About the Authors

Marian L. Dale

dalem@ohsu.edu

Affiliations Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America, Parkinson’s Disease Research, Education and Clinical Center, P3-PADRECC, Veterans Affairs Portland Healthcare System (VAPORHCS), Portland, Oregon, United States of America

Fay B. Horak

Affiliations Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America, Parkinson’s Disease Research, Education and Clinical Center, P3-PADRECC, Veterans Affairs Portland Healthcare System (VAPORHCS), Portland, Oregon, United States of America

W. Geoffrey Wright

Affiliation Departments of Physical Therapy and Bioengineering, Temple University, Philadelphia, Pennsylvania, United States of America

Bernadette M. Schoneburg

Affiliation Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America

John G. Nutt

Affiliation Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America

Martina Mancini

Affiliation Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America

Competing Interests

Yes. I have read the journal's policy and the authors of this manuscript have the following competing interests: FBH: OHSU and FH have a significant financial interest in APDM, a company that may have a commercial interest in the results of this research and technology. This potential institutional and individual conflict has been reviewed and managed by OHSU. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Author Contributions

Conceptualization: BS FH JN. Data curation: MM. Formal analysis: MM. Funding acquisition: BS. Investigation: BS MM. Methodology: FH MM. Project administration: FB BS MM. Resources: FH JN. Supervision: FH JN. Validation: MM WW. Visualization: MM. Writing – original draft: MD. Writing – review & editing: MD FH MM JN WW.