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

The effect of taste on swallowing: A scoping and systematic review

Consuming foods and liquids for nutrition requires the coordination of several muscles. Swallowing is triggered and modified by sensory inputs from the aerodigestive tract. Taste has recently received attention as a potential modulator of swallowing physiology, function, and neural activation; additionally, taste impairment is a sequela of COVID-19. This review presents factors impacting taste and swallowing, systematically summarizes the existing literature, and assesses the quality of included studies. A search was conducted for original research including taste stimulation, deglutition-related measure(s), and human participants. Study design, independent and dependent variables, and participant characteristics were coded; included studies were assessed for quality and risk of bias. Forty-eight articles were included after abstract and full-text review. Synthesis was complicated by variable sensory components of stimuli (taste category and intensity, pure taste vs. flavor, chemesthesis, volume/amount, consistency, temperature), participant characteristics, confounding variables such as genetic taster status, and methods of measurement. Most studies had a high risk of at least one type of bias and were of fair or poor quality. Interpretation is limited by wide variability in methods, taste stimulation, confounding factors, and lower-quality evidence. Existing studies suggest that taste can modulate swallowing, but more rigorous and standardized research is needed

Genetic Taster Status as a Mediator of Neural Activity and Swallowing Mechanics in Healthy Adults

As part of a larger study examining relationships between taste properties and swallowing, we assessed the influence of genetic taster status (GTS) on measures of brain activity and swallowing physiology during taste stimulation in healthy men and women. Twenty-one participants underwent videofluoroscopic swallowing study (VFSS) and functional magnetic resonance imaging (fMRI) during trials of high-intensity taste stimuli. The precisely formulated mixtures included sour, sweet-sour, lemon, and orange taste profiles and unflavored controls. Swallowing physiology was characterized via computational analysis of swallowing mechanics plus other kinematic and temporal measures, all extracted from VFSS recordings. Whole-brain analysis of fMRI data assessed blood oxygen responses to neural activity associated with taste stimulation. Swallowing morphometry, kinematics, temporal measures, and neuroimaging analysis revealed differential responses by GTS. Supertasters exhibited increased amplitude of most pharyngeal movements, and decreased activity in the primary somatosensory cortex compared to nontasters and midtasters. These preliminary findings suggest baseline differences in swallowing physiology and the associated neural underpinnings associated with GTS. Given the potential implications for dysphagia risk and recovery patterns, GTS should be included as a relevant variable in future research regarding swallowing function and dysfunction

Genetic Taster Status as a Mediator of Neural Activity and Swallowing Mechanics in Healthy Adults

As part of a larger study examining relationships between taste properties and swallowing, we assessed the influence of genetic taster status (GTS) on measures of brain activity and swallowing physiology during taste stimulation in healthy men and women. Twenty-one participants underwent videofluoroscopic swallowing study (VFSS) and functional magnetic resonance imaging (fMRI) during trials of high-intensity taste stimuli. The precisely formulated mixtures included sour, sweet-sour, lemon, and orange taste profiles and unflavored controls. Swallowing physiology was characterized via computational analysis of swallowing mechanics plus other kinematic and temporal measures, all extracted from VFSS recordings. Whole-brain analysis of fMRI data assessed blood oxygen responses to neural activity associated with taste stimulation. Swallowing morphometry, kinematics, temporal measures, and neuroimaging analysis revealed differential responses by GTS. Supertasters exhibited increased amplitude of most pharyngeal movements, and decreased activity in the primary somatosensory cortex compared to nontasters and midtasters. These preliminary findings suggest baseline differences in swallowing physiology and the associated neural underpinnings associated with GTS. Given the potential implications for dysphagia risk and recovery patterns, GTS should be included as a relevant variable in future research regarding swallowing function and dysfunction

Brain activity associated with taste stimulation: A mechanism for neuroplastic change?

Abstract Purpose 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. Methods Five taste stimuli (unflavored, sour, sweet‐sour, lemon, and orange suspensions) were administered in timing‐regulated and temperature‐controlled 3 mL 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. Results 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. Conclusions 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