Impairments of Social Motor Coordination in Schizophrenia

Leonardo Fontenelle,Stéphane Raffard,Manuel Varlet,Ludovic Marin,Jonathan Del-Monte,Benoît G Bardy,Delphine Capdevielle,R C Schmidt,Jean-Philippe Boulenger

doi:10.1371/journal.pone.0029772

Abstract

It has been demonstrated that motor coordination of interacting people plays a crucial role in the success of social exchanges. Abnormal movements have been reported during interpersonal interactions of patients suffering from schizophrenia and a motor coordination breakdown could explain this social interaction deficit, which is one of the main and earliest features of the illness. Using the dynamical systems framework, the goal of the current study was (i) to investigate whether social motor coordination is impaired in schizophrenia and (ii) to determine the underlying perceptual or cognitive processes that may be affected. We examined intentional and unintentional social motor coordination in participants oscillating hand-held pendulums from the wrist. The control group consisted of twenty healthy participant pairs while the experimental group consisted of twenty participant pairs that included one participant suffering from schizophrenia. The results showed that unintentional social motor coordination was preserved while intentional social motor coordination was impaired. In intentional coordination, the schizophrenia group displayed coordination patterns that had lower stability and in which the patient never led the coordination. A coupled oscillator model suggests that the schizophrenia group coordination pattern was due to a decrease in the amount of available information together with a delay in information transmission. Our study thus identified relational motor signatures of schizophrenia and opens new perspectives for detecting the illness and improving social interactions of patients.

Highlights

It has been demonstrated that the interaction at the level of body movements plays a crucial role in the success of social exchanges
Using the dynamical systems methodology, the goal of the current study was to evaluate the dynamics of social motor coordination in people with schizophrenia in order to further characterize their abnormal interpersonal movements and understand the processes affected by the pathology
To test first whether the preferred frequencies of movements in schizophrenia could be affected and could destabilize social motor coordination, we compared the preferred frequencies of patients and control participants without and before visual interaction

Summary

Introduction

It has been demonstrated that the interaction at the level of body movements plays a crucial role in the success of social exchanges. In studies that have evaluated both intentional and unintentional interpersonal coordination, in-phase and anti-phase patterns of motor coordination, characterized by relative phase values of 0u and 180u, are preferentially adopted by visually coupled individuals [18,19,20,21] Such patterns occur spontaneously and intermittently when the participants are not instructed to synchronize their movements (i.e., unintentional coordination) and can be stably maintained when the coordination is intentional. For both unintentional and intentional coordination, the stability of these patterns — characterized by the variability of the relative phase — is moderated by the difference between the preferred frequencies of actors’ movements with higher stability obtained when their preferred frequencies are close to each other [18,22]. Their stability depends on the strength of the perceptual coupling linking two people, which is mediated by how the actors visually attend to the movements of each other [22,23,24]

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