Preference of position in the proximity of various sugars revealed by location analysis of Drosophila melanogaster.

Feeding behaviors are determined by two main factors. One is the internal state, such as hunger or previous experiences; the other is external factors, such as sensory stimulation. During starvation, animals must balance food-seeking behavior with energy conservation. The fruit fly, Drosophila melanogaster, serves as a useful model for studying food selectivity and various behaviors related to food intake. However, few studies have directly connected food selectivity with other behaviors, such as locomotor activity and sleep. In this study, we report that flies exhibited a preference for specific positions and spent more time in the proximity of sweet sugars, such as sucrose and sucralose, but not non-sweet and nutritious sugars like xylitol and sorbitol. On the other hand, prolonged exposure to sorbitol increased the staying time of flies in the proximity of sorbitol. Additionally, after starvation, flies immediately exhibited a position preference in the proximity of sorbitol. These findings suggest that flies prefer the proximity of sweet food, and starvation alters their preference for nutritious food, which may be beneficial for their survival.

FGF21 as a mediator of adaptive changes in food intake and macronutrient preference in response to protein restriction.

Free-feeding animals navigate complex nutritional landscapes in which food availability, cost, and nutritional value can vary markedly. Animals have thus developed neural mechanisms that enable the detection of nutrient restriction, and these mechanisms engage adaptive physiological and behavioral responses that limit or reverse this nutrient restriction. This review focuses specifically on dietary protein as an essential and independently defended nutrient. Adequate protein intake is required for life, and ample evidence exists to support an active defense of protein that involves behavioral changes in food intake, food preference, and food motivation, likely mediated by neural changes that increase the reward value of protein foods. Available evidence also suggests that the circulating hormone fibroblast growth factor 21 (FGF21) acts in the brain to coordinate these adaptive changes in food intake, making it a unique endocrine signal that drives changes in macronutrient preference in the context of protein restriction. This article is part of the Special Issue on "Food intake and feeding states".

Sweet liking predicts liking and familiarity of some alcoholic beverages, but not alcohol intake: A population study using a split-sample approach.

Sweetness has been proposed to be an important quality in the decision to consume alcohol, and strong preferences for sweet tastes have been associated with alcohol abuse. However, alcohol is characterized by a number of other sensory properties, including astringency and bitterness that may drive preference and consumption. Spinelli et al. (2021) classified individuals into three sweet-sensory liking clusters (High Sweet-Liking, Moderate Sweet-Liking, and Inverted-U) that differed in their sweetness optima and sensory-liking patterns (relationship between liking and sweetness, bitterness and astringency perception in a food model). The current paper replicates the sweet sensory-liking clusters in a new set of participants (n = 1976), and extends the predicted value of these clusters examining their relationship to wine and other types of alcoholic beverages by gender using a split-sample approach on a total of over 3000 adults. The sweet sensory-liking clusters had a predictive relationship for the familiarity and liking of some alcoholic beverages characterized by stronger tastes, but not weekly alcohol intake levels. Thus, although sweet sensory-liking clusters may be associated with the type of beverages and frequency with which a person will drink and enjoy a type of alcoholic beverage, they are poor predictors of the quantity of alcohol that a person ingests over the course of a week.

Neuroscience tools to study the effect of the presentation form on food-evoked emotion for senior population.

The elderly population holds significance among consumers because many of them experience alterations in taste and smell or suffer from physical disorders. These factors can lead to reduced food intake, malnutrition, and, consequently, serious health problems. Therefore, there is a need to develop tailored products for seniors, offering both nutrition and appealing foods with easily consumable textures. Among the various characteristics of food, appearance stands out as one of the most critical aspects influencing food preferences and choices. Surprisingly, there is limited knowledge about how food shape affects the holistic emotional responses of seniors. The objective of this study was to investigate the impact of food shape on the emotional responses of seniors. This exploration involved the use of explicit methods, such as self-reported questionnaires, and implicit methods, including the measurement of skin conductance responses and facial expressions, as well as their combination. To achieve this goal, we enlisted the participation of 50 individuals (54 % women) from the senior population aged between 55 and 75 years. These participants evaluated two food products with identical sensory characteristics in terms of taste, texture, and flavor. However, these products differed in terms of their shape. We measured their degree of liking and emotional responses using a 7-point hedonic scale, EsSense25, in conjunction with galvanic skin response, and facial expressions, which served as representatives of behavioural and physiological responses. The multivariate analysis allowed to examine sample configurations by gender and establish associations between variables. The combination of implicit and explicit methods led to better discrimination of samples of the same category than the use of each of the methods independently. Although both samples elicited equivalent liking perceptions, they evoked distinct emotional responses, measured at cognitive, physiological, and behavioural levels. In general, men and women experienced different emotions while observing, smelling, handling, or consuming both samples, both consciously and unconsciously. This newfound knowledge could be valuable when designing food products for this demographic. The ultimate goal is to engage consumers and enhance their enjoyment of the food experience by offering more visually appealing food options.

Metabolic sensing in AgRP regulates sucrose preference and dopamine release in the nucleus accumbens.

Hunger increases the motivation for calorie consumption, often at the expense of low-taste appeal. However, the neural mechanisms integrating calorie-sensing with increased motivation for calorie consumption remain unknown. Agouti-related peptide (AgRP) neurons in the arcuate nucleus of the hypothalamus sense hunger, and the ingestion of caloric solutions promotes dopamine release in the absence of sweet taste perception. Therefore, we hypothesised that metabolic-sensing of hunger by AgRP neurons would be essential to promote dopamine release in the nucleus accumbens in response to caloric, but not non-caloric solutions. Moreover, we examined whether metabolic sensing in AgRP neurons affected taste preference for bitter solutions under conditions of energy need. Here we show that impaired metabolic sensing in AgRP neurons attenuated nucleus accumbens dopamine release in response to sucrose, but not saccharin, consumption. Furthermore, metabolic sensing in AgRP neurons was essential to distinguish nucleus accumbens dopamine response to sucrose consumption when compared with saccharin. Under conditions of hunger, metabolic sensing in AgRP neurons increased the preference for sucrose solutions laced with the bitter tastant, quinine, to ensure calorie consumption, whereas mice with impaired metabolic sensing in AgRP neurons maintained a strong aversion to sucrose/quinine solutions despite ongoing hunger. In conclusion, we demonstrate normal metabolic sensing in AgRP neurons drives the preference for calorie consumption, primarily when needed, by engaging dopamine release in the nucleus accumbens.

Comparing body composition between the sweet-liking phenotypes: experimental data, systematic review and individual participant data meta-analysis.

BACKGROUND: Legislation aimed at reducing sugar intake assumes that sweet-liking drives overconsumption. However, evidence that a greater liking for sweet taste is associated with unhealthier body size is mixed and complicated by relatively small samples, an overreliance on body mass index (BMI) and lack of classification using sweet-liking phenotypes. METHODS: We first examined body size data in two larger samples with sweet-liking phenotyping: extreme sweet-likers, moderate sweet-likers and sweet-dislikers. Adults (18-34yrs), attended a two-session lab-based experiment involving phenotyping for sweet-liking status and a bioelectrical impedance body composition measurement (Experiment One: N = 200; Experiment Two: N = 314). Secondly, we conducted an individual participant data (IPD) meta-analysis: systematic searches across four databases identified 5736 potential articles. Of these, 53 papers met our search criteria: a taste assessment that measured liking using sucrose (>13.7% w/v), which allowed sweet-liking phenotyping and included either BMI, body fat percentage (BF%), fat-free mass (FFM) or waist-circumference. RESULTS: A significant effect of sweet-liking phenotype on FFM was found in both Experiment One and Two, with extreme sweet-likers having significantly higher FFM than sweet-dislikers. In Experiment One, sweet-dislikers had a significantly higher BF% than extreme sweet-likers and moderate sweet-likers. However, as these data are from one research group in a young, predominantly westernised population, and the results did not perfectly replicate, we conducted the IPD meta-analyses to further clarify the findings. Robust one-stage IPD meta-analyses of 15 studies controlling for sex revealed no significant differences in BF% (n = 1836) or waist-circumference (n = 706). For BMI (n = 2368), moderate sweet-likers had slightly lower BMI than extreme sweet-likers, who had the highest overall BMI. Most interestingly, for FFM (n = 768), moderate sweet-likers and sweet-dislikers showed significantly lower FFM than extreme sweet-likers. CONCLUSION: The higher BMI often seen in sweet-likers may be due to a larger FFM and questions the simple model where sweet liking alone is a risk factor for obesity.

An advance in novel intelligent sensory technologies: From an implicit-tracking perspective of food perception.

Food sensory evaluation mainly includes explicit and implicit measurement methods. Implicit measures of consumer perception are gaining significant attention in food sensory and consumer science as they provide effective, subconscious, objective analysis. A wide range of advanced technologies are now available for analyzing physiological and psychological responses, including facial analysis technology, neuroimaging technology, autonomic nervous system technology, and behavioral pattern measurement. However, researchers in the food field often lack systematic knowledge of these multidisciplinary technologies and struggle with interpreting their results. In order to bridge this gap, this review systematically describes the principles and highlights the applications in food sensory and consumer science of facial analysis technologies such as eye tracking, facial electromyography, and automatic facial expression analysis, as well as neuroimaging technologies like electroencephalography, magnetoencephalography, functional magnetic resonance imaging, and functional near-infrared spectroscopy. Furthermore, we critically compare and discuss these advanced implicit techniques in the context of food sensory research and then accordingly propose prospects. Ultimately, we conclude that implicit measures should be complemented by traditional explicit measures to capture responses beyond preference. Facial analysis technologies offer a more objective reflection of sensory perception and attitudes toward food, whereas neuroimaging techniques provide valuable insight into the implicit physiological responses during food consumption. To enhance the interpretability and generalizability of implicit measurement results, further sensory studies are needed. Looking ahead, the combination of different methodological techniques in real-life situations holds promise for consumer sensory science in the field of food research.

Does vaping affect the taste and smell perception? An exploratory study with New Zealand young adults.

OBJECTIVE: The study aimed to assess potential effects of vaping on individual taste and smell perception in a sample of young adult New Zealanders. DESIGN: This cross-sectional study measured taste and smell perception using intensity and hedonic ratings to two olfactory (i.e., vanillin, methional) and two gustatory stimuli (i.e., sucrose, monosodium glutamate), representing sweet and savoury flavours. Detection sensitivities to sucrose and vanillin were also assessed using a forced choice detection paradigm aligned with the signal detection framework. MANCOVAs were employed to compare sensory perception between groups based on vaping use frequency. Additional regression analyses were conducted to identify potential predictors of intensity and hedonic sensory ratings. SETTING: Participants were recruited from the University of Otago student population and surrounding neighbourhoods of Dunedin, New Zealand in 2023. PARTICIPANTS: The study included 213 university students (98 vapers and 115 non-vapers) RESULTS: We found a significant difference in hedonic ratings for vanillin, indicating a stronger preference among non-vapers. However, no other differences between the two groups were significant. Notably, the use of tobacco and mint flavours were emerged as significant predictors for hedonic responses to the savoury smell and sweet taste stimulus, respectively. No significant differences were observed between groups in the ability to detect weak stimuli. CONCLUSIONS: Our findings suggest that vape use, particularly with specific flavours, may be associated with alterations in hedonic responses to smells. This finding may have potential implications for how vaping affects on food preferences and dietary choices.

Lingual Taste Nerve Transection Alters Food Selection, Relative Macronutrient Intake, and Meal Patterns in Rats Consuming a Cafeteria Diet without Changing Total Energy Intake.

The control of ingestive behavior is complex and involves input from many different sources, including the gustatory system. Signals transmitted via the taste nerves trigger responses that promote or discourage ingestion. The lingual taste nerves innervate 70% of taste buds, yet their role in the control of food selection and intake remarkably remains relatively underinvestigated. Here we used our custom five-item Food Choice Monitor to compare postsurgical behavioral responses to chow and a five-choice cafeteria diet (CAF) between male rats that had sham surgery (SHAM) or histologically verified transection of the chorda tympani and glossopharyngeal nerves (2NX). Compared with SHAM rats, 2NX rats ate significantly more of the high-fat CAF foods. The altered food choices led to dramatically increased fat intake and substantially reduced carbohydrate intake by 2NX vs SHAM rats. Furthermore, whether offered chow or CAF, 2NX rats ate fewer, larger meals each day. Eating rates implied that, compared with SHAM, 2NX rats were equally motivated to consume CAF but less motivated to eat chow. Even with these differences, energy intake and weight gain trajectories remained similar between SHAM and 2NX rats. Although some rats experienced CAF before surgery, contrary to our expectations, the effects of prior CAF experience on postsurgical eating were minimal. In conclusion, although total energy intake was unaffected, our results clearly indicate that information from one or both lingual taste nerves has a critical role in food selection, regulation of macronutrient intake, and meal termination but not long-term energy balance.

Life-History Trade-Offs in Drosophila: Flies Select a Diet to Maximize Reproduction at the Expense of Lifespan.

Macronutrient intake impacts physiology, behavior, and gene expression in a wide range of organisms. We used the response surface methodology to compare how life history traits, lifespan, and reproduction differ as a function of protein and carbohydrate intakes under choice and no-choice feeding regimens in the fruit fly, Drosophila melanogaster. We found that when offered a choice of nutritionally complementary foods mated female flies regulated toward a protein to carbohydrate ratio (P:C) that was associated with shortened lifespan and maximal egg production when compared to response surfaces derived from flies fed 1 of a range of fixed diets differing in P:C (no-choice regimen). This difference in lifespan between choice and no-choice feeding was not seen in males or virgin flies, reflecting the fact that increased protein intake is triggered by mating to support egg production. However, whereas in mated females a higher P:C intake was associated with greater egg production under both choice and no-choice feeding, contrary to expectations, choice-fed mated flies laid fewer eggs than no-choice flies on equivalent macronutrient intakes, perhaps reflecting that they had to ingest twice the volume of food to attain an equivalent intake of nutrients than no-choice flies on a diet of equivalent P:C ratio.

Bitter taste function-related genes are implicated in the behavioral association between taste preference and ethanol preference in male mice.

Alcohol use disorder in humans is highly heritable, and as a term is synonymous with alcoholism, alcohol dependence, and alcohol addiction. Defined by the NIAAA as a medical condition characterized by an impaired ability to stop or control alcohol use despite adverse social, occupational, or health consequences, the genetic basis of alcohol dependence is much studied. However, an intriguing component to alcohol acceptance exists outside of genetics or social factors. In fact, mice of identical genetic backgrounds without any prior experience of tasting ethanol display widely varying preferences to it, far beyond those seen for typical taste solutions. Here, we hypothesized that a preference for ethanol, which tastes both bitter and sweet to humans, would be influenced by taste function. Using a mouse model of taste behavior, we tested preferences for bitter and sweet in mice that, without training or previous experience, either preferred or avoided ethanol solutions in consumption trials. Data showed clear sex differences, in which male mice that preferred ethanol also preferred a bitter quinine solution, whereas female mice that preferred ethanol also preferred a sweet sucralose solution. Male mice preferring ethanol also exhibited lower expression levels of mRNA for genes encoding the bitter taste receptors T2R26 and T2R37, and the bitter transducing G-protein subunit GNAT3, suggesting that the higher ethanol preference observed in the male mice may be due to bitter signaling, including that arising from ethanol, being weaker in this group. Results further support links between ethanol consumption and taste response, and may be relevant to substance abuse issues in human populations.

Mapping expectancy-based appetitive placebo effects onto the brain in women.

Suggestions about hunger can generate placebo effects on hunger experiences. But, the underlying neurocognitive mechanisms are unknown. Here, we show in 255 women that hunger expectancies, induced by suggestion-based placebo interventions, determine hunger sensations and economic food choices. Functional magnetic resonance imaging in a subgroup (n = 57/255) provides evidence that the strength of expecting the placebo to decrease hunger moderates medial prefrontal cortex activation at the time of food choice and attenuates ventromedial prefrontal cortex (vmPFC) responses to food value. Dorsolateral prefrontal cortex activation linked to interference resolution formally mediates the suggestion-based placebo effects on hunger. A drift-diffusion model characterizes this effect by showing that the hunger suggestions bias participants' food choices and how much they weigh tastiness against the healthiness of food, which further moderates vmPFC-dlPFC psychophysiological interactions when participants expect decreased hunger. Thus, suggestion-induced beliefs about hunger shape hunger addressing economic choices through cognitive regulation of value computation within the prefrontal cortex.

Nutrigenomics: SNPs correlated to Food Preferences and Susceptibilities.

Background: Nutrigenomics explores the intricate interplay between single nucleotide polymorphisms (SNPs), food preferences, and susceptibilities. Methods: This study delves into the influence of SNPs on food sensitivities, allergies, tyramine intolerance, and taste preferences. Genetic factors intricately shape physiological reactions to dietary elements, with polymorphisms contributing to diverse sensitivities and immune responses. Results: Tyramine intolerance, arising from metabolic inefficiencies, unveils genetic markers exerting influence on enzyme function. SNPs transcend genetic diversity by exerting substantial impact on food sensitivities/allergies, with specific variants correlating to heightened susceptibilities. Genes accountable for digesting food components play pivotal roles. Given the rising prevalence of food sensitivities/allergies, understanding genetic foundations becomes paramount. In the realm of taste and food preferences, SNPs sculpt perception and choice, yielding variances in taste perception and preferences for sweetness, bitterness, and umami. This genetic medley extends its reach to encompass wider health implications. Conclusions: In this review article, we have focused on how polymorphisms wield significant sway over physiological responses, sensitivities, and dietary inclinations. Unraveling these intricate relationships illuminates the path to personalized nutrition, potentially revolutionizing tailored recommendations and interventions.

Obesity-mediated Lipoinflammation Modulates Food Reward Responses.

Accumulation of white adipose tissue (WAT) during obesity is associated with the development of chronic low-grade inflammation, a biological process known as lipoinflammation. Systemic and central lipoinflammation accumulates pro-inflammatory cytokines including IL-6, IL-1ß and TNF-α in plasma and also in brain, disrupting neurometabolism and cognitive behavior. Obesity-mediated lipoinflammation has been reported in brain regions of the mesocorticolimbic reward circuit leading to alterations in the perception and consumption of ultra-processed foods. While still under investigation, lipoinflammation targets two major outcomes of the mesocorticolimbic circuit during food reward: perception and motivation ("Wanting") and the pleasurable feeling of feeding ("Liking"). This review will provide experimental and clinical evidence supporting the contribution of obesity- or overnutrition-related lipoinflammation affecting the mesocorticolimbic reward circuit and enhancing food reward responses. We will also address neuroanatomical targets of inflammatory profiles that modulate food reward responses during obesity and describe potential cellular and molecular mechanisms of overnutrition linked to addiction-like behavior favored by brain lipoinflammation.

Sweet taste preference is associated with greater hypothalamic response to glucose and longitudinal weight gain.

The hypothalamus has an abundant expression of sweet taste receptors that play a role in glucose sensing and energy homeostasis. Evidence suggests that liking "sweets" can be associated with weight gain, but the relationship between sweet taste preference and hypothalamic regulation of appetite is unknown. This study tested the hypothesis that sweet taste preference is associated with increased hypothalamic activation in response to glucose (a purported neural marker for weight gain risk) and greater longitudinal increases in body mass index (BMI). Fifty-four adults aged 18-35 years with a mean (± SD) BMI of 27.99 ± 5.32 kg/m2 completed the study. Height and weight were measured at baseline and 6-12 months later in a subset of 36 participants. Sweet taste preference was assessed via the Monell 2-series, forced-choice tracking procedure. Arterial spin labeling magnetic resonance imaging was performed before and after oral glucose ingestion to determine hypothalamic blood flow response to glucose. Linear models were used to examine relationships between sweet taste preference and the hypothalamic response to glucose and longitudinal changes in BMI, adjusting for age, sex, and baseline BMI. Sweet taste preference was positively associated with glucose-linked hypothalamic blood flow (beta = 0.017, p = 0.043), adjusted for age, sex and BMI. We also observed a positive association between sweet taste preference and longitudinal change in BMI (beta = 0.088, p = 0.015), adjusted for age, sex and baseline BMI. These findings suggest that heightened sweet taste preference is associated with glucose-linked hypothalamic activation and may be linked to increased susceptibility for weight gain.

Development, sensitivity and reliability of a French version of the Leeds food preference questionnaire (LFPQ-fr) for the evaluation of food preferences and reward.

BACKGROUND: There is a growing global interest in the evaluation of food reward, necessitating the adaptation of culturally appropriate instruments for use in empirical studies. This work presents the development and validation of a culturally adapted French version of the Leeds Food Preference Questionnaire (LFPQ-fr). METHODS: The LFPQ-fr was developed and validated in healthy-weight adults using the following systematic approach: i) selection and validation of appropriate food pictures; ii) linguistic translation of liking and wanting constructs in the target population (n = 430; 81% female; 42.2 ± 12.7 years); iii) validation of the sensitivity and reliability of the task performed in a fasted state and in response to a standardized test meal (n = 50; 50% female; 30.0 ± 8.4 years). RESULTS: During the first and second phases, the nutritional and perceptual validation of culturally appropriate food pictures and pertinent reward constructs, respectively, was demonstrated in a healthy-weight French sample. Findings from the third phase indicated that all food reward components were sensitive to the test meal and showed moderate to high agreement in both fasted (Lin's CCC =0.72-0.94) and fed (Lin's CCC = 0.53-0.80) appetitive states between visit 1 (V1) and visit (V2). Except for explicit liking fat bias, all primary outcomes were statistically consistent in fasted and fed states between V1 and V2. Changes in fat and taste biases in response to a standardized meal for all primary outcomes were also consistent between V1 and V2 except for explicit liking fat bias (Lin's CCC = 0.49- 0.72). CONCLUSION: The LFPQ-fr developed and tested in this study is a reproducible and reliable method to assess food reward in both the fasted and fed states in a healthy-weight French population.

Decreased retronasal olfaction and taste perception in obesity are related to saliva biochemical and microbiota composition.

Understanding the individual factors that modulate flavor perception is a central issue for the development of personalized diets strategies to fight obesity. This study aimed to investigate differences in flavor perception between adults with normal weight and those with obesity, as well as some potential biological factors related to these differences. To do that, liking and flavor perception intensity were measured against retronasal olfactory (pineapple, butter, tropical and chocolate) and taste attributes (sweetness, umami and bitter) in 77 individuals grouped as normalweight or obese, according to their body mass index (BMI). Unstimulated saliva was collected from all participants and characterized in terms of salivary flow, total protein content, total antioxidant capacity, total esterase activity and bacterial composition through 16S rDNA amplicon sequencing. The results showed that participants displayed differences in flavor perception according to their BMI group. Thus, the group with obesity showed significant lower liking and intensity scores for low calorie related food aroma (pineapple and tropical), lower taste intensity scores for sweet and umami, and a higher acceptability for umami than the group with normal weight. Significant differences between BMI groups were observed for salivary biochemical variables and specific bacterial taxa, some of which were significantly correlated to flavor intensity. This work suggests for the first time the existence of an oral-brain axis that might contribute to the development or perpetuation of obesity, which opens new and interesting avenues of research.

A value accumulation account of unhealthy food choices: testing the influence of outcome salience under varying time constraints.

People often engage in unhealthy eating despite having an explicit goal to follow a healthy diet, especially under certain conditions such as a lack of time. A promising explanation from the value accumulation account is that food choices are based on the sequential consideration of the values of multiple outcomes, such as health and taste outcomes. Unhealthy choices may result if taste is considered before health. We examined whether making a health outcome more salient could alter this order, thereby leading to more healthy choices even under time pressure. Two studies examined the time-dependent effect of outcome values and salience on food choices. Participants first completed priming trials on which they rated food items on healthiness (health condition), tastiness (taste condition), or both healthiness and tastiness (control condition). They then completed blocks of binary choice trials between healthy and tasty items. The available response time was manipulated continuously in Study 1 (N = 161) and categorically in Study 2 (N = 318). As predicted, results showed that the values of health and taste outcomes influenced choices and that priming led to more choices in line with the primed outcomes even when time was scarce. We did not obtain support for the prediction that the priming effect is time-dependent in the sense that primed outcomes are considered before non-primed outcomes. Together, these findings suggest that increasing the value and salience of a health outcome may be effective ways to increase healthy choices, even under poor conditions such as time pressure.

Recruitment of dlPFC during dietary self-regulation predicts the transience of regulatory effects.

Recent work on the cognitive regulation of dietary decision-making suggests that regulation can alter both the choices that people make in the moment and longer-lasting preferences. However, it is unclear what mechanisms lead to temporary or lingering changes. To address this question, we used fMRI during a task employing the cognitive regulation of food choice and assessed changes in food preference from baseline to post-regulation. We found evidence that regulation may result in a temporary reconfiguration of the neural drivers of choice, de-emphasizing goal-inconsistent value-related computations in the ventromedial prefrontal cortex and resulting in more goal-consistent changes in value-related computations in the dorsolateral prefrontal cortex (dlPFC). Moreover, we find that the extent to which the dlPFC was recruited to represent different regulatory goals during the moment of choice negatively predicted the extent to which those regulatory goals produced lingering changes in preference. Our results suggest that the recruitment of the dlPFC in the service of regulation may have a downside: it is effective at changing behavior in the moment, but its effects on preferences are transient.

Dietary experience with glucose and fructose fosters heightened avidity for glucose-containing sugars independent of TRPM5 taste transduction in mice.

OBJECTIVE: Experience with metabolically distinct sugars, glucose and fructose, enhances attraction to the orosensory properties of glucose over fructose. To gain insight into which sensory signals are affected, we investigated how this nutritive learning reshapes behavioral responding to various sugars in brief access taste tests in C57BL6/J (B6) mice and assessed whether sugar-exposed mice lacking the TRPM5 channel involved in G-protein coupled taste transduction could acquire these types of preferences for glucose-containing sugars. METHODS: B6, TRPM5 knockout (KO), and TRPM5 heterozygous (Het) mice were given extensive access to water (sugar naïve) or 0.316, 0.56, and 1.1 M glucose and fructose (sugar-exposed) and then tested, whilst food deprived, for their relative avidities for glucose, fructose, sucrose, maltose, and/or a non-metabolizable glucose analog in a series of taste tests. RESULTS: Sugar-exposed B6 mice licked relatively more for glucose than fructose, driven by an increased avidity for glucose, not an avoidance of fructose, and licked more for maltose, compared to their sugar-naïve counterparts. Sugar-exposed B6 mice did not lick with such avidity for a non-metabolizable glucose analog. TRPM5 KO mice took longer to acquire the sugar discrimination than the Het controls, but both groups ultimately licked significantly more for glucose than fructose. Het mice displayed clear preferential licking for sucrose over fructose, while licking comparably high for glucose, sucrose, and maltose. KO mice licked significantly more for maltose than sucrose. CONCLUSIONS: Collectively, the findings suggest that ingestive experience with glucose and fructose primarily reprograms behavioral responding to a TRPM5-independent orosensory signal generated by glucose-containing sugars.