Action-Monitoring Alterations as Indicators of Predictive Deficits in Schizophrenia.

A flexible and dynamically adjustable behavior is crucial to adapt to a continuously changing environment. In order to optimally adapt, we need to learn from the consequences of our behavior. We usually learn through different kinds of prediction errors, which occur when we experience unexpected situations due to false predictions. With this literature review, we intended to contribute to current etiological models that ascribe various positive symptoms (particularly delusions and hallucinations) in patients with schizophrenia to false prediction errors and deficient predictive learning. We discuss alterations in the electrophysiological measure of the error-related negativity/error negativity (ERN/Ne) as a global deficit and a trait in schizophrenia, as they have been observed in different samples of patients with schizophrenia, in individuals at high-risk and individuals with subclinical schizotypal traits. As the ERN/Ne can itself be considered the result of predictive processes (evaluation of current action outcomes as worse than expected), we propose that the reported alterations indicate that patients suffering from schizophrenic illnesses fail to adequately classify the outcomes of their actions as better or worse than expected due to a deficit in self-monitoring. Furthermore, we discuss results in further action-monitoring components, such as the correct response negativity (CRN)-a smaller negativity elicited by correct responses; and error positivity (Pe)-a later positivity assumed to reflect conscious error processing. The reported results show normal Pe amplitudes and normal post-error adjustments (adaptations after committed error to improve performance), indicating an intact later and conscious processing. From the results of diminished differences between ERN/Ne and CRN amplitudes, we conclude a general predictive deficit in early aspects of self-monitoring associated with positive symptoms in patients with schizophrenia.