title: Adaptation to random and systematic errors: Comparison of amputee and non-amputee control interfaces with varying levels of process noise.
abstract: The objective of this study was to understand how people adapt to errors when using a myoelectric control interface. We compared adaptation across 1) non-amputee subjects using joint angle, joint torque, and myoelectric control interfaces, and 2) amputee subjects using myoelectric control interfaces with residual and intact limbs (five total control interface conditions). We measured trial-by-trial adaptation to self-generated errors and random perturbations during a virtual, single degree-of-freedom task with two levels of feedback uncertainty, and evaluated adaptation by fitting a hierarchical Kalman filter model. We have two main results. First, adaptation to random perturbations was similar across all control interfaces, whereas adaptation to self-generated errors differed. These patterns matched predictions of our model, which was fit to each control interface by changing the process noise parameter that represented system variability. Second, in amputee subjects, we found similar adaptation rates and error levels between residual and intact limbs. These results link prosthesis control to broader areas of motor learning and adaptation and provide a useful model of adaptation with myoelectric control. The model of adaptation will help us understand and solve prosthesis control challenges, such as providing additional sensory feedback.
authors.affiliation: Department of Mechanical Engineering, Valparaiso University, Valparaiso, Indiana, United States of America.
authors.forename: Reva E
authors.identifier: http://orcid.org/0000-0002-3725-0754
authors.initials: RE
authors.lastname: Johnson
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois, United States of America.|Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois, United States of America.|Department of Physiology, Northwestern University, Chicago, Illinois, United States of America.
authors.forename: Konrad P
authors.initials: KP
authors.lastname: Kording
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois, United States of America.|Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois, United States of America.
authors.forename: Levi J
authors.initials: LJ
authors.lastname: Hargrove
authors.affiliation: Institute of Biomedical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada.|Department of Electrical and Computer Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada.
authors.forename: Jonathon W
authors.initials: JW
authors.lastname: Sensinger
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000674:Amputees; D004576:Electromyography; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D008328:Man-Machine Systems; D008875:Middle Aged