities, pairwise comparisons revealed all flavored stimuli were rated as more intense than the plain profile, sour was perceived as more intense and less palatable than all other profiles, and orange was rated as more palatable than sour, lemon, and plain tastants. Taste strips have useful implications for dysphagia management, as they could offer safe and patient-preferred flavor profiles to potentially provide advantageous swallowing and neural hemodynamic responses.

Exploring brain functional connectivity in patients with taste loss: a pilot study.

In a previous neuroimaging study, patients with taste loss showed stronger activations in gustatory cortices compared to people with normal taste function during taste stimulations. The aim of the current study was to examine whether there are changes in central-nervous functional connectivity in patients with taste loss. We selected 26 pairs of brain regions related to taste processing as our regions of interests (ROIs). Functional magnetic resonance imaging (fMRI) was used to measure brain responses in seven patients with taste loss and 12 healthy controls as they received taste stimulations (taste condition) and water (water condition). The data were analysed using ROI-to-ROI functional connectivity analysis (FCA). We observed weaker functional connectivity in the patient group between the left and right orbitofrontal cortex in the taste condition and between the left frontal pole and the left superior frontal gyrus in the water condition. These results suggested that patients with taste loss experience changes of functional connectivity between brain regions not only relevant to taste processing but also to cognitive functions. While further studies are needed, fMRI might be helpful in diagnosing taste loss as an additional tool in exceptional cases.

Brainactivity associated with taste stimulation: A mechanism for neuroplastic change?

Neuroplasticity may be enhanced by increasing brain activation and bloodflow in neural regions relevant to the target behavior. We administered precisely formulated and dosed taste stimuli to determine whether the associated brain activity patterns included areas that underlie swallowing control. Five taste stimuli (unflavored, sour, sweet-sour, lemon, and orange suspensions) were administered in timing-regulated and temperature-controlled 3mL doses via a customized pump/tubing system to 21 healthy adults during functional magnetic resonance imaging (fMRI). Whole-brain analyses of fMRI data assessed main effects of taste stimulation as well as differential effects of taste profile. Differences in brain activity associated with taste stimulation overall as well as specific stimulus type were observed in key taste and swallowing regions including the orbitofrontal cortex, insula, cingulate, and pre- and postcentral gyri. Overall, taste stimulation elicited increased activation in swallowing-related brain regions compared to unflavored trials. Different patterns of blood oxygen level-dependent (BOLD) signal were noted by taste profile. For most areas, sweet-sour and sour trials elicited increases in BOLD compared to unflavored trials within that region, whereas lemon and orange trials yielded reductions in BOLD. This was despite identical concentrations of citric acid and sweetener in the lemon, orange, and sweet-sour solutions. These results suggest that neural activity in swallowing-relevant regions can be amplified with taste stimuli and may be differentially affected by specific properties within very similar taste profiles. These findings provide critical foundational information for interpreting disparities in previous studies of taste effects on brain activity and swallowing function, defining optimal stimuli to increase brain activity in swallowing-relevant regions, and harnessing taste to enhance neuroplasticity and recovery for persons with swallowing disorders.

Interconnected sub-networks of the macaque monkey gustatory connectome.

Macroscopic taste processing connectivity was investigated using functional magnetic resonance imaging during the presentation of sour, salty, and sweet tastants in anesthetized macaque monkeys. This examination of taste processing affords the opportunity to study the interactions between sensory regions, central integrators, and effector areas. Here, 58 brain regions associated with gustatory processing in primates were aggregated, collectively forming the gustatory connectome. Regional regression coefficients (or β-series) obtained during taste stimulation were correlated to infer functional connectivity. This connectivity was then evaluated by assessing its laterality, modularity and centrality. Our results indicate significant correlations between same region pairs across hemispheres in a bilaterally interconnected scheme for taste processing throughout the gustatory connectome. Using unbiased community detection, three bilateral sub-networks were detected within the graph of the connectome. This analysis revealed clustering of 16 medial cortical structures, 24 lateral structures, and 18 subcortical structures. Across the three sub-networks, a similar pattern was observed in the differential processing of taste qualities. In all cases, the amplitude of the response was greatest for sweet, but the network connectivity was strongest for sour and salty tastants. The importance of each region in taste processing was computed using node centrality measures within the connectome graph, showing centrality to be correlated across hemispheres and, to a smaller extent, region volume. Connectome hubs exhibited varying degrees of centrality with a prominent leftward increase in insular cortex centrality. Taken together, these criteria illustrate quantifiable characteristics of the macaque monkey gustatory connectome and its organization as a tri-modular network, which may reflect the general medial-lateral-subcortical organization of salience and interoception processing networks.

Basic Taste Sensation Recognition From EEG Based on Multiscale Convolutional Neural Network With Residual Learning

Taste sensation recognition is a keystone for taste-related Brain-Computer Interface (BCI). A commonly used measurement of brain activity in response to specific stimulation is through electroencephalography (EEG) signals. However, it remains challenging to develop accurate and generalizable EEG-based measurement for human taste sensation. This paper proposes EEG-MSRNet, a novel fully convolutional neural network for EEG-based classification of basic taste sensations (blank, sour, sweet, bitter, salty, umami). Firstly, a multi-scale temporal convolution operation with residual learning is designed to extract features in different frequencies from the down-sampled EEG signals. Subsequently, a multi-scale spatial convolution operation represents the features in a cross-channel manner. Finally, a convolutional layer and global average pooling (GAP) layer are introduced to make predictions with the feature representation instead of the commonly used fully connected layers for classification. An experimental procedure is developed to acquire the EEG signals under taste stimulation. Comparison experiments and ablation studies have proved the stable and generalizable recognition performance of EEG-MSRNet on our self-collected EEG dataset. The results suggest that our EEG-based system with EEG-MSRNet is effective and generalizable for taste sensation recognition, which provides a powerful measurement for taste-related BCI such as taste disorder diagnosis and virtual taste.

THE IMPACT OF CONSUMER FATIGUE FROM MAKING DECISION ON THE FORMATION OF BRAND LOYALTY

Purpose. The purpose of the article is the formation of theoretical, methodological and practical foundations for the implementation of marketing tools to assess the impact of consumer fatigue from making everyday decisions on brand loyalty and purchasing behaviour in stores. Methodology of research. The theoretical and methodological basis of the article was formed by the provisions of behavioural economics, neuro-marketing, and branding. The study is based on the dialectical method of learning the influence of consumer fatigue from decision-making on brand loyalty. General scientific and special methods are used within the limits of the mentioned approach, in particular: comparison – to determine the advantages and disadvantages of different groups of marketing tools; questionnaire survey – for a pilot study of the criteria for making a decision on the purchase of goods by consumers in stores; mathematical modelling – for evaluating the data obtained during the experiment and determining the tendencies of choosing the company's product or brand by consumers during fatigue; analysis and synthesis – to form a mechanism for the implementation of neuro-marketing tools by companies; induction and deduction – to interpret conclusions based on research results. Findings. The phenomenon of consumer decision fatigue resulting from repeated choice-making is explored, leading to mental exhaustion and impaired behaviour control, affecting brand loyalty. A concept is formulated for the application of neuro-marketing tools to understand consumer behaviour in retail stores, which engages all human sensory organs, including audio influence, visualization, tactile stimulation, scent influence, and taste stimulation. Pilot study of the purchasing behaviour of consumers in a state of physical or mental fatigue and without it was conducted. It has been established that closer to the evening, consumer fatigue from decision-making is observed, as during the day people may be under the influence of stressful factors, depleting emotional and cognitive resources. The factors that are important in making a decision regarding the choice of a product of a certain brand are singled out. The hypothesis regarding the influence of consumer fatigue from decision-making on the formation of brand loyalty was confirmed. Originality. The concept is formulated of using neuromarketing tools for a better understanding of consumer behavior in stores, a more detailed analysis of the decision-making process and their purchasing behavior, the formation of habits and loyalty to company brands, consumer reactions to product packaging and labeling in a state of fatigue. Practical value. The results of the pilot study will help create more effective marketing campaigns using a personalized approach to consumers and simplified communication. Key words: consumer behaviour, decision fatigue, marketing, shopping in stores, brand loyalty, neuro-marketing.

Neuromorphic Gustatory System with Salt-Taste Perception, Information Processing, and Excessive-Intake Warning Capabilities.

Emulation of the process of a biological gustatory system could benefit the reconstruction of sense of taste. Here we demonstrate the first neuromorphic gustatory system that emulates the ability of taste perception, information processing, and excessive-intake warning functions. The system integrates a chitosan-derived ion-gel sensor, SnO2 nanowire artificial synapses, and an effect-executive unit. The system accomplish perception and encoding behaviors for taste stimulation without using complex circuits and multivariate analysis, showing short response delay (<1 s), long taste memory duration (>2 h), and a wide perceptive concentration range (0.02-6 wt % salt solution). Especially, SnO2 NW artificial synapses have extremely small response voltage (1 mV), exceeding the biological level by orders of magnitude, representing so-far the highest sensitivity record. This work provides a promising strategy to develop bioinspired and biointegrated electronics with the intention of mimicking and restoring the functions of biological sensory systems.

Expression profile of the zinc transporter ZnT3 in taste cells of rat circumvallate papillae and its role in zinc release, a potential mechanism for taste stimulation.

Zinc is an essential trace element, and its deficiency causes taste dysfunction. Zinc accumulates in zinc transporter (ZnT)3-expressing presynaptic vesicles in hippocampal neurons and acts as a neurotransmitter in the central nervous system. However, the distribution of zinc and its role as a signal transmitter in taste buds remain unknown. Therefore, we examined the distribution of zinc and expression profiles of ZnT3 in taste cells and evaluated zinc release from isolated taste cells upon taste stimuli. Taste cells with a spindle or pyriform morphology were revealed by staining with the fluorescent zinc dye ZnAF-2DA and autometallography in the taste buds of rat circumvallate papillae. Znt3 mRNA levels were detected in isolated taste buds. ZnT3-immunoreactivity was found in phospholipase-β2-immunopositive type II taste cells and aromatic amino acid decarboxylase-immunopositive type III cells but not in nucleoside triphosphate diphosphohydrolase 2-immunopositive type I cells. Moreover, we examined zinc release from taste cells using human transient receptor potential A1-overexpressing HEK293 as zinc-sensor cells. These cells exhibited a clear response to isolated taste cells exposed to taste stimuli. However, pretreatment with magnesium-ethylenediaminetetraacetic acid, an extracellular zinc chelator - but not with zinc-ethylenediaminetetraacetic acid, used as a negative control - significantly decreased the response ratio of zinc-sensor cells. These findings suggest that taste cells release zinc to the intercellular area in response to taste stimuli and that zinc may affect signaling within taste buds.

A case of combined glossopharyngeal and trigeminal neuralgia triggered by taste stimulation

A case of combined glossopharyngeal and trigeminal neuralgia triggered by taste stimulation

Olfaction and gustatory senses promote feeding through different pathways in yellowtail, Seriola quinqueradiata

For sustainable aquaculture, the replacement of dietary fishmeal with plant protein is becoming more common because fishmeal resources are limited. However, in the case of carnivorous fish such as yellowtail (Seriola quinqueradiata), reducing the dietary fishmeal level often causes low feed intake. Improving feed intake is important in the use of a non- and low-fishmeal diet. However, little is known about the mechanisms that regulate feeding in yellowtail. The relationship between appetite, feeding behaviour, and food intake needs to be examined to elucidate the mechanisms of feeding regulation. The senses of smell (olfaction) and taste (gustation) are important for feeding in fish. However, it is unclear how each of these senses stimulates feeding behaviour, appetite, and feed intake. In this study, the effects of olfactory and gustatory stimuli on feeding behaviour, brain expression of neuropeptide Y (NPY), and feed intake in yellowtail were investigated using a strong olfactory stimulant (alanine, Ala) and a strong gustatory stimulant (proline, Pro). By using observation tanks, feeding behaviour was divided into ‘search’ and ‘bite’. Ala promoted ‘search’ feeding behaviour and significantly decreased npy mRNA expression in the olfactory bulb and telencephalon as the olfactory centre and hypothalamus as the appetite centre. No increment in feed intake was found in the Ala-supplemented diets compared to the control diet. Meanwhile, Pro increased npy mRNA expression in the gustatory centre (cerebellum), promoted ‘bite’ feeding behaviour, and increased feed intake. Odour stimulation promoted ‘search’ through npy mRNA expression but was not reflected in feed intake. Taste stimulation promoted ‘bite’ through npy mRNA expression, which increased feed intake. Thus, olfactory and gustatory senses may promote feeding through different pathways in the yellowtail. These results will contribute to increasing the feeding amount of non- and low-fishmeal diet in the feed of yellowtail towards sustainable aquaculture.

Characteristics and Impact of the rNST GABA Network on Neural and Behavioral Taste Responses.

The rostral nucleus of the solitary tract (rNST), the initial CNS site for processing gustatory information, is comprised of two major cell types, glutamatergic excitatory and GABAergic inhibitory neurons. Although many investigators have described taste responses of rNST neurons, the phenotypes of these cells were unknown. To directly compare the response characteristics of both inhibitory and noninhibitory neurons, we recorded from mice expressing Channelrhodopsin-2 (ChR2) under the control of GAD65, a synthetic enzyme for GABA. We observed that chemosensitive profiles of GABAergic taste neurons (G+TASTE) were similar to non-GABA taste neurons (G-TASTE) but had much lower response rates. We further observed a novel subpopulation of GABA cells located more ventrally in the nucleus that were unresponsive to taste stimulation (G+UNR), suggesting pathways for inhibition initiated by centrifugal sources. This preparation also allowed us to determine how optogenetic activation of the rNST GABA network impacted the taste responses of G-TASTE neurons. Activating rNST inhibitory circuitry suppressed gustatory responses of G-TASTE neurons across all qualities and chemosensitive types of neurons. Although the tuning curves of identified G-TASTE were modestly sharpened, the overall shape of response profiles and the ensemble pattern remained highly stable. These neurophysiological effects were consistent with the behavioral consequences of activating GAD65-expressing inhibitory neurons using DREADDs. In a brief-access licking task, concentration-response curves to both palatable (sucrose, maltrin) and unpalatable (quinine) stimuli were shifted to the right when GABA neurons were activated. Thus, the rNST GABAergic network is poised to modulate taste intensity across the qualitative and hedonic spectrum.

Taste Preferences and Orosensory Feed Testing Behavior in Barramundi Lates calcarifer (Latidae, Perciformes)

In the cultivation of barramundi Lates calcarifer, one of the key factors is developing new commercial feeds that are nutritionally adequate and attractive to fish. The sensory quality of feeds can be improved by taste stimulants. The aim of the present study is to examine the taste attractiveness of 21 free L-amino acids and 4 basic taste substances (0.1–0.001 M). The feeding behavior that accompanied the orosensory testing of feed is also studied. Agar pellets flavored with each taste substance were individually offered to barramundi juveniles (5–9 cm, 4–10 g). Citric acid, cysteine, and alanine were palatable; sucrose and 7 amino acids had an aversive taste; sodium chloride, calcium chloride, and 12 amino acids did not influence the consumption of pellets. Taste preferences for amino acids are positively correlated in 6 out of 21 fish species, which confirms high species specificity of taste preferences in fishes. Barramundi often make repeated grasps and rejections of pellets regardless of their palatability, which led to the destruction of pellets in up to 50% of trials. When swallowing, fish retain pellets several times longer, and pellet fragmentation occurs more often, than in the case of final refusal of pellets. The data presented here can be used to improve the cultivation of barramundi.

A novel quantified palatability evaluation method (saliva evaluation combined with electronic tongue evaluation) for Traditional Chinese Medicine oral formulations based on oral stimulation

This study investigates the usefulness of saliva determination for the palatability evaluation of Traditional Chinese Medicine (TCM) oral formulations as a complement to the electronic tongue (E-tongue) method. In this study, the response threshold and intensity of saliva amount evaluation method on different concentration of five taste standard substances was verified with the human sense and E-tongue sense. Fifty-eight kinds of TCM oral formulations and basic taste substances were utilized to assess the applicability of the novel method, which compared with the results of E-tongue evaluation. According to the PCA map, the oral stimulation of TCM oral formulations were divided into three groups (Group 1: SM < 0.05; Group 2: SM = 0.05; Group 3: SM > 0.05). In this study, the results of PLS revealed that the responses of E-tongue sensors could be characterized 71.9% of the SM information (R2 = 71.9%). These showed that the taste stimulation of TCM had certain influence in SM. And the sensors of CA, JE, GA, and HA were critical parameters on palatability evaluation of TCM oral formulations. In conclusion, SM can be used to characterize the chemical and mechanical senses of TCM oral formulation. And it can be predicted the palatability of TCM according to the classification results of E-tongue.

SWALLOWING ACTIVATION USING SENSORY STIMULATION IN PATIENTS WITH SEVERE DISORDERS OF CONSCIOUSNESS.

ObjectiveSwallowing disorders are systematically present in patients with severe brain injury, disorders of consciousness, and subsequently poor quality of life. The study hypothesis was that taste and smell could improve swallowing function and quality of life in such patients, who are fed by gastrostomy tube.MethodsEight patients with unresponsive wakefulness syndrome were included in this study. All patients had been in a stable state for at least 2 years, and the delay between the neurological event and the study was always more than 2 years. Strong tastes and smells were selected using the Pfister olfactory classification. Taste and smell stimulations were performed every weekday, Monday to Friday, for 1 week (5 sessions) by a speech and language therapist. Evaluation of swallowing was performed before the first session and after the fifth session, and included the number of spontaneous swallows during 10 min, the presence of drooling, and spontaneous tongue and velum mobility.ResultsThe number of spontaneous swallows at the initial evaluation was 6.8 ± 5.1 n/min. At the final evaluation there was a significant increase in the number of spontaneous swallows (9.1 ± 4.1 n/min, p < 0.01).ConclusionThis clinical observation has shown that taste and smell stimulations are relevant in clinical practice to improve spontaneous swallowing.LAY ABSTRACTSwallowing disorders are systematically present in patients with severe brain injury, disorders of consciousness, and subsequent poor quality of life. The study hypothesis was that taste and smell could improve swallowing function in such patients who require exclusive feeding by gastrostomy tube. The study showed that, in patients with severe DoC, taste and smell stimulations increased the number of spontaneous swallows. Based on these findings, taste and smell stimulations could be used in clinical practice to improve swallowing function and overall quality of life.

Individual Sweet Taste Perception Influences Salivary Characteristics After Orosensory Stimulation With Sucrose and Noncaloric Sweeteners.

Emerging evidence points to a major role of salivary flow and viscoelastic properties in taste perception and mouthfeel. It has been proposed that sweet-tasting compounds influence salivary characteristics. However, whether perceived differences in the sensory properties of structurally diverse sweet-tasting compounds contribute to salivary flow and saliva viscoelasticity as part of mouthfeel and overall sweet taste perception remains to be clarified. In this study, we hypothesized that the sensory diversity of sweeteners would differentially change salivary characteristics in response to oral sweet taste stimulation. Therefore, we investigated salivary flow and saliva viscoelasticity from 21 healthy test subjects after orosensory stimulation with sucrose, rebaudioside M (RebM), sucralose, and neohesperidin dihydrochalcone (NHDC) in a crossover design and considered the basal level of selected influencing factors, including the basal oral microbiome. All test compounds enhanced the salivary flow rate by up to 1.51 ± 0.12 g/min for RebM compared to 1.10 ± 0.09 g/min for water within the 1st min after stimulation. The increase in flow rate was moderately correlated with the individually perceived sweet taste (r = 0.3, p < 0.01) but did not differ between the test compounds. The complex viscosity of saliva was not affected by the test compounds, but the analysis of covariance showed that it was associated (p < 0.05) with mucin 5B (Muc5B) concentration. The oral microbiome was of typical composition and diversity but was strongly individual-dependent (permutational analysis of variance (PERMANOVA): R2 = 0.76, p < 0.001) and was not associated with changes in salivary characteristics. In conclusion, this study indicates an impact of individual sweet taste impressions on the flow rate without measurable changes in the complex viscosity of saliva, which may contribute to the overall taste perception and mouthfeel of sweet-tasting compounds.