1. Neuroscience
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Cerebellar patients have intact feedback control that can be leveraged to improve reaching

  1. Amanda M Zimmet
  2. Di Cao
  3. Amy J Bastian
  4. Noah J Cowan  Is a corresponding author
  1. Johns Hopkins University, United States
  2. Kennedy Krieger Institute, United States
Research Article
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Cite this article as: eLife 2020;9:e53246 doi: 10.7554/eLife.53246


It is thought that the brain does not simply react to sensory feedback, but rather uses an internal model of the body to predict the consequences of motor commands before sensory feedback arrives. Time-delayed sensory feedback can then be used to correct for the unexpected—perturbations, motor noise, or a moving target. The cerebellum has been implicated in this predictive control process. Here we show that the feedback gain in patients with cerebellar ataxia matches that of healthy subjects, but that patients exhibit substantially more phase lag. This difference is captured by a computational model incorporating a Smith predictor in healthy subjects that is missing in patients, supporting the predictive role of the cerebellum in feedback control. Lastly, we improve cerebellar patients’ movement control by altering (phase advancing) the visual feedback they receive from their own self movement in a simplified virtual reality setup.

Data availability

All data generated or analyzed during this study will be openly on the JHU Data Archive under DOI 10.7281/T1/BCARLC.The data will be available here: https://archive.data.jhu.edu/dataverse/LIMBS

The following data sets were generated

Article and author information

Author details

  1. Amanda M Zimmet

    Biomedical Engineering, Johns Hopkins University, Baltimore, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1457-3072
  2. Di Cao

    Mechanical Engineering, Johns Hopkins University, Baltimore, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1547-9929
  3. Amy J Bastian

    Kennedy Krieger Institute, Baltimore, United States
    Competing interests
    No competing interests declared.
  4. Noah J Cowan

    Mechanical Engineering, Johns Hopkins University, Baltimore, United States
    For correspondence
    Competing interests
    Noah J Cowan, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2502-3770


National Institutes of Health (HD040289)

  • Amy J Bastian
  • Noah J Cowan

Applied Physics Laboratory Graduate Fellowship

  • Amanda M Zimmet

National Science Foundation (1825489)

  • Di Cao
  • Amy J Bastian
  • Noah J Cowan

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.


Human subjects: The experimental protocol was approved by the Institutional Review Board at Johns Hopkins University School of Medicine (protocol # IRB00182673) and all participants gave informed consent prior to joining this study, according to the Declaration of Helsinki.

Reviewing Editor

  1. Richard B Ivry, University of California, Berkeley, United States

Publication history

  1. Received: November 1, 2019
  2. Accepted: October 6, 2020
  3. Accepted Manuscript published: October 7, 2020 (version 1)
  4. Version of Record published: October 21, 2020 (version 2)


© 2020, Zimmet et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.


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