Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques

Abstract Individuals with cerebellar ataxia face significant challenges in controlling reaching, especially when multi-joint movements are involved. This study investigated the effects of kinematic and dynamic demands on reaching using a home-based virtual reality task. Participants with and without...

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Main Authors: Kyunggeune Oh, Di Cao, Noah J. Cowan, Amy J. Bastian
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-03731-z
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author Kyunggeune Oh
Di Cao
Noah J. Cowan
Amy J. Bastian
author_facet Kyunggeune Oh
Di Cao
Noah J. Cowan
Amy J. Bastian
author_sort Kyunggeune Oh
collection DOAJ
description Abstract Individuals with cerebellar ataxia face significant challenges in controlling reaching, especially when multi-joint movements are involved. This study investigated the effects of kinematic and dynamic demands on reaching using a home-based virtual reality task. Participants with and without cerebellar ataxia reached to target locations designed to elicit a range of coordination strategies between shoulder and elbow joint movements. Compared with control subjects, cerebellar subjects presented greater initial reaching direction errors, larger hand trajectory curvatures, and more variability. Kinematic simulations indicated that early hand movement errors were sensitive to the required onset times and rates of joint movements and were most impaired when opposite direction joint movements were required (e.g., elbow extension with shoulder flexion). Dynamic analysis revealed that cerebellar participants’ movements were more impaired in reaching directions where interaction torques would normally assist the desired elbow and shoulder movements. These reach directions were also those that required joint movements in opposite directions. Overall, our data suggest that reaching deficits in cerebellar ataxia result from (1) the early-phase motion planning deficits that are exacerbated by stringent timing coordination requirements and (2) the inability to compensate for interaction torques, particularly when they assist the intended movement.
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issn 2045-2322
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publishDate 2025-07-01
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spelling doaj-art-e945ba81180340cfaf74836e1c67d07e2025-08-20T03:45:20ZengNature PortfolioScientific Reports2045-23222025-07-0115111710.1038/s41598-025-03731-zCerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torquesKyunggeune Oh0Di Cao1Noah J. Cowan2Amy J. Bastian3Center for Movement Studies, Kennedy Krieger InstituteDepartment of Mechanical Engineering, Johns Hopkins UniversityDepartment of Mechanical Engineering, Johns Hopkins UniversityCenter for Movement Studies, Kennedy Krieger InstituteAbstract Individuals with cerebellar ataxia face significant challenges in controlling reaching, especially when multi-joint movements are involved. This study investigated the effects of kinematic and dynamic demands on reaching using a home-based virtual reality task. Participants with and without cerebellar ataxia reached to target locations designed to elicit a range of coordination strategies between shoulder and elbow joint movements. Compared with control subjects, cerebellar subjects presented greater initial reaching direction errors, larger hand trajectory curvatures, and more variability. Kinematic simulations indicated that early hand movement errors were sensitive to the required onset times and rates of joint movements and were most impaired when opposite direction joint movements were required (e.g., elbow extension with shoulder flexion). Dynamic analysis revealed that cerebellar participants’ movements were more impaired in reaching directions where interaction torques would normally assist the desired elbow and shoulder movements. These reach directions were also those that required joint movements in opposite directions. Overall, our data suggest that reaching deficits in cerebellar ataxia result from (1) the early-phase motion planning deficits that are exacerbated by stringent timing coordination requirements and (2) the inability to compensate for interaction torques, particularly when they assist the intended movement.https://doi.org/10.1038/s41598-025-03731-zCerebellumAtaxiaCoordinationReachingKinematicsDynamics
spellingShingle Kyunggeune Oh
Di Cao
Noah J. Cowan
Amy J. Bastian
Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
Scientific Reports
Cerebellum
Ataxia
Coordination
Reaching
Kinematics
Dynamics
title Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
title_full Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
title_fullStr Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
title_full_unstemmed Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
title_short Cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
title_sort cerebellar reaching ataxia is exacerbated by timing demands and assistive interaction torques
topic Cerebellum
Ataxia
Coordination
Reaching
Kinematics
Dynamics
url https://doi.org/10.1038/s41598-025-03731-z
work_keys_str_mv AT kyunggeuneoh cerebellarreachingataxiaisexacerbatedbytimingdemandsandassistiveinteractiontorques
AT dicao cerebellarreachingataxiaisexacerbatedbytimingdemandsandassistiveinteractiontorques
AT noahjcowan cerebellarreachingataxiaisexacerbatedbytimingdemandsandassistiveinteractiontorques
AT amyjbastian cerebellarreachingataxiaisexacerbatedbytimingdemandsandassistiveinteractiontorques