Objective: To investigate the sense of agency in patients with myoclonus-dystonia (DYT-SGCE) compared to healthy volunteers (HV).

Background: Sense of agency is an action-related cognitive function defined as the experience of controlling one’s own actions. Sense of agency is altered in movement disorders. The cerebellum is one of key structures related to the sense of agency and to the pathophysiology of various dystonic syndromes. We hypothesize that in myoclonus-dystonia, cerebellar dysfunction may contribute to symptoms expression and abnormal sense of agency.

Method: We compared the sense of agency using an explicit agency task between 19 DYT-SGCE patients and 24 HV. We investigated the neuronal correlates of sense of agency in brain regions of interest using multimodal neuroimaging.

Results: DYT-SGCE showed an impairment in their sense of agency in the task condition where the action and it’s outcome were temporally delayed. DYT-SGCE also showed grey matter abnormalities in the motor cerebellum, which also had an increased functional connectivity with pre-SMA. In DYT-SGCE motor cerebellum also exerted a lower inhibitory effect on the pre-SMA and received lower excitatory effect from the pre-SMA, which also showed increased self-inhibition. Grey matter alterations of motor cerebellum and functional connectivity abnormalities between the motor cerebellum and pre-SMA both correlated with impairment in sense of agency in DYT-SGCE. Increased self-inhibition within the pre-SMA also correlated with less severe myoclonus.

Conclusion: Our results add disruption of higher-level cognitive processes to the spectrum of neurological and psychiatric dysfunctions, already identified amongst DYT-SGCE. This dysfunction may contribute to the emergence of DYT-SGCE’s phenotype by disrupting the cerebellum’s modulatory effect on the pre-SMA.

References: Haggard P. Sense of agency in the human brain. Nat Rev Neurosci. 2017;18(4):196–207.
Seghezzi S, Convertino L, Zapparoli L. Sense of agency disturbances in movement disorders: A comprehensive review. Conscious Cogn. 2021;96:103228.
Parr T, Limanowski J, Rawji V, Friston K. The computational neurology of movement under active inference. Brain. 2021;144(6):1799–818.
Roze E, Lang AE, Vidailhet M. Myoclonus-dystonia: classification, phenomenology, pathogenesis, and treatment. Curr Opin Neurol. 2018;31(4):484–90.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/abnormal-sense-of-agency-is-involved-in-myoclonus-dystonia-phenotype-through-a-cerebellar-impairment/