Habit, choice, and addiction

Abstract

Addiction was suggested to emerge from the progressive dominance of habits over goaldirected behaviors. However, it is generally assumed that habits do not persist in choice settings. Therefore, it is unclear how drug habits may persist in real-world scenarios where this factor predominates. Here, we discuss the poor translational validity of the habit construct, which impedes our ability to determine its role in addiction. New evidence of habitual behavior in a drug choice setting are then described and discussed. Interestingly, habitual preference did not promote drug choice but instead favored abstinence. Here, we propose several clues to reconcile these unexpected results with the habit theory of addiction, and we highlight the need in experimental research to face the complexity of drug addicts' decision-making environments by investigating drug habits in the context of choice and in the presence of cues. On a theoretical level, we need to consider more complex frameworks, taking into account continuous interactions between goal-directed and habitual systems, and alternative decision-making models more representative of real-world conditions. Drugs promote habitA large number of studies in rodents show that drugs of abuse promote habit. Following drug selfadministration training, drugs can be devalued using either sensory-specific satiety or conditioned taste aversion (CTA) before responding for the drug is tested under extinction (box 1). Using this procedure, it was shown that responding for ethanol [11][12][13][14][15][16][17], cocaine [18,19] and nicotine [20,21] becomes habitual after various length of training. In some studies, the transition to habit was faster for the drug compared to a non-drug reward suggesting stronger facilitation of habit formation for drug-seeking [11,13,15,18,21]. Interestingly, studies in which rats are trained to self-administer cocaine or heroin in a seeking-taking schedule (e.g. heterogeneous chains; seeking RI30 -taking FR1 on separate levers) reveal that rats correctly encode the contingency between the seeking response,

Probing the decision-making mechanisms underlying choice between drug and nondrug rewards in rats

“…It is tempting to speculate that the habitual system would process the action value (or "action policy") while the SCM offers a mechanism by which habit translates in preference in a choice setting between two simultaneous options. This assumption is in agreement with a recent theory suggesting that decision-making does not necessarily require computation of the economic value by the brain [55]. Overall, our analysis suggests that habitual responding for the drug and the nondrug reward is engaged after extended training and selected via a race-like competition mechanism, thus indicating that the SCM is not a general model of choice as initially proposed [26,28], but rather constitutes a specific model of habitual choice.…”

“…Furthermore, this study offers a new framework to understand how habit can translate in preference in a choice setting between a drug and a nondrug reward. This theoretical framework will ultimately allow progress in our understanding of the relation between habits and choice and their respective role in substance use disorder [56].…”

Context, attention, and the switch between habit and goal-direction in behavior

“…The ability to form habits makes functional sense, because their automaticity presumably leaves cognitive capacity (e.g., working memory space) to process other things so that we can get around the world without fumbling over the routine. Of course, habits also have a dark side; despite their usefulness, they are considered by some to be important in the development of maladaptive behaviors like drug dependence, compulsions, and obsessive-compulsive disorders (e.g., Everitt & Robbins, 2005Robbins et al, 2019;White, 1996; but see Hogarth, 2020;Vandaele & Ahmed, 2020). Consistent with a role for them in addictions, exposure to drugs of abuse can hasten the development of habit (or the loss of goaldirection) as measured by reinforcer devaluation techniques like the ones described above (e.g., Corbit et al, 2012;Corbit et al, 2014;Furlong et al, 2014;Furlong et al, 2018;Nelson & Killcross, 2006.…”

Mesolimbic dopamine adapts the rate of learning from action

“…6) , or leading to suboptimal policy learning (Fig. 3) --both intriguing perspectives on the mixtures of adaptive and maladaptive learning observed in the context of addiction 79,80 . Finally, our results underscore the importance of matching exogenous mDA stimulation to measured signals, and support the idea that extended, high-magnitude mDA stimulation is an important model of addiction 81 that is dissociable from natural learning about rewards.…”