Individual Differences In Reward Sensitivity Research Articles

Dopamine multilocus genetic profiles predict sex differences in reactivity of the human reward system.

Sex differences in the neural processing of decision-making are of high interest as they may have pronounced effects on reward- and addiction-related processes. In these, the neurotransmitter dopamine plays a central role by modulating the responsiveness of the reward circuitry. The present functional magnetic resonance imaging study aimed to explore sex and dopamine transmission interactions in decision-making. 172 subjects (111 women) performed a behavioral self-control task assessing reward-related activation during acceptance and rejection of conditioned rewards. Participants were genotyped for six key genetic polymorphisms in the dopamine system that have previously been associated with individual differences in reward sensitivity or dopaminergic transmission in the human striatum, such as rs7118900 (dopamine receptor D2 (DRD2) Taq1A), rs1554929 (DRD2 C957T), rs907094 (DARPP-32), rs12364283 (DRD2), rs6278 (DRD2), and rs107656 (DRD2). The selected polymorphisms were combined in a so-called multilocus genetic composite (MGC) score reflecting the additive effect of different alleles conferring relative increased dopamine transmission in every individual. We successfully demonstrated that reward-related activation in the ventral striatum and ventral tegmental area (VTA) was significantly modulated by biologically informed MGC profiles and sex. When comparing men and women with low MGC profiles that may indicate lower dopamine transmission, only women displayed a reduced down-regulation of activation in the mesolimbic system during reward rejection and additionally, a significant non-linear u-shape relationship between MGC score and VTA activation. Taken together, by integrating neuroimaging and genetics, the present findings contribute to a better understanding of the effects of sex differences on the human brain.

Which Child Will Benefit From a Behavioral Intervention for ADHD? A Pilot Study to Predict Intervention Efficacy From Individual Reward Sensitivity

Objective: This article aims to assess whether individual differences in reward sensitivity can be used to predict which children with attention-deficit/hyperactivity disorder (ADHD) will benefit most from behavioral interventions that include reinforcement. Methods: A 12-week behavioral intervention was offered to 21 children with ADHD and their parents. Reward sensitivity was assessed prior to the intervention using a combination of psychological and physiological measures. ADHD symptoms were assessed pre- and posttreatment using the Strengths and Weaknesses of ADHD and Normal behavior (SWAN) rating scale. Results: Lower scores on one of the questionnaire scales were associated with greater pre/posttreatment differences in ADHD symptoms. Conclusion: We found that pre/posttreatment change was associated with one measure of parent-rated reward sensitivity. Children with low impulsive negative behavior toward gaining reward improved most during treatment. This result suggests that aspects of reward-related behaviors in ADHD may be useful to predict the effectiveness of treatment.

Reward sensitivity and electrodermal responses to actions and outcomes in a go/no-go task.

Skin conductance response (SCR) is used in psychophysiological research to measure the reactions of the autonomic nervous system to reward and punishment. While there is consistent evidence that SCR increases to both aversive and appetitive stimuli, it remains unclear whether SCR simply represents a general index of arousal to motivationally significant outcomes or may also differentiate action or inhibition of action that lead to such outcomes. Furthermore, individual differences in trait sensitivity to reward and punishment can influence physiological arousal during approach and avoidance behaviors. Yet, their inter-relationships have not been examined. To address these gaps, we employed a reward go/no-go task with ⅔ go and ⅓ no-go trials and an individually titrated go response window. Correct go and no-go responses were rewarded while incorrect responses were penalized. We examined whether SCR varied with outcome (win vs. loss), action (go vs. no-go), and individual differences in reward sensitivity (SR) and sex. The results showed greater SCRs to loss vs. win, to go vs. no-go success, and to go success in positive correlation with SR. Further, SCR mediated the relationship between SR and go success rate. In sex differences, men exhibited greater SCR which was more predictive of go success rate relative to women. In contrast, SCR was more predictive of no-go success rate in women. Thus, SCR varies according to behavioral contingency, outcome, sex, and reward sensitivity. These findings add to the literature by characterizing the individual and behavioral factors that may influence physiological arousal in response to salient events.

Individual Differences in Reward Sensitivity Modulate the Distinctive Effects of Conscious and Unconscious Rewards on Executive Performance.

Executive control can be driven by conscious and unconscious monetary cues. This has raised the exciting question regarding the role of conscious and unconscious reward in the regulation of executive control. Similarities and differences have been uncovered between unconscious and conscious processing of monetary rewards. In the present study, we explored whether individual differences associated with reward sensitivity foster these variations on memory-updating—a core component process of executive control. Participants (N = 60) with low, medium, and high reward sensitivity were selected and performed a numerical memory-updating task. At the beginning of each trial, a high (1 euro) or a low (5 cents) reward was presented subliminally (24 ms) or supraliminally (300 ms). Participants earned the reward by responding correctly. Participants with low reward sensitivity performed better for the high reward only in the subliminal condition. For participants with medium reward sensitivity, performance improved with high reward in both subliminal and supraliminal conditions. When participants had high reward sensitivity scores, the effect of reward was stronger in the supraliminal condition than the subliminal condition. These results show that the distinctive effects of conscious and unconscious rewards on executive performance are modulated by individual differences in reward sensitivity. We discuss this finding with reference to models of conscious/unconscious processing of reward stimuli.

Rewarding effects of physical activity predict sensitivity to the acute subjective effects of d-amphetamine in healthy volunteers.

While individual differences in reward sensitivity are believed to generalize across drugs and alternative rewards, this notion has received little empirical attention in human research. Here, we tested whether individual differences in the subjective rewarding effects of physical activity were associated with the subjective response to d-amphetamine administration. Healthy volunteers ( n=95; age 18-35 years) completed questionnaires measuring the self-reported pleasurable effects of physical activity and other covariates, and this was followed by two double-blind counterbalanced sessions during which they received either 20 mg oral d-amphetamine or placebo. Subjective drug effects measures were collected before and repeatedly after drug administration. Subjective d-amphetamine-related effects were then reduced via principal components analysis into latent factors of "positive mood," "arousal," and "drug high." Multiple regression models controlling for placebo-related scores, session order, demographics, body mass index, level of physical activity, and use of other drugs showed that degree of self-reported physical activity reward was positively associated with d-amphetamine-induced positive mood and arousal ( βs≥0.25, ps≤0.04), but was not associated with d-amphetamine-induced changes in drug high ( β=0.13, p=0.24). These results provide novel evidence suggesting that individual differences in reward sensitivity cross over between d-amphetamine reward and physical activity reward in humans.

Striatal reward sensitivity predicts therapy-related neural changes in alcohol addiction.

Individual differences in reward sensitivity along with weakened executive control are characteristic for alcohol use disorder (AUD). Emerging translational models of psychotherapy propose the integration of such neurobiological risk profiles to elucidate the mechanisms underlying behavior change in order to improve intervention efficacy. The primary aim of the study was to investigate whether striatal baseline reward sensitivity can be used as a neurobiological predictor of intervention-specific changes in neural functioning during AUD therapy. Fifty-eight detoxified AUD patients were randomly assigned to either receive cue exposure training (CET+TAU, N=40) or treatment as usual (TAU only, N=18). Pre- and post-treatment sensitivity to reward was assessed by a functional magnetic resonance imaging monetary reward paradigm. A moderated multiple regression analysis revealed a positive relationship between striatal baseline reward sensitivity and activation changes in the superior frontal gyrus and anterior cingulate cortex (ACC) after CET+TAU in contrast to a negative relationship after TAU only. Over all subjects, a stronger signal change in the superior frontal gyrus and ACC was associated with increased self-efficacy to abstain alcohol. These results provide evidence that reward sensitivity at baseline predicts neural changes in inhibitory networks after receiving CET+TAU. Striatal reward sensitivity might be a promising neurobiological marker to inform therapeutic decisions.

Monetary reward magnitude effects on behavior and brain function during goal-directed behavior

Reward may modulate the cognitive processes required for goal achievement, while individual differences in personality may affect reward modulation. Our aim was to test how different monetary reward magnitudes modulate brain activation and performance during goal-directed behavior, and whether individual differences in reward sensitivity affect this modulation. For this purpose, we scanned 37 subjects with a parametric design in which we varied the magnitude of monetary rewards (€0, €0.01, €0.5, €1 or €1.5) in a blocked fashion while participants performed an interference counting-Stroop condition. The results showed that the brain activity of left dorsolateral prefrontal cortex (DLPFC) and the striatum were modulated by increasing and decreasing reward magnitudes, respectively. Behavioral performance improved as the magnitude of monetary reward increased while comparing the non reward (€0) condition to any other reward condition, or the lower €0.01 to any other reward condition, and this improvement was related with individual differences in reward sensitivity. In conclusion, the locus of influence of monetary incentives overlaps the activity of the regions commonly involved in cognitive control.

Individual differences in the time course of reward processing: Stage-specific links with depression and impulsivity

Reward dysfunction has been implicated in a wide range of psychological disorders, including internalizing and externalizing psychopathology. Basic neuroscience research has shown that reward is a multistage process, yet it is unclear how specific stages relate to individual differences in reward sensitivity. The current study utilized event-related potentials elicited during a monetary incentive task to parse sub-stages within anticipatory and consummatory reward processing. Effects of depressive symptoms and trait impulsivity were examined at each sub-stage (N=92). Reward anticipation modulated neural activity across three sub-stages: cue detection (cue-P3), approach behavior (contingent negative variation, CNV), and outcome anticipation (stimulus preceding negativity). Reward delivery modulated activity across two sub-stages: initial evaluation (reward positivity, RewP), and allocation of attention (feedback-P3). Sensation seeking predicted faster reaction times, as well as cue-P3 and RewP amplitudes. Depression and lack of premeditation interacted to predict CNV and RewP amplitudes. Results demonstrate that individual differences in reward functioning are stage-specific.

Food Approach and Food Avoidance in Young Children: Relation with Reward Sensitivity and Punishment Sensitivity

It has recently been suggested that individual differences in Reward Sensitivity and Punishment Sensitivity may determine how children respond to food. These temperamental traits reflect activity in two basic brain systems that respond to rewarding and punishing stimuli, respectively, with approach and avoidance. Via parent-report questionnaires, we investigate the associations of the general motivational temperamental traits Reward Sensitivity and Punishment Sensitivity with Food Approach and Food Avoidance in 98 preschool children. Consistent with the conceptualization of Reward Sensitivity in terms of approach behavior and Punishment Sensitivity in terms of avoidance behavior, Reward Sensitivity was positively related to Food Approach, while Punishment Sensitivity was positively related to Food Avoidance. Future research should integrate these perspectives (i.e., general temperamental traits Reward Sensitivity and Punishment Sensitivity, and Food Approach and Avoidance) to get a better understanding of eating behavior and related body weight.

Adolescent behavioral and neural reward sensitivity: a test of the differential susceptibility theory.

Little is known about the causes of individual differences in reward sensitivity. We investigated gene–environment interactions (GxE) on behavioral and neural measures of reward sensitivity, in light of the differential susceptibility theory. This theory states that individuals carrying plasticity gene variants will be more disadvantaged in negative, but more advantaged in positive environments. Reward responses were assessed during a monetary incentive delay task in 178 participants with and 265 without attention-deficit/hyperactivity disorder (ADHD), from N=261 families. We examined interactions between variants in candidate plasticity genes (DAT1, 5-HTT and DRD4) and social environments (maternal expressed emotion and peer affiliation). HTTLPR short allele carriers showed the least reward speeding when exposed to high positive peer affiliation, but the most when faced with low positive peer affiliation or low maternal warmth. DAT1 10-repeat homozygotes displayed similar GxE patterns toward maternal warmth on general task performance. At the neural level, DRD4 7-repeat carriers showed the least striatal activation during reward anticipation when exposed to high maternal warmth, but the most when exposed to low warmth. Findings were independent of ADHD severity. Our results partially confirm the differential susceptibility theory and indicate the importance of positive social environments in reward sensitivity and general task performance for persons with specific genotypes.

Brain connectivity reflects human aesthetic responses to music.

Humans uniquely appreciate aesthetics, experiencing pleasurable responses to complex stimuli that confer no clear intrinsic value for survival. However, substantial variability exists in the frequency and specificity of aesthetic responses. While pleasure from aesthetics is attributed to the neural circuitry for reward, what accounts for individual differences in aesthetic reward sensitivity remains unclear. Using a combination of survey data, behavioral and psychophysiological measures and diffusion tensor imaging, we found that white matter connectivity between sensory processing areas in the superior temporal gyrus and emotional and social processing areas in the insula and medial prefrontal cortex explains individual differences in reward sensitivity to music. Our findings provide the first evidence for a neural basis of individual differences in sensory access to the reward system, and suggest that social-emotional communication through the auditory channel may offer an evolutionary basis for music making as an aesthetically rewarding function in humans.

Characterizing individual differences in reward sensitivity from the brain networks involved in response inhibition

A “disinhibited” cognitive profile has been proposed for individuals with high reward sensitivity, characterized by increased engagement in goal-directed responses and reduced processing of negative or unexpected cues, which impairs adequate behavioral regulation after feedback in these individuals. This pattern is manifested through deficits in inhibitory control and/or increases in RT variability. In the present work, we aimed to test whether this profile is associated with the activity of functional networks during a stop-signal task using independent component analysis (ICA). Sixty-one participants underwent fMRI while performing a stop-signal task, during which a manual response had to be inhibited. ICA was used to mainly replicate the functional networks involved in the task (Zhang and Li, 2012): two motor networks involved in the go response, the left and right fronto-parietal networks for stopping, a midline error-processing network, and the default-mode network (DMN), which was further subdivided into its anterior and posterior parts. Reward sensitivity was mainly associated with greater activity of motor networks, reduced activity in the midline network during correct stop trials and, behaviorally, increased RT variability. All these variables explained 36% of variance of the SR scores. This pattern of associations suggests that reward sensitivity involves greater motor engagement in the dominant response, more distractibility and reduced processing of salient or unexpected events, which may lead to disinhibited behavior.

Harmonic and frequency modulated ultrasonic vocalizations reveal differences in conditioned and unconditioned reward processing

Novelty and sensation seeking (NSS) and ultrasonic vocalizations (USVs) are both used as measures of individual differences in reward sensitivity in rodent models. High responders in the inescapable novelty screen have a greater response to low doses of amphetamine and acquire self-administration more rapidly, while the novelty place preference screen is positively correlated with compulsive drug seeking. These screens are uncorrelated and implicated in separate drug abuse models. 50kHz USVs measure affective state in rats and are evoked by positive stimuli. NSS and USVs are each implicated in drug response, self-administration, and reveal differences in individual behavior, yet their relationship with each other is not understood. The present study screened rats for their response to novelty and measured USVs of all call types in response to heterospecific play to determine the relationships between these individual difference traits. Generally, we hypothesized that 50kHz USVs would be positively correlated with the NPP screen, and that 22kHz would be positively correlated with the IEN screen. Results indicate none of the screens were correlated indicating they are measuring different individual difference traits. However, examination of the subtypes of USVs indicated harmonic USVs and the novelty place preference were positively correlated. Harmonic 50kHz USVs increased in response to reward associated context, suggesting animals conditioned to the heterospecific tickle arena and anticipated rewarding stimuli, while FM only increased in response to tickling. USV subtypes can be used to elucidate differences in attribution of incentive value across conditioned stimuli and receipt of rewarding stimuli. These data provide strong support that harmonic and FM USVs can be used to understand reward processing in addition to NSS.

Individual differences in sensitivity to reward and punishment and neural activity during reward and avoidance learning.

In this functional neuroimaging study, we investigated neural activations during the process of learning to gain monetary rewards and to avoid monetary loss, and how these activations are modulated by individual differences in reward and punishment sensitivity. Healthy young volunteers performed a reinforcement learning task where they chose one of two fractal stimuli associated with monetary gain (reward trials) or avoidance of monetary loss (avoidance trials). Trait sensitivity to reward and punishment was assessed using the behavioral inhibition/activation scales (BIS/BAS). Functional neuroimaging results showed activation of the striatum during the anticipation and reception periods of reward trials. During avoidance trials, activation of the dorsal striatum and prefrontal regions was found. As expected, individual differences in reward sensitivity were positively associated with activation in the left and right ventral striatum during reward reception. Individual differences in sensitivity to punishment were negatively associated with activation in the left dorsal striatum during avoidance anticipation and also with activation in the right lateral orbitofrontal cortex during receiving monetary loss. These results suggest that learning to attain reward and learning to avoid loss are dependent on separable sets of neural regions whose activity is modulated by trait sensitivity to reward or punishment.

Reward sensitivity predicts ice cream-related attentional bias assessed by inattentional blindness

The cognitive mechanism underlying the association between individual differences in reward sensitivity and food craving is unknown. The present study explored the mechanism by examining the role of reward sensitivity in attentional bias toward ice cream cues. Forty-nine college students who displayed high level of ice cream craving (HICs) and 46 who displayed low level of ice cream craving (LICs) performed an inattentional blindness (IB) task which was used to assess attentional bias for ice cream. In addition, reward sensitivity and coping style were assessed by the Behavior Inhibition System/Behavior Activation System Scales and Simplified Coping Style Questionnaire. Results showed significant higher identification rate of the critical stimulus in the HICs than LICs, suggesting greater attentional bias for ice cream in the HICs. It was indicated that attentional bias for food cues persisted even under inattentional condition. Furthermore, a significant correlation was found between the attentional bias and reward sensitivity after controlling for coping style, and reward sensitivity predicted attentional bias for food cues. The mediation analyses showed that attentional bias mediated the relationship between reward sensitivity and food craving. Those findings suggest that the association between individual differences in reward sensitivity and food craving may be attributed to attentional bias for food-related cues.

Abnormal reward functioning across substance use disorders and major depressive disorder: Considering reward as a transdiagnostic mechanism

A common criticism of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2013) is that its criteria are based more on behavioral descriptions than on underlying biological mechanisms. Increasingly, calls have intensified for a more biologically-based approach to conceptualizing, studying, and treating psychological disorders, as exemplified by the Research Domain Criteria Project (RDoC). Among the most well-studied neurobiological mechanisms is reward processing. Moreover, individual differences in reward sensitivity are related to risk for substance abuse and depression. The current review synthesizes the available preclinical, electrophysiological, and neuroimaging literature on reward processing from a transdiagnostic, multidimensional perspective. Findings are organized with respect to key reward constructs within the Positive Valence Systems domain of the RDoC matrix, including initial responsiveness to reward (physiological ‘liking’), approach motivation (physiological ‘wanting’), and reward learning/habit formation. In the current review, we (a) describe the neural basis of reward, (b) elucidate differences in reward activity in substance abuse and depression, and (c) suggest a framework for integrating these disparate literatures and discuss the utility of shifting focus from diagnosis to process for understanding liability and co-morbidity. Ultimately, we believe that an integrative focus on abnormal reward functioning across the full continuum of clinically heterogeneous samples, rather than within circumscribed diagnostic categories, might actually help to refine the phenotypes and improve the prediction of onset and recovery of these disorders.

Association between serotonin Cumulative Genetic Score and the Behavioral Approach System (BAS): Moderation by early life environment

The present study investigates if genetic variation in the serotonergic system interacts with early adversity to predict changes in the Behavioral Approach System (BAS), a system that taps into reward processing. In a sample of community adults (N=236) the influence of single serotonergic candidate polymorphisms on BAS was analyzed, we also examined the aggregate contribution of these genetic variants by creating a Cumulative Genetic Score (CGS). A CGS quantifies an individual’s cumulative risk by aggregating the number of risk alleles across the candidate polymorphisms. After individual gene analysis, three candidate genes rs7305115 (TPH2), rs6311 (HTR2A), and rs6295 (HTR1A) were combined into the CGS. There were no significant interactions between individual candidate polymorphisms and childhood adversity, but the CGS interacted with childhood adversity to explain a significant amount of variance (11.6%) in the BAS. Findings suggest that genetic variations in the serotonergic system in combination with childhood adversity contribute to individual differences in reward sensitivity.

A new window to understanding individual differences in reward sensitivity from attentional networks

Existing evidence suggests that the presence of reward cues modifies the activity in attentional networks, however, the nature of these influences remains poorly understood. Here, we performed independent component analysis (ICA) in two fMRI datasets corresponding to two incentive delay tasks, which compared the response to reward (money and erotic pictures) and neutral cues, and yielded activations in the ventral striatum using a general linear model approach. Across both experiments, ICA revealed that both the right frontoparietal network and default mode network time courses were positively and negatively modulated by reward cues, respectively. Moreover, this dual neural response pattern was enhanced in individuals with strong reward sensitivity. Therefore, ICA may be a complementary tool to investigate the relevant role of attentional networks on reward processing, and to investigate reward sensitivity in normal and pathological populations.

Reward sensitivity modulation of brain activity during response inhibition

This work investigated the relationship between individual differences in reward sensitivity and the activity of brain regions involved in response inhibition. Participants (n = 51, 20 females) performed a stop-signal task while undergoing fMRI scanning. Inhibition of dominant responses during the task was associated to activation of bilateral anterior insula. Parameter estimates from these activation clusters were extracted to run an ROI analysis. Reward sensitivity, as measured by the Sensitivity to Reward (SR) scale from the SPSRQ (Torrubia et al., 2001), was negatively correlated with activity in right anterior insula. A whole-brain correlation analysis was also conducted, in which SR scores were negatively correlated with activity in the anterior cingulate cortex and the left supramarginal gyrus. These results suggest that individual differences in reward sensitivity may involve differences in cognitive processing that are manifested as distinct patterns of brain activation, even in the absence of explicit reward contingencies.

Implicit reward-focused eating expectancies as a mediator of reward sensitivity and externally-cued eating style

The increasing rate of obesity in recent decades is argued as being due by our unprecedented access to high calorie food. However, despite this, many still maintain a healthy weight. We propose that individual differences in reward sensitivity places some people at a heightened risk of noticing and seeking out such food. In the current study, implicit learning of rewarding outcomes associated with palatable food was hypothesised as one mechanism by which reward sensitivity and eating are linked. Using a moderated-mediation model in a sample of 117 university women, high reward sensitive women showed a greater approach response on a computerised behavioural task of eating expectancies following exposure to food images. This, in turn, was associated with higher scores on externally-cued eating. This study further supports individual differences in reward sensitivity and the propensity to respond in an approach fashion following food cue exposure via implicit food associations.