Aberrant connectivity in auditory precision encoding in schizophrenia spectrum disorder and across the continuum of psychotic-like experiences

• Published in: Schizophrenia research 2020-08, Vol.222, p.185-194
• Main Authors: Larsen, Kit Melissa, Dzafic, Ilvana, Darke, Hayley, Pertile, Holly, Carter, Olivia, Sundram, Suresh, Garrido, Marta I.
• Format: Article
• Language: English
• Subjects: Auditory Perception; Bayes Theorem; Dynamic causal modelling; EEG; Humans; MMN; Posterior probability maps; Psychosis; Psychotic Disorders; Schizophrenia; Schizotypy
• ISSN: 0920-9964; 1573-2509
• DOI: 10.1016/j.schres.2020.05.061

The ability to generate a precise internal model of statistical regularities is impaired in schizophrenia. Predictive coding accounts of schizophrenia suggest that psychotic symptoms may be explained by a failure to build precise beliefs or a model of the world. The precision of this model may vary with context. For example, in a noisy environment the model will be more imprecise compared to a model built in an environment with lower noise. However compelling, this idea has not yet been empirically studied in schizophrenia. Methods: In this study, 62 participants engaged in a stochastic mismatch negativity paradigm with high and low precision. We included inpatients with a schizophrenia spectrum disorder (N = 20), inpatients with a psychiatric disorder but without psychosis (N = 20), and healthy controls (N = 22), with comparable sex ratio and age distribution. Bayesian mapping and dynamic causal modelling were employed to investigate the underlying microcircuitry of precision encoding of auditory stimuli. Results: We found strong evidence (exceedance P > 0.99) for differences in the underlying connectivity associated with precision encoding between the three groups as well as on the continuum of psychotic-like experiences assessed across all participants. Critically, we show changes in interhemispheric connectivity between the two inpatient groups, with some connections further aligning on the continuum of psychotic-like experiences. Conclusions: While our results suggest continuity in backward connectivity alterations with psychotic-like experiences regardless of diagnosis, they also point to specificity for the schizophrenia spectrum disorder group in interhemispheric connectivity alterations.