Altered motor network dynamics in myoclonus-dystonia

Area of Science:

• Neuroscience
• Systems Neuroscience
• Clinical Neurology

Background:

• Myoclonus-dystonia (M-D) pathophysiology remains unclear, with suspected involvement of basal ganglia-thalamo-cortical (BGTC) and cerebello-thalamo-cortical (CTC) networks.
• Understanding network alterations is crucial for elucidating M-D mechanisms.

Purpose of the Study:

• To investigate static and dynamic functional connectivity within BGTC and CTC networks in M-D patients at rest using fMRI.
• To correlate network features with clinical measures of M-D severity, anxiety, depression, and cognition.

Main Methods:

• Resting-state fMRI data analyzed using Independent Component Analysis (ICA) to identify BGTC and CTC networks.
• Static functional connectivity (within- and between-network) and dynamic functional connectivity (state-based analysis using k-means clustering) were assessed.
• Clinical data collected using standardized scales (CGI-S, HADS, MoCA).

Main Results:

• M-D patients exhibited increased static within-network functional connectivity in the left supramarginal gyrus within cognitive control networks (P<0.05 FDR).
• Dynamic analysis revealed three distinct connectivity states in BGTC and CTC circuits.
• M-D patients spent less time in a state characterized by sensorimotor segregation and high inter-network connectivity within domains, potentially indicating reduced basal ganglia and cerebellar contributions.

Conclusions:

• Findings support disrupted brain network dynamics in BGTC and CTC circuits in M-D, suggesting compromised basal ganglia and cerebellar function.
• Altered cerebellar and anterior parietal connectivity may underlie impaired sensory prediction in motor planning, contributing to irregular movements in M-D.
• No significant correlation found between fMRI findings and motor symptom severity.