TY - JOUR
T1 - How does the motor system correct for errors in time and space during locomotor adaptation?
AU - Malone, Laura A.
AU - Bastian, Amy J.
AU - Torres-Oviedo, Gelsy
PY - 2012/7/15
Y1 - 2012/7/15
N2 - Walking is a complex behavior for which the healthy nervous system favors a smooth, symmetric pattern. However, people often adopt an asymmetric walking pattern after neural or biomechanical damage (i.e., they limp). To better understand this aberrant motor pattern and how to change it, we studied walking adaptation to a split-belt perturbation where one leg is driven to move faster than the other. Initially, healthy adult subjects take asymmetric steps on the split-belt treadmill, but within 10-15 min people adapt to reestablish walking symmetry. Which of the many walking parameters does the nervous system change to restore symmetry during this complex act (i.e., what motor mappings are adapted to restore symmetric walking in this asymmetric environment)? Here we found two parameters that met our criteria for adaptive learning: a temporal motor output consisting of the duration between heel-strikes of the two legs (i.e., "when" the feet land) and a spatial motor output related to the landing position of each foot relative to one another (i.e., "where" the feet land). We found that when subjects walk in an asymmetric environment they smoothly change their temporal and spatial motor outputs to restore temporal and spatial symmetry in the interlimb coordination of their gait. These changes in motor outputs are stored and have to be actively deadapted. Importantly, the adaptation of temporal and spatial motor outputs is dissociable since subjects were able to adapt their temporal motor output without adapting the spatial output. Taken together, our results suggest that temporal and spatial control for symmetric gait can be adapted separately, and therefore we could potentially develop interventions targeting either temporal or spatial walking deficits.
AB - Walking is a complex behavior for which the healthy nervous system favors a smooth, symmetric pattern. However, people often adopt an asymmetric walking pattern after neural or biomechanical damage (i.e., they limp). To better understand this aberrant motor pattern and how to change it, we studied walking adaptation to a split-belt perturbation where one leg is driven to move faster than the other. Initially, healthy adult subjects take asymmetric steps on the split-belt treadmill, but within 10-15 min people adapt to reestablish walking symmetry. Which of the many walking parameters does the nervous system change to restore symmetry during this complex act (i.e., what motor mappings are adapted to restore symmetric walking in this asymmetric environment)? Here we found two parameters that met our criteria for adaptive learning: a temporal motor output consisting of the duration between heel-strikes of the two legs (i.e., "when" the feet land) and a spatial motor output related to the landing position of each foot relative to one another (i.e., "where" the feet land). We found that when subjects walk in an asymmetric environment they smoothly change their temporal and spatial motor outputs to restore temporal and spatial symmetry in the interlimb coordination of their gait. These changes in motor outputs are stored and have to be actively deadapted. Importantly, the adaptation of temporal and spatial motor outputs is dissociable since subjects were able to adapt their temporal motor output without adapting the spatial output. Taken together, our results suggest that temporal and spatial control for symmetric gait can be adapted separately, and therefore we could potentially develop interventions targeting either temporal or spatial walking deficits.
KW - Human locomotion
KW - Kinematics
KW - Motor control
KW - Motor learning
KW - Walking
UR - http://www.scopus.com/inward/record.url?scp=84864009022&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84864009022&partnerID=8YFLogxK
U2 - 10.1152/jn.00391.2011
DO - 10.1152/jn.00391.2011
M3 - Article
C2 - 22514294
AN - SCOPUS:84864009022
SN - 0022-3077
VL - 108
SP - 672
EP - 683
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 2
ER -