An initial study of neural responses to monetary incentives as related to treatment outcome in cocaine dependence

Blunted Neurobehavioral Loss Anticipation Predicts Relapse to Stimulant Drug Use

BACKGROUND

Patients with stimulant use disorder experience high rates of relapse. While neurobehavioral mechanisms involved in initiating drug use have been studied extensively, less research has focused on relapse.

METHODS

To assess motivational processes involved in relapse and diagnosis, we acquired functional magnetic resonance imaging responses to nondrug (monetary) gains and losses in detoxified patients with stimulant use disorder (n = 68) and community control participants (n = 42). In a prospective multimodal design, we combined imaging of brain function, brain structure, and behavior to longitudinally track subsequent risk for relapse.

RESULTS

At the 6-month follow-up assessment, 27 patients remained abstinent, but 33 had relapsed. Patients with blunted anterior insula (AIns) activity during loss anticipation were more likely to relapse, an association that remained robust after controlling for potential confounds (i.e., craving, negative mood, years of use, age, and gender). Lower AIns activity during loss anticipation was associated with lower self-reported negative arousal to loss cues and slower behavioral responses to avoid losses, which also independently predicted relapse. Furthermore, AIns activity during loss anticipation was associated with the structural coherence of a tract connecting the AIns and the nucleus accumbens, as was functional connectivity between the AIns and nucleus accumbens during loss processing. However, these neurobehavioral responses did not differ between patients and control participants.

CONCLUSIONS

Taken together, the results of the current study show that neurobehavioral markers predicted relapse above and beyond conventional self-report measures, with a cross-validated accuracy of 72.7%. These findings offer convergent multimodal evidence that implicates blunted avoidance motivation in relapse to stimulant use and may therefore guide interventions targeting individuals who are most vulnerable to relapse.

Residual deficits in functional brain activity after chronic cocaine self-administration in rhesus monkeys

Previous studies in humans and in animals have shown dramatic effects of cocaine on measures of brain function that persist into abstinence. The purpose of this study was to examine the neurobiological consequences of abstinence from cocaine, using a model that removes the potential confound of cocaine cues. Adult male rhesus monkeys self-administered cocaine (0.3 mg/kg/injection; N = 8) during daily sessions or served as food-reinforcement controls (N = 4). Two times per week, monkeys were placed in a neutral environment and presented with a cartoon video for ~30 min, sometimes pre- and sometimes post-operant session, but no reinforcement was presented during the video. After ~100 sessions and when the cocaine groups had self-administered 900 mg/kg cocaine, the final experimental condition was a terminal 2-[14C]-deoxyglucose procedure, which occurred in the neutral (cartoon video) environment; for half of the monkeys in each group, this occurred after 1 day of abstinence and for the others after 30 days of abstinence. Rates of local cerebral glucose metabolism were measured in 57 brain regions. Global rates of cerebral metabolism were significantly lower in animals 1 day and 30 days post-cocaine self-administration when compared to those of food-reinforced controls. Effects were larger in 30- vs. 1-day cocaine abstinence, especially in prefrontal, parietal and cingulate cortex, as well as dorsal striatum and thalamus. Because these measures were obtained from monkeys while in a neutral environment, the deficits in glucose utilization can be attributed to the consequences of cocaine exposure and not to effects of conditioned stimuli associated with cocaine.

Biomarkers of Relapse in Cocaine Use Disorder: A Narrative Review

Introduction: Cocaine use disorder is a chronic disease with severe consequences and a high relapse rate. There is a critical need to explore the factors influencing relapse in order to achieve more efficient treatment outcomes. Furthermore, there is a great need for easy-to-measure, repeatable, and valid biomarkers that can predict treatment response or relapse. Methods: We reviewed the available literature on the Pubmed database concerning the biomarkers associated with relapse in CUD, including central nervous system-derived, genetic, immune, oxidative stress, and “other” biomarkers. Results: Fifty-one articles were included in our analysis. Twenty-five imaging brain anatomic and function assessment studies, mostly using fMRI, examined the role of several structures such as the striatum activity in abstinence prediction. There were fewer studies assessing the use of neuropsychological factors, neurotrophins, or genetic/genomic factors, immune system, or oxidative stress measures to predict abstinence. Conclusion: Several biomarkers have been shown to have predictive value. Prospective studies using combined multimodal assessments are now warranted.

Alcohol use and interoception - A narrative review

Interoception, defined as the ability to perceive and interpret body signals, may play an important role in alcohol use disorder (AUD). Earlier studies suggested an association between interoception impairment and known risk factors for AUD (e.g., alexithymia, emotion dysregulation, impulsivity, pain). Neurobiological studies show that the neurotoxicity of alcohol affects various elements of the interoceptive system (especially the insula) at structural and functional levels, with differential short/long term impacts. Conversely, primary interoceptive impairments may promote alcohol consumption and foster the evolution towards addiction. Despite convincing evidence demonstrating that interoception impairment may be an important contributor to the development and course of AUD, only a few studies directly evaluated interoceptive abilities in AUD. The research shows that interoceptive accuracy, the objective component of interoception, is lower in AUD individuals, and is correlated with craving and emotion dysregulation. Interoceptive sensibility is in turn higher in AUD individuals compared to healthy controls. Moreover, there is evidence that therapy focused on improving the ability to sense signals from the body in addiction treatment is effective. However, important methodological limitations in interoceptive measures persist, and it is therefore necessary to further investigate the associations between interoception and AUD.

Decreased reward-related brain function prospectively predicts increased substance use

Substance use and addiction are prominent global health concerns and are associated with abnormalities in reward sensitivity. Reward sensitivity and approach motivation are supported by a fronto-striatal neural circuit including the orbitofrontal cortex (OFC), ventral striatum (VS), and dorsal striatum (DS). Although research highlights abnormalities in reward neural circuitry among individuals with problematic substance use, questions remain about whether such use arises from excessively high, or excessively low, reward sensitivity. This study examined whether reward-related brain function predicted subsequent substance use course. Participants were 79 right-handed individuals (Mage = 21.52, SD = 2.19 years), who completed a monetary incentive delay (MID) fMRI task, and follow-up measures assessing substance use frequency and impairment. The average duration of the follow-up period was 9.1 months. Regions-of-interest analyses focused on the reward anticipation phase of the MID. Decreased activation in the VS during reward anticipation predicted increased substance use frequency at follow-up. Decreased DS activation during reward anticipation predicted increased substance use frequency at follow-up, but this finding did not pass correction for multiple comparisons. Analyses adjusted for relevant covariates, including baseline substance use and the presence or absence of a lifetime substance use disorder prior to MRI scanning. Results support the reward hyposensitivity theory, suggesting that decreased reward-related brain function is a risk factor for increased substance use. Results have implications for understanding the pathophysiology of problematic substance use and highlight the importance of the fronto-striatal reward circuit in the development and maintenance of addiction. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Reward processing in trichotillomania and skin picking disorder

Trichotillomania (hair pulling disorder) and skin picking disorder are common and often debilitating mental health conditions, grouped under the umbrella term of body focused repetitive behaviors (BFRBs). Although the pathophysiology of BFRBs is incompletely understood, reward processing dysfunction has been implicated in the etiology and sustention of these disorders. The purpose of this study was to probe reward processing in BFRBs. 159 adults (125 with a BFRB [83.2% (n = 104) female] and 34 healthy controls [73.5% (n = 25) female]) were recruited from the community for a multi-center between-group comparison using a functional imaging (fMRI) monetary reward task. Differences in brain activation during reward anticipation and punishment anticipation were compared between BFRB patients and controls, with stringent correction for multiple comparisons. All group level analyses controlled for age, sex and scanning site. Compared to controls, BFRB participants showed marked hyperactivation of the bilateral inferior frontal gyrus (pars opercularis and pars triangularis) compared to controls. In addition, BFRB participants exhibited increased activation in multiple areas during the anticipation of loss (right fusiform gyrus, parahippocampal gyrus, cerebellum, right inferior parietal lobule; left inferior frontal gyrus). There were no significant differences in the win-lose contrast between the two groups. These data indicate the existence of dysregulated reward circuitry in BFRBs. The identified pathophysiology of reward dysfunction may be useful to tailor future treatments.

Binge drinking is associated with altered resting state functional connectivity of reward-salience and top down control networks

Binge drinking is characterized by bouts of high-intensity alcohol intake and is associated with an array of health-related harms. Even though the transition from occasional impulsive to addictive alcohol use is not well understood, neurobiological models of addiction suggest that repeated cycles of intoxication and withdrawal contribute to the development of addiction in part through dysregulation of neurofunctional networks. Research on the neural sequelae associated with binge drinking is scant but resting state functional connectivity (RSFC) studies of alcohol use disorders (AUD) indicate that the development and maintenance of long-term excessive drinking may be mediated by network-level disruptions. The present study examined RSFC in young adult binge (BD) and light (LD) drinkers with seeds representing the networks subserving reward (the nucleus accumbens and caudate nucleus), salience (anterior cingulate cortex, ACC), and executive control (inferior frontal cortex, IFC). BDs exhibited enhanced connectivity between the striatal reward areas and the orbitofrontal cortex and the ACC, which is consistent with AUD studies and may be indicative of alcohol-motivated appetitive behaviors. Conversely, BDs demonstrated lower connectivity between the IFC and hippocampus which was associated with higher craving. This may indicate impaired ability to suppress unwanted thoughts and a failure to employ memory of the harmful consequences of heavy drinking in prospective plans and intentions. The observed greater connectivity of the reward/salience network and the lower prefrontal-hippocampal connectivity were associated with hazardous drinking levels indicating that dysregulation of neurofunctional networks may underlie binge drinking patterns.

Reward-Related Responses and Tonic Craving in Cocaine Addiction: An Imaging Study of the Monetary Incentive Delay Task

BACKGROUND

Cocaine addiction is associated with altered sensitivity to natural reinforcers and intense drug craving. However, previous findings on reward-related responses were mixed, and few studies have examined whether reward responses relate to tonic cocaine craving.

METHODS

We combined functional magnetic resonance imaging and a monetary incentive delay task to investigate these issues. Imaging data were processed with published routines, and the results were evaluated with a corrected threshold. We compared reward responses of 50 cocaine-dependent individuals (CDs) and 45 healthy controls (HCs) for the ventral striatum (VS) and the whole brain. We also examined the regional responses in association with tonic cocaine craving, as assessed by the Cocaine Craving Questionnaire (CCQ) in CDs. We performed mediation analyses to evaluate the relationship between regional responses, CCQ score, and recent cocaine use.

RESULTS

The VS showed higher activation to large as compared with small or no wins, but this reward-related activity did not differ between CDs and HCs. The precentral gyrus (PCG), anterior insula, and supplementary motor area showed higher activation during large vs no wins in positive correlation with the CCQ score in CDs. Mediation analyses suggested that days of cocaine use in the prior month contributed to higher CCQ scores and, in turn, PCG reward responses.

CONCLUSIONS

The results highlight a unique relationship between reward responses of the primary motor cortex, tonic cocaine craving, and recent cocaine use. The motor cortex may partake in the cognitive motor processes critical to drug-seeking behavior in addicted individuals.

Sexual incentive delay in the scanner: Sexual cue and reward processing, and links to problematic porn consumption and sexual motivation

BACKGROUND AND AIMS

The use of pornography, while unproblematic for the majority, can grow into addiction-like behavior which in its extreme form is labeled as compulsive sexual behavioral disorder in the ICD-11 (WHO, 2018). The aim of this study was to investigate the addiction-specific reactivity to cues in order to better understand underlying mechanisms in the development of this disorder.

METHODS

We have used an optimized Sexual Incentive Delay Task to study brain activity in reward associated brain areas during an anticipation phase (with cues predicting pornographic videos, control videos or no videos) and a corresponding delivery phase in healthy men. Correlations to indicators of problematic pornography use, the time spent on pornography use, and trait sexual motivation were analyzed.

RESULTS

The results of 74 men showed that reward-related brain areas (amygdala, dorsal cingulate cortex, orbitofrontal cortex, nucleus accumbens, thalamus, putamen, caudate nucleus, and insula) were significantly more activated by both the pornographic videos and the pornographic cues than by control videos and control cues, respectively. However, we found no relationship between these activations and indicators of problematic pornography use, time spent on pornography use, or with trait sexual motivation.

DISCUSSION AND CONCLUSIONS

The activity in reward-related brain areas to both visual sexual stimuli as well as cues indicates that optimization of the Sexual Incentive Delay Task was successful. Presumably, associations between reward-related brain activity and indicators for problematic or pathological pornography use might only occur in samples with increased levels and not in a rather healthy sample used in the present study.

Noradrenergic correlates of chronic cocaine craving: neuromelanin and functional brain imaging

Preclinical studies have implicated noradrenergic (NA) dysfunction in cocaine addiction. In particular, the NA system plays a central role in motivated behavior and may partake in the regulation of craving and drug use. Yet, human studies of the NA system are scarce, likely hampered by the difficulty in precisely localizing the locus coeruleus (LC). Here, we used neuromelanin imaging to localize the LC and quantified LC neuromelanin signal (NMS) intensity in 44 current cocaine users (CU; 37 men) and 59 nondrug users (NU; 44 men). We also employed fMRI to investigate cue-induced regional responses and LC functional connectivities, as quantified by generalized psychophysiological interaction (gPPI), in CU. Imaging data were processed by published routines and the findings were evaluated with a corrected threshold. We examined how these neural measures were associated with chronic cocaine craving, as assessed by the Cocaine Craving Questionnaire (CCQ). Compared to NU, CU demonstrated higher LC NMS for all probabilistic thresholds defined of 50-90% of the peak. In contrast, NMS of the ventral tegmental area/substantia nigra (VTA/SN) did not show significant group differences. Drug as compared to neutral cues elicited higher activations of many cortical and subcortical regions, none of which were significantly correlated with CCQ score. Drug vs. neutral cues also elicited "deactivation" of bilateral parahippocampal gyri (PHG) and PHG gPPI with a wide array of cortical and subcortical regions, including the ventral striatum and, with small volume correction, the LC. Less deactivation of the PHG (r = 0.40, p = 0.008) and higher PHG-LC gPPI (r = 0.44, p = 0.003) were positively correlated with the CCQ score. In contrast, PHG-VTA/SN connectivity did not correlate with the CCQ score. Together, chronic cocaine exposure may induce higher NMS intensity, suggesting neurotoxic effects on the LC. The correlation of cue-elicited PHG LC connectivity with CCQ score suggests a noradrenergic correlate of chronic cocaine craving. Potentially compensating for memory functions as in neurodegenerative conditions, cue-elicited PHG LC circuit connectivity plays an ill-adaptive role in supporting cocaine craving.

Enhanced neural responses in specific phases of reward processing in individuals with Internet gaming disorder

BACKGROUND AND AIMS

Internet gaming disorder (IGD) has become a global health problem. The self-regulation model noted that a shift to reward system, whether due to overwhelming reward-seeking or impaired control, can lead to self-regulation failures, e.g., addiction. The present study focused on the reward processing of IGD, aiming to provide insights into the etiology of IGD. Reward processing includes three phases: reward anticipation, outcome monitoring and choice evaluation. However, it is not clear which phases of reward processing are different between individuals with IGD and healthy controls (HC).

METHODS

To address this issue, the present study asked 27 individuals with IGD and 26 HC to complete a roulette task during a functional MRI scan.

RESULTS

Compared with HC, individuals with IGD preferred to take risks in pursuit of high rewards behaviorally and showed exaggerated brain activity in the striatum (nucleus accumbens and caudate) during the reward anticipation and outcome monitoring but not during the choice evaluation.

DISCUSSION

These results reveal that the oversensitivity of the reward system to potential and positive rewards in college students with IGD drives them to approach risky options more frequently although they are able to assess the risk values of options and the correctness of decisions properly as HC do.

CONCLUSIONS

These findings provide partial support for the application of the self-regulation model to the IGD population. Moreover, this study enriches this model from the perspective of three phases of reward processing and provides specific targets for future research regarding effective treatment of IGD.

A voxel-wise meta-analysis of task-based functional MRI studies on impaired gain and loss processing in adults with addiction

BACKGROUND

Disturbances in gain and loss processing have been extensively reported in adults with addiction, a brain disorder characterized by obsession with addictive substances or behaviours. Previous studies have provided conflicting results with respect to neural abnormalities in gain processing in addiction, and few investigations into loss processing.

METHODS

We conducted voxel-wise meta-analyses of abnormal task-evoked regional activities in adults with substance dependence and gambling addiction during the processing of gains and losses not related to their addiction (mainly monetary). We identified 24 studies, including 465 participants with substance dependence, 81 with gambling addiction and 490 healthy controls.

RESULTS

Compared with healthy controls, all participants with addictions showed hypoactivations in the prefrontal cortex, striatum and insula and hyperactivations in the default mode network during gain anticipation; hyperactivations in the prefrontal cortex and both hyper- and hypoactivations in the striatum during loss anticipation; and hyperactivations in the occipital lobe during gain outcome. In the substance dependence subgroup, activity in the occipital lobe was increased during gain anticipation but decreased during loss anticipation.

LIMITATIONS

We were unable to conduct meta-analyses in the gambling addiction subgroup because of a limited data set. We did not investigate the effects of clinical variables because of limited information.

CONCLUSION

The current study identified altered brain activity associated with higher- and lower-level function during gain and loss processing for non-addiction (mainly monetary) stimuli in adults with substance dependence and gambling addiction. Adults with addiction were more sensitive to anticipatory gains than losses at higher- and lower-level brain areas. These results may help us to better understand the pathology of gain and loss processing in addiction.

Neural activation during anticipation of monetary gain or loss does not associate with positive subjective response to alcohol in binge drinkers

BACKGROUND

Alcohol use disorder (AUD) remains an unresolved source of morbidity and mortality. Psychopharmacological challenge studies and neuroimaging experiments are two methods used to identify risk of problematic substance use. The present study combined these two approaches by examining associations between self-reported stimulation, sedation, liking or wanting more after a dose of alcohol and neural-based responses to anticipation of monetary gain and loss.

METHODS

Young adult binge drinkers (N = 56) aged 21-29, with no history of Substance Use Disorder completed five experimental sessions. These included four laboratory sessions in which they rated their subjective responses to alcohol (0.8 g/kg for men, 0.68 g/kg for women) or placebo, and a single functional magnetic resonance imaging session in which they completed a monetary incentive delay task. During the scan, we recorded neural signal related to anticipation of winning $5 or $1.50 compared to winning no money (WinMoney-WinZero), losing $5 or $1.50 compared to losing no money (LoseMoney-LoseZero), and winning $5 or $1.50 compared to losing $5 or $1.50 (WinMoney-LoseMoney), in reward related regions.

RESULTS

There were no significant associations between subjective ratings of "Feel Drug Effect", "Like Drug Effect", "Want More", stimulation or sedation following the acute alcohol challenge and neural activation in reward related regions during anticipation of monetary gain or loss.

CONCLUSIONS

These results suggest that sensitivity of neural reward circuits is not directly related to rewarding subjective experiences from alcohol. Taken together with previous studies, the present findings indicate that the association between the subjective effects of drugs and reward-related brain activity depends on the drugs, tasks or subject samples under study.

Striatal activation to monetary reward is associated with alcohol reward sensitivity

One well-known phenotypic risk factor for the development of alcohol use disorder is sensitivity to the rewarding effects of alcohol. In the present study, we examined whether individuals who are sensitive to alcohol reward are also sensitive to nondrug rewards, thereby reflecting a broader individual difference risk factor. Specifically, we tested the hypothesis that subjective response to acute rewarding effects of alcohol would be related to neural activation during monetary reward receipt relative to loss (in the absence of alcohol). Community-recruited healthy young social drinkers (N = 58) completed four laboratory sessions in which they received alcohol (0.8 g/kg) and placebo in alternating order under double-blind conditions, providing self-report measures of subjective response to alcohol at regular intervals. At a separate visit 1-3 weeks later, they completed a reward-guessing game, the 'Doors' task, during fMRI in a drug-free state. Participants who reported greater motivation (i.e., wanting) to consume more alcohol after a single moderate dose of alcohol also exhibited greater neural activation in the bilateral ventral caudate and the nucleus accumbens during reward receipt relative to loss. Striatal activation was not related to other subjective ratings including alcohol-induced sedation, stimulation, or pleasure (i.e., feeling, liking). Our study is the first to show that measures of alcohol reward are related to neural indices of monetary reward in humans. These results support growing evidence that individual differences in responses to drug and nondrug reward are linked and together form a risk profile for drug use or abuse, particularly in young adults.

Motivational factors modulate left frontoparietal network during cognitive control in cocaine addiction

Cocaine addiction is characterized by alterations in motivational and cognitive processes involved in goal-directed behavior. Recent studies have shown that addictive behaviors can be attributed to alterations in the activity of large functional networks. The aim of this study was to investigate how cocaine addiction affected the left frontoparietal network during goal-directed behavior in a stop-signal task (SST) with reward contingencies by correct task performance. Twenty-eight healthy controls (HC) and 30 abstinent cocaine-dependent patients (ACD) performed SST with monetary reward contingencies while undergoing a functional magnetic resonance imaging scan. The results showed that the left frontoparietal network (FPN) displayed an effect of cocaine addiction depending on reward contingencies rather than inhibition accuracy; and, second, we observed a negative correlation between dependence severity and the modulation of the left FPN network by the monetary reward in ACD. These findings highlight the role of the left FPN in the motivational effects of cocaine dependence.

Brain networks underlying vulnerability and resilience to drug addiction

Resting-state functional connectivity provides novel insight into variations in neural networks associated with addiction to stimulant drugs in individuals with and without a family history of addiction, and both with and without personal drug use. An increased risk for addiction, either because of drug use or genetic/psychosocial vulnerability, is associated with hypoconnectivity in frontostriatal networks, which may weaken goal-directed decision-making. Resilience against addiction development, by contrast, is characterized by hyperconnectivity in two corticostriatal pathways, possibly reflecting compensatory responses in networks associated with regulatory control over habitual behaviors. It is thus conceivable that defying the risk of developing stimulant drug addiction requires increased efforts to control behavior—a hypothesis that may open up new pathways for therapeutic and preventative strategies.

Regular drug use can lead to addiction, but not everyone who takes drugs makes this transition. How exactly drugs of abuse interact with individual vulnerability is not fully understood, nor is it clear how individuals defy the risks associated with drugs or addiction vulnerability. We used resting-state functional MRI (fMRI) in 162 participants to characterize risk- and resilience-related changes in corticostriatal functional circuits in individuals exposed to stimulant drugs both with and without clinically diagnosed drug addiction, siblings of addicted individuals, and control volunteers. The likelihood of developing addiction, whether due to familial vulnerability or drug use, was associated with significant hypoconnectivity in orbitofrontal and ventromedial prefrontal cortical-striatal circuits—pathways critically implicated in goal-directed decision-making. By contrast, resilience against a diagnosis of substance use disorder was associated with hyperconnectivity in two networks involving 1) the lateral prefrontal cortex and medial caudate nucleus and 2) the supplementary motor area, superior medial frontal cortex, and putamen—brain circuits respectively implicated in top-down inhibitory control and the regulation of habits. These findings point toward a predisposing vulnerability in the causation of addiction, related to impaired goal-directed actions, as well as countervailing resilience systems implicated in behavioral regulation, and may inform novel strategies for therapeutic and preventative interventions.

Bouncing back: Brain rehabilitation amid opioid and stimulant epidemics

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Frontoparietal event related potentials predict/track recovery.

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Frontostriatal functional magnetic resonance imaging signals predict/track recovery.

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Transcranial magnetic left prefrontal stimulation reduces craving and drug use.

Recent methamphetamine and opioid use epidemics are a major public health concern. Chronic stimulant and opioid use are characterized by significant psychosocial, physical and mental health costs, repeated relapse, and heightened risk of early death. Neuroimaging research highlights deficits in brain processes and circuitry that are linked to responsivity to drug cues over natural rewards as well as suboptimal goal-directed decision-making. Despite the need for interventions, little is known about (1) how the brain changes with prolonged abstinence or as a function of various treatments; and (2) how symptoms change as a result of neuromodulation. This review focuses on the question: What do we know about changes in brain function during recovery from opioids and stimulants such as methamphetamine and cocaine? We provide a detailed overview and critique of published research employing a wide array of neuroimaging methods – functional and structural magnetic resonance imaging, electroencephalography, event-related potentials, diffusion tensor imaging, and multiple brain stimulation technologies along with neurofeedback – to track or induce changes in drug craving, abstinence, and treatment success in stimulant and opioid users. Despite the surge of methamphetamine and opioid use in recent years, most of the research on neuroimaging techniques for recovery focuses on cocaine use. This review highlights two main findings: (1) interventions can lead to improvements in brain function, particularly in frontal regions implicated in goal-directed behavior and cognitive control, paired with reduced drug urges/craving; and (2) the targeting of striatal mechanisms implicated in drug reward may not be as cost-effective as prefrontal mechanisms, given that deep brain stimulation methods require surgery and months of intervention to produce effects. Overall, more studies are needed to replicate and confirm findings, particularly for individuals with opioid and methamphetamine use disorders.

Neural reward response to substance-free activity images in opiate use disorder patients with depressive symptoms

BACKGROUND

Deficits in the ability to experience reward from natural, substance-free activities and stimuli is a common mechanism contributing to both opiate use disorder and depressive symptoms, and is a target of behavioral-focused treatments for substance use and depression. Although the neural response to monetary, positive affect-eliciting and social images has been investigated, the neural response to images representing substance-free activity engagement remains untested. The current study tested the neural response to anticipation and receipt of substance-free activity engagement images and monetary reward in opiate use disorder patients with elevated depressive symptoms compared to healthy controls.

METHODS

Sixteen male opiate use disorder detoxification patients with elevated depressive symptoms (Beck Depression Inventory (BDI-II) ≥ 14) (OUDD M_age = 32.19 years, SD = 8.17 years) and seventeen male healthy controls (BDI-II < 14) (HC: M_age = 26.82 years, SD = 5.29 years) completed the Monetary Incentive Delay (MID) and newly developed Activity Incentive Delay (AID) tasks. Within- and between-group whole-brain contrasts tested activation during anticipation ([reward]-[non-reward]) and receipt ([win]-[non-win]) of substance-free activity image, monetary, and substance-free activity relative to monetary (AID-MID), reward.

RESULTS

OUDD demonstrated significantly lower activation in reward regions during anticipation and significantly greater activation during receipt of substance-free activity image reward compared to HC. OUDD demonstrated significantly lower activation during anticipation of substance-free activity reward relative to monetary reward, compared to HC.

CONCLUSIONS

The observed reduction in frontostriatal response to reward anticipation of substance-free activity engagement images in OUDD, yet increased neural response to reward receipt, supports theory linking reductions in reward processing with deficits in motivation for substance-free activity engagement.

Effects of familial risk and stimulant drug use on the anticipation of monetary reward: an fMRI study

The association between stimulant drug use and aberrant reward processing is well-documented in the literature, but the nature of these abnormalities remains elusive. The present study aims to disentangle the separate and interacting effects of stimulant drug use and pre-existing familial risk on abnormal reward processing associated with stimulant drug addiction. We used the Monetary Incentive Delay task, a well-validated measure of reward processing, during fMRI scanning in four distinct groups: individuals with familial risk who were either stimulant drug-dependent (N = 41) or had never used stimulant drugs (N = 46); and individuals without familial risk who were either using stimulant drugs (N = 25) or not (N = 48). We first examined task-related whole-brain activation followed by a psychophysiological interaction analysis to further explore brain functional connectivity. For analyses, we used a univariate model with two fixed factors (familial risk and stimulant drug use). Our results showed increased task-related activation in the putamen and motor cortex of stimulant-using participants. We also found altered task-related functional connectivity between the putamen and frontal regions in participants with a familial risk (irrespective of whether they were using stimulant drugs or not). Additionally, we identified an interaction between stimulant drug use and familial risk in task-related functional connectivity between the putamen and motor-related cortical regions in potentially at-risk individuals. Our findings suggest that abnormal task-related activation in motor brain systems is associated with regular stimulant drug use, whereas abnormal task-related functional connectivity in frontostriatal brain systems, in individuals with familial risk, may indicate pre-existing neural vulnerability for developing addiction.

The thalamus in drug addiction: from rodents to humans

Impairments in response inhibition and salience attribution (iRISA) have been proposed to underlie the clinical symptoms of drug addiction as mediated by cortico-striatal-thalamo-cortical networks. The bulk of evidence supporting the iRISA model comes from neuroimaging research that has focused on cortical and striatal influences with less emphasis on the role of the thalamus. Here, we highlight the importance of the thalamus in drug addiction, focusing on animal literature findings on thalamic nuclei in the context of drug-seeking, structural and functional changes of the thalamus as measured by imaging studies in human drug addiction, particularly during drug cue and non-drug reward processing, and response inhibition tasks. Findings from the animal literature suggest that the paraventricular nucleus of the thalamus, the lateral habenula and the mediodorsal nucleus may be involved in the reinstatement, extinction and expression of drug-seeking behaviours. In support of the iRISA model, the human addiction imaging literature demonstrates enhanced thalamus activation when reacting to drug cues and reduced thalamus activation during response inhibition. This pattern of response was further associated with the severity of, and relapse in, drug addiction. Future animal studies could widen their field of focus by investigating the specific role(s) of different thalamic nuclei in different phases of the addiction cycle. Similarly, future human imaging studies should aim to specifically delineate the structure and function of different thalamic nuclei, for example, through the application of advanced imaging protocols at higher magnetic fields (7 Tesla).This article is part of a discussion meeting issue 'Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists'.

Reward activation in childhood predicts adolescent substance use initiation in a high-risk sample

BACKGROUND

Substance use at an early age conveys substantial risk for later substance-related problems. A better understanding of early risk factors could result in more timely and effective intervention. This study investigated the predictive utility of the brain's response to reward anticipation as a risk factor for early substance use initiation.

METHODS

Participants were 34 children (25 male) at high risk for alcohol and other substance use disorders from a longitudinal functional magnetic resonance imaging study, scanned at a mean age of 10.5 years (SD = 1.2) when participants were substance-naïve. We used a monetary incentive delay task to examine the hemodynamic response of the nucleus accumbens to gain and loss anticipation. Logistic regression was used to test the hypothesis that these brain response patterns would have predictive utility over and above early externalizing behaviors and family history of substance use disorder, two key risk factors for substance use problems, in differentiating those who initiated substance use before age 16 (n = 18) and those who did not (n = 16).

RESULTS

Greater nucleus accumbens activation during monetary gain anticipation in childhood increased the likelihood of initiating substance use during early adolescence (p = .023). The model that comprised neural data in addition to early externalizing behaviors and family history showed significantly better fit than the model without neural data (χ²₂ = 7.38, p = .025).

CONCLUSIONS

Heightened gain anticipation activation in the nucleus accumbens may predispose individuals to early substance use, beyond the risk conveyed by other known factors.

A Roadmap for Integrating Neuroscience Into Addiction Treatment: A Consensus of the Neuroscience Interest Group of the International Society of Addiction Medicine

Although there is general consensus that altered brain structure and function underpins addictive disorders, clinicians working in addiction treatment rarely incorporate neuroscience-informed approaches into their practice. We recently launched the Neuroscience Interest Group within the International Society of Addiction Medicine (ISAM-NIG) to promote initiatives to bridge this gap. This article summarizes the ISAM-NIG key priorities and strategies to achieve implementation of addiction neuroscience knowledge and tools for the assessment and treatment of substance use disorders. We cover two assessment areas: cognitive assessment and neuroimaging, and two interventional areas: cognitive training/remediation and neuromodulation, where we identify key challenges and proposed solutions. We reason that incorporating cognitive assessment into clinical settings requires the identification of constructs that predict meaningful clinical outcomes. Other requirements are the development of measures that are easily-administered, reliable, and ecologically-valid. Translation of neuroimaging techniques requires the development of diagnostic and prognostic biomarkers and testing the cost-effectiveness of these biomarkers in individualized prediction algorithms for relapse prevention and treatment selection. Integration of cognitive assessments with neuroimaging can provide multilevel targets including neural, cognitive, and behavioral outcomes for neuroscience-informed interventions. Application of neuroscience-informed interventions including cognitive training/remediation and neuromodulation requires clear pathways to design treatments based on multilevel targets, additional evidence from randomized trials and subsequent clinical implementation, including evaluation of cost-effectiveness. We propose to address these challenges by promoting international collaboration between researchers and clinicians, developing harmonized protocols and data management systems, and prioritizing multi-site research that focuses on improving clinical outcomes.

Application of Research Domain Criteria to childhood and adolescent impulsive and addictive disorders: Implications for treatment

The Research Domain Criteria (RDoC) initiative provides a large-scale, dimensional framework for the integration of research findings across traditional diagnoses, with the long-term aim of improving existing psychiatric treatments. A neurodevelopmental perspective is essential to this endeavor. However, few papers synthesizing research findings across childhood and adolescent disorders exist. Here, we discuss how the RDoC framework may be applied to the study of childhood and adolescent impulsive and addictive disorders in order to improve neurodevelopmental understanding and to enhance treatment development. Given the large scope of RDoC, we focus on a single construct highly relevant to addictive and impulsive disorders - initial responsiveness to reward attainment. Findings from genetic, molecular, neuroimaging and other translational research methodologies are highlighted.

Tick-tock goes the croc: a high-density EEG study of risk-reactivity and binge-drinking

Links between individual differences in risk processing and high-risk behaviors such as binge-drinking have long been the focus of active research. However, investigations in this area almost exclusively utilize decision-making focused paradigms. This emphasis makes it difficult to assess links between risk behaviors and raw risk reactivity independent of decision and feedback processes. A deeper understanding of this association has the potential to shed light on the role of risk reactivity in high-risk behavior susceptibility. To contribute toward this aim, this study utilizes a popular risk-taking game, the crocodile dentist, to assess links between individual differences in decision-free risk-reactivity and reported binge-drinking frequency levels. In this task, participants engage in a series of decision-free escalating risk responses. Risk-reactivity was assessed by measuring late positive potential responses toward risk-taking action initiation cues using high-density 256-Channel EEG. The results indicate that, after controlling for overall alcohol consumption frequency, higher rates of reported binge-drinking are associated with both increased general risk-taking responsivity and increased risk-reactivity escalation as a function of risk level. These findings highlight intriguing links between risk reactivity and binge-drinking frequency, making key contributions in the areas of risk-taking and affective science.

The anticipation and outcome phases of reward and loss processing: A neuroimaging meta-analysis of the monetary incentive delay task

The processing of rewards and losses are crucial to everyday functioning. Considerable interest has been attached to investigating the anticipation and outcome phases of reward and loss processing, but results to date have been inconsistent. It is unclear if anticipation and outcome of a reward or loss recruit similar or distinct brain regions. In particular, while the striatum has widely been found to be active when anticipating a reward, whether it activates in response to the anticipation of losses as well remains ambiguous. Furthermore, concerning the orbitofrontal/ventromedial prefrontal regions, activation is often observed during reward receipt. However, it is unclear if this area is active during reward anticipation as well. We ran an Activation Likelihood Estimation meta‐analysis of 50 fMRI studies, which used the Monetary Incentive Delay Task (MIDT), to identify which brain regions are implicated in the anticipation of rewards, anticipation of losses, and the receipt of reward. Anticipating rewards and losses recruits overlapping areas including the striatum, insula, amygdala and thalamus, suggesting that a generalised neural system initiates motivational processes independent of valence. The orbitofrontal/ventromedial prefrontal regions were recruited only during the reward outcome, likely representing the value of the reward received. Our findings help to clarify the neural substrates of the different phases of reward and loss processing, and advance neurobiological models of these processes.

Regional cerebral blood flow predictors of relapse and resilience in substance use recovery: A coordinate-based meta-analysis of human neuroimaging studies

BACKGROUND

Predicting relapse vulnerability can inform level-of-care and personalized substance use treatment. Few reliable predictors of relapse risk have been identified from traditional clinical, psychosocial, and demographic variables. However, recent neuroimaging findings highlight the potential prognostic import of brain-based signals, indexing the degree to which neural systems have been perturbed by addiction. These proposed "neuromarkers" forecast the likelihood, severity, and timing of relapse but the reliability and generalizability of such effects remains to be established.

METHODS

Activation likelihood estimation was used to conduct a preliminary quantitative, coordinate-based meta-analysis of the addiction neuroprediction literature; specifically, studies wherein baseline measures of regional cerebral blood flow were prospectively associated with substance use treatment outcomes. Consensus patterns of activation associated with relapse vulnerability (greater activation predicts poorer outcomes) versus resilience (greater activation predicts improved outcomes) were specifically investigated.

RESULTS

Twenty-four eligible studies yielded 134 foci, representing 923 subjects. Consensus activation was identified in right putamen and claustrum (p < .05, cluster-corrected) in relation to positive and negative treatment outcomes - likely reflecting variability in measurement context (e.g., task, sample characteristics) across datasets. A single cluster in rostral-ventral anterior cingulate cortex (rACC) was associated with relapse resilience, specifically (p < .05, cluster-corrected); no significant vulnerability-related clusters were identified.

CONCLUSIONS

Right putamen activation has been associated with relapse vulnerability and resilience, while increased baseline rACC activation has been consistently associated with improved treatment outcomes. Methodological heterogeneity within the existing literature, however, limits firm conclusions and future work will be necessary to confirm and clarify these results.

Neuroimaging meta-analysis of cannabis use studies reveals convergent functional alterations in brain regions supporting cognitive control and reward processing

Lagging behind rapid changes to state laws, societal views, and medical practice is the scientific investigation of cannabis's impact on the human brain. While several brain imaging studies have contributed important insight into neurobiological alterations linked with cannabis use, our understanding remains limited. Here, we sought to delineate those brain regions that consistently demonstrate functional alterations among cannabis users versus non-users across neuroimaging studies using the activation likelihood estimation meta-analysis framework. In ancillary analyses, we characterized task-related brain networks that co-activate with cannabis-affected regions using data archived in a large neuroimaging repository, and then determined which psychological processes may be disrupted via functional decoding techniques. When considering convergent alterations among users, decreased activation was observed in the anterior cingulate cortex, which co-activated with frontal, parietal, and limbic areas and was linked with cognitive control processes. Similarly, decreased activation was observed in the dorsolateral prefrontal cortex, which co-activated with frontal and occipital areas and linked with attention-related processes. Conversely, increased activation among users was observed in the striatum, which co-activated with frontal, parietal, and other limbic areas and linked with reward processing. These meta-analytic outcomes indicate that cannabis use is linked with differential, region-specific effects across the brain.

Toward biomarkers of the addicted human brain: Using neuroimaging to predict relapse and sustained abstinence in substance use disorder

The ability to predict relapse is a major goal of drug addiction research. Clinical and diagnostic measures are useful in this regard, but these measures do not fully and consistently identify who will relapse and who will remain abstinent. Neuroimaging approaches have the potential to complement these standard clinical measures to optimize relapse prediction. The goal of this review was to survey the existing drug addiction literature that either used a baseline functional or structural neuroimaging phenotype to longitudinally predict a clinical outcome, or that examined test-retest of a neuroimaging phenotype during a course of abstinence or treatment. Results broadly suggested that, relative to individuals who sustained abstinence, individuals who relapsed had (1) enhanced activation to drug-related cues and rewards, but reduced activation to non-drug-related cues and rewards, in multiple corticolimbic and corticostriatal brain regions; (2) weakened functional connectivity of these same corticolimbic and corticostriatal regions; and (3) reduced gray and white matter volume and connectivity in prefrontal regions. Thus, beyond these regions showing baseline group differences, reviewed evidence indicates that function and structure of these regions can prospectively predict - and normalization of these regions can longitudinally track - important clinical outcomes including relapse and adherence to treatment. Future clinical studies can leverage this information to develop novel treatment strategies, and to tailor scarce therapeutic resources toward individuals most susceptible to relapse.

Insular and cingulate attenuation during decision making is associated with future transition to stimulant use disorder

AIMS

To understand processes placing individuals at risk for stimulant (amphetamine and cocaine) use disorder.

DESIGN

Longitudinal study.

SETTING

University of California, San Diego Department of Psychiatry, CA, USA.

PARTICIPANTS

Occasional stimulant users (OSU; n = 184) underwent a baseline clinical interview and a functional magnetic resonance imaging (fMRI) session. On the basis of a follow-up clinical interview completed 3 years later, OSU (n = 147) were then categorized as problem stimulant users (PSU: n = 36; those who developed stimulant use disorders in the interim) or desisted stimulant users (DSU: n = 74; those who stopped using). OSU who did not meet criteria for PSU or DSU (n = 37) were included in dimensional analyses.

MEASUREMENTS

fMRI blood oxygen level-dependent (BOLD) contrast percentage signal change from baseline collected during a Paper-Scissors-Rock task was examined during three decision-making conditions, those resulting in: (1) wins, (2) ties and (3) losses. These data were used as dependent variables in categorical analyses comparing PSU and DSU, as well as dimensional analyses including interim drug use as predictors, controlling for baseline drug use.

FINDINGS

PSU exhibited lower anterior cingulate, middle insula, superior temporal, inferior parietal, precuneus and cerebellum activation than DSU across all three conditions (significant brain clusters required > 19 neighboring voxels to exceed F_(1,108)  = 5.58, P < 0.01 two-tailed; all Cohen's d > 0.83). Higher interim marijuana use was linked to lower pre-central and superior temporal activation during choices resulting in wins (> 19 neighboring voxels to exceed t = 2.61, P < 0.01 two-tailed; R² change > 0.11).

CONCLUSIONS

Individuals who transition from stimulant use to stimulant use disorder appear to show alterations in neural processing of stimulus valuation and outcome monitoring, patterns also evident in chronic stimulant use disorder. Attenuated anterior cingulate and insular processing may constitute a high-risk neural processing profile, which could be used to calculate risk scores for individuals experimenting with stimulants.

Machine Learning of Functional Magnetic Resonance Imaging Network Connectivity Predicts Substance Abuse Treatment Completion

BACKGROUND

Successfully treating illicit drug use has become paramount, yet elusive. Devising specialized treatment interventions could increase positive outcomes, but it is necessary to identify risk factors of poor long-term outcomes to develop specialized, efficacious treatments. We investigated whether functional network connectivity (FNC) measures were predictive of substance abuse treatment completion using machine learning pattern classification of functional magnetic resonance imaging data.

METHODS

Treatment-seeking stimulant- or heroin-dependent incarcerated participants (n = 139; 89 women) volunteered for a 12-week substance abuse treatment program. Participants performed a response inhibition Go/NoGo functional magnetic resonance imaging task prior to onset of the substance abuse treatment. We tested whether FNC related to the anterior cingulate cortex would be predictive of those who would or would not complete a 12-week substance abuse treatment program.

RESULTS

Machine learning pattern classification models using FNC between networks incorporating the anterior cingulate cortex, striatum, and insula predicted which individuals would (sensitivity: 81.31%) or would not (specificity: 78.13%) complete substance abuse treatment. FNC analyses predicted treatment completion above and beyond other clinical assessment measures, including age, sex, IQ, years of substance use, psychopathy, anxiety and depressive symptomatology, and motivation for change.

CONCLUSIONS

Aberrant neural network connections predicted substance abuse treatment outcomes, which could illuminate new targets for developing interventions designed to reduce or eliminate substance use while facilitating long-term outcomes. This work represents the first application of machine-learning models of FNC analyses of functional magnetic resonance imaging data to predict which substance abusers would or would not complete treatment.

Neural responses to negative outcomes predict success in community-based substance use treatment

BACKGROUND AND AIMS

Patterns of brain activation have demonstrated promise as prognostic indicators in substance dependent individuals (SDIs) but have not yet been explored in SDIs typical of community-based treatment settings.

DESIGN

Prospective clinical outcome design, evaluating baseline functional magnetic resonance imaging data from the Balloon Analogue Risk Task (BART) as a predictor of 3-month substance use treatment outcomes.

SETTING

Community-based substance use programs in Bloomington, Indiana, USA.

PARTICIPANTS

Twenty-three SDIs (17 male, aged 18-43 years) in an intensive outpatient or residential treatment program; abstinent 1-4 weeks at baseline.

MEASUREMENTS

Event-related brain response, BART performance and self-report scores at treatment onset, substance use outcome measure (based on days of use).

FINDINGS

Using voxel-level predictive modeling and leave-one-out cross-validation, an elevated response to unexpected negative feedback in bilateral amygdala and anterior hippocampus (Amyg/aHipp) at baseline successfully predicted greater substance use during the 3-month study interval (P ≤ 0.006, cluster-corrected). This effect was robust to inclusion of significant non-brain-based covariates. A larger response to negative feedback in bilateral Amyg/aHipp was also associated with faster reward-seeking responses after negative feedback (r₍₂₃₎  = -0.544, P = 0.007; r₍₂₃₎  = -0.588, P = 0.003). A model including Amyg/aHipp activation, faster reward-seeking after negative feedback and significant self-report scores accounted for 45% of the variance in substance use outcomes in our sample.

CONCLUSIONS

An elevated response to unexpected negative feedback in bilateral amygdala and anterior hippocampus (Amyg/aHipp) appears to predict relapse to substance use in people attending community-based treatment.

Cocaine addiction is associated with abnormal prefrontal function, increased striatal connectivity and sensitivity to monetary incentives, and decreased connectivity outside the human reward circuit

Cocaine addiction has been associated with increased sensitivity of the human reward circuit to drug-related stimuli. However, the capacity of non-drug incentives to engage this network is poorly understood. Here, we characterized the functional sensitivity to monetary incentives and the structural integrity of the human reward circuit in abstinent cocaine-dependent (CD) patients and their matched controls. We assessed the BOLD response to monetary gains and losses in 30 CD patients and 30 healthy controls performing a lottery task in a magnetic resonance imaging scanner. We measured brain gray matter volume (GMV) using voxel-based morphometry and white matter microstructure using voxel-based fractional anisotropy (FA). Functional data showed that, after monetary incentives, CD patients exhibited higher activation in the ventral striatum than controls. Furthermore, we observed an inverted BOLD response pattern in the prefrontal cortex, with activity being highest after unexpected high gains and lowest after losses. Patients showed increased GMV in the caudate and the orbitofrontal cortex, increased white matter FA in the orbito-striatal pathway but decreased FA in antero-posterior association bundles. Abnormal activation in the prefrontal cortex correlated with GMV and FA increases in the orbitofrontal cortex. While functional abnormalities in the ventral striatum were inversely correlated with abstinence duration, structural alterations were not. In conclusion, results suggest abnormal incentive processing in CD patients with high salience for rewards and punishments in subcortical structures but diminished prefrontal control after adverse outcomes. They further suggest that hypertrophy and hyper-connectivity within the reward circuit, to the expense of connectivity outside this network, characterize cocaine addiction.

The roles of valuation and reward processing in cognitive function and psychiatric disorders

In neuroeconomics, valuation refers to the process of assigning values to states and actions on the basis of the animal's current representation of the environment, while reward processing corresponds to processing the feedback received from the environment to update the values of states and actions. In this article, we review the brain circuits associated with valuation and reward processing and argue that these are fundamental processes critical to many cognitive functions. Specifically, we focus on the role of valuation and reward processing in attention, memory, decision making, and learning. Next, the extant neuroimaging literature on a number of psychiatric disorders is reviewed (i.e., addiction, pathological gambling, schizophrenia, and mood disorders), and an argument is made that associated deficits in cognitive functions can be explained in terms of abnormal valuation and reward processing. The review concludes with the impact of this framework in clinical settings and prescriptions for future research, in particular with regard to the conversions of qualitatively different valuation systems into a system of common currency.

Dissociable neural processes during risky decision-making in individuals with Internet-gaming disorder

Risk-taking is purported to be central to addictive behaviors. However, for Internet gaming disorder (IGD), a condition conceptualized as a behavioral addiction, the neural processes underlying impaired decision-making (risk evaluation and outcome processing) related to gains and losses have not been systematically investigated. Forty-one males with IGD and 27 healthy comparison (HC) male participants were recruited, and the cups task was used to identify neural processes associated with gain- and loss-related risk- and outcome-processing in IGD. During risk evaluation, the IGD group, compared to the HC participants, showed weaker modulation for experienced risk within the bilateral dorsolateral prefrontal cortex (DLPFC) (t = - 4.07; t = - 3.94; PFWE  < 0.05) and inferior parietal lobule (IPL) (t = - 4.08; t = - 4.08; PFWE  < 0.05) for potential losses. The modulation of the left DLPFC and bilateral IPL activation were negatively related to addiction severity within the IGD group (r = - 0.55; r = - 0.61; r = - 0.51; PFWE  < 0.05). During outcome processing, the IGD group presented greater responses for the experienced reward within the ventral striatum, ventromedial prefrontal cortex, and orbitofrontal cortex (OFC) (t = 5.04, PFWE  < 0.05) for potential gains, as compared to HC participants. Within the IGD group, the increased reward-related activity in the right OFC was positively associated with severity of IGD (r = 0.51, PFWE  < 0.05). These results provide a neurobiological foundation for decision-making deficits in individuals with IGD and suggest an imbalance between hypersensitivity for reward and weaker risk experience and self-control for loss. The findings suggest a biological mechanism for why individuals with IGD may persist in game-seeking behavior despite negative consequences, and treatment development strategies may focus on targeting these neural pathways in this population.

Dissociable Effects of Cocaine Dependence on Reward Processes: The Role of Acute Cocaine and Craving

The relative impact of chronic vs acute cocaine on dependence-related variability in reward processing in cocaine-dependent individuals (CD) is not well understood, despite the relevance of such effects to long-term outcomes. To dissociate these effects, CD (N=15) and healthy controls (HC; N=15) underwent MRI two times while performing a monetary incentive delay task. Both scans were identical across subjects/groups, except that, in a single-blind, counterbalanced design, CD received intravenous cocaine (30 mg/70 kg) before one session (CD+cocaine) and saline in another (CD+saline). Imaging analyses focused on activity related to anticipatory valence (gain/loss), anticipatory magnitude (small/medium/large), and reinforcing outcomes (successful/unsuccessful). Drug condition (cocaine vs saline) and group (HC vs CD+cocaine or CD+saline) did not influence valence-related activity. However, compared with HC, magnitude-related activity for gains was reduced in CD in the left cingulate gyrus post-cocaine and in the left putamen in the abstinence/saline condition. In contrast, magnitude-dependent activity for losses increased in CD vs HC in the right inferior parietal lobe post-cocaine and in the left superior frontal gyrus post-saline. Across outcomes (ie, successful and unsuccessful) activity in the right habenula decreased in CD in the abstinence/saline condition vs acute cocaine and HC. Cocaine-dependent variability in outcome- and loss-magnitude activity correlated negatively with ratings of cocaine craving and positively with how high subjects felt during the scanning session. Collectively, these data suggest dissociable effects of acute cocaine on non-drug reward processes, with cocaine consumption partially ameliorating dependence-related insensitivity to reinforcing outcomes/'liking', but having no discernible effect on dependence-related alterations in incentive salience/'wanting'. The relationship of drug-related affective sequelae to non-drug reward processing suggests that CD experience a general alteration of reward function and may be motivated to continue using cocaine for reasons beyond desired drug-related effects. This may have implications for individual differences in treatment efficacy for approaches that rely on reinforcement strategies (eg, contingency management) and for the long-term success of treatment.

The involvement of the striatum in decision making

Decision making has been extensively studied in the context of economics and from a group perspective, but still little is known on individual decision making. Here we discuss the different cognitive processes involved in decision making and its associated neural substrates. The putative conductors in decision making appear to be the prefrontal cortex and the striatum. Impaired decision-making skills in various clinical populations have been associated with activity in the prefrontal cortex and in the striatum. We highlight the importance of strengthening the degree of integration of both cognitive and neural substrates in order to further our understanding of decision-making skills. In terms of cognitive paradigms, there is a need to improve the ecological value of experimental tasks that assess decision making in various contexts and with rewards; this would help translate laboratory learnings into real-life benefits. In terms of neural substrates, the use of neuroimaging techniques helps characterize the neural networks associated with decision making; more recently, ways to modulate brain activity, such as in the prefrontal cortex and connected regions (eg, striatum), with noninvasive brain stimulation have also shed light on the neural and cognitive substrates of decision making. Together, these cognitive and neural approaches might be useful for patients with impaired decision-making skills. The drive behind this line of work is that decision-making abilities underlie important aspects of wellness, health, security, and financial and social choices in our daily lives.

Low-anxiety rats are more sensitive to amphetamine in comparison to high-anxiety rats

This study utilised the two injection protocol of sensitisation (TIPS) and the conditioned place preference test to validate and extend previous findings on the effects of amphetamine on positive reinforcement-related 50 kHz ultrasonic vocalisation (USV) in rats. We also examined changes in the expression of c-Fos and the NMDA receptor 2B (GluN2B) subunit, markers of neuronal activity and plasticity, in brain regions of rats in response to TIPS. We used low anxiety-responsive (LR) and high anxiety-responsive (HR) rats, which are known to exhibit different fear-conditioned response strengths, different susceptibilities to amphetamine in the TIPS procedure and different amphetamine-dependent 50 kHz USV responses. The LR rats, compared to the HR rats, not only vocalised much more intensely but also spent significantly more time in the amphetamine-paired compartment. After the second dose of amphetamine, the LR rats exhibited more c-Fos and GluN2B activation in layers II and III of the M1/M2 motor cortex area and prefrontal cortex (PRE, PRL, IL) and also presented with more GluN2B activation in the basal amygdala. These data reveal that HR and LR rats exhibit different levels of reactivity in the cortical-limbic pathway, which controls reward-related motivational processes. These findings contribute to the general hypothesis that heterogeneity in emotional processes is one of the causes of sensitisation to amphetamine and drug addiction.

Altered reward expectancy in individuals with recent methamphetamine dependence

BACKGROUND

Chronic methamphetamine use may lead to changes in reward-related function of the ventral striatum and caudate nucleus. Whether methamphetamine-dependent individuals show heightened reactivity to positively valenced stimuli (i.e. positive reinforcement mechanisms), or an exaggerated response to negatively valenced stimuli (i.e. driven by negative reinforcement mechanisms) remains unclear. This study investigated neural functioning of expectancy and receipt for gains and losses in adults with (METH+) and without (METH-) histories of methamphetamine dependence.

METHODS

Participants (17 METH+; 23 METH-) performed a probabilistic feedback expectancy task during blood-oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI). Participants were given visual cues probabilistically associated with monetary gain, loss, or neutral outcomes. General linear models examined the BOLD response to: (1) anticipation of gains and losses, and (2) gain and loss monetary outcomes.

RESULTS

METH+ had less BOLD response to loss anticipation than METH- in the ventral striatum and posterior caudate. METH+ also showed more BOLD response to loss outcomes than to gain outcomes in the anterior and posterior caudate, whereas METH- did not show differential responses to the valence of outcomes.

DISCUSSION

METH+ individuals showed attenuated neural response to anticipated gains and losses, but their response to loss outcomes was greater than to gain outcomes. A decreased response to loss anticipation, along with a greater response to loss outcomes, suggests an altered ability to evaluate future risks and benefits based upon prior experience, which may underlie suboptimal decision-making in METH+ individuals that increases the likelihood of risky behavior.

The ICCAM platform study: An experimental medicine platform for evaluating new drugs for relapse prevention in addiction. Part B: fMRI description

OBJECTIVES

We aimed to set up a robust multi-centre clinical fMRI and neuropsychological platform to investigate the neuropharmacology of brain processes relevant to addiction - reward, impulsivity and emotional reactivity. Here we provide an overview of the fMRI battery, carried out across three centres, characterizing neuronal response to the tasks, along with exploring inter-centre differences in healthy participants.

EXPERIMENTAL DESIGN

Three fMRI tasks were used: monetary incentive delay to probe reward sensitivity, go/no-go to probe impulsivity and an evocative images task to probe emotional reactivity. A coordinate-based activation likelihood estimation (ALE) meta-analysis was carried out for the reward and impulsivity tasks to help establish region of interest (ROI) placement. A group of healthy participants was recruited from across three centres (total n=43) to investigate inter-centre differences. Principle observations: The pattern of response observed for each of the three tasks was consistent with previous studies using similar paradigms. At the whole brain level, significant differences were not observed between centres for any task.

CONCLUSIONS

In developing this platform we successfully integrated neuroimaging data from three centres, adapted validated tasks and applied whole brain and ROI approaches to explore and demonstrate their consistency across centres.

Reward Contingencies Improve Goal-Directed Behavior by Enhancing Posterior Brain Attentional Regions and Increasing Corticostriatal Connectivity in Cocaine Addicts

The dopaminergic system provides the basis for the interaction between motivation and cognition. It is triggered by the possibility of obtaining rewards to initiate the neurobehavioral adaptations necessary to achieve them by directing the information from motivational circuits to cognitive and action circuits. In drug addiction, the altered dopamine (DA) modulation of the meso-cortico-limbic reward circuitry, such as the prefrontal cortex (PFC), underlies the disproportionate motivational value of drug use at the expense of other non-drug reinforcers and the user's loss of control over his/her drug intake. We examine how the magnitude of the reward affects goal-directed processes in healthy control (HC) subjects and abstinent cocaine dependent (ACD) patients by using functional magnetic resonance imaging (fMRI) during a counting Stroop task with blocked levels of monetary incentives of different magnitudes (€0, €0.01, €0.5, €1 or €1.5). Our results showed that increasing reward magnitude enhances (1) performance facilitation in both groups; (2) left dorsolateral prefrontal cortex (DLPFC) activity in HC and left superior occipital cortex activity in ACD; and (3) left DLPFC and left putamen connectivity in ACD compared to HC. Moreover, we observed that (4) dorsal striatal and pallidum activity was associated with craving and addiction severity during the parametric increases in the monetary reward. In conclusion, the brain response to gradients in monetary value was different in HC and ACD, but both groups showed improved task performance due to the possibility of obtaining greater monetary rewards.

A preliminary study of longitudinal neuroadaptation associated with recovery from addiction

BACKGROUND

Few studies have explored longitudinal change in event-related brain responses during early recovery from addiction. Moreover, existing findings yield evidence of both increased and decreased signaling within reward and control centers over time. The current study explored reward- and control-related signals in a risky decision-making task and specifically investigated parametric modulations of the BOLD signal, rather than signal magnitude alone. It was hypothesized that risk-related signals during decision-making and outcome evaluation would reflect recovery and that change in specific signals would correspond with improved treatment outcomes.

METHODS

Twenty-one substance dependent individuals were recruited upon enrollment in community-based substance use treatment programs, wherein they received treatment-as-usual. Participants completed functional neuroimaging assessments at baseline and 3-month follow-up while performing the Balloon Analogue Risk Task (BART). Risk- and reward-sensitive signals were identified using parametric modulators. Substance use was tracked throughout the 3-month study interval using the timeline follow-back procedure.

RESULTS

Longitudinal contrasts of parametric modulators suggested improved formation of risk-informed outcome expectations at follow-up. Specifically, a greater response to high risk (low-likelihood) positive feedback was identified in caudal anterior cingulate cortex (ACC) and a greater response to low risk (low-likelihood) negative feedback was identified in caudal ACC and inferior frontal gyrus. In addition, attenuation of a ventromedial prefrontal cortex (vmPFC) "reward-seeking" signal (i.e., increasing response with greater reward) during risky decisions at follow-up was associated with less substance use during the study interval.

CONCLUSIONS

Changes in risk- and reward-related signaling in ACC/vmPFC appear to reflect recovery and may support sobriety.

Brain reward system's alterations in response to food and monetary stimuli in overweight and obese individuals

The brain's reward system is crucial to understand obesity in modern society, as increased neural responsivity to reward can fuel the unhealthy food choices that are driving the growing obesity epidemic. Brain's reward system responsivity to food and monetary rewards in individuals with excessive weight (overweight and obese) versus normal weight controls, along with the relationship between this responsivity and body mass index (BMI) were tested. The sample comprised 21 adults with obesity (BMI > 30), 21 with overweight (BMI between 25 and 30), and 39 with normal weight (BMI < 25). Participants underwent a functional magnetic resonance imaging (fMRI) session while performing two tasks that involve the processing of food (Willing to Pay) and monetary rewards (Monetary Incentive Delay). Neural activations within the brain reward system were compared across the three groups. Curve fit analyses were conducted to establish the association between BMI and brain reward system's response. Individuals with obesity had greater food-evoked responsivity in the dorsal and ventral striatum compared with overweight and normal weight groups. There was an inverted U-shape association between BMI and monetary-evoked responsivity in the ventral striatum, medial frontal cortex, and amygdala; that is, individuals with BMIs between 27 and 32 had greater responsivity to monetary stimuli. Obesity is associated with greater food-evoked responsivity in the ventral and dorsal striatum, and overweight is associated with greater monetary-evoked responsivity in the ventral striatum, the amygdala, and the medial frontal cortex. Findings suggest differential reactivity of the brain's reward system to food versus monetary rewards in obesity and overweight. Hum Brain Mapp 38:666-677, 2017. © 2016 Wiley Periodicals, Inc.

Anticipatory reward processing among cocaine-dependent individuals with and without concurrent methadone-maintenance treatment: Relationship to treatment response

BACKGROUND

Cocaine dependence among opioid-dependent methadone-maintained individuals is a significant public health problem and is particularly challenging to treat. The neurobiology of this clinically complex population has not been previously assessed using fMRI.

METHODS

fMRI data from cocaine-dependent, methadone-maintained (CD-MM) patients (n=24), cocaine-dependent (CD) patients (n=20) and healthy comparison (HC) participants (n=21) were acquired during monetary incentive delay task performance. All patients were scanned prior to treatment for cocaine dependence. Between-group differences in anticipatory reward and loss processing were assessed using whole-brain ANOVAs in SPM12 (pFWE<0.05). Correlations between durations of abstinence during treatment and BOLD responses within the insula and caudate were also explored.

RESULTS

Main effects of diagnostic group, primarily involving decreased BOLD responses among CD-MM patients in comparison to HCs, were observed during anticipatory reward and loss processing within regions of posterior cingulate cortex, precuneus, inferior frontal gyrus and dorsolateral prefrontal cortex. BOLD responses within the right caudate were negatively associated with percentage of cocaine-negative urines during treatment among CD-MM patients, but not among non-methadone-maintained CD patients.

CONCLUSIONS

These data suggest neurofunctional differences that may be related to treatment outcomes for behavioral therapies between cocaine-dependent individuals with and without methadone-maintenance treatment. These findings may relate to differences in treatment efficacies and to the elevated relapse rates observed in methadone-maintained populations.

Cocaine dependence and thalamic functional connectivity: a multivariate pattern analysis

Cocaine dependence is associated with deficits in cognitive control. Previous studies demonstrated that chronic cocaine use affects the activity and functional connectivity of the thalamus, a subcortical structure critical for cognitive functioning. However, the thalamus contains nuclei heterogeneous in functions, and it is not known how thalamic subregions contribute to cognitive dysfunctions in cocaine dependence. To address this issue, we used multivariate pattern analysis (MVPA) to examine how functional connectivity of the thalamus distinguishes 100 cocaine-dependent participants (CD) from 100 demographically matched healthy control individuals (HC). We characterized six task-related networks with independent component analysis of fMRI data of a stop signal task and employed MVPA to distinguish CD from HC on the basis of voxel-wise thalamic connectivity to the six independent components. In an unbiased model of distinct training and testing data, the analysis correctly classified 72% of subjects with leave-one-out cross-validation (p < 0.001), superior to comparison brain regions with similar voxel counts (p < 0.004, two-sample t test). Thalamic voxels that form the basis of classification aggregate in distinct subclusters, suggesting that connectivities of thalamic subnuclei distinguish CD from HC. Further, linear regressions provided suggestive evidence for a correlation of the thalamic connectivities with clinical variables and performance measures on the stop signal task. Together, these findings support thalamic circuit dysfunction in cognitive control as an important neural marker of cocaine dependence.

Biomarkers for Success: Using Neuroimaging to Predict Relapse and Develop Brain Stimulation Treatments for Cocaine-Dependent Individuals

Cocaine dependence is one of the most difficult substance use disorders to treat. While the powerful effects of cocaine use on behavior were documented in the 19th century, it was not until the late 20th century that we realized cocaine use was affecting brain tissue and function. Following a brief introduction (Section 1), this chapter will summarize our current knowledge regarding alterations in neural circuit function typically observed in chronic cocaine users (Section 2) and highlight an emerging body of literature which suggests that pretreatment limbic circuit activity may be a reliable predictor of clinical outcomes among individuals seeking treatment for cocaine (Section 3). Finally, as the field of addiction research strives to translate this neuroimaging data into something clinically meaningful, we will highlight several new brain stimulation approaches which utilize functional brain imaging data to design noninvasive brain stimulation interventions for individuals seeking treatment for substance dependence disorders (Section 4).

Neurofunctional Reward Processing Changes in Cocaine Dependence During Recovery

Although reward processing appears altered in addiction, few studies track neurofunctional changes following treatment or relate these to measures of reduced drug use. The current study examined neurofunctional alterations in reward processing in cocaine dependence (CD) pretreatment and posttreatment to determine whether these changes relate to clinically meaningful outcome indicators. Treatment-seeking CD outpatients (N=29) underwent functional magnetic resonance imaging while performing a monetary incentive delay task (MIDT) pretreatment and posttreatment. The MIDT parses anticipatory from outcome phases of reward/loss processing. Abstinence indicators (negative urines, days abstinent from cocaine during follow-up) were collected throughout treatment and up to 1 year later. Healthy control (HC) participants (N=28) were also scanned twice with the MIDT. Relative to pretreatment, at posttreatment CD participants demonstrated increased anticipatory reward activity in the midbrain, thalamus, and precuneus (pFWE<0.05). Increased midbrain activity correlated with cocaine abstinence during the 1-year follow-up. Ventral striatal (VS) activity during loss anticipation correlated negatively with negative urine screens. HC group test-retest results showed decreased ventromedial prefrontal cortex activity during winning outcomes. CD-HC group-by-time differences revealed increased left inferior frontal gyrus activity in the CD group during anticipatory phases at posttreatment. In CD participants, increased posttreatment activity in dopamine-innervated regions suggests lowered thresholds in anticipatory signaling for non-drug rewards. Midbrain and VS responses may represent biomarkers associated with CD abstinence. Abstinence-related neurobiological changes occur in similar regions implicated during active use and may possibly be used to track progress during short- and long-term recovery.

Alexithymia and Addiction: A Review and Preliminary Data Suggesting Neurobiological Links to Reward/Loss Processing

Alexithymia, characterized by impairments in emotional awareness, is common among individuals with substance use disorders. Research on alexithymia suggests that it is a trait that may contribute to substance dependence. This paper will review alexithymia as it relates to substance use and substance use disorders, considering its potential role in the maintenance and treatment of these disorders. We will then describe how neural correlates associated with alexithymia may shed light on how alexithymia relates to addiction. Finally, we present preliminary fMRI data that examines how alexithymia may relate to the neurobiological correlates of reward/loss processing in individuals with cocaine dependence. While preliminary, these findings suggest a role of alexithymia in reward anticipation in cocaine-dependent individuals.

Problematic Internet Users Show Impaired Inhibitory Control and Risk Taking with Losses: Evidence from Stop Signal and Mixed Gambles Tasks

According to the balance model of self-regulation, dysfunction of the inhibitory control and reward processing might be a behavioral marker for addiction and problematic behaviors. Although several studies have separately examined the inhibitory control or reward processing of individuals exhibiting problematic Internet use (PIU), no study has explored these two functions simultaneously to examine the potential imbalance of these functions. This study aimed to investigate whether the self-regulatory failure of PIU individuals results from deficits in both inhibitory control [indexed with the stop signal reaction time (SSRT) in a stop signal task] and risk taking with losses (measured as the acceptance rates of risky gables or the ratio of win/loss in a mixed gambles task). The results revealed that PIU individuals, compared with controls, showed decreased SSRT and increased error rates as well as reduced risk taking with losses. Correlational analyses revealed a significant positive relationship between the SSRT and risk taking with losses. These findings suggest that both the inhibitory control and reward functions are impaired in PIU individuals and reveal an association between these two systems. These results strengthen the balance model of self-regulation theory's argument that deficits in inhibitory control and risk taking with losses may assist in identifying risk markers for early diagnosis, progression, and prediction of PIU.

Shared neural basis of social and non-social reward deficits in chronic cocaine users

Changed reward functions have been proposed as a core feature of stimulant addiction, typically observed as reduced neural responses to non-drug-related rewards. However, it was unclear yet how specific this deficit is for different types of non-drug rewards arising from social and non-social reinforcements. We used functional neuroimaging in cocaine users to investigate explicit social reward as modeled by agreement of music preferences with music experts. In addition, we investigated non-social reward as modeled by winning desired music pieces. The study included 17 chronic cocaine users and 17 matched stimulant-naive healthy controls. Cocaine users, compared with controls, showed blunted neural responses to both social and non-social reward. Activation differences were located in the ventromedial prefrontal cortex overlapping for both reward types and, thus, suggesting a non-specific deficit in the processing of non-drug rewards. Interestingly, in the posterior lateral orbitofrontal cortex, social reward responses of cocaine users decreased with the degree to which they were influenced by social feedback from the experts, a response pattern that was opposite to that observed in healthy controls. The present results suggest that cocaine users likely suffer from a generalized impairment in value representation as well as from an aberrant processing of social feedback.