Amplified Striatal Responses to Near-Miss Outcomes in Pathological Gamblers

Neural mechanisms of behavioral addiction: An ALE meta-analysis and MACM analysis

Background and aims

Behavioral addictions (BAs) represent complex and multifaceted disorders often associated with maladaptive neural alteration. To deepen our understanding of the essence of BAs, this study focuses on the neural mechanisms underlying its three stages: reward seeking, self-control, and decision-making. The aim of the current meta-analysis is to investigate the brain regions and neural networks involved in BAs.

Methods

Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we systematically searched for relevant articles published before September 1, 2024, in the Web of Science and PubMed databases, and supplemented our search with Google Scholar. We conducted analyses using activation likelihood estimation (ALE) meta-analysis and meta-analytic connectivity modeling (MACM) analyses.

Results

A total of 50 functional magnetic resonance imaging studies involving 906 participants were included. The findings showed that individuals with BAs exhibited hyperactivation in the right inferior frontal gyrus (IFG), bilateral caudate and left middle frontal gyrus (MFG), and a high degree of connectivity was found between the right caudate, left caudate, and right IFG. These findings indicated that BAs were associated with the fronto-striatal circuits. Individuals with BAs demonstrate specific neural activation patterns in the reward seeking, self-control, and decision-making stages, characterized by differences in activation and functional connectivity of brain regions associated with these stages.

Discussion and conclusions

This study verifies the pivotal role of the fronto-striatal circuits in BAs and highlights the specific patterns of brain activity in different stages of addictive behavior. These findings expand our understanding of neural mechanisms underlying BAs and supports and provide partial support for the I-PACE model.

Striatal dopamine D2/D3 receptor regulation of human reward processing and behaviour

Signalling at dopamine D2/D3 receptors is thought to underlie motivated behaviour, pleasure experiences and emotional expression based on animal studies, but it is unclear if this is the case in humans or how this relates to neural processing of reward stimuli. Using a randomised, double-blind, placebo-controlled, crossover neuroimaging study, we show in healthy humans that sustained dopamine D2/D3 receptor antagonism for 7 days results in negative symptoms (impairments in motivated behaviour, hedonic experience, verbal and emotional expression) and that this is related to blunted striatal response to reward stimuli. In contrast, 7 days of partial D2/D3 agonism does not disrupt reward signalling, motivated behaviour or hedonic experience. Both D2/D3 antagonism and partial agonism induce motor impairments, which are not related to striatal reward response. These findings identify a central role for D2/D3 signalling and reward processing in the mechanism underlying motivated behaviour and emotional responses in humans, with implications for understanding neuropsychiatric disorders such as schizophrenia and Parkinson's disease.

Neurotransmitters crosstalk and regulation in the reward circuit of subjects with behavioral addiction

Behavioral addictive disorders (BADs) have become a significant societal challenge over time. The central feature of BADs is the loss of control over engaging in and continuing behaviors, even when facing negative consequences. The neurobiological underpinnings of BADs primarily involve impairments in the reward circuitry, encompassing the ventral tegmental area, nucleus accumbens in the ventral striatum, and prefrontal cortex. These brain regions form networks that communicate through neurotransmitter signaling, leading to neurobiological changes in individuals with behavioral addictions. While dopamine has long been associated with the reward process, recent research highlights the role of other key neurotransmitters like serotonin, glutamate, and endorphins in BADs' development. These neurotransmitters interact within the reward circuitry, creating potential targets for therapeutic intervention. This improved understanding of neurotransmitter systems provides a foundation for developing targeted treatments and helps clinicians select personalized therapeutic approaches.

The modulation of reward expectancy on the processing of near-miss outcomes: An ERP study

A near-miss is a situation in which a gambler almost wins but falls short by a small margin, which motivates gambling by making it feel like success is within reach. Existing research has extensively investigated the influence of contextual information on near-miss outcome processing; however, the impact of reward expectancy has received limited attention thus far. To address this gap, we utilized the wheel of fortune task and event-related potential technique (ERP) to quantify the electrophysiological responses associated with gambling outcomes at different levels of reward expectancy. Behaviorally, near-miss outcomes elicited a greater occurrence of counterfactual thoughts, feelings of regret, and heightened anticipation of rewards for subsequent trials compared to full-miss outcomes. ERP findings indicated that in contrast to full-miss outcomes, near-miss outcomes diminished feedback-related negativities (FRNs) and amplified P300s when reward expectancy was low, but amplified FRNs and diminished P300s when reward expectancy was high. These findings provide valuable insights into the neural mechanisms underlying the processing of outcome proximity and reward expectancy.

Power and Gambling: Dispositional Power Predicts Persistence on a Computerized Scratchcard Task

In gambling contexts, near-misses tend to be perceived as more aversive yet elicit greater motivation to continue playing than clear losses. The current research aimed to examine these effects in the context of situational and dispositional social power. In a pre-registered online study, Hong Kong Chinese undergraduate students (N = 238) with varying levels of gambling involvement completed a measure assessing their general beliefs about their ability to influence others and were then randomly assigned to imagine themselves in a position of high or low power. Participants subsequently played a computerized scratchcard task that delivered wins, near-misses, and clear losses and took trial-by-trial ratings of valence, arousal, and motivation. Following a mandatory phase, persistence was measured via the number of additional scratchcards participants chose to purchase. The results generally corroborated previous findings of different subjective appraisals to near-misses vs. clear losses, but surprisingly found that near-misses were considered to be more pleasant than clear losses. Situational power did not differentially modify these responses. Nevertheless, a main effect of dispositional power emerged in that participants who felt chronically high in power were twice as likely to purchase additional scratchcards compared to their low dispositional power counterparts. This study suggests that a generalized sense of power but not situational power triggers approach motivation in the form of prolonged gambling play.

Effects of dopamine and opioid receptor antagonism on the neural processing of social and nonsocial rewards

Rewards are a broad category of stimuli inducing approach behavior to aid survival. Extensive evidence from animal research has shown that wanting (the motivation to pursue a reward) and liking (the pleasure associated with its consumption) are mostly regulated by dopaminergic and opioidergic activity in dedicated brain areas. However, less is known about the neuroanatomy of dopaminergic and opioidergic regulation of reward processing in humans, especially when considering different types of rewards (i.e., social and nonsocial). To fill this gap of knowledge, we combined dopaminergic and opioidergic antagonism (via amisulpride and naltrexone administration) with functional neuroimaging to investigate the neurochemical and neuroanatomical bases of wanting and liking of matched nonsocial (food) and social (interpersonal touch) rewards, using a randomized, between-subject, placebo-controlled, double-blind design. While no drug effect was observed at the behavioral level, brain activity was modulated by the administered compounds. In particular, opioid antagonism, compared to placebo, reduced activity in the medial orbitofrontal cortex during consumption of the most valued social and nonsocial rewards. Dopamine antagonism, however, had no clear effects on brain activity in response to reward anticipation. These findings provide insights into the neurobiology of human reward processing and suggest a similar opioidergic regulation of the neural responses to social and nonsocial reward consumption.

Gambling and virtual reality: unraveling the illusion of near-misses effect

Introduction

Studying gambling behavior is a crucial element in reducing the impact of problem gambling. Nevertheless, most current research is carried out in controlled laboratory settings rather than real-life situations, which raises concerns about how applicable the findings are in the broader context. Virtual reality (VR) has proven to be a valuable tool and has been utilized in various experimental scenarios. A limited number of studies have employed VR to investigate gambling behaviors, and few have explored them in an older adolescent context.

Methods

This study examined the behavioral and physiological effects of gambling behavior, including problem gambling, gaming addiction, and risk-taking decision-making in a sample of 36 high-school students aged between 18 to 20 years using an ad-hoc constructed VR scenario designed to simulate a slot-machine platform.

Results

The behavioral results highlighted that participants reporting more problem gambling were sensitive to near-misses: i.e., they bet more after near-misses than after losses. This result may reflect the false belief that gamblers, after near-misses, are closer to winning. Physiological data showed that participants exhibited heart rate deceleration during the anticipation of the outcome, which has been suggested to represent a marker of feedback anticipation processing and hyposensitivity to losses.

Discussion

Overall, this study provides evidence for a new VR tool to assess gambling behaviors and new insights into gambling-related behavioral and physiological factors. Implications for the treatment of problem gambling are discussed.

Abnormal frontostriatal connectivity and serotonin function in gambling disorder: A preliminary exploratory study

Background

The neurobiological mechanisms of gambling disorder are not yet fully characterized, limiting the development of treatments. Defects in frontostriatal connections have been shown to play a major role in substance use disorders, but data on behavioral addictions, such as gambling disorder, are scarce. The aim of this study was to 1) investigate whether gambling disorder is associated with abnormal frontostriatal connectivity and 2) characterize the key neurotransmitter systems underlying the connectivity abnormalities.

Methods

Fifteen individuals with gambling disorder and 17 matched healthy controls were studied with resting-state functional connectivity MRI and three brain positron emission tomography scans, investigating dopamine (18F-FDOPA), opioid (11C-carfentanil) and serotonin (11C-MADAM) function. Frontostriatal connectivity was investigated using striatal seed-to-voxel connectivity and compared between the groups. Neurotransmitter systems underlying the identified connectivity differences were investigated using region-of-interest and voxelwise approaches.

Results

Individuals with gambling disorder showed loss of functional connectivity between the right nucleus accumbens (NAcc) and a region in the right dorsolateral prefrontal cortex (DLPFC) (PFWE <0.05). Similarly, there was a significant Group x right NAcc interaction in right DLPFC 11C-MADAM binding (p = 0.03) but not in 18F-FDOPA uptake or 11C-carfentanil binding. This was confirmed in voxelwise analyses showing a widespread Group x right NAcc interaction in the prefrontal cortex 11C-MADAM binding (PFWE <0.05). Right NAcc 11C-MADAM binding potential correlated with attentional impulsivity in individuals with gambling disorder (r = -0.73, p = 0.005).

Discussion

Gambling disorder is associated with right hemisphere abnormal frontostriatal connectivity and serotonergic function. These findings will contribute to understanding the neurobiological mechanism and may help identify potential treatment targets for gambling disorder.

Dynamic expectations: Behavioral and electrophysiological evidence of sub-second updates in reward predictions

Expectations are often dynamic: sports fans know that expectations are rapidly updated as games unfold. Yet expectations have traditionally been studied as static. Here we present behavioral and electrophysiological evidence of sub-second changes in expectations using slot machines as a case study. In Study 1, we demonstrate that EEG signal before the slot machine stops varies based on proximity to winning. Study 2 introduces a behavioral paradigm to measure dynamic expectations via betting, and shows that expectation trajectories vary as a function of winning proximity. Notably, these expectation trajectories parallel Study 1's EEG activity. Studies 3 (EEG) and 4 (behavioral) replicate these findings in the loss domain. These four studies provide compelling evidence that dynamic sub-second updates in expectations can be behaviorally and electrophysiologically measured. Our research opens promising avenues for understanding the dynamic nature of reward expectations and their impact on cognitive processes.

Neural fingerprints of gambling disorder using diffusion tensor imaging

Gambling disorder (GD) is a behavioral addiction associated with personal, social and occupational consequences. Thus, examining GD's clinical relationship with its neural substrates is critical. We compared neural fingerprints using diffusion tensor imaging (DTI) in GD subjects undergoing treatment relative to healthy volunteers (HV). Fifty-three (25 GD, 28 age-matched HV) males were scanned with structural magnetic resonance imaging (MRI) and DTI. We applied probabilistic tractography based on DTI scanning data, preprocessed and analyzed using permutation testing of individual connectivity weights between regions for group comparison. Permutation-based comparisons between group-averaged connectomes highlighted significant structural differences. The GD group demonstrated increased connectivity, and striatal network reorganisation, contrasted by reduced connectivity within and to frontal lobe nodes. Modularity analysis revealed that the GD group had fewer hubs integrating information across the brain. We highlight GD neural changes involved in controlling risk-seeking behaviors. The observed striatal restructuring converges with previous research, and the increased connectivity affects subnetworks highly active in gambling situations, although these findings are not significant when correcting for multiple comparisons. Modularity analysis underlines that, despite connectivity increases, the GD connectome loses hubs, impeding its neuronal network coherence. Together, these results demonstrate the feasibility of using whole-brain computational modeling in assessing GD.

Dynamic expectations: Behavioral and electrophysiological evidence of sub-second updates in reward predictions

Expectations are often dynamic: any sports fan knows that expectations are rapidly updated as games unfold. Yet expectations have traditionally been studied as static. Here, using slot machines as a case study, we provide parallel behavioral and electrophysiological evidence of sub-second moment-to-moment changes in expectations. In Study 1, we show that the dynamics of the EEG signal before the slot machine stopped differed depending on the nature of the outcome, including not only whether the participant won or lost, but also how close they came to winning. In line with our predictions, Near Win Before outcomes (the slot machine stops one item before a match) were similar to Wins, but different than Near Win After (the machine stops one item after a match) and Full Miss (the machine stops two or three items from a match). In Study 2, we designed a novel behavioral paradigm to measure moment-to-moment changes in expectations via dynamic betting. We found that different outcomes also elicited unique expectation trajectories in the deceleration phase. Notably, these behavioral expectation trajectories paralleled Study 1's EEG activity in the last second prior to the machine's stop. In Studies 3 (EEG) and 4 (behavior) we replicated these findings in the loss domain where a match entails a loss. Again, we found a significant correlation between behavioral and EEG results. These four studies provide the first evidence that dynamic sub-second updates in expectations can be behaviorally and electrophysiologically measured. Our findings open up new avenues for studying the ongoing dynamics of reward expectations and their role in healthy and unhealthy cognition.

Autonomic responses during Gambling: the Effect of Outcome Type and Sex in a large community sample of young adults

Psychological theories consider autonomic arousal to be a reinforcer for problem gambling. Structural characteristics such as near-misses, which are non-win events that come close to a real win, have been shown to elicit win-like responses while increasing motivation and gambling persistence. This study investigated the autonomic and subjective responses of young adults to different gambling outcomes. This study also investigated sex differences in autonomic and subjective responses to different gambling outcomes.Participants from Sweden (n = 270) performed a computerized slot machine task that produced wins, near-misses (before and after payline) and full-misses. Phasic measurements of heart rate (HR) and skin conductance responses (SCR) were recorded during gambling performance and ratings of perceived chance of winning, pleasure and motivation to play were collected following each gambling outcome.Autonomic responses differed across slot machine outcomes as indicated by HR and SCR. Compared with other gambling outcomes, near-misses elicited the largest HR accelerations, and they also elicited larger HR decelerations and SCRs relative to full-misses. Near-misses before and after payline elicited differential psychophysiological responses and subjective reports, suggesting different emotional processing of near-miss subtypes. Females showed increased SCRs and motivation following win outcomes compared with males.In conclusion, wins, near-misses and full-misses generate differential physiological and subjective responses among young adults. Autonomic responses to wins differed between male and female players, emphasizing the need to consider sex differences when investigating the role of autonomic arousal in gambling.

Potential Biological Markers and Treatment Implications for Binge Eating Disorder and Behavioral Addictions

The reward system is highly relevant to behavioral addictions such as gambling disorder (GD), internet gaming disorder (IGD), and food addiction/binge eating disorder (FA/BED). Among other brain regions, the ventral striatum (VS) has been implicated in reward processing. The main objective of the present state-of-the-art review was to explore in depth the specific role of the VS in GD, IGD and FA/BED, understanding it as a possible biomarker of these conditions. Studies analyzing brain changes following interventions for these disorders, and especially those that had explored possible treatment-related changes in VS, are discussed. More evidence is needed on how existing treatments (both pharmacological and psychobehavioral) for behavioral addictions affect the activation of the VS and related circuitry.

Development and Validation of a Near Miss Scale for Assessing Gambling Tendency

Although near-miss is an important tendency indicator for gambling addiction, no scale has been developed to evaluate these feelings. In this study, the aim is to develop a Near Miss Scale (NMS) to assess the tendency of gambling. In the first step, a 38-item measurement tool was prepared by the first author, which was examined by 8 experts. According to their comments and opinions, a 32-item 5-point Likert-type pre-form was created. The study was conducted with 600 gamblers in Northern Cyprus between December 2018-March 2019 and data from 563 of them were included in the statistical analysis. In the questionnaire, Socio-demographic form, Gambling Craving Scale (GCS), South Oaks Gambling Screening Test (SOGST) and NMS were used. With the SPSS 23 and R Studio statistical programs, after calculating the item-total correlations of the items in the NMS form, items with low item total-correlation values were excluded from the scale and 30 items were analysed statistically. In the study, it was seen that the factor loads of the relevant items in NMS were between .715 and .896. Confirmatory factor analysis (CFA) showed that a single factor model in the scale was valid. NMS had a positive correlation with SOGST (r = 0.601) and GCS (r = 0.752). The 2-week test-retest results of NMS with a Cronbach alpha of 0.981 were determined as 0.972. The validity and reliability results suggest that NMS is a valid and reliable as 30-item, one-dimensional measurement tool for assessing gambling tendency among gamblers.

Opioid antagonism modulates wanting-related frontostriatal connectivity

Theoretical accounts distinguish between motivational (‘wanting’) and hedonic (‘liking’) dimensions of rewards. Previous animal and human research linked wanting and liking to anatomically and neurochemically distinct brain mechanisms, but it remains unknown how the different brain regions and neurotransmitter systems interact in processing distinct reward dimensions. Here, we assessed how pharmacological manipulations of opioid and dopamine receptor activation modulate the neural processing of wanting and liking in humans in a randomized, placebo-controlled, double-blind clinical trial. Reducing opioid receptor activation with naltrexone selectively reduced wanting of rewards, which on a neural level was reflected by stronger coupling between dorsolateral prefrontal cortex and the striatum under naltrexone compared with placebo. In contrast, reducing dopaminergic neurotransmission with amisulpride revealed no robust effects on behavior or neural activity. Our findings thus provide insights into how opioid receptors mediate neural connectivity related to specifically motivational, not hedonic, aspects of rewards.

The neural basis of gambling disorder: An activation likelihood estimation meta-analysis

Previous imaging studies suggested that impairments of prefrontal-striatal and limbic circuits are correlated to excessive gambling. However, the neural underpinnings of gambling disorder (GD) continue to be the topic of debate. The present study aimed to identify structural changes in GD and differentiate the specific brain activity patterns associated with decision-making and reward-processing. We performed a systematic review complemented by Activation likelihood estimation (ALE) meta-analyses on morphometric and functional studies on neural correlates of GD. The ALE meta-analysis on structural studies revealed that patients with GD showed significant cortical grey-matter thinning in the right ventrolateral and ventromedial prefrontal cortex compared to healthy subjects. The ALE meta-analyses on functional studies revealed that patients with GD showed a significant hyperactivation in the medial prefrontal cortex and in the right ventral striatum during decision-making and gain processing compared to healthy subjects. These findings suggest that GD is related to an alteration of brain mechanisms underlying top-down control and appraisal of gambling-related stimuli and provided indications to develop new interventions in clinical practice.

"Should've known better": Counterfactual processing in disordered gambling

Counterfactual thinking is a component of human decision-making that entails "if only" thinking about unselected choices and outcomes. It is associated with strong emotional responses of regret (when the obtained outcome is inferior to the counterfactual) and relief (vice versa). Counterfactual thinking may play a role in various cognitive phenomena in disordered gambling, such as the effects of near-misses. This study compared individuals with gambling disorder (n = 46) and healthy controls (n = 25) on a behavioural economic choice task that entailed choosing between two gambles, designed to measure counterfactual thinking. Participants provided affect ratings following both the obtained and the non-obtained outcomes. Choices were analyzed using a computational model that derived parameters reflecting sensitivity to expected value, risk variance, and anticipated regret. In the computational choice model, the group with gambling disorder showed increased sensitivity to anticipated regret, reduced sensitivity to expected value, and increased preference for high risk-variance gambles. On the affect ratings, the group with gambling disorder displayed blunted emotional sensitivity to obtained and counterfactual outcomes. Effect sizes of the group differences were modest. Participants with gambling disorder show wide-ranging alterations in decision-making processes and emotional reactivity to choice outcomes. Altered sensitivity to anticipatory regret in gambling disorder may contribute to the development of gambling-related cognitive distortions, and the influences of gambling marketing.

Using pharmacological manipulations to study the role of dopamine in human reward functioning: A review of studies in healthy adults

Dopamine (DA) plays a key role in reward processing and is implicated in psychological disorders such as depression, substance use, and schizophrenia. The role of DA in reward processing is an area of highly active research. One approach to this question is drug challenge studies with drugs known to alter DA function. These studies provide good experimental control and can be performed in parallel in laboratory animals and humans. This review aimed to summarize results of studies using pharmacological manipulations of DA in healthy adults. 'Reward' is a complex process, so we separated 'phases' of reward, including anticipation, evaluation of cost and benefits of upcoming reward, execution of actions to obtain reward, pleasure in response to receiving a reward, and reward learning. Results indicated that i) DAergic drugs have different effects on different phases of reward; ii) the relationship between DA and reward functioning appears unlikely to be linear; iii) our ability to detect the effects of DAergic drugs varies depending on whether subjective, behavioral, imaging measures are used.

Common neurobiological and psychological underpinnings of gambling and substance-use disorders

Both psychological and neurobiological studies in gambling disorder have increased in the past 10-15 years. This review examines the current state of the literature, with a focus on recent magnetic resonance imaging (MRI) studies in gambling disorder. The review compares and contrasts findings across gambling and substance-use disorders. Additionally, features with arguably particular relevance to gambling disorder (e.g., "near-miss" processing) are described, as well as their relationship to choice behaviors. More broadly, the review informs on how these studies advance our understanding of brain-behavior relationships relating to decision-making and key features of addictive disorders.

Dopaminergic signaling of uncertainty and the aetiology of gambling addiction

Although there is increasing clinical recognition of behavioral addictions, of which gambling disorder is the prototype example, there is a limited understanding of the psychological properties of (non-substance-related) behaviors that enable them to become 'addictive' in a way that is comparable to drugs of abuse. According to an influential application of reinforcement learning to substance addictions, the direct effects of drugs to release dopamine can create a perpetual escalation of incentive salience. This article focusses on reward uncertainty, which is proposed to be the core feature of gambling that creates the capacity for addiction. We describe the neuro-dynamics of the dopamine response to uncertainty that may allow a similar escalation of incentive salience, and its relevance to behavioral addictions. We review translational evidence from both preclinical animal models and human clinical research, including studies in people with gambling disorder. Further, we describe the evidence for 1) the effects of the omission of expected reward as a stressor and to promote sensitization, 2) the effect of the resolution of reward uncertainty as a source of value, 3) structural characteristics of modern Electronic Gaming Machines (EGMs) in leveraging these mechanisms, 4) analogies to the aberrant salience hypothesis of psychosis for creating and maintaining gambling-related cognitive distortions. This neurobiologically-inspired model has implications for harm profiling of other putative behavioral addictions, as well as offering avenues for enhancing neurological, pharmacological and psychological treatments for gambling disorder, and harm reduction strategies for EGM design.

Neurophysiological Correlates of the Near-Miss Effect in Gambling

The near-miss effect in gambling refers to a losing situation that is (or perceived to be) close to a win by the gambler. This effect is one of the many cognitive distortions that can occur during gambling games. The main objective of the present study was to analyze the electrophysiological correlates of the near-miss effect via an event-related potential (ERP) study examining four distinct gambling outcomes: win, full miss, near-miss before the payline, and near-miss after the payline. This study comprised 23 healthy voluntary participants (10 women) with ages ranging between 19 and 34 years (M = 22.5; SD = 3.65). All participants completed the South Oaks Gambling Screen and played a computerized slot machine, programed to induce the near-miss effect and specifically designed for an ERP study. By splitting the near-miss effect in two subtypes (before and after the payline), increased feedback-related negativity (FRN) was found for the near-misses after the payline in comparison to losses and also to near-misses before the payline. Results also indicated an increased P300 amplitude for the near-misses before the payline compared both with losses and with near-misses after the payline. The results suggest that both FRN and P300 present different sensitivities to near-miss subtypes, suggesting a payline effect that is not demonstrated when the data of near-misses before and after the payline are analyzed together. This is the first study to analyze the effect of the near-miss subtype in an ERP study and confirms the findings of previous behavioral studies.

Scratch Card Near-Miss Outcomes Increase the Urge to Gamble, but Do Not Impact Further Gambling Behaviour: A Pre-registered Replication and Extension

Scratch card near-misses, outcomes in which two out of three required jackpot symbols are uncovered, have been shown to erroneously increase the urge to continue gambling. It remains unknown if and how these outcomes influence further gambling behaviour. Previous studies examining the influence of near-misses on purchasing behaviour offered a low-stakes gamble to participants after experiencing a near-miss or a regular loss. We sought to investigate the influence of these outcomes on scratch card purchasing behaviour with a stronger test of participants’ gambling behavior by having them either “cash out” or risk all of their winnings to purchase another card. Additionally, we sought to test an original hypothesis that endorsement of the illusion of control might influence the decision to purchase additional scratch cards. We pre-registered our hypotheses, sample size, and data analysis plan. 138 subjects experienced two custom-made scratch card games that included a win on the first card (for all participants) and either a regular loss or a near-miss in the final outcome position on the second card (between-subjects manipulation). Although near-miss outcomes increased the urge to continue gambling relative to regular losses, no differences in the rates of purchasing were found between the conditions. Additionally, no support for our hypotheses concerning the influence of the illusion of control in near-miss outcomes was found. These results are discussed in terms of previous studies on scratch card gambling behaviour and subjective reactivity.

Neural and neurocognitive markers of vulnerability to gambling disorder: a study of unaffected siblings

Psychological and neurobiological markers in individuals with gambling disorder (GD) could reflect transdiagnostic vulnerability to addiction or neuroadaptive consequences of long-term gambling. Using an endophenotypic approach to identify vulnerability markers, we tested the biological relatives of cases with GD. Male participants seeking treatment for GD (n = 20) were compared with a male control group (n = 18). Biological siblings of cases with GD (n = 17, unrelated to the current GD group) were compared with a separate control group (n = 19) that overlapped partially with the GD control group. Participants completed a comprehensive assessment of clinical scales, neurocognitive functioning, and fMRI of unexpected financial reward. The GD group displayed elevated levels of self-report impulsivity and delay discounting, and increased risk-taking on the Cambridge Gamble Task. We did not observe impaired motor impulsivity on the stop-signal task. Siblings of GD showed some overlapping effects; namely, elevated impulsivity (negative urgency) and increased risk-taking on the Cambridge Gamble Task. We did not observe any differences in the neural response to win outcomes, either in the GD or sibling analysis compared with their control group. Within the GD group, activity in the thalamus and caudate correlated negatively with gambling severity. Increased impulsivity and risk-taking in GD are present in biological relatives of cases with GD, suggesting these markers may represent pre-existing vulnerability to GD.

Altered orbitofrontal sulcogyral patterns in gambling disorder: a multicenter study

Gambling disorder is a serious psychiatric condition characterized by decision-making and reward processing impairments that are associated with dysfunctional brain activity in the orbitofrontal cortex (OFC). However, it remains unclear whether OFC functional abnormalities in gambling disorder are accompanied by structural abnormalities. We addressed this question by examining the organization of sulci and gyri in the OFC. This organization is in place very early and stable across life, such that OFC sulcogyral patterns (classified into Types I, II, and III) can be regarded as potential pre-morbid markers of pathological conditions. We gathered structural brain data from nine existing studies, reaching a total of 165 individuals with gambling disorder and 159 healthy controls. Our results, supported by both frequentist and Bayesian statistics, show that the distribution of OFC sulcogyral patterns is skewed in individuals with gambling disorder, with an increased prevalence of Type II pattern compared with healthy controls. Examination of gambling severity did not reveal any significant relationship between OFC sulcogyral patterns and disease severity. Altogether, our results provide evidence for a skewed distribution of OFC sulcogyral patterns in gambling disorder and suggest that pattern Type II might represent a pre-morbid structural brain marker of the disease. It will be important to investigate more closely the functional implications of these structural abnormalities in future work.

Neuroimaging of reward mechanisms in Gambling disorder: an integrative review

Gambling disorder (GD) was reclassified as a behavioral addiction in the DSM-5 and shares clinical and behavioral features with substance use disorders (SUDs). Neuroimaging studies of GD hold promise in isolating core features of the addiction syndrome, avoiding confounding effects of drug neurotoxicity. At the same time, a neurobiologically-grounded theory of how behaviors like gambling can become addictive remains lacking, posing a significant hurdle for ongoing decisions in addiction nosology. This article integrates research on reward-related brain activity (functional MRI) and neurotransmitter function (PET) in GD, alongside the consideration of structural MRI data as to whether these signals more likely reflect pre-existing vulnerability or neuroadaptive change. Where possible, we point to qualitative similarities and differences with established markers for SUDs. Structural MRI studies indicate modest changes in regional gray matter volume and diffuse reductions in white matter integrity in GD, contrasting with clear structural deterioration in SUDs. Functional MRI studies consistently identify dysregulation in reward-related circuitry (primarily ventral striatum and medial prefrontal cortex), but evidence is mixed as to the direction of these effects. The need for further parsing of reward sub-processes is emphasized, including anticipation vs outcome, gains vs. losses, and disorder-relevant cues vs natural rewards. Neurotransmitter PET studies indicate amplified dopamine (DA) release in GD, in the context of minimal differences in baseline DA D2 receptor binding, highlighting a distinct profile from SUDs. Preliminary work has investigated further contributions of opioids, GABA and serotonin. Neuroimaging data increasingly highlight divergent profiles in GD vs. SUDs. The ability of gambling to perpetually activate DA (via maximal uncertainty) may contribute to neuroimaging similarities between GD and SUDs, whereas the supra-physiological DA effects of drugs may partly explain differences in the neuroimaging profile of the two syndromes. Coupled with consistent observations of correlations with gambling severity and related clinical variables within GD samples, the overall pattern of effects is interpreted as a likely combination of shared vulnerability markers across GD and SUDs, but with further experience-dependent neuroadaptive processes in GD.

Prior Exposure to Salient Win-Paired Cues in a Rat Gambling Task Increases Sensitivity to Cocaine Self-Administration and Suppresses Dopamine Efflux in Nucleus Accumbens: Support for the Reward Deficiency Hypothesis of Addiction

Rats trained to perform a version of the rat gambling task (rGT) in which salient audiovisual cues accompany reward delivery, similar to commercial gambling products, show greater preference for risky options. Given previous demonstrations that probabilistic reinforcement schedules can enhance psychostimulant-induced increases in accumbal DA and locomotor activity, we theorized that performing this cued task could perpetuate a proaddiction phenotype. Significantly more rats developed a preference for the risky options in the cued versus uncued rGT at baseline, and this bias was further exacerbated by cocaine self-administration, whereas the choice pattern of optimal decision-makers was unaffected. The addition of reward-paired cues therefore increased the proportion of rats exhibiting a maladaptive cognitive response to cocaine self-administration. Risky choice was not associated with responding for conditioned reinforcement or a marker of goal/sign-tracking, suggesting that reward-concurrent cues precipitate maladaptive choice via a unique mechanism unrelated to simple approach toward, or responding for, conditioned stimuli. Although "protected" from any resulting decision-making impairment, optimal decision-makers trained on the cued rGT nevertheless self-administered more cocaine than those trained on the uncued task. Collectively, these data suggest that repeated engagement with heavily cued probabilistic reward schedules can drive addiction vulnerability through multiple behavioral mechanisms. Rats trained on the cued rGT also exhibited blunted locomotor sensitization and lower basal accumbal DA levels, yet greater cocaine-induced increases in accumbal DA efflux. Gambling in the presence of salient cues may therefore result in an adaptive downregulation of the mesolimbic DA system, rendering individuals more sensitive to the deleterious effects of taking cocaine.SIGNIFICANCE STATEMENT Impaired cost/benefit decision making, exemplified by preference for the risky, disadvantageous options on the Iowa Gambling Task, is associated with greater risk of relapse and treatment failure in substance use disorder. Understanding factors that enhance preference for risk may help elucidate the neurobiological mechanisms underlying maladaptive decision making in addiction, thereby improving treatment outcomes. Problem gambling is also highly comorbid with substance use disorder, and many commercial gambling products incorporate salient win-paired cues. Here we show that adding reward-concurrent cues to a rat analog of the IGT precipitates a hypodopaminergic state, characterized by blunted accumbal DA efflux and attenuated locomotor sensitization, which may contribute to the enhanced responsivity to uncertain rewards or the reinforcing effects of cocaine we observed.

An fMRI study of decision-making under sunk costs in gambling disorder

The sunk cost effect is the tendency to continue an investment, or take an action, even though it has higher future costs than benefits, if costs of time, money, or effort were previously incurred. This type of decision bias is pervasive in real life and has been studied in various disciplines. Previous studies and clinical observations suggest that decision-making under sunk costs is altered in gambling disorder (GD). However, the neural mechanisms of decision-making under sunk costs in GD remain largely unknown, and so is their association with the clinical characteristics of this patient group. Here, by combining functional magnetic resonance imaging and the task that demonstrated a clear example of the sunk cost effect, we investigated the neural correlates during decision-making under sunk costs in GD. We found no significant differences in the strength of the sunk cost effect between the GD and healthy control (HC) groups. However, the strength of the sunk cost effect in patients with GD showed a significant negative correlation with abstinence period and a marginally significant positive correlation with the duration of illness. We also found a reduction in the neural activation in the dorsal medial prefrontal cortex during decision-making under sunk costs for the GD group compared with the HC group. Furthermore, in patients with GD, the levels of activation in this area negatively correlated with the duration of illness. These findings have important clinical implications. This study will contribute to a better understanding of the mechanisms underlying altered decision-making abilities in GD.

Increased Striatal Dopamine Synthesis Capacity in Gambling Addiction

BACKGROUND

The hypothesis that dopamine plays an important role in the pathophysiology of pathological gambling is pervasive. However, there is little to no direct evidence for a categorical difference between pathological gamblers and healthy control subjects in terms of dopamine transmission in a drug-free state. Here we provide evidence for this hypothesis by comparing dopamine synthesis capacity in the dorsal and ventral parts of the striatum in 13 pathological gamblers and 15 healthy control subjects.

METHODS

This was achieved using [¹⁸F]fluoro-levo-dihydroxyphenylalanine dynamic positron emission tomography scans and striatal regions of interest that were hand-drawn based on visual inspection of individual structural magnetic resonance imaging scans.

RESULTS

Our results show that dopamine synthesis capacity was increased in pathological gamblers compared with healthy control subjects. Dopamine synthesis was 16% higher in the caudate body, 17% higher in the dorsal putamen, and 17% higher in the ventral striatum in pathological gamblers compared with control subjects. Moreover, dopamine synthesis capacity in the dorsal putamen and caudate head was positively correlated with gambling distortions in pathological gamblers.

CONCLUSIONS

Taken together, these results provide empirical evidence for increased striatal dopamine synthesis in pathological gambling.

Dopaminergic Drug Effects on Probability Weighting during Risky Decision Making

Dopamine has been associated with risky decision-making, as well as with pathological gambling, a behavioral addiction characterized by excessive risk-taking behavior. However, the specific mechanisms through which dopamine might act to foster risk-taking and pathological gambling remain elusive. Here we test the hypothesis that this might be achieved, in part, via modulation of subjective probability weighting during decision making. Human healthy controls (n = 21) and pathological gamblers (n = 16) played a decision-making task involving choices between sure monetary options and risky gambles both in the gain and loss domains. Each participant played the task twice, either under placebo or the dopamine D₂/D₃ receptor antagonist sulpiride, in a double-blind counterbalanced design. A prospect theory modelling approach was used to estimate subjective probability weighting and sensitivity to monetary outcomes. Consistent with prospect theory, we found that participants presented a distortion in the subjective weighting of probabilities, i.e., they overweighted low probabilities and underweighted moderate to high probabilities, both in the gain and loss domains. Compared with placebo, sulpiride attenuated this distortion in the gain domain. Across drugs, the groups did not differ in their probability weighting, although gamblers consistently underweighted losing probabilities in the placebo condition. Overall, our results reveal that dopamine D₂/D₃ receptor antagonism modulates the subjective weighting of probabilities in the gain domain, in the direction of more objective, economically rational decision making.

Cognitive distortions and gambling near-misses in Internet Gaming Disorder: A preliminary study

Increased cognitive distortions (i.e. biased processing of chance, probability and skill) are a key psychopathological process in disordered gambling. The present study investigated state and trait aspects of cognitive distortions in 22 individuals with Internet Gaming Disorder (IGD) and 22 healthy controls. Participants completed the Gambling Related Cognitions Scale as a trait measure of cognitive distortions, and played a slot machine task delivering wins, near-misses and full-misses. Ratings of pleasure (“liking”) and motivation to play (“wanting”) were taken following the different outcomes, and gambling persistence was measured after a mandatory phase. IGD was associated with elevated trait cognitive distortions, in particular skill-oriented cognitions. On the slot machine task, the IGD group showed increased “wanting” ratings compared with control participants, while the two groups did not differ regarding their “liking” of the game. The IGD group displayed increased persistence on the slot machine task. Near-miss outcomes did not elicit stronger motivation to play compared to full-miss outcomes overall, and there was no group difference on this measure. However, a near-miss position effect was observed, such that near-misses stopping before the payline were rated as more motivating than near-misses that stopped after the payline, and this differentiation was attenuated in the IGD group, suggesting possible counterfactual thinking deficits in this group. These data provide preliminary evidence for increased incentive motivation and cognitive distortions in IGD, at least in the context of a chance-based gambling environment.

Neuroscience in gambling policy and treatment: an interdisciplinary perspective

Neuroscientific explanations of gambling disorder can help people make sense of their experiences and guide the development of psychosocial interventions. However, the societal perceptions and implications of these explanations are not always clear or helpful. Two workshops in 2013 and 2014 brought together multidisciplinary researchers aiming to improve the clinical and policy-related effects of neuroscience research on gambling. The workshops revealed that neuroscience can be used to improve identification of the dangers of products used in gambling. Additionally, there was optimism associated with the diagnostic and prognostic uses of neuroscience in problem gambling and the provision of novel tools (eg, virtual reality) to assess the effectiveness of new policy interventions before their implementation. Other messages from these workshops were that neuroscientific models of decision making could provide a strong rationale for precommitment strategies and that interdisciplinary collaborations are needed to reduce the harms of gambling.

Gambling disorder: an integrative review of animal and human studies

Gambling disorder (GD), previously called pathological gambling and classified as an impulse control disorder in DSM-III and DSM-IV, has recently been reclassified as an addictive disorder in the DSM-5. It is widely recognized as an important public health problem associated with substantial personal and social costs, high rates of psychiatric comorbidity, poor physical health, and elevated suicide rates. A number of risk factors have been identified, including some genetic polymorphisms. Animal models have been developed in order to study the underlying neural basis of GD. Here, we discuss recent advances in our understanding of the risk factors, disease course, and pathophysiology. A focus on a phenotype-based dissection of the disorder is included in which known neural correlates from animal and human studies are reviewed. Finally, current treatment approaches are discussed, as well as future directions for GD research.

Gambling with Rose-Tinted Glasses on: Use of Emotion-Regulation Strategies Correlates with Dysfunctional Cognitions in Gambling Disorder Patients

Background and aims Existing research shows that gambling disorder patients (GDPs) process gambling outcomes abnormally when compared against healthy controls (HCs). These anomalies present the form of exaggerated or distorted beliefs regarding the expected utility of outcomes and one's ability to predict or control gains and losses, as well as retrospective reinterpretations of what caused them. This study explores the possibility that the emotional regulation strategies GDPs use to cope with aversive events are linked to these cognitions. Methods 41 GDPs and 45 HCs, matched in sociodemographic variables, were assessed in gambling severity, emotion-regulation strategies (cognitive emotion-regulation questionnaire, CERQ), and gambling-related cognitions (gambling-related cognitions scale, GRCS). Results GDPs showed higher scores in all gambling-related cognition dimensions. Regarding emotion regulation, GDPs were observed to use self-blame and catastrophizing, but also positive refocusing, more often than controls. Additionally, in GDPs, putatively adaptive CERQ strategies shared a significant portion of variance with South Oaks gambling screen severity and GRCS beliefs. Shared variability was mostly attributable to the roles of refocusing on planning and putting into perspective at positively predicting severity and the interpretative bias (GDPs propensity to reframe losses in a more benign way), respectively. Discussion and conclusions Results show links between emotion-regulation strategies and problematic gambling-related behaviors and cognitions. The pattern of those links supports the idea that GDPs use emotion-regulation strategies, customarily regarded as adaptive, to cope with negative emotions, so that the motivational and cognitive processing of gambling outcomes becomes less effective in shaping gambling-related behavior.