Our results demonstrate that model-based control can reliably be improved independent of construct severity for most measures. This suggests that incentives may be a useful intervention for boosting model-based control across a range of symptom and trait severity.

Aberrant insula-derived intrinsic connectivity patterns are observed in cocaine users and include dysfunctions in insula to striatal connectivity, which is furthermore linked to increased impulsivity pertaining to forethought.

This paper reviews progress in the application of computational models to personality, developmental, and clinical neuroscience. We first describe the concept of a computational phenotype, a collection of parameters derived from computational models fit to behavioral and neural data. This approach represents individuals as points in a continuous parameter space, complementing traditional trait and symptom measures. One key advantage of this representation is that it is mechanistic: The parameters have interpretations in terms of cognitive processes, which can be translated into quantitative predictions about future behavior and brain activity. We illustrate with several examples how this approach has led to new scientific insights into individual differences, developmental trajectories, and psychopathology. We then survey some of the challenges that lay ahead.

The law of least mental effort states that, everything else being equal, the brain tries to minimize mental effort expenditure during task performance by avoiding decisions that require greater cognitive demands. Prior studies have shown associations between disruptions in effort expenditure and specific psychiatric illnesses (e.g., schizophrenia and depression) or clinically-related symptoms and traits (e.g., anhedonia and apathy), yet no research has explored this issue transdiagnostically. Specifically, this research has largely focused on a single diagnostic category, symptom, or trait. However, abnormalities in effort expression could be related to several different psychiatrically-relevant constructs that cut across diagnostic boundaries. Therefore, we examined the relationship between avoidance of mental effort and a diverse set of clinically-related symptoms and traits, and transdiagnostic latent factors in a large sample (n = 811). Only lack of perseverance, a dimension of impulsiveness, was associated with increased avoidance of mental effort. In contrast, several constructs were associated with less mental effort avoidance, including positive urgency, distress intolerance, obsessive-compulsive symptoms, disordered eating, and a factor consisting of compulsive behavior and intrusive thoughts. These findings demonstrate that deviations from normative effort expenditure are associated with a number of constructs that are common to several forms of psychiatric illness.

Background Markers of chronic cocaine exposure on neural mechanisms in animals and humans is of great interest. The probabilistic reversal-learning task may be an effective way to examine dysfunction associated with cocaine addiction. However the exact nature of the performance deficits observed in cocaine users has yet to be disambiguated. Method Data from a probabilistic reversal-learning task performed by 45 cocaine users and 41 controls was compared and fit to a Bayesian hidden Markov model (HMM). Results Cocaine users demonstrated the predicted performance deficit in achieving the reversal criterion relative to controls. The deficit appeared to be due to excessive switching behavior as evidenced by responsivity to false feedback and spontaneous switching. This decision-making behavior could be captured by a single parameter in an HMM and did not require an additional parameter to represent perseverative errors. Conclusions Cocaine users are characterized by excessive switching behavior on the reversal-learning task. While there may be a compulsive component to behavior on this task, impulsive decision-making may be more relevant to observed impairment. This is important in building diagnostic tools to quantify the degree to which each type of dysfunction is present in individuals, and may play a role in developing treatments for those dysfunctions.

The tension between habits and plans is reflected in everyday decision-making. Habits are computationally cheap, but fail to flexibly adapt to changes in the environment. Planning is a flexible decision-making strategy, but requires greater resources. Arbitration between habits and plans has been formalized using reinforcement learning algorithms that distinguish between model-free control (habits) and model-based control (plans). Evidence about these two decision-making approaches suggests model-based control follows a developmental trajectory, emerging during adolescence, strengthening during young adulthood, and declining in older adulthood. The normative decline in planning (model-based control) presents the opportunity to develop interventions to increase flexible decision-making. Therefore, we asked if incentives could be used to increase model-based control in older adults. We expected older adults would fail to increase model-based control in response to incentives. This prediction was based upon prior research suggesting older adulthood is associated with deficits in representing and updating the expected value of rewards. Contrary to our expectations, in Experiment 1 we found that incentives could be used to boost model-based control in older adults sampled from an online population. We hypothesized this may be due to previous experience with the task (or with similar tasks). In Experiment 2, a naïve sample of older adults did not boost model-based control in response to incentives. These results suggest that incentives may be a useful intervention to increase model-based planning in older adulthood, but this may require extensive experience with the incentive structure.

Background: Theory of mind (ToM) is an aspect of social cognition which refers in part to the capacity to perceive and understand other people's mental state. Deficits in these mentalizing processes are commonly observed in both schizophrenia and Autism Spectrum Disorder (ASD), and are thus evident in disorders with very different symptoms and clinical presentations. The aim of this study was to conduct a meta-analysis of all published data examining ToM deficits in schizophrenia and autism in order to determine whether these two disorders have distinct deficit profiles across multiple domains of ToM. We additionally aimed to explore the relationship between clinical symptoms and phase of illness on ToM deficits in schizophrenia. Methods: A literature search identified 74 eligible studies in schizophrenia involving 3555 cases and 22 studies in ASD involving 810 cases, as of August 2016. Meta-analyses were conducted to calculate the pooled effect size of deficits for each patient group in each ToM domain. Results: As expected, significant theory of mind deficits were observed in both schizophrenia and ASD. Strikingly, the most significantly impaired ToM domain in schizophrenia was understanding verbal intention (g = −1.33) followed by indirect speech (g = −1.09), second-order false belief (g = −0.89), faux-pas −0.88), emotional ToM (g = −0.76) and firstorder false belief (g = −0.61). Understanding visual intention was not significantly impaired. In ASD, the most impaired domain was understanding indirect speech (g = −1.40), followed by faux-pas (g = −1.27), emotional ToM (g = −0.75), and understanding false belief (g = −0.467). Intention inferencing was not significantly impaired in ASD (g = −0.01). Planned meta-regression analyses revealed that positive symptoms significantly modulated the magnitude of deficit across several ToM domains in schizophrenia. Conclusion: Common symptoms of schizophrenia, such as paranoia and persecutory ideas, chime with the greatest observed ToM deficit observed here, which was understanding verbal intention, which was not impaired in ASD. Conversely, understanding meaning in speech was most impaired in ASD, but this was less impaired in schizophrenia. This study reveals that schizophrenia and ASD populations have distinct ToM deficit profiles. Understanding differences in ToM deficit profiles can help differentiate the clinical phenotypes of these disorders in a way that might enhance the identification of disorder-specific behavioral markers and the development of explanatory models and new treatments. Background: The mechanism of auditory hallucinations has been avidly pursued for decades although its formation remains largely cryptic. Another domain of clinical symptoms in schizophrenia is reduced working memory, for which the "phonological loop" is the elementary component. The phonological loop is a subvocal rehearsal of verbal information to support working memory for holding information while other information is manipulated. We hypothesize that auditory hallucinations and w...