title: Predicting and correcting ataxia using a model of cerebellar function.
abstract: Cerebellar damage results in uncoordinated, variable and dysmetric movements known as ataxia. Here we show that we can reliably model single-joint reaching trajectories of patients (n = 10), reproduce patient-like deficits in the behaviour of controls (n = 11), and apply patient-specific compensations that improve reaching accuracy (P < 0.02). Our approach was motivated by the theory that the cerebellum is essential for updating and/or storing an internal dynamic model that relates motor commands to changes in body state (e.g. arm position and velocity). We hypothesized that cerebellar damage causes a mismatch between the brain's modelled dynamics and the actual body dynamics, resulting in ataxia. We used both behavioural and computational approaches to demonstrate that specific cerebellar patient deficits result from biased internal models. Our results strongly support the idea that an intact cerebellum is critical for maintaining accurate internal models of dynamics. Importantly, we demonstrate how subject-specific compensation can improve movement in cerebellar patients, who are notoriously unresponsive to treatment.
authors.affiliation: 1 Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore MD, USA2 Kennedy Krieger Institute, Baltimore MD, USA3 Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore MD, USA4 Department of Biomedical Engineering, University of Southern California, Los Angeles CA, USA.
authors.forename: Nasir H
authors.initials: NH
authors.lastname: Bhanpuri
authors.affiliation: 5 Department of Mechanical Engineering, Stanford University, Stanford CA, USA6 Department of Mechanical Engineering, The Johns Hopkins University, Baltimore MD, USA.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Okamura
authors.affiliation: 2 Kennedy Krieger Institute, Baltimore MD, USA3 Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore MD, USA bastian@kennedykrieger.org.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Bastian
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002524:Cerebellar Ataxia / Q000473:pathology* / Q000503:physiopathology*; D002531:Cerebellum / Q000473:pathology* / Q000503:physiopathology*; D003198:Computer Simulation; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009068:Movement / Q000502:physiology; D011237:Predictive Value of Tests; D011597:Psychomotor Performance
keywords: ataxia; cerebellum; computational model; dysmetria; internal model