Alterations in the dopaminergic system have been implicated in both animal and human obesity. However, to date, a comprehensive model on the nature and functional relevance of this relationship is missing. In particular, human data remain equivocal in that seemingly inconsistent reports exist of positive, negative or even no relationships between dopamine D2/D3 receptor availability in the striatum and measures of obesity. Further, data on receptor availability have been commonly interpreted as reflecting receptor density, despite the possibility of an alternative interpretation, namely alterations in the basal levels of endogenous dopaminergic tone. Here, we provide a unifying framework that is able to explain the seemingly contradictory findings and offer an alternative and novel perspective on existing data. In particular, we suggest (i) a quadratic relationship between alterations in the dopaminergic system and degree of obesity, and (ii) that the observed alterations are driven by shifts in the balance between general dopaminergic tone and phasic dopaminergic signalling. The proposed model consistently integrates human data on molecular and behavioural characteristics of overweight and obesity. Further, the model provides a mechanistic framework accounting not only for the consistent observation of altered (food) reward–responsivity but also for the differences in reinforcement learning, decision-making behaviour and cognitive performance associated with measures of obesity.

Neurobiological theories of bipolar spectrum disorder (BSD) propose that the emotional dysregulation characteristic of BSD stems from disrupted prefrontal control over subcortical limbic structures (Strakowski et al., 2012; Depue & Iacono, 1989). However, existing neuroimaging research on functional connectivity between frontal and limbic brain regions remains inconclusive, and is unable to adequately characterize global functional network dynamics. Graph theoretical analysis provides a framework for understanding the local and global connections of the brain and comparing these connections between groups (Sporns et al., 2004). The purpose of this study was to investigate resting state functional connectivity in individuals at low and high risk for BSD based on moderate versus high reward sensitivity, both with and without a BSD diagnosis, using graph theoretical network analysis. Results demonstrated decreased connectivity in a cognitive control region (dorsolateral prefrontal cortex), but increased connectivity of a brain region involved in the detection and processing of reward (bilateral orbitofrontal cortex), among participants at high risk for BSD. Participants with BSD showed increased inter-module connectivity of the dorsal anterior cingulate cortex (ACC). Reward sensitivity was associated with decreased global and local efficiency, and interacted with BSD risk group status to predict inter-module connectivity. Findings are discussed in relation to neurobiological theories of BSD. / Psychology

Eating disorders involve the inability to appropriately regulate a behavioral response to food due to impaired reward sensitivity, affect regulation and cognitive control, resulting in deleterious effects on the individual's physical and mental well-being. In this way eating disorders may be analogous to addictive disorders (e.g. alcoholism). Furthermore, eating and addictive disorders co-occur at very high rates and appear to have similar contributing mechanisms (impaired reward sensitivity, impaired affect regulation and impaired cognitive control). Overvaluation of weight and shape concerns appears to be one unique characteristic of eating disorders, not shared with addiction. The current study examined the relationship between impaired reward sensitivity, impaired affect regulation and impaired cognitive control with addiction vulnerability. Furthermore, weight and shape concerns were examined as a potential moderator of the relationship between addiction vulnerability and binge eating. A total of 1000 undergraduate students completed self-report measures examining the three posited mechanisms for addiction vulnerability and disordered eating. A subset of 101 students (50 binge-eaters and 51 non-binge eaters) also completed behavioral measures of the three posited mechanisms. The results of this study support the proposed model that weight and shape concerns moderate the relationship between addiction vulnerability and binge eating. Results also demonstrated on a behavioral task that individuals who endorsed binge eating were more likely to act impulsively and quit the PASAT-C task faster than control subjects. Furthermore, they demonstrated a greater increase in irritability while completing the task which may have resulted in their desire to quit the task earlier. No differences were found on behavioral measures of reward sensitivity (delay discount task) or cognitive control (stop signal task). Future studies should continue to examine the construct of addiction vulnerability to provide additional validity for the construct as well as examine it in the context of all forms of disordered eating. / Psychology

Mobile electronic devices such as smartphones are playing an increasingly pervasive role in our daily activities. A growing body of literature is beginning to investigate how mobile technology habits might relate to individual differences in cognitive traits. The present study is an investigation into how individual differences in intertemporal preference, impulse control, and reward sensitivity, are predictive of the degree to which people engage with their smartphones, in two separate experiments. Experiment 1 utilized behavioral and self-reported measures for each of the aforementioned cognitive traits to examine their relationships with Mobile Technology Engagement (MTE) as defined in Wilmer & Chein (2016). The results replicated earlier work demonstrating that mobile technology engagement is positively correlated with a tendency to discount delayed rewards. A positive relationship was also observed between MTE and reward sensitivity. In an attempt to investigate the neural origins of the relationship observed in Experiment 1, Experiment 2 examined the association between mobile technology usage and white matter connectivity from the ventral striatum (vSTR) to the ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC), pathways that have been previously implicated as biological markers for individual differences in intertemporal preference. Regression analyses revealed that both pathways predicted delay discounting performance, but only vSTR-vmPFC predicted mobile technology engagement. Taken together, the results of these two experiments provide important foundational evidence for both neural and cognitive factors that predict how individuals engage with mobile technology. / Psychology

Evolutionary models of adolescent and young adult risk-taking posit that risk-taking increases during this period of the life span as a strategic way for males, in particular, to show dominance, increase perceptions of attractiveness by the opposite-sex, and maximize their chances of acquiring a romantic partner (and ultimately produce offspring). Consistent with this perspective, existing research demonstrates that attractive females increase risk-taking in single males, in part by enhancing males’ sensitivity to rewards and diminishing their ability to inhibit impulsive behavior. By contrast, romantically committed males engage in less risk taking than their single counterparts, although the mechanisms underlying the effect of romantic partners/partnerships on male risk-taking are less clear. In the present study, I employed a behavioral paradigm that has been used in prior studies of peer influence to examine how romantic partners affect decision-making processes and risk-taking behavior in young heterosexual males (18 to 24 years old). I also explored whether there are particular individual and relationship characteristics that moderate the effect of romantic partners on males’ decision-making. This study was conducted using a sample of 134 romantically involved males (mean age=20.2, SD=1.65; 64% White) who were randomly assigned to participate in one of three experimental conditions: alone, in the presence of an attractive female confederate, or in the presence of their romantic partner. Across conditions, I compared males’ behavioral performance on five outcome measures: risk taking (using the Stoplight Task), preference for immediate rewards (using a Delay Discounting Task), reward learning and cost avoidance (using a modified version of the Iowa Gambling Task), and inhibitory control over both neutral and emotionally charged stimuli (using cognitive and emotional versions of the Stroop Task). I found that the presence of romantic partners diminishes risk taking in males, but that romantic partners do not have a significant impact on males’ sensitivity to rewards (neither immediate nor long-term), sensitivity to loss (i.e., cost avoidance), or their ability to inhibit attention to interfering—neutral or emotional—stimuli. However, improvements in cognitive control in the presence of romantic partners were observed among males who report low levels of passionate love. That is, mildly infatuated males exhibited better cognitive control in the presence of their romantic partners relative to mildly infatuated males who were alone. Partner presence had no such effects among males who reported being highly infatuated with their girlfriends. The presence of an attractive female stranger triggered a protective response among romantically involved males—prompting them to take fewer risks (when they are highly committed to their partners), to more quickly avoid decisions that lead to long-term loss (among older males only), and to exhibit better cognitive control (only among males in relatively longer relationships). The presence of an attractive female stranger did not affect males’ sensitivity to rewards. Evidently, the relative impact of an attractive female stranger on males’ risk taking and decision-making is highly dependent on individual and relationship factors, a finding that emphasizes the importance of context when it comes to understanding males’ relative susceptibility to temptation (e.g., other females) and opportunities for potential risk (e.g., infidelity). By contrast, the dampening effect of romantic partners on male risk taking is neither dependent on individual or relationship characteristics nor the result of romantic partners’ influence on reward sensitivity or inhibitory control. However, given the finding that romantic partners enhance cognitive control when feelings of passionate love are relatively low, future research should examine how passionate love and cognitive control interact to predict risk taking. Although I could not identify potential mechanisms to explain why the presence of romantic partners diminishes males’ risk-taking, the current study demonstrates that under specific circumstances—such as when there is high relationship commitment or when the relationship is relatively long—the presence of an attractive female stranger can stimulate romantically involved males to engage regulatory processes that may contribute to their reduced inclination toward risky behavior in that context. This finding is consistent with prior studies and suggests that the presence of tempting stimuli and potential threats to relationship fidelity can trigger males’ deliberate engagement of regulatory processes in effort to maintain their current romantic relationship. In contrast, males’ reduced inclination to engage in risky behavior in the presence of their romantic partners may be automatically activated (without inducing a particular psychological state) regardless of individual and relationship characteristics. / Psychology

The motivational value of food is lower during satiety compared to fasting. Dynamic changes in motivational value promote food seeking or meal cessation. In obesity this mechanism might be compromised since obese subjects ingest energy beyond homeostatic needs. Thus, lower adaptation of eating behaviour with respect to changes in motivational value might cause food overconsumption in obesity. To test this hypothesis, we implemented a selective satiation procedure to investigate the relationship between obesity and the size of the behavioural devaluation effect in humans. Lean to obese men (mean age 25.9, range 19–30 years; mean BMI 29.1, range 19.2–45.1 kg/m2) were trained on a free operant paradigm and learned to associate cues with the possibility to win different food rewards by pressing a button. After the initial training phase, one of the rewards was devalued by consumption. Response rates for and wanting of the different rewards were measured pre and post devaluation. Behavioural sensitivity to reward devaluation, measured as the magnitude of difference between pre and post responses, was regressed against BMI. Results indicate that (1) higher BMI compared to lower BMI in men led to an attenuated behavioural adjustment to reward devaluation, and (2) the decrease in motivational value was associated with the decrease in response rate between pre and post. Change in explicitly reported motivational value, however, was not affected by BMI. Thus, we conclude that high BMI in men is associated with lower behavioural adaptation with respect to changes in motivational value of food, possibly resulting in automatic overeating patterns that are hard to control in daily life.

The motivational value of food is lower during satiety compared to fasting. Dynamic changes in motivational value promote food seeking or meal cessation. In obesity this mechanism might be compromised since obese subjects ingest energy beyond homeostatic needs. Thus, lower adaptation of eating behaviour with respect to changes in motivational value might cause food overconsumption in obesity. To test this hypothesis, we implemented a selective satiation procedure to investigate the relationship between obesity and the size of the behavioural devaluation effect in humans. Lean to obese men (mean age 25.9, range 19–30 years; mean BMI 29.1, range 19.2–45.1 kg/m2) were trained on a free operant paradigm and learned to associate cues with the possibility to win different food rewards by pressing a button. After the initial training phase, one of the rewards was devalued by consumption. Response rates for and wanting of the different rewards were measured pre and post devaluation. Behavioural sensitivity to reward devaluation, measured as the magnitude of difference between pre and post responses, was regressed against BMI. Results indicate that (1) higher BMI compared to lower BMI in men led to an attenuated behavioural adjustment to reward devaluation, and (2) the decrease in motivational value was associated with the decrease in response rate between pre and post. Change in explicitly reported motivational value, however, was not affected by BMI. Thus, we conclude that high BMI in men is associated with lower behavioural adaptation with respect to changes in motivational value of food, possibly resulting in automatic overeating patterns that are hard to control in daily life.

Aims: To examine whether personality traits predict the course of addictive behaviours in general and whether predictive associations differ between non-substance related (NR) and substance related (SR) addictive behaviours. Methodology: We recruited 338 individuals (19–27 y, 59 % female) from a random community sample with NR, SR, or no DSM-5 addictive disorder. Predictors were the Big Five personality traits (NEO-FFI) and reward and punishment sensitivity (BIS/BAS questionnaire). Outcomes were the slopes of addictive behaviours (i. e., quantity, frequency, and number of DSM-5 criteria) over three years. Bayesian multiple regressions were used to analyse the probabilities for each hypothesis. Results: The evidence that higher neuroticism, lower conscientiousness, lower agreeableness, higher extraversion, lower openness, higher reward sensitivity, and lower punishment sensitivity predict increased addictive behaviours over time was, overall, moderate to high (69 % to 99 %) and varied by trait and outcome. Predictive associations were mostly higher for NR compared with SR addictive behaviours. Conclusions: Personality traits predict the course of addictive behaviours, but associations were only about half as large as expected. While some personality traits, such as lower conscientiousness, predict increases in both NR and SR addictive behaviours over time, others, such as lower punishment sensitivity, seem to specifically predict increases in NR addictive behaviours. / Zielsetzung: Untersuchung der Vorhersage des Verlaufs von abhängigem Verhalten durch Persönlichkeitsmerkmale und Prüfung, ob sich diese prädiktiven Assoziationen zwischen verhaltensbezogenem (VB) und substanzbezogenem (SB) abhängigen Verhalten unterscheiden. Methodik: Wir rekrutierten 338 Personen (19–27 Jahre, 59 % weiblich) aus einer kommunalen Zufallsstichprobe mit einer VB-, einer SB- oder keiner DSM-5-Abhängigkeit. Prädiktoren waren die „Big Five“-Persönlichkeitsmerkmale (NEO-FFI) und die Belohnungs- und Bestrafungssensitivität (BIS/BAS-Fragebogen). Die Outcomes waren der Verlauf des abhängigen Verhaltens (d. h. Menge und Häufigkeit des Konsums und Anzahl der erfüllten DSM-5-Kriterien) über drei Jahre. Zur Analyse der Wahrscheinlichkeiten für jede Hypothese wurden Bayes‘sche multiple Regressionsanalysen verwendet. Ergebnisse: Die Evidenz, dass höherer Neurotizismus, geringere Gewissenhaftigkeit, geringere Verträglichkeit, höhere Extraversion, geringere Offenheit, höhere Belohnungssensitivität und geringere Bestrafungssensitivität eine Zunahme von Merkmalen abhängigen Verhaltens im Laufe der Zeit vorhersagen, war insgesamt moderat bis hoch (69 % bis 99 %) und variierte je nach Persönlichkeitsmerkmal und Outcome. Die prädiktiven Assoziationen waren meist höher für VB im Vergleich zu SB abhängigen Verhalten. Schlussfolgerungen: Persönlichkeitsmerkmale sagen den Verlauf des abhängigen Verhaltens voraus, allerdings waren die Zusammenhänge nur etwa halb so groß wie erwartet. Während einige Persönlichkeitsmerkmale, wie z. B. eine geringere Gewissenhaftigkeit, im Laufe der Zeit eine Zunahme des VB und des SB abhängigen Verhaltens vorhersagen, scheinen andere, wie z. B. eine geringere Sensibilität für Bestrafung, speziell eine Zunahme des VB abhängigen Verhaltens vorherzusagen.