Probabilistic Reversal Learning in Schizophrenia: Stability of Deficits and Potential Causal Mechanisms

Abstract

Although individuals with schizophrenia show impaired feedback-driven learning on probabilistic reversal learning (PRL) tasks, the specific factors that contribute to these deficits remain unknown. Recent work has suggested several potential causes including neurocognitive impairments, clinical symptoms, and specific types of feedback-related errors. To examine this issue, we administered a PRL task to 126 stable schizophrenia outpatients and 72 matched controls, and patients were retested 4 weeks later. The task involved an initial probabilistic discrimination learning phase and subsequent reversal phases in which subjects had to adjust their responses to sudden shifts in the reinforcement contingencies. Patients showed poorer performance than controls for both the initial discrimination and reversal learning phases of the task, and performance overall showed good test-retest reliability among patients. A subgroup analysis of patients (n = 64) and controls (n = 49) with good initial discrimination learning revealed no between-group differences in reversal learning, indicating that the patients who were able to achieve all of the initial probabilistic discriminations were not impaired in reversal learning. Regarding potential contributors to impaired discrimination learning, several factors were associated with poor PRL, including higher levels of neurocognitive impairment, poor learning from both positive and negative feedback, and higher levels of indiscriminate response shifting. The results suggest that poor PRL performance in schizophrenia can be the product of multiple mechanisms.

Volatility estimates increase choice switching and relate to prefrontal activity in schizophrenia

“…We present two core findings: First, medicated patients both overestimated their prior higher-level belief about the volatility of the environment and exhibited an increased influence of volatility estimates on lower-level learning of actionoutcome contingencies. This provides a computational explanation of the increased switching behavior seen in patients with schizophrenia, both in this and in previous studies (8,(11)(12)(13)(14)(15)(16). We replicate this finding in an independent cohort of unmedicated patients.…”

“…Replicating previous studies (8,(11)(12)(13)(14)(15)(16), patients were impaired in flexible decisionmaking driven by enhanced switching between choice options. Using computational modeling of hierarchical Bayesian learning, we demonstrate a possible underlying learning mechanism: an enhanced prior belief about the environment being volatile combined and a stronger influence of volatility on lower-level learning of action-outcome contingencies.…”

“…In such tasks, schizophrenia is characterized by increased switching between choice options (8,(11)(12)(13)(14)(15)(16). The underlying mechanisms of this instable behavior remain unknown but can be targeted by computational modeling (17).…”

Explaining Delusions: Reducing Uncertainty Through Basic and Computational Neuroscience

“…They exhibit increased switching and achieve fewer performance-dependent reversals, even when learning of initial stimulus-outcome associations appears intact. [91][92][93][94][95] This switching correlates with positive symptoms in both deterministic and probabilistic tasks. 93,96,97 In fact, patients with the highest positive symptom ratings exhibit the highest rates of switching, and they require fewer trials (i.e., less evidence) to alter responding after a reversal occurs.…”

“…103 Intriguingly, recent analyses of reversal learning point to patient subgroups among both unmedicated, drug-naive patients (in the earliest stages of the illness) and medicated patients in the chronic phase. [91][92][93][94][95] Unlike healthy controls and patients who successfully navigate the task, a subgroup with higher positive symptoms exhibited reduced prefrontal cortex activation and choice behavior inconsistent with a Hidden Markov Model (a computational estimation of beliefs about reversals and contingency stability updated trial-by-trial 93 ). Patients who switch excessively also have more positive symptoms.…”