Objective: We investigated whether deficits in motor representation are associated with alterations of the sense of agency in dystonic patients.

Background: Abnormalities of the cognitive processing of movement have been shown in dystonia. The sense of agency, which is the experience of initiating and controlling one’s own actions, has never been studied in these patients.

Methods: We used an explicit metacognitive agency task where participants had to catch targets with a cursor by moving the computer’s mouse. The task included several conditions where the control over the cursor could be disrupted by adding a spatial or a temporal discrepancy between the mouse and cursor’s movements. Participants had to acknowledge these discrepancies and reflect them in metacognitive judgements of agency.

Results: Twenty cervical dystonia patients and 20 matched controls were included in the study. With equal performance in the task, cervical dystonia patients did not fully recognize alterations of agency when a temporal lag was added between their movement and the visual feedback. Moreover, they relied predominantly on their perceived performance to provide judgements of agency, and less on their objective degree of controls. There was no correlation between agency scores and clinical severity of dystonia measured by the Toronto Western Spasmodic Torticollis Rating Scale.

Conclusions: We showed abnormal metacognitive processing of agency in cervical dystonia patients, even for motor actions not affected by dystonia. The exact contribution of abnormal agency to dystonia pathophysiology remains to be clarified.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-sense-of-agency-is-altered-in-cervical-dystonia/