Evidence for a Time-Invariant Phase Variable in Human Ankle Control
Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or...
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| Format: | Article |
| Language: | en_US |
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Public Library of Science
2014
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| Online Access: | http://hdl.handle.net/1721.1/86302 |
| _version_ | 1811098003307495424 |
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| author | Gregg, Robert D. Hargrove, Levi J. Sensinger, Jonathon W. Rouse, Elliott J. |
| author2 | Program in Media Arts and Sciences (Massachusetts Institute of Technology) |
| author_facet | Program in Media Arts and Sciences (Massachusetts Institute of Technology) Gregg, Robert D. Hargrove, Levi J. Sensinger, Jonathon W. Rouse, Elliott J. |
| author_sort | Gregg, Robert D. |
| collection | MIT |
| description | Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms). In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control. |
| first_indexed | 2024-09-23T17:08:06Z |
| format | Article |
| id | mit-1721.1/86302 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T17:08:06Z |
| publishDate | 2014 |
| publisher | Public Library of Science |
| record_format | dspace |
| spelling | mit-1721.1/863022022-09-29T23:54:12Z Evidence for a Time-Invariant Phase Variable in Human Ankle Control Gregg, Robert D. Hargrove, Levi J. Sensinger, Jonathon W. Rouse, Elliott J. Program in Media Arts and Sciences (Massachusetts Institute of Technology) Rouse, Elliott Jay Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms). In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control. United States Army Medical Research Acquisition Activity (USAMRAA grant W81XWH-09-2-0020) National Institute of Neurological Disorders and Stroke (U.S.) (NIH award number F31NS074687) Burroughs Wellcome Fund (Career Award at the Scientific Interface) 2014-04-30T19:50:16Z 2014-04-30T19:50:16Z 2014-02 2013-07 Article http://purl.org/eprint/type/JournalArticle 1932-6203 http://hdl.handle.net/1721.1/86302 Gregg, Robert D., Elliott J. Rouse, Levi J. Hargrove, and Jonathon W. Sensinger. “Evidence for a Time-Invariant Phase Variable in Human Ankle Control.” Edited by Manabu Sakakibara. PLoS ONE 9, no. 2 (February 18, 2014): e89163. en_US http://dx.doi.org/10.1371/journal.pone.0089163 PLoS ONE Creative Commons Attribution http://creativecommons.org/licenses/by/4.0/ application/pdf Public Library of Science PLoS |
| spellingShingle | Gregg, Robert D. Hargrove, Levi J. Sensinger, Jonathon W. Rouse, Elliott J. Evidence for a Time-Invariant Phase Variable in Human Ankle Control |
| title | Evidence for a Time-Invariant Phase Variable in Human Ankle Control |
| title_full | Evidence for a Time-Invariant Phase Variable in Human Ankle Control |
| title_fullStr | Evidence for a Time-Invariant Phase Variable in Human Ankle Control |
| title_full_unstemmed | Evidence for a Time-Invariant Phase Variable in Human Ankle Control |
| title_short | Evidence for a Time-Invariant Phase Variable in Human Ankle Control |
| title_sort | evidence for a time invariant phase variable in human ankle control |
| url | http://hdl.handle.net/1721.1/86302 |
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