Hedonic Reactions Research Articles

Opioid and orexin hedonic hotspots in rat orbitofrontal cortex and insula.

Hedonic hotspots are brain sites where particular neurochemical stimulations causally amplify the hedonic impact of sensory rewards, such as "liking" for sweetness. Here, we report the mapping of two hedonic hotspots in cortex, where mu opioid or orexin stimulations enhance the hedonic impact of sucrose taste. One hedonic hotspot was found in anterior orbitofrontal cortex (OFC), and another was found in posterior insula. A suppressive hedonic coldspot was also found in the form of an intervening strip stretching from the posterior OFC through the anterior and middle insula, bracketed by the two cortical hotspots. Opioid/orexin stimulations in either cortical hotspot activated Fos throughout a distributed "hedonic circuit" involving cortical and subcortical structures. Conversely, cortical coldspot stimulation activated circuitry for "hedonic suppression." Finally, food intake was increased by stimulations at several prefrontal cortical sites, indicating that the anatomical substrates in cortex for enhancing the motivation to eat are discriminable from those for hedonic impact.

A method for the assessment of facial hedonic reactions in newborns

ObjectiveThis study describes a quantitative and qualitative methodology to assess hedonic responses to sweet stimulus in healthy newborns. MethodsA descriptive, cross‐sectional, observational study, with healthy newborns (up to 24h of life), between 37 and 42 gestational weeks, vaginally born and breastfed previously to all tests. The evaluation of the newborns reactions was performed by hedonic facial expression analysis, characterized by facial expressions with rhythmic serial tongue protrusion after neutral or sweet solution intake. Initially, 1mL of water solution was provided to the newborn, followed by a 1‐minute recording. Afterwards, the same amount of 25% sucrose solution was provided, performing a second recording. The concordance between researchers was analyzed by the Bland–Altman statistical method. ResultsA total of 100 newborns (n=49 males, n=51 females; mean lifetime=15h 12min±6h 29min) were recorded for neutral and sucrose solution intake, totaling 197 videos (n=3 missing in the water treatment). These videos were double‐blind analyzed and the test revealed a 90% concordance between the two trained researchers, in relation to both solutions. The intraclass correlation coefficient was 0.99 for both solutions, with a significant increase in frequency of hedonic expressions evoked by sucrose solution intake. ConclusionsThese results confirm that the proposed method has an efficient power to detect significant differences between neutral and sucrose stimuli. In conclusion, this evaluation method of hedonic facial reactions in newborns reflects the response to a specific taste.

Spontaneous Hedonic Reactions to Social Media Cues.

Why is it so difficult to resist the desire to use social media? One possibility is that frequent social media users possess strong and spontaneous hedonic reactions to social media cues, which, in turn, makes it difficult to resist social media temptations. In two studies (total N = 200), we investigated less-frequent and frequent social media users' spontaneous hedonic reactions to social media cues using the Affect Misattribution Procedure-an implicit measure of affective reactions. Results demonstrated that frequent social media users showed more favorable affective reactions in response to social media (vs. control) cues, whereas less-frequent social media users' affective reactions did not differ between social media and control cues (Studies 1 and 2). Moreover, the spontaneous hedonic reactions to social media (vs. control) cues were related to self-reported cravings to use social media and partially accounted for the link between social media use and social media cravings (Study 2). These findings suggest that frequent social media users' spontaneous hedonic reactions in response to social media cues might contribute to their difficulties in resisting desires to use social media.

Suvorexant, an orexin/hypocretin receptor antagonist, attenuates motivational and hedonic properties of cocaine

Orexins ('hypocretins') are peptides produced by neurons of the hypothalamus that project to structures implicated in reward and emotion processing. Converging evidence demonstrates functional roles of orexin signaling in arousal, sleep/wakefulness and motivated behaviors for natural and drug rewards. Suvorexant, a dual orexin receptor antagonist, recently received approval from the US Food and Drug Administration to treat insomnia. In Experiment 1, rats self-administered cocaine under a progressive-ratio schedule of reinforcement and the effects of suvorexant on motivation to self-administer cocaine were measured. In Experiment 2, the effects of suvorexant on cocaine reward were assessed by using a place conditioning paradigm, and 50-kHz ultrasonic vocalizations were also recorded to track changes in hedonic reactivity to cocaine. To rule out potentially confounding effects of suvorexant-induced somnolence, locomotor activity was also measured. In Experiment 3, the effects of suvorexant on cocaine-evoked elevations in ventral striatal dopamine were examined. Data reveal that suvorexant (i) reduced the number of cocaine infusions earned during progressive-ratio self-administration; (ii) attenuated initial positive hedonic reactivity to cocaine and prevented cocaine place preference; (iii) did not affect cocaine-induced hyperlocomotion and (iv) reduced cocaine-induced elevations in extracellular ventral striatal dopamine. The present study examined the therapeutic potential of suvorexant in rodent models of cocaine use disorder. These results contribute toward a growing literature supporting therapeutic roles of orexin receptor antagonists in treating substance use disorders.

Measuring the drinking experience of beer in real context situations. The impact of affects, senses, and cognition

Product experience is shaped by the interaction between the human systems and the product. Human systems include a sensory system to perceive the surrounding world, an affective system that evokes emotional responses to certain stimuli, and a cognitive system that makes meaning and processes information. We hypothesise that experience is a combination between these three systems rather than a linear continuum of hedonic reactions. In order to test this hypothesis, we conducted a study measuring the experience of drinking craft and industrial beers. A total of 400 consumers were invited to drink beer, rate their liking and select a set of phrases that better described their drinking experience. Results showed no significant difference in expected liking and purchase intention between the eight beers evaluated. However, a difference between beers was observed for the CATA phrases. Cognitive phrases were more frequently checked for craft beers, while sensory, and affective phrases were more frequently checked for industrial beers. A Multiple Factor Analysis for Contingency Tables showed that the sensory and cognitive systems were more related to liking than the affective system.

A method for the assessment of facial hedonic reactions in newborns

ObjectiveThis study describes a quantitative and qualitative methodology to assess hedonic responses to sweet stimulus in healthy newborns. MethodsA descriptive, cross-sectional, observational study, with healthy newborns (up to 24h of life), between 37 and 42 gestational weeks, vaginally born and breastfed previously to all tests. The evaluation of the newborns reactions was performed by hedonic facial expression analysis, characterized by facial expressions with rhythmic serial tongue protrusion after neutral or sweet solution intake. Initially, 1mL of water solution was provided to the newborn, followed by a 1-minute recording. Afterwards, the same amount of 25% sucrose solution was provided, performing a second recording. The concordance between researchers was analyzed by the Bland–Altman statistical method. ResultsA total of 100 newborns (n=49 males, n=51 females; mean lifetime=15h 12min±6h 29min) were recorded for neutral and sucrose solution intake, totaling 197 videos (n=3 missing in the water treatment). These videos were double-blind analyzed and the test revealed a 90% concordance between the two trained researchers, in relation to both solutions. The intraclass correlation coefficient was 0.99 for both solutions, with a significant increase in frequency of hedonic expressions evoked by sucrose solution intake. ConclusionsThese results confirm that the proposed method has an efficient power to detect significant differences between neutral and sucrose stimuli. In conclusion, this evaluation method of hedonic facial reactions in newborns reflects the response to a specific taste.

A consumer-based approach to salt reduction: Case study with bread

In recent years high sodium intake has raised growing concern worldwide. A widespread reduction of salt concentration in processed foods has been claimed as one of the most effective strategies to achieve a short-term impact on global health. However, one of the major challenges in reducing salt in food products is its potential negative impact on consumer perception. For this reason, gradual salt reduction has been recommended. In this context, the aim of the present work was to present a consumer-based approach to salt reduction, using bread as case study. Two consumer studies with a total of 303 consumers were carried out. In the first study, four sequential difference thresholds were determined through paired-comparison tests, starting at a salt concentration of 2%. In the second study, 99 consumers performed a two-bite evaluation of their sensory and hedonic perception of five bread samples: a control bread containing 2% salt and four samples with reduced salt content according to the difference thresholds determined in the first study. Survival analysis was used to determine average difference thresholds, which ranged from 9.4% to 14.3% of the salt concentration of the control bread. Results showed that salt concentration significantly influenced consumer overall liking of the bread samples. However, large heterogeneity was found in consumer hedonic reaction towards salt reduction: two groups of consumers with different preference and hedonic sensitivity to salt reduction were found. Results from the present work confirm that cumulative series of small salt reductions may be a feasible strategy for reducing the sodium content of bread without affecting consumer hedonic perception and stress the importance of considering consumer perception in the design of gradual salt reduction programmes.

Effect of combined oral doses of Δ(9)-tetrahydrocannabinol (THC) and cannabidiolic acid (CBDA) on acute and anticipatory nausea in rat models.

The purpose of this study was to evaluate the potential of oral combined cannabis constituents to reduce nausea. The objective of this study was to determine the effect of combining subthreshold oral doses of Δ(9)-tetrahydrocannabinol (THC) and cannabidiolic acid (CBDA) on acute and anticipatory nausea in rat models of conditioned gaping. The potential of intragastric (i.g.) administration of THC, CBDA, or combined doses, to interfere with acute nausea-induced conditioned gaping (acute nausea) or the expression of contextually elicited conditioned gaping (anticipatory nausea), was evaluated. For acute nausea, i.g. administration of subthreshold doses of THC (0.5 and 1mg/kg) or CBDA (0.5 and 1μg/kg) significantly suppressed acute nausea-induced gaping, whereas higher individual doses of both THC and CBDA were maximally effective. Combined i.g. administration of higher doses of THC and CBDA (2.5mg/kg THC-2.5μg/kg CBDA; 10mg/kg THC-10μg/kg CBDA; 20mg/kg THC-20μg/kg CBDA) also enhanced positive hedonic reactions elicited by saccharin solution during conditioning. For anticipatory nausea, combined subthreshold i.g. doses of THC (0.1mg/kg) and CBDA (0.1μg/kg) suppressed contextually elicited conditioned gaping. When administered i.g., THC was effective on its own at doses ranging from 1 to 10mg/kg, but CBDA was only effective at 10μg/kg. THC alone was equally effective by intraperitoneal (i.p.) and i.g. administration, whereas CBDA alone was more effective by i.p. administration (Rock et al. in Psychopharmacol (Berl) 232:4445-4454, 2015) than by i.g. administration. Oral administration of subthreshold doses of THC and CBDA may be an effective new treatment for acute nauseaandanticipatory nausea and appetite enhancement in chemotherapy patients.

Pleasure From Another's Pain: The Influence of a Target's Hedonic States on Attributions of Immorality and Evil.

Can people's feelings about harm (i.e., their hedonic reactions) lead them to be morally condemned, even if they do not cause the harm themselves? We show that individuals who experience pleasure at serious harm that has befallen another person are judged both immoral and evil. This effect occurs for harm-causing actors, and for observers who play no role in causing the harm; actors can also be judged as immoral and evil when they experience mere indifference (Study 1). Observers are more likely to be similarly judged when they experience direct rather than indirect pleasure from harm caused to another (Study 2). The effects of pleasure are dissociable from those of malevolent desires (Study 3). Targets' experience of pleasure at the harm caused to another person leads to the social exclusion of observers (Studies 1-3) and the harsh punishment of actors, including the death penalty (Studies 1, 4a, and 4b).

Influence of label design on children’s perception of two snack foods: Comparison of rating and choice-based conjoint analysis

The contribution of package design to the marketing of food products targeted at children has increased in the last years, which makes it necessary to study how label design affects children’s perception of food products in order to inform policy design and development. Considering that methodological selection is one of the major challenges when conducting research with children, the present work aimed at comparing rating and choice-based conjoint to study the influence of three design variables (cartoon characters, nutrition claims and traffic-light system) on the hedonic reaction of school-aged children towards labels of two popular snack foods: yogurt and sponge cake. A total of 238 children in grades 1–6 from a private primary school in Montevideo (Uruguay) participated in the study. Participants were divided into two groups of similar size who performed either a rating or a choice-based conjoint task. The rating-based conjoint involved the evaluation of 8 labels using a hedonic scale, whereas in the choice task children had to select the label they would like the most from each of 8 pairs of labels. None of the variables was found to significantly affect children’s hedonic scores in the rating-based conjoint analysis. On the contrary, choice-based conjoint proved to be easily understood and enabled to discriminate among labels. Results from this approach showed that the inclusion of cartoon characters and nutrition claims positively influenced children’s preferences. Implications for research and policy making in label design for children are discussed.

Music Influences Hedonic and Taste Ratings in Beer.

The research presented here focuses on the influence of background music on the beer-tasting experience. An experiment is reported in which different groups of customers tasted a beer under three different conditions (N = 231). The control group was presented with an unlabeled beer, the second group with a labeled beer, and the third group with a labeled beer together with a customized sonic cue (a short clip from an existing song). In general, the beer-tasting experience was rated as more enjoyable with music than when the tasting was conducted in silence. In particular, those who were familiar with the band that had composed the song, liked the beer more after having tasted it while listening to the song, than those who knew the band, but only saw the label while tasting. These results support the idea that customized sound-tasting experiences can complement the process of developing novel beverage (and presumably also food) events. We suggest that involving musicians and researchers alongside brewers in the process of beer development, offers an interesting model for future development. Finally, we discuss the role of attention in sound-tasting experiences, and the importance that a positive hedonic reaction toward a song can have for the ensuing tasting experience.

“I Like it!” Preference Actions Separated from Hedonic Reactions

AbstractIn 1952–1957, Peryam and colleagues developed nine ordinal phrases of liking and dislike to assess consumers' dispositions to accept or reject a food or drink. They named their questionnaire a Food Preference Scale. Others called it the Hedonic Scale, which means assessment of pleasure, not choice. It is still widely assumed that the word “like” distinguishes felt pleasure from observed wanting to consume the sample. The quantitative results presented here complement an earlier qualitative finding that preference scores do not provide evidence of the experiencing of pleasure. Rather, “I like it!” simply indicates high acceptance of the sampled variant of a product. Nevertheless, in this experiment, some assessors did also get a convulsive thrill from oral stimulation, as distinct from just enjoying the mouthful, or being pleased by it. However, this sensual pleasure came only from strongly disliked levels of stimulation and is probably unique to samples sensed as intensely sweet.Practical ApplicationsThis experiment's separation of preference from pleasure depended on overcoming practitioners' division between sensory vocabulary and preference scores. Instead of seeking statistical patterns that bridge the supposed gap between sensory concepts and acts of acceptance, sensory studies should design test samples capable of measuring the impact of specified variations in the product range, first on a fully integrative judgment such as match to the personal ideal, or to the most familiar or usual brand. Second, if analytical characterization might help to test the specification, samples can be rated on vocabulary learned in life or in the laboratory, with one anchor on the standard to be matched, such “exactly as I like it” or “just right” (not “like extremely” or “just about right”), and only one other anchor, such as “neither like nor dislike” or “just too wrong to be tolerable.” Existing data collection and analysis software are easily adapted this way.

Orexin in Rostral Hotspot of Nucleus Accumbens Enhances Sucrose ‘Liking’ and Intake but Scopolamine in Caudal Shell Shifts ‘Liking’ Toward ‘Disgust’ and ‘Fear’

The nucleus accumbens (NAc) contains a hedonic hotspot in the rostral half of medial shell, where opioid agonist microinjections are known to enhance positive hedonic orofacial reactions to the taste of sucrose ('liking' reactions). Within NAc shell, orexin/hypocretin also has been reported to stimulate food intake and is implicated in reward, whereas blockade of muscarinic acetylcholine receptors by scopolamine suppresses intake and may have anti-reward effects. Here, we show that NAc microinjection of orexin-A in medial shell amplifies the hedonic impact of sucrose taste, but only within the same anatomically rostral site, identical to the opioid hotspot. By comparison, at all sites throughout medial shell, orexin microinjections stimulated 'wanting' to eat, as reflected by increases in intake of palatable sweet chocolates. At NAc shell sites outside the hotspot, orexin selectively enhanced 'wanting' to eat without enhancing sweetness 'liking' reactions. In contrast, microinjections of the antagonist scopolamine at all sites in NAc shell suppressed sucrose 'liking' reactions as well as suppressing intake of palatable food. Conversely, scopolamine increased aversive 'disgust' reactions elicited by bitter quinine at all NAc shell sites. Finally, scopolamine microinjections localized to the caudal half of medial shell additionally generated a fear-related anti-predator reaction of defensive treading and burying directed toward the corners of the transparent chamber. Together, these results confirm a rostral hotspot in NAc medial shell as a unique site for orexin induction of hedonic 'liking' enhancement, similar to opioid enhancement. They also reveal distinct roles for orexin and acetylcholine signals in NAc shell for hedonic reactions and motivated behaviors.

Long-lasting deficits in hedonic and nucleus accumbens reactivity to sweet rewards by sugar overconsumption during adolescence.

Adolescence is a critical period characterized by major neurobiological changes. Chronic stimulation of the reward system might constitute an important factor in vulnerability to pathological development. In spite of the dramatic increase in the consumption of sweet palatable foods during adolescence in our modern societies, the long-term consequences of such exposure on brain reward processing remain poorly understood. Here, we investigated in rats the long-lasting effects of sugar overconsumption during their adolescence on their adult reactivity to the hedonic properties of sweet rewards. Adolescent rats with continuous access to 5% sucrose solution (from postnatal day 30-46) showed escalating intake. At adulthood (post-natal day 70), using two-bottle free choice tests, sucrose-exposed rats showed lower intake than non-exposed rats suggesting decreased sensitivity to the rewarding properties of sucrose. In Experiment 1, we tested their hedonic-related orofacial reactions to intraoral infusion of tasty solutions. We showed that sucrose-exposed rats presented less hedonic reactions in response to sweet tastes leaving the reactivity to water or quinine unaltered. Hence, in Experiment 2, we observed that this hedonic deficit is associated with lower c-Fos expression levels in the nucleus accumbens, a brain region known to play a central role in hedonic processing. These findings demonstrate that a history of high sucrose intake during the critical period of adolescence induces long-lasting deficits in hedonic treatment that may contribute to reward-related disorders.

The extinction procedure modifies a conditioned flavor preference in nonhungry rats only after revaluation of the unconditioned stimulus.

In 3 experiments rats experienced 2 flavors, each paired with sucrose, in order to establish a conditioned preference to each. One (flavor Fe) was then presented alone (an extinction procedure) prior to a choice test between Fe and the flavor that did not undergo extinction (Fne). Hungry rats showed a preference for Fne over Fe (Experiment 1A), but rats that were not food-deprived showed no effect of extinction when given a choice between Fe and Fne immediately after extinction (Experiment 1B) or after an interval in which reexposure to sucrose was given (Experiment 2). The extinction procedure was not without effect, however, as Fe was preferred over Fne after sucrose had been devalued by pairing with lithium chloride, and Fne was preferred over Fe after a procedure likely to enhance the value of the sucrose (Experiment 3). The explanations considered propose that preference conditioning establishes a range of associations between the flavor and the various properties of sucrose (its nutritional value, its taste, the hedonic reaction it evokes). It is suggested that the form of learning that mediates revaluation effects is sensitive to extinction whereas that responsible for performance on a consumption test is not. (PsycINFO Database Record

Odor Perception in Children with Autism Spectrum Disorder and its Relationship to Food Neophobia.

Atypical sensory functioning in Autism Spectrum Disorder (ASD) has been well documented in the last decade for the visual, tactile and auditory systems, but olfaction in ASD is still understudied. The aim of the present study was to examine whether children with ASD and neuro-typically (NT) developed children differed in odor perception, at the cognitive (familiarity and identification ability), sensorimotor (olfactory exploration) and affective levels (hedonic evaluation). Because an important function of the sense of smell is its involvement in eating, from food selection to appreciation and recognition, a potential link between odor perception and food neophobia was also investigated. To these ends, 10 children between 6 and 13 years old diagnosed with ASD and 10 NT control children were tested. To compare performance, 16 stimuli were used and food neophobia was assessed by the parents on a short food neophobia scale. Results revealed that (i) significant hedonic discrimination between attractive and aversive odors was observed in NT (p = 0.005; d = 2.378) and ASD children (p = 0.042; d = 0.941), and (ii) hedonic discrimination level was negatively correlated with food neophobia scores in ASD (p = 0.007) but not NT children. In conclusion, this study offers new insights into odor perception in ASD children, highlighting a relationship between odor hedonic reactivity and eating behavior. This opens up new perspectives on both (i) the role of olfaction in the construction of eating behavior in ASD children, and (ii) the measurement and meaning of food neophobia in this population.

Anhedonia in pigs? Effects of social stress and restraint stress on sucrose preference

The fact that consumption of normally palatable foods is affected by stress in both humans and rats suggests a means to assess hedonic reaction in non-verbal animals. However, little is known about anhedonia and stress in productive animals such as pigs. Thus we examined the separate effects of social stress and restraint stress in 42-day old pigs on the preference for dilute sucrose solutions over water. Pigs in the social stress group (SS) were mixed with unfamiliar animals from separate pens for two 20minute periods (Experiment 1). Pigs in the restraint stress group (RS) were immobilized three times a day, for 3-min periods, on 3 consecutive days (Experiment 2). Consumption of dilute sucrose solutions and water was examined after these stress manipulations and in the unstressed control groups (CG). Pigs were tested in pairs (12 control and 12 experimental) with a choice between water and sucrose solutions (at either 0.5% or 1%) during 30min sessions. In both experiments CG pigs showed higher intakes of 0.5% and 1% sucrose solutions over water. Neither SS nor RS pigs consumed more 0.5% sucrose than water, but both groups did consume more 1% sucrose than water. Both social stress and restraint stress reduced sucrose preference at low concentrations but not at higher concentrations suggesting that stress may limit food consumption in pigs unless a palatable feed is present. In addition, the results suggest that stress reduces the hedonic impact of dilute sucrose. Therefore, sucrose preference may be a useful test for the presence of stress and anhedonia in pigs.

Changes in mu-opioid receptor expression and function in the mesolimbic system after long-term access to a palatable diet.

The incidence of obesity in both adults and children is rising. In order to develop effective treatments for obesity, it is important to understand how diet can induce changes in the brain that could promote excessive intake of high-calorie foods and alter the efficacy of therapeutic targets. The mu-opioid receptor is involved in regulating the motivation for and hedonic reaction to food. Here, we review the literature examining changes in the expression and function of mu-opioid receptors in the mesolimbic system of rodents after extended access to a high-fat diet. We also review how maternal diet can induce long-term changes in the expression or function of mu-opioid receptors in the mesolimbic system of offspring. Understanding the behavioural and therapeutic implications of these changes requires further study.

Commentary: Cafeteria diet impairs expression of sensory-specific satiety and stimulus-outcome learning.

Commentary: Cafeteria diet impairs expression of sensory-specific satiety and stimulus-outcome learning.

Selection of sucrose concentration depends on the effort required to obtain it: studies using tetrabenazine, D1, D2, and D3 receptor antagonists.

Low doses of dopamine (DA) antagonists and accumbens DA depletions reduce food-reinforced instrumental behavior but do not impair primary food motivation, causing animals to reallocate behavior away from food-reinforced tasks with high response requirements and select less effortful alternatives. However, it is uncertain if this same pattern of effects would occur if sucrose was used as the reinforcer. These experiments studied the impact of DA depletion and antagonism on performance of an effort-related choice task using sucrose as the reinforcer, as well as sucrose consumption, preference, and taste reactivity tests. The effects of DA manipulations were assessed using a task in which rats chose between lever pressing on a fixed ratio 7 schedule for 5.0% sucrose versus freely consuming a less concentrated solution (0.3%). The DA depleting agent tetrabenazine shifted effort-related choice, decreasing lever pressing for 5.0% sucrose but increasing intake of the concurrently available 0.3% sucrose. Tetrabenazine did not affect sucrose appetitive taste reactivity, or sucrose consumption or preference, in free consumption tests. The D1 antagonist ecopipam and the D2 antagonist haloperidol also shifted choice behavior at doses that did not alter sucrose consumption or preference. In contrast, sucrose pre-exposure reduced consumption across all conditions. D3 antagonism had no effects. D1 and D2 receptor blockade and DA depletion reduce the tendency to work for sucrose under conditions that leave fundamental aspects of sucrose motivation (intake, preference, hedonic reactivity) intact. These findings have implications for studies employing sucrose intake or preference in animal models of depression.