1
|
Jiang A, Grover FM, Bucklin M, Deol J, Shafer A, Gordon KE. Prior uncertainty impedes discrete locomotor adaptation. PLoS One 2024; 19:e0291284. [PMID: 38363788 PMCID: PMC10871477 DOI: 10.1371/journal.pone.0291284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 02/04/2024] [Indexed: 02/18/2024] Open
Abstract
The impact of environmental uncertainty on locomotor adaptation remains unclear. Environmental uncertainty could either aid locomotor adaptation by prompting protective control strategies that stabilize movements to assist learning or impede adaptation by reducing error sensitivity and fostering hesitance to pursue corrective movements. To explore this, we investigated participants' adaptation to a consistent force field after experiencing environmental uncertainty in the form of unpredictable balance perturbations. We compared the performance of this group (Perturbation) to the adaptive performance of a group that did not experience any unpredictable perturbations (Non-Perturbation). Perturbations were delivered using a cable-driven robotic device applying lateral forces to the pelvis. We assessed whole-body center of mass (COM) trajectory (COM signed deviation), anticipatory postural adjustments (COM lateral offset), and first step width. The Perturbation group exhibited larger disruptions in COM trajectory (greater COM signed deviations) than the Non-Perturbation group when first walking in the force field. While the COM signed deviations of both groups decreased towards baseline values, only the Non-Perturbation group returned to baseline levels. The Perturbation groups COM signed deviations remained higher, indicating they failed to fully adapt to the force field before the end. The Perturbation group also did not adapt their COM lateral offset to counter the predictable effects of the force field as the Non-Perturbation group did, and their first step width increased more slowly. Our findings suggest that exposure to unpredictable perturbations impeded future sensorimotor adaptations to consistent perturbations.
Collapse
Affiliation(s)
- Aojun Jiang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - Francis M. Grover
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Mary Bucklin
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - Jasjit Deol
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Anna Shafer
- Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States of America
| | - Keith E. Gordon
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States of America
| |
Collapse
|
2
|
Bucklin MA, Deol J, Brown G, Perreault EJ, Gordon KE. Optimism persists when walking in unpredictable environments. Sci Rep 2023; 13:6853. [PMID: 37100839 PMCID: PMC10133317 DOI: 10.1038/s41598-023-33662-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
Humans continuously modulate their control strategies during walking based on their ability to anticipate disturbances. However, how people adapt and use motor plans to create stable walking in unpredictable environments is not well understood. Our purpose was to investigate how people adapt motor plans when walking in a novel and unpredictable environment. We evaluated the whole-body center of mass (COM) trajectory of participants as they performed repetitions of a discrete goal-directed walking task during which a laterally-directed force field was applied to the COM. The force field was proportional in magnitude to forward walking velocity and randomly directed towards either the right or left each trial. We hypothesized that people would adapt a control strategy to reduce the COM lateral deviations created by the unpredictable force field. In support of our hypothesis, we found that with practice the magnitude of COM lateral deviation was reduced by 28% (force field left) and 44% (force field right). Participants adapted two distinct unilateral strategies, implemented regardless of if the force field was applied to the right or to the left, that collectively created a bilateral resistance to the unpredictable force field. These strategies included an anticipatory postural adjustment to resist against forces applied to the left, and a more lateral first step to resist against forces applied to the right. In addition, during catch trials when the force field was unexpectedly removed, participants exhibited trajectories similar to baseline trials. These findings were consistent with an impedance control strategy that provides a robust resistance to unpredictable perturbations. However, we also found evidence that participants made predictive adaptations in response to their immediate experience that persisted for three trials. Due to the unpredictable nature of the force field, this predictive strategy would sometimes result in greater lateral deviations when the prediction was incorrect. The presence of these competing control strategies may have long term benefits by allowing the nervous system to identify the best overall control strategy to use in a novel environment.
Collapse
Affiliation(s)
- Mary A Bucklin
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave, Suite 1100, Chicago, IL, 60611, USA.
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA.
| | - Jasjit Deol
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave, Suite 1100, Chicago, IL, 60611, USA
| | - Geoffrey Brown
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave, Suite 1100, Chicago, IL, 60611, USA
| | - Eric J Perreault
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
- Shirley Ryan Ability Lab, Chicago, IL, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, USA
| | - Keith E Gordon
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave, Suite 1100, Chicago, IL, 60611, USA
- Research Service, Edward Hines Jr. VA Hospital, Hines, IL, USA
| |
Collapse
|