Primary Reinforcer Research Articles

Ventral frontostriatal circuitry mediates the computation of reinforcement from symbolic gains and losses.

Reinforcement learning (RL), particularly in primates, is often driven by symbolic outcomes. However, it is usually studied with primary reinforcers. To examine the neural mechanisms underlying learning from symbolic outcomes, we trained monkeys on a task in which they learned to choose options that led to gains of tokens and avoid choosing options that led to losses of tokens. We then recorded simultaneously from the orbitofrontal cortex (OFC), ventral striatum (VS), amygdala (AMY), and mediodorsal thalamus (MDt). We found that the OFC played a dominant role in coding token outcomes and token prediction errors. The other areas contributed complementary functions, with the VS coding appetitive outcomes and the AMY coding the salience of outcomes. The MDt coded actions and relayed information about tokens between the OFC and VS. Thus, the OFC leads the processing of symbolic RL in the ventral frontostriatal circuitry.

Appetitive conditioning with pornographic stimuli elicits stronger activation in reward regions than monetary and gaming-related stimuli.

Appetitive conditioning plays an important role in the development and maintenance of pornography-use and gaming disorders. It is assumed that primary and secondary reinforcers are involved in these processes. Despite the common use of pornography and gaming in the general population appetitive conditioning processes in this context are still not well studied. This study aims to compare appetitive conditioning processes using primary (pornographic) and secondary (monetary and gaming-related) rewards as unconditioned stimuli (UCS) in the general population. Additionally, it investigates the conditioning processes with gaming-related stimuli as this type of UCS was not used in previous studies. Thirty-one subjects participated in a differential conditioning procedure in which four geometric symbols were paired with either pornographic, monetary, or gaming-related rewards or with nothing to become conditioned stimuli (CS + porn, CS + game, CS + money, and CS-) in an functional magnetic resonance imaging study. We observed elevated arousal and valence ratings as well as skin conductance responses for each CS+ condition compared to the CS-. On the neural level, we found activations during the presentation of the CS + porn in the bilateral nucleus accumbens, right medial orbitofrontal cortex, and the right ventral anterior cingulate cortex compared to the CS-, but no significant activations during CS + money and CS + game compared to the CS-. These results indicate that different processes emerge depending on whether primary and secondary rewards are presented separately or together in the same experimental paradigm. Additionally, monetary and gaming-related stimuli seem to have a lower appetitive value than pornographic rewards.

Computational Mechanisms Underlying Motivation to Earn Symbolic Reinforcers.

Reinforcement learning is a theoretical framework that describes how agents learn to select options that maximize rewards and minimize punishments over time. We often make choices, however, to obtain symbolic reinforcers (e.g., money, points) that are later exchanged for primary reinforcers (e.g., food, drink). Although symbolic reinforcers are ubiquitous in our daily lives, widely used in laboratory tasks because they can be motivating, mechanisms by which they become motivating are less understood. In the present study, we examined how monkeys learn to make choices that maximize fluid rewards through reinforcement with tokens. The question addressed here is how the value of a state, which is a function of multiple task features (e.g., the current number of accumulated tokens, choice options, task epoch, trials since the last delivery of primary reinforcer, etc.), drives value and affects motivation. We constructed a Markov decision process model that computes the value of task states given task features to then correlate with the motivational state of the animal. Fixation times, choice reaction times, and abort frequency were all significantly related to values of task states during the tokens task (n = 5 monkeys, three males and two females). Furthermore, the model makes predictions for how neural responses could change on a moment-by-moment basis relative to changes in the state value. Together, this task and model allow us to capture learning and behavior related to symbolic reinforcement.

Aversive conditioning is impaired in impulsive individuals: A study on learning asymmetries

Background and objectivesAppetitive and aversive conditioning are thought to be involved in the development and maintenance of mental disorders including anxiety, mood, eating, and substance use disorders. However, few studies measure the relative strength of appetitive and aversive associations, and their relevance to the risk of mental disorders. This study aims to address this gap. MethodsWe tested how readily healthy volunteers acquire appetitive vs. aversive associations. 150 participants associated complex 3D objects with either gain or loss and made decisions to gain or avoid losing points. We investigated the relationship of a learning asymmetry with neuroticism, impulsivity, and anhedonia, to test the hypothesis that a stronger learning asymmetry corresponds to more extreme scores on these traits. ResultsImpulsivity was positively associated with the learning asymmetry (R2 = .10). This resulted from an inverse relation with the strength of aversive associations, indicating that impulsive individuals are worse at aversive learning. However, appetitive associations did not differ significantly. No correlations with neuroticism or anhedonia were found. LimitationsConditioning studies typically use primary reinforcers and a CS-. Lacking these may make these results less comparable to other studies. ConclusionsWe demonstrate that the learning asymmetry can measure individual differences linked to personality traits, and that impulsivity, normally linked with appetitive learning, also influences aversive learning. These results enable additional studies of learning asymmetry in relation to mental disorders, which could include measurements of mental health symptoms to provide further insight into how appetitive and aversive learning interacts with mental disorders.

Cue-induced reinstatement of seeking behavior in male rats is independent from the rewarding value of the primary reinforcer: Effect of mGluR5 blockade

Environmental conditioning factors have a profound impact on alcohol-seeking behavior and the maintenance of alcohol use in individuals with alcohol dependence. Cues associated with alcohol, depending on the perceived value of the primary reinforcer, gain salience and can trigger relapse.This study investigates the correlation between the reward magnitude of the primary reinforcer and the reinstatement evoked by cues predictive of their availability in male rats. Rat self-administration procedures were used to test reinstatement, with reinforcers consisting of 10% alcohol, 10% sucrose, or 2% sodium chloride (NaCl) experienced under need-state conditions. The effect of MTEP ([(2-methyl-1,3-thiazol-4-yl) ethynyl] pyridine), a selective metabotropic glutamate receptor 5 (mGluR5) antagonist, on motivation and reinstatement behaviors was also evaluated. Resultsdemonstrate that under Fixed Ratio 1 (FR1) schedule, the three reinforcers maintain operant responding with the following order of magnitude 10% sucrose >2% NaCl >10% alcohol > water. Under a progressive ratio (PR) schedule of reinforcement, rats exhibit a significantly higher breakpoint for 2% NaCl (under Na-depletion), followed by 10% sucrose and 10% alcohol. After extinction, a significant reinstatement is observed with the magnitude order of 10% sucrose >10% alcohol >2% NaCl. However, only re-exposure to alcohol-paired cues induced significant reinstatement of alcohol-seeking after 4 and 8 months. Treatment with MTEP significantly reduces reinstatement of responding across all reinforcers, with the strongest effect observed on alcohol-seeking. These findings suggest that mGluR5 plays a general role in controlling cue-reactivity, but the effect is prominent in the case of alcohol compared to natural rewards.In conclusion, the results demonstrate a remarkable dissociation between the rewarding magnitude of the primary reinforcer and its ability to trigger relapse upon presentation of a cue previously associated with it. Importantly, alcohol, despite having lower intrinsic motivational value compared to a natural reward (sucrose) or a consummatory stimulus experienced under need state conditions (NaCl), can elicit more robust and longer-term reinstatement of seeking responses. Finally, our data demonstrate a significant involvement of the mGluR5 system in the regulation of seeking behavior.

An assessment of token value and effectiveness: A replication.

The purpose of the current study was to conduct a systematic replication of Fiske et al. (2015) to extend the behavior-analytic literature on token reinforcement. Specifically, the researchers addressed several of the limitations of Fiske et al. by including specific conditioning procedures, creating a controlled history of reinforcement with the token system, including participants with and without disabilities to extend the generality of the findings, and equating the magnitude of reinforcement across the primary and paired-token conditions. The current study evaluated the reinforcing value of tokens by using progressive-ratio schedules to compare the efficacy of primary reinforcement, paired tokens, and unpaired tokens. The results suggest that paired tokens may function as reinforcers, but they were not as consistently effective as primary reinforcers.

Primary rewards and aversive outcomes have comparable effects on attentional bias.

Attention is biased toward stimuli previously associated with reward. The same is true for aversive conditioning; stimuli previously associated with an aversive outcome also bias attention, suggesting that motivational salience guides attention. Most research that supports this conclusion has manipulated monetary gain-a secondary reinforcer-for reward learning, and electric shocks-a primary punisher-for aversive conditioning, making it difficult to directly compare their influence on attention. Therefore, in the present study, we matched for reinforcer dimensions by using primary taste as reinforcers/punishers and assessed their influence on attention. In a training phase, participants learned to associate three colors with sweet juice (reward), salt water (aversive), and no outcome (neutral), respectively. The two primary reinforcers were equated for valence based on choices made in a prior decision-making task. In a later test phase, these three colors were used for targets and distractors in a task in which participants oriented to a shape-defined target. An attentional bias in favor of the aversively conditioned and reward-associated colors was evident when comparing to the neutral color. Importantly, a direct comparison of rewarded and aversive stimuli revealed no significant differences. These results suggest that when matched for reinforcer dimensions and valence, reward and aversive outcomes bias attention in a similar manner and their effects are comparable, providing further evidence in support of the motivational salience account of learning-dependent attention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Abstinence-Induced Nicotine Seeking Relays on a Persistent Hypoglutamatergic State within the Amygdalo-Striatal Neurocircuitry.

Nicotine robustly sustains smoking behavior by acting as a primary reinforcer and by enhancing the incentive salience of the nicotine-associated stimuli. The motivational effects produced by environmental cues associated with nicotine delivery can progressively manifest during abstinence resulting in reinstatement of nicotine seeking. However, how the activity in reward neuronal circuits is transformed during abstinence-induced nicotine seeking is not yet fully understood. In here we used a contingent nicotine and saline control self-administration model to disentangle the contribution of cue-elicited seeking responding for nicotine after drug abstinence in male Wistar rats. Using ex vivo electrophysiological recordings and a network analysis approach, we defined temporal and brain-region specific amygdalo-striatal glutamatergic alterations that occur during nicotine abstinence. The results from this study provide critical evidence indicating a persistent hypoglutamatergic state within the amygdalo-striatal neurocircuitry over protracted nicotine abstinence. During abstinence-induced nicotine seeking, electrophysiological recordings showed progressive neuroadaptations in dorsal and ventral striatum already at 14-d abstinence while neuroadaptations in subregions of the amygdala emerged only after 28-d abstinence. The observed neuroadaptations pointed to a brain network involving the amygdala and the dorsolateral striatum (DLS) to be implied in cue-induced reinstatement of nicotine seeking. Together these data suggest long-lasting neuroadaptations that might reflect neuroplastic changes responsible to abstinence-induced nicotine craving. Neurophysiological transformations were detected within a time window that allows therapeutic intervention advancing clinical development of preventive strategies in nicotine addiction.

Development of a nicotine aerosol self-administration model in rats and the effects of e-liquid flavors.

Electronic nicotine delivery system (ENDS) use is maintained by the positive reinforcement associated with preferred flavors. These flavors become conditioned reinforcers through pairings with primary reinforcers. This study sought to extend prior research with intravenous nicotine self-administration and develop a more ecologically valid preclinical model of aerosol self-administration in rats that incorporated flavors paired with sucrose. Rats were first trained to respond for oral sucrose with or without raspberry flavor to establish the flavor as a conditioned reinforcer for some groups. Rats were then exposed to aerosol self-administration. All groups responded for raspberry-flavored aerosol with or without nicotine. Rats responded more for raspberry flavored sucrose than unflavored sucrose. Despite raspberry increasing responding for sucrose, the flavor did not function as a conditioned reinforcer during aerosol self-administration and did not increase responding for nicotine. Throughout the aerosol self-administration phase, most groups responded more on the active than inactive lever, and some groups increased their response when the fixed ratio value was increased. At the end of the study, rats in nicotine groups earned similar or fewer aerosol deliveries than rats in vehicle groups. Aerosolized nicotine did not function as a reinforcer in this study, whereas aerosolized raspberry flavor may have maintained self-administration. Further preclinical investigation is needed to articulate the impact of flavors on ENDS use and whether they offset some aversive effects of nicotine or maintain responding on their own. If flavors reduce some aversive effects of self-administered nicotine, then policies to regulate flavors in e-liquids are prudent.

Reinforcement enhancement by nicotine: A novel abuse-liability assessment of e-cigarettes in young adults.

Nicotine can act as a primary positive reinforcer, and as negative reinforcer to relieve withdrawal; we tested whether it can also enhance the reinforcing efficacy of non-drug reinforcers. Young-adult never-users were delivered nicotine via e-cigarette, and a videogame reinforcer was used to test nicotine enhancement. Three dose groups were tested (placebo-only, 6 or 12-mg nicotine), and participants returned to the lab for several sessions over the course of 1 month. Those in the two nicotine-dose groups received placebo on some occasions and nicotine on others; nicotine enhancement of the videogame reinforcer was assessed in a within-subjects fashion by comparing each of the two nicotine groups' dedicated nicotine dose to placebo. In the placebo-only group, progressive-ratio (PR) schedule breakpoints did not alter as a function of videogame exposure, suggesting that the videogame retained its basic-reinforcing properties throughout the study. For the two groups that received nicotine, both doses of nicotine increased PR-schedule breakpoints for the videogame reinforcer relative to the placebo condition. Although nicotine was associated with greater subjective evaluation of the enjoyment of the videogame, it was unrelated to the enjoyment of the e-cigarette device. No evidence was found that nicotine elevated either anhedonia or withdrawal symptoms in the timeframe of the study. The results provide initial evidence that nicotine enhancement, via electronic cigarettes, occurs in non-frequent users of nicotine products and may be a reason they can develop nicotine dependence in the absence of withdrawal and direct effects of nicotine. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Elucidating the reinforcing effects of nicotine: a tribute to Nadia Chaudhri.

Nadia Chaudhri worked with us as a graduate student in the Center for Neuroscience at the University of Pittsburgh from 1999 until she earned her PhD in 2005, a time that coincided with the discovery in our lab of the dual reinforcing actions of nicotine, a concept that she played an important role in shaping. The research that was described in her doctoral thesis is among the foundational pillars of the now well-accepted notion that nicotine acts as both a primary reinforcer and an amplifier of other reinforcer stimuli. This reinforcement-enhancing action of nicotine is robust and likely to be a powerful driver of nicotine use. Below, we discuss the evidence that these two actions of nicotine - primary reinforcement and reinforcement enhancement - are distinct and dissociable, a finding that Nadia was closely associated with. We go on to address two other topics that greatly interested Nadia during that time, the generalizability of the reinforcement-enhancing action of nicotine to multiple classes of reinforcing stimuli and potential sex differences in the dual reinforcing actions of nicotine. The research has greatly expanded since Nadia's involvement, but the core ideas that she helped to develop remain central to the concept of the dual reinforcing actions of nicotine and its importance for understanding the drivers of nicotine use.

Self-management interventions for reducing challenging behaviors among school-age students: A systematic review.

Challenging classroom behaviors can interfere with student social and academic functioning and may be harmful to everyone in schools. Self-management interventions within schools can address these concerns by helping students develop necessary social, emotional, and behavioral skills. Thus, the current systematic review synthesized and analyzed school-based self-management interventions used to address challenging classroom behaviors. The current study aimed to inform practice and policy by (a) evaluating the effectiveness of self-management interventions at improving classroom behaviors and academic outcomes and (b) examining the state of research for self-management interventions based on existing literature. Comprehensive search procedures included electronically searching online databases (e.g., EBSCO Academic Search Premier, MEDLINE, ERIC, PsycINFO), hand-searching 19 relevant journals (e.g., School Mental Health, Journal of School Psychology), reference-list searching 21 relevant reviews, and searching gray literature (e.g., contacting authors, searching online dissertation/theses databases and national government clearinghouses/websites). Searches were completed through December of 2020. Included studies employed either a multiple group-design (i.e., experimental or quasi-experimental) or single-case experimental research design and met the following criteria: (a) utilized a self-management intervention, (b) conducted in a school setting, (c) included school-aged students, and (d) assessed classroom behaviors. Standard data collection procedures expected by the Campbell Collaboration were used in the current study. Analyses for single-case design studies incorporated three-level hierarchical models to synthesize main effects, and meta-regression for moderation. Further, robust variance estimation was applied to both single-case design and group-design studies to account for dependency issues. Our final single-case design sample included 75 studies, 236 participants, and 456 effects (i.e., 351 behavioral outcomes and 105 academic outcomes). Our final group-design sample included 4 studies, 422 participants, and 11 total behavioral effects. Most studies occurred in the United States, in urban communities, in public schools, and in elementary settings. Single-case design results indicated that self-management interventions significantly and positively impacted both student classroom behaviors (LRRi = 0.69, 95% confidence interval [CI] [0.59, 0.78]) and academic outcomes (LRRi = 0.58, 95% CI [0.41, 0.76]). Single-case results were found to be moderated by student race and special education status, whereas intervention effects were more pronounced for African American students (F = 5.56, p = 0.02) and students receiving special education services (F = 6.87, p = 0.01). Single-case results were not found to be moderated by intervention characteristics (i.e., intervention duration, fidelity assessment, fidelity method, or training). Despite positive findings for single-case design studies, risk of bias assessment indicated methodological shortcomings that should be considered when interpreting findings. A significant main effect of self-management interventions for improving classroom behaviors was also revealed for group-design studies (g = 0.63, 95% CI [0.08, 1.17]). However, these results should be interpreted with caution given the small number of included group-design studies. The current study, conducted using comprehensive search/screening procedures and advanced meta-analytic techniques, adds to the large amount of evidence indicating that self-management interventions can be successfully used to address student behaviors and academic outcomes. In particular, the use specific self-management elements (i.e., self-determining a performance goal, self-observing and recording progress, reflecting on a target behavior, and administering primary reinforcers) should be considered within current interventions as well as in the development of future interventions. Future research should aim to assess the implementation and effects of self-management at the group or classroom-level within randomized controlled trials.

Elements of a compound elicit little conditioned reinforcement.

The acquisition of instrumental responding can be supported by primary reinforcers or by conditional (also known as secondary) reinforcers that themselves have an association to a primary reinforcer. While primary reinforcement has been heavily studied for the past century, the associative basis of conditioned reinforcement has received comparatively little experimental examination. Yet conditioned reinforcement has been employed as an important behavioral assay in neuroscience studies, and thus an analysis of its associative basis is called for. We evaluated the extent to which an element from a previously trained compound would facilitate conditioned reinforcement. Three groups of rats received Pavlovian conditioning with a visual-auditory compound cue followed by food. After training, a lever was made available that, when pressed, produced the same trained compound (group compound), only the auditory cue (group element), or a novel auditory cue (group control). The rats in group compound pressed the lever at a higher rate than did rats in either group element or group control, demonstrating a strong conditioned reinforcement effect only in group compound. Interestingly, there was almost no difference in responding between group element and group control. The implications of this generalization decrement in conditioned reinforcement are discussed-particularly as they relate to research in behavioral neuroscience. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Using Primary Reinforcement to Enhance Translatability of a Human Affect and Decision-Making Judgment Bias Task.

Good translatability of behavioral measures of affect (emotion) between human and nonhuman animals is core to comparative studies. The judgment bias (JB) task, which measures "optimistic" and "pessimistic" decision-making under ambiguity as indicators of positive and negative affective valence, has been used in both human and nonhuman animals. However, one key disparity between human and nonhuman studies is that the former typically use secondary reinforcers (e.g., money) whereas the latter typically use primary reinforcers (e.g., food). To address this deficiency and shed further light on JB as a measure of affect, we developed a novel version of a JB task for humans using primary reinforcers. Data on decision-making and reported affective state during the JB task were analyzed using computational modeling. Overall, participants grasped the task well, and as anticipated, their reported affective valence correlated with trial-by-trial variation in offered volume of juice. In addition, previous findings from monetary versions of the task were replicated: More positive prediction errors were associated with more positive affective valence, a higher lapse rate was associated with lower affective arousal, and affective arousal decreased as a function of number of trials completed. There was no evidence that more positive valence was associated with greater "optimism," but instead, there was evidence that affective valence influenced the participants' decision stochasticity, whereas affective arousal tended to influence their propensity for errors. This novel version of the JB task provides a useful tool for investigation of the links between primary reward and punisher experience, affect, and decision-making, especially from a comparative perspective.

Carrots for the donkey: Influence of evaluative conditioning and training on self-paced exercise intensity and delay discounting of exercise in healthy adults.

To choose exercise over alternative behaviours, subjective reward evaluation of the potential choices is a principal step in decision making. However, the selection of exercise intensity might integrate acute visceral responses (i.e. pleasant or unpleasant feelings) and motives related to goals (i.e. enjoyment, competition, health). To understand the factors determining the selection of exercise in its intensity and evaluation as a modality, we conducted a study combining exercise training and evaluative conditioning. Evaluative conditioning was performed by using a novel technique using a primary reinforcer (sweetness) as the unconditioned stimulus and physical strain i.e. heart rate elevation as the conditioned stimulus during interval training, using a randomized control design (N = 58). Pre, post-three weeks interval training w/o conditioning, and after 4 weeks follow-up, participants were tested on self-paced speed selection on treadmill measuring heart rate, subjective pleasantness, and effort levels, as well as delay-discounting of exercise and food rewards. Results revealed that the selection of exercise intensity was significantly increased by adaptation to training and evaluative conditioning, revealing the importance of visceral factors as well as learned expected rewards. Delay discounting rates of self-paced exercise were transiently reduced by training but not affected by evaluative conditioning. In conclusion, exercise decisions are suggested to separate the decision-making process into a modality-specific cognitive evaluation of exercise, and an exercise intensity selection based on acute visceral experience integrating effort, pleasantness, and learned rewards.

Emotional reactivity to binge food and erotic cues in women with bulimia nervosa symptoms

BackgroundStudies on food cue reactivity have documented that altered responses to high-calorie food are associated with bulimic symptomatology, however, alterations in sexual motivations and behaviors are also associated clinical features in this population, which justify their inclusion as a research target. Here, we study responses to erotic cues—alongside food, neutral and aversive cues—to gain an understanding of specificity to food versus a generalized sensitivity to primary reinforcers.MethodsWe recorded peripheral psychophysiological indices –the startle reflex, zygomaticus, and corrugator responses—and self-reported emotional responses (valence, arousal, and dominance) in 75 women completing the Bulimia Test-Revised (BULIT-R). Multiple regression analysis tested whether BULIT-R symptoms were predicted by self-reported and psychophysiological responses to food versus neutral and erotic versus neutral images.ResultsThe results showed that individuals with higher bulimic symptoms were characterized by potentiated eye blink startle response during binge food (vs. neutral images) and more positive valence ratings during erotic (vs. neutral) cues.ConclusionsThe results highlight the negative emotional reactivity of individuals with elevated bulimic symptoms toward food cues, which could be related to the risk of progression to full bulimia nervosa and thereby addressed in prevention efforts. Results also point to the potential role of reactivity to erotic content, at least on a subjective level. Theoretical models of eating disorders should widen their conceptual scope to consider reactivity to a broader spectrum of primary reinforcers, which would have implications for cue exposure-based treatments.Plain English summaryWe examined appetitive and aversive cue responses in college women to investigate how bulimic symptoms relate to primary reinforcers such as food and erotic images. We recorded peripheral psychophysiological indices (the startle reflex, zygomaticus, and corrugator responses) and self-reported emotional responses (valence, arousal, and dominance) in 75 college women that were presented with the Spanish version of the Bulimia Test-Revised. The results showed that bulimic symptoms increase both psychophysiological defensiveness toward food cues and subjective pleasure toward erotic cues. The findings suggest a generalized sensitivity to primary reinforcers in the presence of bulimic symptoms, and emphasize the relevance of adopting a wider framework in research and treatment on bulimia nervosa.

Secondary rewards acquire enhanced incentive motivation via increasing anticipatory activity of the lateral orbitofrontal cortex

The motivation to strive for and consume primary rewards such as palatable food is bound by devaluation mechanisms, yet secondary rewards such as money may not be bound by these regulatory mechanisms. The present study therefore aimed at determining diverging devaluation trajectories for primary (chocolate milk) and secondary (money) reinforcers on the behavioral and neural level. Devaluation procedures withrepeated exposure to reward combined with a choice (Experiment 1) and an incentive delay (Experiment 2) paradigm consistently revealed decreasing hedonic value for the primary reward as reflected by decreasing hedonic evaluation and choice preferencewith repeated receipt, while hedonic value and preferences for the secondary reward increased. Concomitantly acquired functional near-infrared spectroscopy (fNIRS) data during the incentive delay paradigm revealed that increasing value of the secondary reward was accompanied by increasing anticipatory activation in the lateral orbitofrontal cortex, while during the consummatory phase the secondary reinforcer associated with higher medial orbitofrontal activity irrespective of devaluation stage. Overall, the findings suggest that-in contrast to primary reinforcers-secondary reinforcers, i.e. money, can acquire progressively enhanced incentive motivation with repeated receipt, suggesting a mechanism which could promote escalating striving to obtain secondary rewards.

Dopamine modulations of reward-driven music memory consolidation.

Music listening provides one of the most significant abstract rewards for humans because hearing music activates the dopaminergic mesolimbic system. Given the strong link between reward, dopamine, and memory, we aimed here to investigate the hypothesis that dopamine-dependent musical reward can drive memory improvements. Twenty-nine healthy participants of both sexes provided reward ratings of unfamiliar musical excerpts that had to be remembered following a consolidation period under three separate conditions: after the ingestion of a dopaminergic antagonist, a dopaminergic precursor, or a placebo. Linear mixed modeling of the intervention data showed that the effect of reward on memory-i.e., the greater the reward experienced while listening to the musical excerpts, the better the memory recollection performance-was modulated by both dopaminergic signaling and individual differences in reward processing. Greater pleasure was consistently associated with better memory outcomes in participants with high sensitivity to musical reward, but this effect was lost when dopaminergic signaling was disrupted in participants with average or low musical hedonia. Our work highlights the flexibility of the human dopaminergic system, which can enhance memory formation not only through explicit and/or primary reinforcers but also via abstract and aesthetic rewards such as music.

The Influence of Friends on Teen Vaping: A Mixed-Methods Approach.

Vaping is popular among adolescents. Previous research has explored sources of information and influence on youth vaping, including marketing, ads, family, peers, social media, and the internet. This research endeavors to expand understanding of peer influence. Our hypothesis is that friends’ influence on teen vapers’ first electronic nicotine delivery systems (ENDS) use varies by demographic variables and awareness of ENDS advertising. In August–October 2017, youth (n = 3174) aged 13–18 completed an online survey to quantify ENDS behaviors and attitudes and were invited to participate in follow-up online research in November-December 2017 to probe qualitative context around perceptions and motivations (n = 76). This analysis focused on the ENDS users, defined as having ever tried any ENDS product, from the survey (n = 1549) and the follow-up research (n = 39). Among survey respondents, friends were the most common source of vapers’ first ENDS product (60%). Most survey respondents tried their first ENDS product while “hanging out with friends” (54%). Among follow-up research participants, the theme of socializing was also prominent. ENDS advertising and marketing through social media had a strong association with friend networks; in fact, the odds of friends as source of the first vaping experience were 2 times higher for those who had seen ENDS ads on social media compared with other types of media. The influence of friends is particularly evident among non-Hispanic Whites, Hispanics/Latinos, those living in urban areas, those living in high-income households, those with higher self-esteem, and those who experiment with vaping. These findings support the premise that peer influence is a primary social influencer and reinforcer for vaping. Being included in a popular activity appears to be a strong driving force.

Disorder specific rewarding stimuli in anorexia nervosa.

To enhance our understanding of reward stimuli in anorexia nervosa (AN) and to provide a basis for future research on reward processes, disorder specific reward stimuli as well as primary and secondary reinforcers were investigated. We developed a set of pictures with "disorder specific reward" stimuli, with the six subcategories "sport," "losing weight," "healthy food," "discipline," "thin bodies," "appreciation of others," and evaluated reward ratings of these "disorder specific reward" stimuli as well as "erotic," "high caloric," and "neutral" stimuli in 25 patients with AN and 25 participants in the comparison group (CG). We found a significant main effect for picture category and a significant interaction. The reward ratings were higher in patients with AN compared with CG for the "disorder specific reward" stimuli. In the reward subcategories, patients with AN had higher reward ratings compared with CG in all categories except of healthy food. The "disorder specific reward" stimuli of the categories "sport," "losing weight," and "healthy food" showed higher reward ratings compared with the categories "discipline," "thin bodies," and "appreciation of others" in patients with AN. The previously used category "thin bodies" used to investigate the reward system might be less effective compared with stimuli from the categories "sport," "losing weight," and "healthy food."