Physiology & Behavior

Inbred mouse strains differ in their postoral appetite stimulating response (appetition) to glucose and fructose. For example, C57BL/6J (B6) and FVB strains learn strong preferences for a flavor (CS+, e.g., cherry) paired with intragastric (IG) glucose infusions, but only FVB mice learned to prefer a CS+ paired with IG fructose infusions. Consistent with these findings, "tasteless" B6 knockout (KO) mice missing the taste signaling protein TRPM5 learn strong preferences for a CS+ added to glucose solution as well as for unflavored glucose but weak or no preferences for a fructose-paired CS+ or unflavored fructose. The present experiment reports that "tasteless" P2X2/P2X3 double-knockout (P2X2/3 DKO) mice, unlike TRPM5 KO mice, learned strong preferences for a CS+ mixed with fructose as well as for unflavored fructose. Whether differences in genetic backgrounds or other factors account for the fructose appetition displayed by P2X2/3 DKO mice but not TRPM5 KO mice remains to be determined.

Dietary choice plays a critical role in metabolic and neurological health, yet the biological factors that shape macronutrient preference remain poorly understood. Evidence from both humans and rodents suggests potential sex differences in the attractiveness of specific nutrients, though findings have been inconsistent and often rely on self-report or diets with mixed macronutrient composition. The present study examined sex differences in macronutrient preference and food-directed behavior in mice using a controlled three-food choice paradigm. Adult male (n = 12) and female (n = 11) C57BL/6J mice were given simultaneous access to foods consisting of fat, sucrose, or a fat-carbohydrate combination across 14 days. Intake, latency to approach, and time spent near each food source were quantified, and estrous cycle stage was monitored in females. Female mice consumed significantly more food than males overall, driven by a selective increase in fat intake. Behavioral measures paralleled these results, with females spending more time in proximity to fat-associated food zones. In contrast, males preferentially consumed the fat-carbohydrate combination and showed weaker nutrient-specific engagement. Estrous cycle stage modestly influenced feeding behavior, with estrus associated with increased overall intake and greater consumption of combination diets, reflecting elevated carbohydrate intake. These findings demonstrate robust sex differences in macronutrient preference and suggest that hormonal state may selectively modulate nutrient-specific feeding behavior.

There is evidence that appetites for specific nutrients can guide foraging behaviour and aid in dietary regulation through associative learning processes that link stimuli to nutrient-specific outcomes. However, most, if not all, examples of such behaviour can be interpreted as being stimulus-bound habits, i.e., reflexive responses induced by environmental stimuli. The control of identified goal-directed actions by nutrient-specific appetites has not been directly assessed. To address this question, we trained rats to press a lever for a high protein reward (whey protein shake) and another lever for a high carbohydrate reward (polycose solution). They were then tested under extinction conditions in which both levers were available following the extended exposure to meals that were high in protein or carbohydrate. When otherwise food-deprived rats had been selectively satiated on protein immediately prior to test, they pressed more on the lever they learned had produced polycose, whereas they pressed the lever they learned had produced whey protein more if they had instead been satiated on carbohydrate. Crucially, the same pattern emerged whether the satiety manipulation was achieved using the same nutrient sources that rats had earned during training (i.e., whey or polycose) or with foods high in the relevant nutrients, indicating that these behaviours were under goal-directed control and sensitive to nutritional state. These results show that actions can be motivated by the nutritional relevance of the instrumental outcome to specific appetites, a relationship that may guide natural foraging decisions.

Prolonged esports play induces cognitive fatigue that is not fully captured by subjective awareness, motivating practical, non-stimulant nutritional strategies supported by objective physiological markers. We here tested whether acute milk protein intake attenuates fatigue-related physiological responses during prolonged esports play and supports subjective state, executive control, and in-game performance. In a randomized, single-blind (assessor-blind), energy-matched controlled crossover study, 15 healthy young adults with esports experience completed two sessions in which they consumed either a milk protein drink or an energy-matched apple juice control before a 3-h virtual soccer task. Physiological measures included pupillometry during gameplay, salivary cortisol, continuous interstitial glucose monitoring, and heart rate. Subjective ratings (VAS) and executive function (flanker task) were assessed across post-ingestion time points, and in-game performance metrics were aggregated within hourly gameplay blocks. Milk protein intake was associated with a coherent pattern of physiological advantages, including larger pupil diameter during gameplay, smoother interstitial glucose dynamics, and lower salivary cortisol, while heart rate showed time-dependent changes without a clear condition effect. These physiological changes co-occurred with higher enjoyment and lower hunger, improved flanker performance, and condition-dependent improvements in in-game performance, most notably higher shot success rate. Additionally, pupil diameter during gameplay was associated with inhibitory-control efficiency on the flanker task. These findings suggest that acute milk protein intake may serve as a practical, non-stimulant nutritional strategy to sustain physiological state and cognitive-behavioral performance during prolonged esports (virtual soccer) play. Highlights- Prolonged esports play models modern digital cognitive activity and cognitive fatigue. - Acute milk protein intake increases pupil diameter during prolonged esports play. - Interstitial glucose dynamics are smoother and salivary cortisol is lower with milk protein. - Enjoyment increases and hunger decreases during 3 h of virtual soccer play. - Executive function and in-game performance improve, most notably shot success rate.

Protein provides essential amino acids critical for survival. Recent research has identified that dietary protein restriction induces physiological and behavioral adaptations and that those adaptations are mediated by liver-produced fibroblast growth factor 21 (FGF21) that acts in the brain. Most of the research on adaptations to dietary protein restriction and the biological factors that mediate those adaptations carries an implicit assumption that the effects of dietary protein restriction are reversible. Rarely is the assumption of reversibility directly examined by varying dietary protein content within animals. Recently collected data on preference for protein versus carbohydrate solutions indicates that when mice are placed on a low (5%) protein diet, preference for protein is rapidly increased. However, when mice are switched from a low to normal (20%) protein diet, relative consumption of protein decreases but preference for protein persists. Re-analysis of published data suggests, similarly, that preference for protein-rich food sources remains elevated following exposure to dietary protein restriction and that calcium influx in the ventral tegmental area of the brain in response to protein consumption also remains persistently elevated following dietary protein restriction. Together, the data suggest that prior protein restriction can exert long-lasting effects on protein preference and on brain activity associated with protein consumption. The finding that the effects of protein restriction do not rapidly reverse implies that protein choice may be a function, not only of current nutritional state, but of historical nutritional conditions. Further, these results suggest that a full understanding of the environmental and biological determinants of protein choice requires studies in which dietary protein intake is varied within subjects.

Unpredictable and insufficient access to food, known as food insecurity, is associated with the development of obesity. However, causal mechanisms underlying this paradoxical relationship remain poorly understood. Using a rat model of food insecurity, this study investigated whether food insecurity causes dysregulated feeding behaviours, specifically impaired gut signal sensitivity and enhanced cue-driven appetitive responses. Adolescent female rats were assigned to receive either ad libitum chow access (Food secure), 90% caloric restriction (Food restricted) or unpredictable quantity and timing of food access (Food insecure), for 4 weeks. After which, rats were returned to an ad libitum chow diet for the remainder of the study. To examine gut signal sensitivity, we measured the effects of cholecystokinin (CCK) on 10% sucrose intake. To examine cue-driven feeding behaviours, we used Pavlovian appetitive conditioning and measured appetitive responses towards a food-predictive cue. Results showed that prior food insecure rats were less sensitive to the intake inhibitory effects of CCK and exhibited enhanced cue-induced appetitive behaviours, when compared to food secure and food restricted groups. Anxiety-like behaviours or learning and memory was not different between groups. At the end of the study, adolescent caloric restriction resulted in reduced fat mass, plasma leptin levels and body weight when compared to food secure, but not food insecure rats, suggesting that adolescent food insecurity somewhat overcame these metabolic effects. Taken together, our findings suggest that adolescent food insecurity impaired gut signal sensitivity and heightened food cue sensitivity, which may cause enduring metabolic and behavioural adaptations that promote overeating and weight gain.

Changes in motivation have been observed following induction of diet-induced obesity. However, to date, results have been contradictory, some authors reporting an increase in motivation to obtain palatable food, but others observing a decrease. Observed differences might be associated with the length of both the evaluation period and exposure to the diet. Therefore, the aim of this study was to evaluate changes in motivation during 20 weeks of exposure to a hypercaloric diet. Performance of the subjects in a progressive ratio schedule was evaluated before and during the exposure to a high-fat, high-sugar choice diet (HFHSc). A decrease in motivation was observed after 2 weeks of diet exposure, low levels of motivation remained throughout 20 weeks. A comparable decrease in motivation took longer (3 weeks) to develop using chow diet in the control group. Overall, our results suggest that, when changes in motivation are being evaluated, long periods of diet exposure made no further contribution, once motivation decreased, it remained low up to 18 weeks. Exposure to a HFHSc diet is a useful animal model of obesity, since it replicates some pathophysiological and psychological features of human obesity such as an increase in fasting glucose levels, body weight and the weight of adipose tissue.

AbstractProlonged esports play can induce cognitive fatigue by placing sustained demands on executive control, decision-making, and stress regulation. Since the brain relies primarily on glucose as an immediate energy source, we hypothesized that a carbohydrate gel designed to prolong post-ingestion glycaemia stabilizes interstitial glucose, attenuates hunger and cognitive fatigue, and helps preserve performance during extended esports play. Eleven healthy young men completed a randomized, double-blind crossover study with two sessions in which they ingested one of two carbohydrate gels matched for total energy and total carbohydrate but differing in carbohydrate composition (high-fructose corn syrup [HFCS]-dominant vs maltodextrin [MDX]-dominant) before gameplay. Interstitial glucose was monitored continuously, while hunger, salivary cortisol, pupil diameter, executive function, and in-game performance were assessed repeatedly. Compared with the control (HFCS-dominant) condition, the glycaemia-prolonging formulation maintained higher interstitial glucose levels during the later phase of gameplay, blunted the progressive increase in hunger, and attenuated cortisol responses. These physiological and subjective advantages were accompanied by better executive control and more adaptive defensive behaviors in-game, including fewer fouls and more interceptions. In contrast, pupil diameter, an index of global arousal, remained unchanged across conditions, suggesting that benefits were not driven by altered arousal but by improved glycaemic stability and appetite regulation. These findings indicate that a carbohydrate formulation that prolongs glycaemia can reduce hunger-linked cognitive fatigue and support task-relevant behavior during prolonged esports play. This low-burden nutritional strategy may help sustain mental performance during prolonged digital activities that impose high cognitive demands. Highlights- A glycaemia-prolonging gel maintained higher interstitial glucose late in esports play - Hunger and salivary cortisol increased less with the glycaemia-prolonging formulation - Executive control and defensive performance improved (fewer fouls, more interceptions) - Pupil diameter was unchanged, suggesting benefits were not driven by altered arousal - A low-burden, glycaemia-stabilizing strategy may help sustain cognitive stamina

Flavor-nutrient learning (FNL) refers to learning associations between a foods flavor and the rewarding appetition signals that arise from post-oral nutrient sensing during or after a meal. In rodent models FNL reliably produces strong flavor preferences and increased intake of nutrient-paired flavors, implicating FNL as a presumptive obesogenic influence in the modern environment. However, evidence that FNL plays a causal role in diet-induced obesity is ambiguous. We have previously shown that degree of weight gain on a high-fat/sugar diet is associated with stronger FNL responses, but direction of causation was unclear. This paper reports three experiments investigating whether individual differences in FNL conditionability are linked to obesity proneness prior to obesity onset. Two experiments comparing selectively-bred obesity-prone vs resistant strains found no strain differences in FNL. A third study in lean, outbred rats evaluated whether baseline individual differences in FNL prospectively predict weight gain on a cafeteria diet. Unexpectedly, rats who showed the strongest learned increase in intake of a nutrient-paired flavor subsequently gained the least weight when switched to cafeteria diet, suggesting FNL protects against weight gain. In fact, individual differences in FNL explained a portion of variance in cafeteria weight gain over and above measured kcal intake, implying a function for FNL in adaptively modulating metabolic responses to energy intake. Collectively, several studies have now shown individual differences in obesity proneness to be either positively correlated, uncorrelated, or negatively correlated with FNL, calling for a more nuanced view of how appetition influences intake and energy balance.

Food is generally hidden in a natural environment and require free-living animals to search for it. Although such food-seeking behaviors involve motivation and exploration, previous studies examined food-seeking simply by measuring the time spent in the food zone or the frequency of pursuing food-cued context. Moreover, after discovering food, animals need to taste and smell it in order to evaluate their nutritional value or possible toxicity. However, researchers could not easily distinguish food-seeking from food-evaluating behaviors because food was visible or accessible throughout each test. Herein, we describe a behavioral protocol that triggers animals to show the behavioral dynamics of food-seeking (e.g., navigation, nose-digging, and paw-digging) and that exclusively elicits food-seeking without provoking any other food-evaluating behaviors. First, we prepared an open-field box with the floor covered with bedding. After we hid foods under the bedding of each corner, the test mice were habituated in this arena for four days (pre-test phase). On the next day (test phase), they were placed under the same conditions, but the foods previously hidden were removed. This process enabled the mice to perceive their surroundings as a food-hidden environment, which induced the animal to exhibit sustained food-seeking. In conclusion, the protocol presented here is a powerful method for provoking multiple forms of food-seeking and quantifies food-seeking independently from other food-related behavioral stages.

Considerable evidence suggests that the motivational control of instrumental action depends on incentive learning; i.e., on the opportunity to learn how the value of the consequences or outcome of an action, (e.g., a specific food) varies under different motivational conditions (e.g., under different degrees of hunger). The current study investigated whether learning the values of high-protein and high-carbohydrate rewards under different degrees of protein and carbohydrate appetite is also necessary for these nutrient-specific appetites to exert control over instrumental performance. Experiment 1 gave differing consummatory experience to whey protein and polycose carbohydrate outcomes under protein and carbohydrate appetite and found that, without the opportunity for incentive learning, the performance of actions earning these outcomes was insensitive to a shift in appetite. However, once the opportunity for incentive learning was provided, the rats increased their instrumental performance on a lever that earned the whey outcome relative to the polycose lever when protein hungry and on the polycose lever relative to the whey lever when carbohydrate hungry. Experiment 2 assessed how these nutrient-specific states exerted this control; whether, once learned, nutrient values were immediately controlled by nutrient appetite or whether this was based on conditional control acquired during experience with the outcomes under different nutrient appetites. We found that exposure to an outcome under a single nutrient-specific state was not sufficient to establish state-specific control. Instead, establishing the conditional control of outcome value required exposure to both the whey and polycose outcomes under both protein and carbohydrate appetites.

Exposure to food rich in fat and sugar (High Fat and Sugar Diet, HFSD) is believed to induce behavioral and neurobiological changes that would produce addiction-like behavior and increase the risks of obesity and overweight. Studies in rodents have led to conflicting results suggesting that several factors such as sex and age of exposure contribute to the development of maladaptive behavior towards food. In addition, it is not clear whether the effects of exposure to HFSD persist after its discontinuation which would indicate long-term risk to develop addiction-like behavior. In this study, we investigated the persistent effects of an intermittent 8-week exposure to HFSD in male and female rats as a function of age of exposure (adult and adolescent). We found that intermittent exposure to HFSD did not alter body weight, but it affected consumption of standard food during the time of exposure in all groups. In addition, in adults, HFSD produced a decrease in the initial baseline responding in FR1 schedules that persisted for 4 weeks in males but not in female rats. However, we found that exposure to HFSD did not affect resistance to punishment measured by progressive shock strength (PSS) break points or motivation for food measured by progressive-ratio break points regardless of sex or age of exposure. Altogether, these results do not provide support to the hypothesis that intermittent exposure to HFSD produce persistent increases in the vulnerability to develop addiction-like behaviors towards palatable food.

Vagus nerve signals from the gut to brain carry information about nutrients and drive food reward. Such signals are disrupted by consuming large amounts of high-calorie foods, necessitating greater food intake to elicit a similar neural response. Non-invasive vagus nerve stimulation (nVNS) via a branch innervating the ear is a candidate treatment for obesity in humans. There is disagreement on the optimal location of nVNS in the ear for experimental and clinical studies. There are also no studies comparing nVNS in hungry and full states. We aimed to compare ear position(s) for nVNS and explore the effects of nVNS during hungry and full states on proxies for autonomic outflow (heart-rate variability) and efferent metabolism (gastric frequency and resting energy expenditure). In a within-subject design, 14 participants (10 women, on average 29.4 +/- 6.7 years old) received nVNS in four different locations (cymba conchae, tragus, earlobe, or tragus AND cymba conchae) on separate days. In each session, participants were asked to consume a palatable chocolate flavored milk. With electrography on the abdomen and indirect calorimetry in a canopy, we measured electro-cardiogram, electro-gastrogram and resting energy expenditure for 15 minutes before and at least 35 minutes after consumption of the palatable drink. We also collected ratings of the palatable drink and internal and other states. Pre-drink consumption (in a hungry state) we observed no differences in the effect of location of acute nVNS on resting energy expenditure and gastric frequency. However, nVNS in cymba conchae decreases heart-rate variability and ratings of how much participants want to consume the drink. After drink consumption and with continued nVNS, gastric frequency is unchanged, and resting energy expenditure increases regardless of stimulation location. Heart-rate variability decreases in all locations, except cymba conchae. We also observe a trend for an increase in gastric frequency in late post-drink consumption time-points in cymba conchae. These results suggest that nVNS in the cymba conchae in a hungry state has a similar acute effect on vagal tone as food consumption: to decrease heart rate variability. This effect then negates the usual postprandial effects of a decrease in heart rate variability as seen in the other nVNS locations. This suggests that nVNS in cymba conchae may act primarily on vagal afferent autonomic (and only modestly on metabolic output) in a similar way as food consumption does. HighlightsO_LIWe measured autonomic outflow and efferent metabolism before and after consumption C_LIO_LIWe manipulated the location of nVNS stimulation in the outer ear C_LIO_LIThe different locations were earlobe, cymba conchae, tragus, cymba conchae+tragus C_LIO_LInVNS in cymba conchae decreases pre-consumption heart-rate variability and wanting C_LIO_LInVNS in other locations decreases post-consumption heart-rate variabilty C_LI

Stress-related disorders encompass diverse behavioral alterations, including impaired social functioning. The zebrafish (Danio rerio) is a valuable model for studying these phenomena, particularly because of its robust and ethologically conserved social behaviors. Unpredictable chronic stress (UCS) produces behavioral, physiological, and molecular changes in zebrafish that parallel core features of human anxiety and depressive disorders; however, its impact on social outcomes remains unclear. Here, we examined whether a 14-day UCS protocol alters social behavior in adult zebrafish using two complementary assays: the social preference test and the shoal cohesion test. Across two independent experiments, UCS did not elicit detectable changes in individual social approach or group-level cohesion. In contrast, UCS induced clear anxiety-like behavior in the novel tank test, validating the stress manipulation, with stressed fish displaying reduced vertical exploration and decreased time in the upper zone. Shoal cohesion measures showed a time-dependent decrease in both groups, consistent with habituation to the testing environment rather than a stress-specific effect. Together, these results suggest that social behavior in adult zebrafish is relatively resilient to UCS under the conditions tested, whereas anxiety-like responses are markedly affected. Future work should investigate whether factors such as stressor intensity, developmental stage, sex composition, or social hierarchy modulate the sensitivity of social behavior to chronic stress.

IntroductionTaste is a key sensory modulator of eating behaviour and thus energy intake. The effects of acute exercise has recently been confirmed especially regarding sweet and salty tastes. Physical activity is a safe and effective countermeasure to certain types of chemosensory losses, especially in older populations. Knowing that taste can be impaired with increased adiposity, it is unknown if the adoption of an active lifestyle on a regular basis can mitigate such impairments. MethodsData were extracted from NHANES 2013-2014 database. Perception of salt and bitter tastes for Tongue Tip Test and Whole Mouth Test, physical activity levels over an 8-9-day period and adiposity were analyzed. Moderation analyses were used to study the impact of adiposity on taste perceptions, with physical activity level as the moderator. ResultsThe 197 participants (130 males) included in this project had a mean{+/-}standard deviation age of 49.1{+/-}5.2 years, a mean body fat percentage of 31.7{+/-}7.6% and mean daily physical activity levels of 11 084{+/-}3531 Monitor-Independent Movement Summary unit (MIMS). The positive association between adiposity and both bitter Tongue Tip Test and overall result (salt+bitter) of Tongue Tip Test were moderated by the adoption of an active lifestyle, with better taste scores observed in individuals achieving higher physical activity levels. When moderation analysis were stratified by gender, the effect of physical activity was no longer significant. PerspectivesThis study is the first to evaluate the influence of an active lifestyle on the preservation of some taste perceptions across a wide range of adiposity levels. While differences in taste can be observed regarding body fat percentage, physical activity moderates that relation only when men and women are analysed together.

Non-human primates (NHP) provide an important model for studying biological mechanisms that underlie behavior and cognition, and are crucial for supplying translational knowledge that can aid the development of new clinical approaches. At the same time, the importance of the 3Rs to minimize suffering during experiments encouraged the development of environmental enrichment programs. Among them, tools for feeding and foraging are central. However, it remains unclear whether the behavioral enrichment tools are used by the animals only for feeding and to satisfy hunger (and hence for survival), or whether these feeding tools serve also as behavioral enrichment in itself (namely, the animals enjoy it per-se). To answer this, we designed a novel dispenser method - that requires significant yet reasonable energetic effort to obtain food - and tested food consumption via the dispenser compared to free-access, namely that did not require any effort on the animal side. We found that primates consumed food from both the dispenser and when presented in free-access, and importantly, that the consumption via the dispenser was in correlation with the consumption in free-access. This was similar across different subjects, different times during the day, and different types of food. We suggest that monkeys can benefit from using the dispenser for food consumption, but also benefit from it for play (i.e. as behavioral enrichment in itself). Such an approach allows non-human-primates to preserve their natural food procurement activities.

Measures of rodent drinking (lick) patterns are used to test how various manipulations affect fluid intake. Decades of research indicate that manipulating the satiating potency of a stimulus affects the number of licking bursts whereas manipulating the hedonic value of the solution affects the size of the licking bursts or rate of licking. This type of analysis has been largely applied to manipulations that modulate drinking that is already occurring (i.e., indirect controls or modulators of intake), but there is a dearth of studies with detailed measures of licking in response to stimuli that are primary drivers of intake (i.e., direct controls). A better understanding of licking behavior in response to direct controls of fluid intake could provide insight into how drinking is stimulated. Accordingly, we analyzed lick patterns after varying doses of primary drivers (direct controls) of intake, angiotensin II, hypertonic saline, or carbochol, in male and female rats. As expected, all treatments dose-dependently increased licks for water. Analysis of licking patterns revealed dose-related increases in burst number after treatment with all stimuli, but dose did not predict burst size or lick rate. Together with previous work on licking patterns these data suggest that direct controls of water intake are more related to processes associated with satiety than to changes in hedonic value of the consumed substance.

Hunger and satiety are interoceptions involved in the control of food intake. How they change across the day and from one day to the next, as well as their relationships with physiological parameters, remain poorly understood. In a five-day laboratory study, 20 healthy male participants (24.2 {+/-} 3.3 years) were given 3 meals per day (breakfast, lunch, dinner), at times based on each individuals internal time. Subjects had a 8-h sleep opportunity at night recorded by polysomnography, during which time they were exposed to 4 different light intensities (0, 3, 8, or 20 lux). Hunger and satiety were assessed before and after each meal. Heart rate was measured continuously and glucose levels were sampled every 15 minutes. We found that: 1) hunger and satiety varied dynamically with the lowest levels at breakfast and the highest at lunch and dinner (p < 0.001); 2) Hunger and satiety were subject-dependent, and keep stable across the five experimental days; 3) heart rate was higher after than before meals (p < 0.0001), and higher around breakfast than dinner; 4) Glycemia before and after meals was respectively stable throughout the day and over the five-day study; 5) interoception was correlated with fluctuations in heart rate, glucose levels and sleep duration. Overall, our results reveal that hunger and satiety perception are individual characteristics. To better understand the role of interoception in food intake control, both hunger and satiety should be measured, but separately in their respective states.

Adolescence is a sensitive period during which unhealthy diets may shape metabolic health and cognition. Diets high in fat and sugar have been linked to obesity, impaired glucose regulation and hippocampus-dependent deficits, but the exposure duration required to affect cognition remains unclear. This study examined whether adolescent-onset exposure to a high-fat high-sucrose (HFHS) diet induces metabolic dysfunction and impairs object-based memory, spatial working memory and spatial pattern separation in male Long Evans rats. Rats were assigned to a control or HFHS diet at four weeks of age and remained on this diet into adulthood. Basal blood glucose was assessed monthly and home-cage behaviour using 48-hour LABORAS recordings. Cognitive testing started after 10 weeks of diet exposure, when basal glucose was elevated in HFHS-fed rats. Object displacement and novel object recognition were used in short open-field test settings, whereas touchscreen-based trial-unique nonmatching-to-location testing (TUNL) assessed spatial working memory and pattern separation across repeated operant sessions. Finally, glucose (in)tolerance and tissue weights were measured. HFHS diet exposure produced a metabolic phenotype, including increased body weight, elevated basal glucose, impaired glucose tolerance and increased liver and gonadal white adipose tissue weights. The diet also altered the general behavioural repertoire, with increased immobility and grooming and reduced rearing. HFHS-fed rats did not differ from controls in object displacement or novel object recognition performance. In the touchscreen task, both groups acquired the task at a comparable rate. Long-delay and spatial separation challenges reduced performance as expected, confirming task sensitivity, but did not reveal diet-related impairments. These findings show that adolescent-onset HFHS diet exposure induces metabolic dysfunction but does not necessarily produce detectable cognitive impairment when behavioural testing starts after 10 weeks of exposure. Longer exposure or advanced diet-induced inflammatory or neurobiological alterations may be required to reveal cognitive consequences.

The short-term effects of light on cognitive processes within the framework of Human Centric Lighting (HCL) remain underexplored and show inconsistent findings. In a laboratory study involving 789 participants, the influence of bright daylight white (BL), warm white (WL), and neutral light on executive functions was investigated using the Attention Network Test (ANT). BL emerged as the most beneficial condition overall, particularly enhancing the alerting component. In contrast, WL was repeatedly associated with negative effects on both alerting and executive attention. Unexpectedly, WL showed advantages in the orienting component, suggesting complex underlying mechanisms that are not yet fully understood. Future studies should examine lighting programs with greater contrast and incorporate physiological measures (e.g., pupillometry, EEG) as well as more differentiated psychological assessments. To explain these findings, the development of integrative models--such as the HCL-effect model proposed by Wessolowski--is essential. Light is more than a visual stimulus; it modulates attention and cognition. This insight should be systematically considered in the design of work, learning, and living environments.