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...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2014-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3928429?pdf=render |
| _version_ | 1819183216267886592 |
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| author | Robert D Gregg Elliott J Rouse Levi J Hargrove Jonathon W Sensinger |
| author_facet | Robert D Gregg Elliott J Rouse Levi J Hargrove Jonathon W Sensinger |
| author_sort | Robert D Gregg |
| collection | DOAJ |
| 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 | 2024-12-22T22:58:30Z |
| format | Article |
| id | doaj.art-46314e2c037f4c01b0ec7ee0dde5d35f |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-22T22:58:30Z |
| publishDate | 2014-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-46314e2c037f4c01b0ec7ee0dde5d35f2022-12-21T18:09:44ZengPublic Library of Science (PLoS)PLoS ONE1932-62032014-01-0192e8916310.1371/journal.pone.0089163Evidence for a time-invariant phase variable in human ankle control.Robert D GreggElliott J RouseLevi J HargroveJonathon W SensingerHuman 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.http://europepmc.org/articles/PMC3928429?pdf=render |
| spellingShingle | Robert D Gregg Elliott J Rouse Levi J Hargrove Jonathon W Sensinger Evidence for a time-invariant phase variable in human ankle control. PLoS ONE |
| 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://europepmc.org/articles/PMC3928429?pdf=render |
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