Addiction as vulnerabilities in the decision process

Drug discrimination learning: Interoceptive stimulus control of behavior and its implications for regulated and dysregulated drug intake

Drug discrimination research has generated rich evidence for the capacity of interoceptive drug stimuli to control behavior by serving as discriminative cues. Owing to its neuropharmacological specificity, drug discrimination learning has been widely used to characterize the stimulus effects and neuropharmacological underpinning of drugs. Apart from such utility, discriminative drug stimuli may help regulate drug use by disambiguating conditioned associations and post-intake outcomes. First, this review summarizes the evidence supporting interoceptive regulation of drug intake from the literature of exteroceptive discriminative control of drug-related behavior, effects of drug priming, and self-titration of drug intake. Second, an overview of interoceptive control of reward-seeking and the animal model of discriminated goal-tracking is provided to illustrate interoceptive stimulus control of the initiation and patterning of drug intake. Third, we highlight the importance of interoceptive control of aversion-avoidance in the termination of drug-use episodes and describe the animal model of discriminated taste avoidance that supports such a position. In bridging these discriminative functions of drug stimuli, we propose that interoceptive drug stimuli help regulate intake by disambiguating whether intake will be rewarding, nonrewarding, or aversive. The reflection and discussion on current theoretical formulations of interoceptive control of drug intake may further scientific advances to improve animal models to study the mechanisms by which interoceptive stimuli regulate drug intake, as well as how alterations of interoceptive processes may contribute to the transition to dysregulated drug use.

Tackling addictive behaviors through memory suppression: A scoping review and perspective

Forgetting is often viewed as a human frailty. However, over the years, it has been considered an adaptive process that allows people to avoid retrieval of undesirable memories, preventing them from suffering and discomfort. Evidence shows that the ability to suppress memories is affected by several psychopathological conditions characterized by persistent unwanted thoughts, including anxiety and posttraumatic stress disorders. Nevertheless, memory suppression (MS) mechanisms in addiction-a clinical condition characterized by recurrent drug-related thoughts that contribute to repeated drug use-have received little attention so far. Addiction theories reveal that drugs change behavior by working on memory systems, particularly on declarative memory, which is related to the retrieval and encoding of drug-related memories. In this review, the main behavioral and neurofunctional findings concerning the Think/No-Think task-an adaptation of the classical Go/No-Go tasks typically used to evaluate the suppression of motor response-are presented. We then show how the memory system can be involved in the craving or anticipation/preoccupation stage of the addiction cycle. Subsequently, the study of MS in the context of addictive behaviors is highlighted as a promising approach for gaining knowledge about the mechanisms contributing to the continuation of addiction. Finally, we discuss how interventions aiming to strengthen this ability could impact the anticipation/preoccupation stage by (i) reducing the accessibility of drug-related memories, (ii) decreasing craving and attention toward drug-related stimuli, and (iii) improving overall inhibition abilities. In conclusion, this review aims to illustrate how the study of MS may be a valuable approach to enhance our understanding of substance use disorders by unveiling the underlying cognitive and neural mechanisms involved, which could have important implications for addiction treatment.

Barriers and facilitators of habit building for long-term adherence to antihypertensive therapy among people with hypertensive disorders in Los Angeles, California: a qualitative study

OBJECTIVES

The aim of this study was to a) explore barriers and facilitators associated with medication-taking habit formation, and b) elicit feedback on the components of an intervention designed to help form strong habits for long-term medication adherence.

DESIGN

The study design was qualitative; we conducted semistructured interviews between September 2021 and February 2022.

SETTING

The interviews were conducted online, with 27 participants recruited at the Cedars-Sinai Medical Center in Los Angeles, California.

PARTICIPANTS

A purposive sample of 20 patients who were over 18 years of age, had been diagnosed with hypertensive disorder (or reported high blood pressure; >140/90 mm Hg) and who were prescribed antihypertensive therapy at the time of recruitment, along with seven providers were interviewed.

RESULTS

Contextual factors included frequent changes to prescription for regimen adjustment, and polypharmacy. Forgetfulness, perceived need for medication, and routine disruptions were identified as possible barriers to habit formation. Facilitators of habit formation included identification of stable routines for anchoring, planning, use of external reminders (including visual reminders) and pillboxes for prescription management, and extrinsic motivation for forming habits. Interestingly, experiencing medication side effects was identified as a possible barrier and a possible facilitator of habit formation. Feedback on study components included increasing text size, and visual appeal of the habit leaflet; and imparting variation in text message content and adjusting their frequency to once a day. Patients generally favoured the use of conditional financial incentives to support habit formation.

CONCLUSION

The study sheds light on some key considerations concerning the contextual factors for habit formation among people with hypertension. As such, future studies may evaluate the generalisability of our findings, consider the role of visual reminders in habit formation and sustenance, and explore possible disruptions to habits.

TRIAL REGISTRATION NUMBER

NCT04029883.

The utility of a latent-cause framework for understanding addiction phenomena

Computational models of addiction often rely on a model-free reinforcement learning (RL) formulation, owing to the close associations between model-free RL, habitual behavior and the dopaminergic system. However, such formulations typically do not capture key recurrent features of addiction phenomena such as craving and relapse. Moreover, they cannot account for goal-directed aspects of addiction that necessitate contrasting, model-based formulations. Here we synthesize a growing body of evidence and propose that a latent-cause framework can help unify our understanding of several recurrent phenomena in addiction, by viewing them as the inferred return of previous, persistent "latent causes". We demonstrate that applying this framework to Pavlovian and instrumental settings can help account for defining features of craving and relapse such as outcome-specificity, generalization, and cyclical dynamics. Finally, we argue that this framework can bridge model-free and model-based formulations, and account for individual variability in phenomenology by accommodating the memories, beliefs, and goals of those living with addiction, motivating a centering of the individual, subjective experience of addiction and recovery.

Behavioural Economics to Improve Antihypertensive Therapy Adherence (BETA): protocol for a pilot randomised controlled trial in Los Angeles

INTRODUCTION

Non-adherence to antihypertensive therapy is one of the major barriers to reducing the risk of cardiovascular disease. Several interventions have targeted higher medication adherence, yet most do not result in sustained adherence. Routinisation has emerged as a potential method for mitigating this problem, but requires high motivation during the relatively long habit formation phase. This pilot randomised controlled trial aims to test the feasibility, acceptability, and preliminary efficacy of behavioural economics-based incentives and text messages to support the routinisation of the medication-taking behaviour for promoting long-term medication adherence.

METHODS AND ANALYSIS

This study will recruit and randomly assign 60 adult patients seeking care for hypertension at the Cedars-Sinai Medical Center in Los Angeles to one of the three groups, Control (n=20), Messages (n=20) and Incentives (n=20) in a 1:1:1 ratio. All participants will receive information about the importance of routinisation and will select an existing behavioural routine ('anchor') to which they will tie their pill-taking to, and the corresponding time. Additionally, participants in the Messages group will receive daily text messages reminding them of the importance of routines, while those in the Incentives group will receive daily text messages and conditional prize drawings. The interventions will be delivered over three months. Participants will be followed for six months post-intervention to measure behavioural persistence. Surveys will be administered at baseline, month-3 and month-9 visits. Primary outcomes include: (1) electronically measured mean medication adherence during the intervention period and (2) post-intervention period; and (3) mean timely medication adherence based around the time of the participants' anchor during the intervention period, and (4) post-intervention period.

ETHICS AND DISSEMINATION

The study was approved by the Cedars-Sinai Institutional Review Board (Study ID: Pro00057764). Findings will be published in scientific peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04029883.

The commission of crime from the perspective of decision-making differences

A criminal act can be regarded as an irrational decision-making process. Therefore, understanding differences in the criminal decision-making process would shed light on criminal behavior. We utilized dual processing theory to propose that offenders' differences in decision-making may cause them to adopt non-adaptive behaviors, such as high reference point setting, abnormal reward-punishment sensitivity, delayed discounting rate, and decision-making style. Our study compares differences in these indicators between offenders (n = 518) and non-offenders (n = 636) in a diverse sample of Chinese adults. The results showed that compared with non-offenders, offenders had higher relative deprivation, reward sensitivity, and delayed discounting rates but lower punishment sensitivity and vigilance in decision-making. A logistic regression analysis also shows that the above factors were significant predictive indicators for the commission of crimes.

Value-based decision-making of cigarette and nondrug rewards in dependent and occasional cigarette smokers: An FMRI study

Little is known about the neural functioning that underpins drug valuation and choice in addiction, including nicotine dependence. Following ad libitum smoking, 19 dependent smokers (smoked≥10/day) and 19 occasional smokers (smoked 0.5-5/week) completed a decision-making task. First, participants stated how much they were willing-to-pay for various amounts of cigarettes and shop vouchers. Second, during functional magnetic resonance imaging, participants decided if they wanted to buy these cigarettes and vouchers for a set amount of money. We examined decision-making behaviour and brain activity when faced with cigarette and voucher decisions, purchasing (vs not purchasing) cigarettes and vouchers, and "value signals" where brain activity correlated with cigarette and voucher value. Dependent smokers had a higher willingness-to-pay for cigarettes and greater activity in the bilateral middle temporal gyrus when faced with cigarette decisions than occasional smokers. Across both groups, the decision to buy cigarettes was associated with activity in the left paracingulate gyrus, right nucleus accumbens, and left amygdala. The decision to buy vouchers was associated with activity in the left superior frontal gyrus, but dependent smokers showed weaker activity in the left posterior cingulate gyrus than occasional smokers. Across both groups, cigarette value signals were observed in the left striatum and ventromedial prefrontal cortex. To summarise, nicotine dependence was associated with greater behavioural valuation of cigarettes and brain activity during cigarette decisions. When purchasing cigarettes and vouchers, reward and decision-related brain regions were activated in both groups. For the first time, we identified value signals for cigarettes in the brain.

Is craving a risk factor for substance use among treatment-seeking individuals with alcohol and other drugs use disorders? A meta-analytic review

BACKGROUND

It is still unclear whether craving should be considered a key risk factor for substance-use behaviors (SUB) among treatment-seeking individuals with alcohol (AUD) and other drugs use disorders. Therefore, this study aims at clarifying this topic using a meta-analytic approach.

METHODS

Cohen's d was computed as effect size (ES) measure. Heterogeneity of ESs was computed using the Q statistic and I² index. The analyses also evaluated the impact assessment length on ESs. Furthermore, proximal effects of craving on SUB were compared to distal ones. The diagnoses of specific substance use disorders (SUDs), together with assessment instruments and research design were considered as additional moderators.

RESULTS

Thirty-six independent studies were included for a total of 4868 treatment-seeking individuals with SUDs. Patients who used substances showed slightly higher levels of craving than abstinent ones. The heterogeneity of results was large and significant. The length of period of assessment was positively related to ESs. The analyses highlighted no differences between pooled ESs of proximal and distal impacts of craving on SUB. The diagnoses of SUDs were significant moderators. Considering AUD, assessment instruments and research design were additional moderators.

CONCLUSIONS

Craving is a modest time-dependent proximal and distal risk factor for SUB among individuals with SUDs. Both the frequency of craving episodes and a heightened reactivity to craving cues are largely associated to SUB among individuals with AUD. Future studies should evaluate the mediating and moderating roles of self-regulatory mechanisms on the relationship between craving and SUB.

Simple Aesthetic Sense and Addiction Emerge in Neural Relations of Cost-Benefit Decision in Foraging

A rudimentary aesthetic sense is found in the stimulus valuations and cost-benefit decisions made by primitive generalist foragers. These are based on factors governing personal economic decisions: incentive, appetite, and learning. We find that the addictive process is an extreme expression of aesthetic dynamics. An interactive, agent-based model, ASIMOV, reproduces a simple aesthetic sense from known neural relations of cost-benefit decision in foraging. In the presence of very high reward, an addiction-like process emerges. A drug-like prey provides extreme reward with no nutritive value, initiating high selectivity and prolonged cravings for drug through reward learning. Varying reward experience, caused by homeostatic changes in the neural circuitry of reward, further establishes the course of addiction, consisting of desensitization, withdrawal, resensitization, and associated changes in nutritional choice and pain sensitivity. These observations are consistent with the early evolution of addiction mechanisms in simple generalist foragers as an aesthetic sense for evaluating prey. ASIMOV is accessible to inspection, modification, and experiment, is adaptable as an educational tool, and provides insight on the possible coevolutionary origins of aesthetics and the addiction process.

"Chasing the first high": memory sampling in drug choice

Although vivid memories of drug experiences are prevalent within clinical contexts and addiction folklore ("chasing the first high"), little is known about the relevance of cognitive processes governing memory retrieval to substance use disorder. Drawing on recent work that identifies episodic memory's influence on decisions for reward, we propose a framework in which drug choices are biased by selective sampling of individual memories during two phases of addiction: (i) downward spiral into persistent use and (ii) relapse. Consideration of how memory retrieval influences the addiction process suggests novel treatment strategies. Rather than try to break learned associations between drug cues and drug rewards, treatment should aim to strengthen existing and/or create new associations between drug cues and drug-inconsistent rewards.

Substance use is associated with reduced devaluation sensitivity

Substance use has been linked to impairments in reward processing and decision-making, yet empirical research on the relationship between substance use and devaluation of reward in humans is limited. We report findings from two studies that tested whether individual differences in substance use behavior predicted reward learning strategies and devaluation sensitivity in a nonclinical sample. Participants in Experiment 1 (N = 66) and Experiment 2 (N = 91) completed subscales of the Externalizing Spectrum Inventory and then performed a two-stage reinforcement learning task that included a devaluation procedure. Spontaneous eye blink rate was used as an indirect proxy for dopamine functioning. In Experiment 1, correlational analysis revealed a negative relationship between substance use and devaluation sensitivity. In Experiment 2, regression modeling revealed that while spontaneous eyeblink rate moderated the relationship between substance use and reward learning strategies, substance use alone was related to devaluation sensitivity. These results suggest that once reward-action associations are established during reinforcement learning, substance use predicted reduced sensitivity to devaluation independently of variation in eyeblink rate. Thus, substance use is not only related to increased habit formation but also to difficulty disengaging from learned habits. Implications for the role of the dopaminergic system in habitual responding in individuals with substance use problems are discussed.

Impulsive decision-making predicts the course of substance-related and addictive disorders

BACKGROUND

This study investigated whether patterns of impulsive decision-making (i) differ between individuals with DSM-5 substance use disorders (SUD) or non-substance-related addictive disorders (ND) and healthy controls, and (ii) predict the increase of SUD and ND severity after one year.

METHODS

In a prospective-longitudinal community study, 338 individuals (19-27 years, 59% female) were included in one of three groups: SUD (n = 100), ND (n = 118), or healthy controls (n = 120). Group differences in four impulsive decision-making facets were analyzed with the Bayesian priors: delay discounting (mean = 0.37, variance = 0.02), probability discounting for gains and for losses (each - 0.16, 0.02), and loss aversion (- 0.44, 0.02). SUD and ND severity were assessed at baseline and after 1 year (n = 312, 92%). Predictive associations between decision-making and SUD/ND severity changes were analyzed with the Bayesian prior: mean = 0.25, variance = 0.016.

RESULTS

Compared with controls, the SUD group displayed steeper delay discounting and lower probability discounting for losses; the ND group displayed lower probability discounting for losses (posterior probabilities > 98%). SUD symptom increase after 1 year was predicted by steeper delay discounting and lower loss aversion; ND symptom increase by lower probability discounting for losses and lower loss aversion (posterior probabilities > 98%). There was low evidence for predictive relations between decision-making and the quantity-frequency of addictive behaviours.

DISCUSSION

Impulsive decision-making characterizes SUD and ND and predicts the course of SUD and ND symptoms but not the engagement in addictive behaviours. Strength of evidence differed between different facets of impulsive decision-making and was mostly weaker than a priori expected.

A fractionated analysis of hot and cool self-regulation in cigarette smokers from different socioeconomic backgrounds

Smoking cigarettes and low socioeconomic status (SES) are both related to impaired cognition. However, it is unknown whether people of lower SES, who comprise most tobacco smokers worldwide, are more susceptible to cognitive impairment associated with smoking. In this non-randomized, cross-sectional study we investigated the effects of cigarette smoking, SES and their interaction on dissociable executive or “cool” and “hot” measures of behavioural self-regulation. Participants (n = 80) were selected among young physically and mentally healthy smokers and non-smokers who had graduated high school and were from different SES backgrounds. Cool self-regulation was measured by executive function tasks that tap inhibition, updating, shifting, dual tasking, planning, access to long-term memory (semantic fluency), and working memory capacity. Hot measures assessed self-reported impulsivity, delay discounting and risk taking. Exposure to tobacco (cotinine, exhaled carbon monoxide, tobacco dependence, cigarette consumption) was assessed to determine to what extent it mediated the cognitive effects of smoking. Nicotine abstinence and its acute effects were controlled, as were sex, age, schooling, and psychiatric symptoms despite the fact that smokers and non-smokers were selected as being as similar as possible in these demographic characteristics. Lower SES (less years of parental schooling) was associated with worse performance on tasks that measured all cool domains except dual tasking and fluency, while smoking status was related to impaired delayed discounting and impulsivity (hot domains), effects that were not mediated by tobacco exposure. Smoking and SES, however, did not interact. In short, impaired performance in measures of most cool skills was associated with SES irrespective of smoking status; in contrast, regardless of SES, smokers showed specific impairment in hot self-regulation domains (more difficulty resisting immediate temptations and weighing future consequences of actions). Possible explanations for the lack of mediation of tobacco exposure on hot skills of smokers are discussed.

Time preferences are reliable across time-horizons and verbal versus experiential tasks

Individual differences in delay-discounting correlate with important real world outcomes, for example education, income, drug use, and criminality. As such, delay-discounting has been extensively studied by economists, psychologists and neuroscientists to reveal its behavioral and biological mechanisms in both human and non-human animal models. However, two major methodological differences hinder comparing results across species. Human studies present long time-horizon options verbally, whereas animal studies employ experiential cues and short delays. To bridge these divides, we developed a novel language-free experiential task inspired by animal decision-making studies. We found that the ranks of subjects' time-preferences were reliable across both verbal/experiential and second/day differences. Yet, discount factors scaled dramatically across the tasks, indicating a strong effect of temporal context. Taken together, this indicates that individuals have a stable, but context-dependent, time-preference that can be reliably assessed using different methods, providing a foundation to bridge studies of time-preferences across species.

Editorial note

This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Let's Open the Decision-Making Umbrella: A Framework for Conceptualizing and Assessing Features of Impaired Decision Making in Addiction

Decision-making impairments play a pivotal role in the emergence and maintenance of addictive disorders. However, a sound conceptualization of decision making as an umbrella construct, encompassing its cognitive, affective, motivational, and physiological subcomponents, is still lacking. This prevents an efficient evaluation of the heterogeneity of decision-making impairments and the development of tailored treatment. This paper thus unfolds the various processes involved in decision making by adopting a critical approach of prominent dual- or triadic-process models, which postulate that decision making is influenced by the interplay of impulsive-automatic, reflective-controlled, and interoceptive processes. Our approach also focuses on social cognition processes, which play a crucial role in decision making and addictive disorders but were largely ignored in previous dual- or triadic-process models. We propose here a theoretical framework in which a range of coordinated processes are first identified on the basis of their theoretical and clinical relevance. Each selected process is then defined before reviewing available results underlining its role in addictive disorders (i.e., substance use, gambling, and gaming disorders). Laboratory tasks for measuring each process are also proposed, initiating a preliminary process-based decision-making assessment battery. This original approach may offer an especially informative view of the constitutive features of decision-making impairments in addiction. As prior research has implicated these features as risk factors for the development and maintenance of addictive disorders, our processual approach sets the scene for novel and transdiagnostic experimental and applied research avenues.

Questionnaire-Based Maladaptive Decision-Coping Patterns Involved in Binge Eating Among 1013 College Students

Binge Eating Disorder (BED), considered a public health problem because of its impact on psychiatric, physical, and social functioning, merits much attention given its elevation to an independent diagnosis in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Similar with substance use disorders, some neuropsychological and personality constructs are potentially implicated in the onset and development of BED, in which poor decision-making has been suggested to facilitate overeating and BED. The objective of this study was to investigate the associations between decision-coping patterns, monetary decision-making, and binge-eating behavior in young adults. A sample of 1013 college students, equally divided into binge-eating and non-binge-eating groups according to the scores on the Binge Eating Scale (BES), were administered multiple measures of decision-making including the Melbourne Decision-Making Questionnaire (MDMQ), the Delay-discounting Test (DDT), and the Probability Discounting Test (PDT). Compared with the non-binge-eating group, the binge-eating group displayed elevated scores on maladaptive decision-making patterns including Procrastination, Buck-passing, and Hypervigilance. Logistic regression model revealed that only Procrastination positively predicted binge eating. These findings suggest that different dimensions of decision-making may be distinctly linked to binge eating among young adults, with Procrastination putatively identified as a risk trait in the development of overeating behavior, which might promote a better understanding of this disorder.

The Web-Surf Task: A translational model of human decision-making

Animal models of decision-making are some of the most highly regarded psychological process models; however, there remains a disconnection between how these models are used for pre-clinical applications and the resulting treatment outcomes. This may be due to untested assumptions that different species recruit the same neural or psychological mechanisms. We propose a novel human foraging paradigm (Web-Surf Task) that we translated from a rat foraging paradigm (Restaurant Row) to evaluate cross-species decision-making similarities. We examined behavioral parallels in human and non-human animals using the respective tasks. We also compared two variants of the human task, one using videos and the other using photos as rewards, by correlating revealed and stated preferences. We demonstrate similarities in choice behaviors and decision reaction times in human and rat subjects. Findings also indicate that videos yielded more reliable and valid results. The joint use of the Web-Surf Task and Restaurant Row is therefore a promising approach for functional translational research, aiming to bridge pre-clinical and clinical lines of research using analogous tasks.

Performance of Smokers with DSM-5 Tobacco Use Disorder in Time-Based Complex Prospective Memory

Studies that investigate time-based complex prospective memory (PM) functioning in participants with substance use disorders (SUD) in consideration of different PM-phases (planning, retention, initiation, execution) are lacking. This study was designed to investigate performance of young adults with DSM-5 tobacco use disorder (TUD) and healthy controls (HC) in different phases of complex PM. Community participants aged 18-35 (N=43) completed the modified Six Elements Test that includes the PM-phases planning, retention, initiation, and execution of a time-based complex PM-task (with delay phases and background activities). TUD participants were current daily smokers and fulfilled at least two DSM-5 TUD criteria. TUD did not differ significantly from HC in task planning errors and timely task initiation. No group differences showed in rule adherence and completeness during task conduction (execution). During execution, TUD showed significantly more deviations (Coef. 0.45; p=0.005) from their originally remembered plans than HC. Young adults with relatively mild TUD do not show general impairments in all phases of short-term, complex, and time-based PM. Future research may investigate whether a greater risk of deviation from originally remembered plans in TUD could play a role in the progression and cessation of smoking behavior.

Dysfunctional decision-making in pathological gambling: pattern specificity and the role of impulsivity

Dysfunctional decision-making in individuals with pathological gambling (PGs) may result from dominating reward-driven processes, indicated by higher impulsivity. In the current study we examined (1) if PGs show specific decision-making impairments related to dominating reward-driven processes rather than to strategic planning deficits and (2) whether these impairments are related to impulsivity. Nineteen PGs according to DSM-IV and 19 matched control subjects undertook the Cambridge Gambling Task (CGT) to assess decision-making. The delay discounting paradigm (DDP) as well as the UPPS Impulsive Behavior Scale (measuring urgency, premeditation, perseverance and sensation seeking) were administered as multidimensional measures of impulsivity. Results revealed that (1) PGs exhibited higher risk seeking and an immediate reward focus in the CGT and, in contrast, comparable strategic planning to the control group. (2) Decision-making impairments were related to more severe delay discounting and, specifically, to increased urgency and less premeditation. Our findings suggest (1) the necessity to disentangle decision-making components in order to improve etiological models of PGs, and (2) that urgency and premeditation are specifically related to disadvantageous decision-making and should be tackled in intervention strategies focusing on emotion tolerance and control strategies.

From prediction error to incentive salience: mesolimbic computation of reward motivation

Reward contains separable psychological components of learning, incentive motivation and pleasure. Most computational models have focused only on the learning component of reward, but the motivational component is equally important in reward circuitry, and even more directly controls behavior. Modeling the motivational component requires recognition of additional control factors besides learning. Here I discuss how mesocorticolimbic mechanisms generate the motivation component of incentive salience. Incentive salience takes Pavlovian learning and memory as one input and as an equally important input takes neurobiological state factors (e.g. drug states, appetite states, satiety states) that can vary independently of learning. Neurobiological state changes can produce unlearned fluctuations or even reversals in the ability of a previously learned reward cue to trigger motivation. Such fluctuations in cue-triggered motivation can dramatically depart from all previously learned values about the associated reward outcome. Thus, one consequence of the difference between incentive salience and learning can be to decouple cue-triggered motivation of the moment from previously learned values of how good the associated reward has been in the past. Another consequence can be to produce irrationally strong motivation urges that are not justified by any memories of previous reward values (and without distorting associative predictions of future reward value). Such irrationally strong motivation may be especially problematic in addiction. To understand these phenomena, future models of mesocorticolimbic reward function should address the neurobiological state factors that participate to control generation of incentive salience.

Immediate Survival Focus: Synthesizing Life History Theory and Dual Process Models to Explain Substance Use

Researchers have recently applied evolutionary life history theory to the understanding of behaviors often conceived of as prosocial or antisocial. In addition, researchers have applied cognitive science to the understanding of substance use and used dual process models, where explicit cognitive processes are modeled as relatively distinct from implicit cognitive processes, to explain and predict substance use behaviors. In this paper we synthesized these two theoretical perspectives to produce an adaptive and cognitive framework for explaining substance use. We contend that this framework provides new insights into the nature of substance use that may be valuable for both clinicians and researchers.

Multiplicity of control in the basal ganglia: computational roles of striatal subregions

The basal ganglia, in particular the striatum, are central to theories of behavioral control, and often identified as a seat of action selection. Reinforcement learning (RL) models--which have driven much recent experimental work on this region--cast striatum as a dynamic controller, integrating sensory and motivational information to construct efficient and enriching behavioral policies. Befitting this informationally central role, the BG sit at the nexus of multiple anatomical 'loops' of synaptic projections, connecting a wide range of cortical and subcortical structures. Numerous pioneering anatomical studies conducted over the past several decades have meticulously catalogued these loops, and labeled them according to the inferred functions of the connected regions. The specific cotermina of the projections are highly localized to several different subregions of the striatum, leading to the suggestion that these subregions perform complementary but distinct functions. However, until recently, the dominant computational framework outlined only a bipartite, dorsal/ventral, division of striatum. We review recent computational and experimental advances that argue for a more finely fractionated delineation. In particular, experimental data provide extensive insight into unique functions subserved by the dorsomedial striatum (DMS). These functions appear to correspond well with theories of a 'model-based' RL subunit, and may also shed light on the suborganization of ventral striatum. Finally, we discuss the limitations of these ideas and how they point the way toward future refinements of neurocomputational theories of striatal function, bringing them into contact with other areas of computational theory and other regions of the brain.

The role of interoception and alliesthesia in addiction

This review presents a novel conceptualization of addiction, integrating the concepts of interoception (i.e., the CNS representation of visceral feelings) and alliesthesia (i.e., that rewarding properties of stimuli are dependent on the internal state of the individual) with existing theories. It is argued that the body state, as defined by the integration of interoceptive information, is a crucial arbiter of the risk for initiation of and transition to compulsive use of addictive compounds. Overall, individuals at risk for drug dependence are characterized by an altered internal bodily state that leads to a change in hedonic and incentive motivational properties of addictive drugs. Specifically, drug dependent individuals experience alliesthesia of interoceptive processing, leading to increased incentive motivational properties of the drug over time and thereby increasing the probability of subsequent use. This extension of previous theories of addiction to include interoception and alliesthesia is based upon a clearly delineated set of neural substrates mediating interoception, key elements of which also recently have been implicated in drug addiction. The model thereby provides new potential targets for interventions that are aimed at changing the internal state that puts the individual at risk for continued substance use.

A neural computational model of incentive salience

Incentive salience is a motivational property with 'magnet-like' qualities. When attributed to reward-predicting stimuli (cues), incentive salience triggers a pulse of 'wanting' and an individual is pulled toward the cues and reward. A key computational question is how incentive salience is generated during a cue re-encounter, which combines both learning and the state of limbic brain mechanisms. Learning processes, such as temporal-difference models, provide one way for stimuli to acquire cached predictive values of rewards. However, empirical data show that subsequent incentive values are also modulated on the fly by dynamic fluctuation in physiological states, altering cached values in ways requiring additional motivation mechanisms. Dynamic modulation of incentive salience for a Pavlovian conditioned stimulus (CS or cue) occurs during certain states, without necessarily requiring (re)learning about the cue. In some cases, dynamic modulation of cue value occurs during states that are quite novel, never having been experienced before, and even prior to experience of the associated unconditioned reward in the new state. Such cases can include novel drug-induced mesolimbic activation and addictive incentive-sensitization, as well as natural appetite states such as salt appetite. Dynamic enhancement specifically raises the incentive salience of an appropriate CS, without necessarily changing that of other CSs. Here we suggest a new computational model that modulates incentive salience by integrating changing physiological states with prior learning. We support the model with behavioral and neurobiological data from empirical tests that demonstrate dynamic elevations in cue-triggered motivation (involving natural salt appetite, and drug-induced intoxication and sensitization). Our data call for a dynamic model of incentive salience, such as presented here. Computational models can adequately capture fluctuations in cue-triggered 'wanting' only by incorporating modulation of previously learned values by natural appetite and addiction-related states.