Reduced readiness potential and post-movement beta synchronization reflect self-disorders in early course schizophrenia

Francesco Luciano Donati,Corrado Sinigaglia,Armando D'Agostino,Davide Maestri,Mattia Cornali,Matteo Fecchio,Chiara Camilla Derchi,Maristella Zalaffi,Simone Sarasso,Cecilia Casetta

doi:10.1038/s41598-021-94356-5

Abstract

Disturbances of conscious awareness, or self-disorders, are a defining feature of schizophrenia. These include symptoms such as delusions of control, i.e. the belief that one’s actions are controlled by an external agent. Models of self-disorders point at altered neural mechanisms of source monitoring, i.e. the ability of the brain to discriminate self-generated stimuli from those driven by the environment. However, evidence supporting this putative relationship is currently lacking. We performed electroencephalography (EEG) during self-paced, brisk right fist closures in ten (M = 9; F = 1) patients with Early-Course Schizophrenia (ECSCZ) and age and gender-matched healthy volunteers. We measured the Readiness Potential (RP), i.e. an EEG feature preceding self-generated movements, and movement-related EEG spectral changes. Self-disorders in ECSCZ were assessed with the Examination of Anomalous Self-Experience (EASE). Patients showed a markedly reduced RP and altered post-movement Event-Related Synchronization (ERS) in the beta frequency band (14–24 Hz) compared to healthy controls. Importantly, smaller RP and weaker ERS were associated with higher EASE scores in ECSCZ. Our data suggest that disturbances of neural correlates preceding and following self-initiated movements may reflect the severity of self-disorders in patients suffering from ECSCZ. These findings point towards deficits in basic mechanisms of sensorimotor integration as a substrate for self-disorders.

Highlights

Disturbances of conscious awareness, or self-disorders, are a defining feature of schizophrenia
In light of the comparator model, these findings indicate that altered mechanisms of forwarding and integrating sensorimotor information are an important feature of SCZ that might contribute to determining SDs
Despite preserved motor output, the readiness potential is greatly reduced in Early-Course Schizophrenia (ECSCZ)

Summary

Introduction

Disturbances of conscious awareness, or self-disorders, are a defining feature of schizophrenia. Models of self-disorders point at altered neural mechanisms of source monitoring, i.e. the ability of the brain to discriminate self-generated stimuli from those driven by the environment. These findings point towards deficits in basic mechanisms of sensorimotor integration as a substrate for self-disorders. The neural plan processed by motor areas is compared with the perceived effects in the sensory cortex (sensory reafference), confirming the self-generated nature of the movement This determines the dampening of self-generated proprioceptive stimuli and sustains the subjective experience of having caused the movement (or sense of agency). These mechanisms could provide a unique translational bridge to explore underlying neurophysiology on one side, and subtle motor abnormalities observed in patients on the o ther[25]

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