Motor disorder in Huntington's disease begins as a dysfunction in error feedback control

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Analysis

Background:

• Huntington's disease (HD) is characterized by progressive motor dysfunction.
• The precise origins of motor control disturbances in HD remain unclear.
• Understanding early motor deficits is crucial for timely intervention.

Purpose of the Study:

• To investigate motor control deficits in asymptomatic HD gene-carriers (AGCs) and manifest HD patients.
• To identify early indicators of HD progression in reaching movements.
• To elucidate the role of error correction in HD-related motor dysfunction.

Main Methods:

• Analysis of reaching movements in AGCs, manifest HD patients, and healthy controls.
• Quantification of movement jerkiness, variability, and corrective responses.
• Assessment of sensitivity to self-generated and externally-generated movement errors.

Main Results:

• Elevated movement jerkiness, a marker of motor dysfunction, was observed in a significant proportion of AGCs, even years before predicted disease onset.
• Movement termination was more impaired and variable than initiation in HD subjects.
• HD subjects exhibited heightened sensitivity to early movement errors and disturbed corrective responses to external perturbations.

Conclusions:

• A dysfunction in motor error correction is a key characteristic of early Huntington's disease, detectable presymptomatically.
• This error correction deficit contributes to the observed jerkiness and impaired movement termination in HD.
• Motor control abnormalities in HD can be identified years before clinical diagnosis and worsen with disease progression.