title: Intersegmental coordination elicited by unexpected multidirectional slipping-like perturbations resembles that adopted during steady locomotion.
abstract: This study aimed at testing the hypothesis that reactive biomechanical responses elicited by unexpected slipping-like perturbations delivered during steady walking are characterized by an intersegmental coordination strategy resembling that adopted during unperturbed walking. Fifteen healthy subjects were asked to manage multidirectional slipping-like perturbations delivered while they walked steadily. The planar covariation law of elevation angles related to lower limb segments was the main observed variable related to unperturbed and perturbed strides. Principal component analysis was used to verify whether elevation angles covaried, both before and after the onset of the perturbation, and, if so, the orientation of the related planes of covariation was compared. Results revealed that the planar covariation law of the unperturbed limb after onset of the perturbation was systematically similar to that seen during steady walking. This occurred despite differences in range of motion and intersubject variability of both elevation and joint angles. The analysis strongly corroborates the hypothesis that the planar covariation law emerges from the interaction between spinal neural networks and limb mechanical oscillators. In particular, fast and stereotyped reactive strategies may result from the interaction among activities of downstream neural networks encrypting well-trained motor schemes, such as those related to walking, limb dynamics, and sensory motor information gathered during the perturbation. In addition, our results allowed us to speculate that rehabilitative treatment based on unexpected perturbations and relying on the plasticity of the central nervous system may also be effective in eliciting unimpaired intralimb coordination in neurological patients.
authors.affiliation: The BioRobotics Institute, Scuola Superiore Sant'Anna, Pontedera, Pisa, Italy;
authors.forename: Federica
authors.identifier: http://orcid.org/0000-0002-7691-4613
authors.initials: F
authors.lastname: Aprigliano
authors.affiliation: The BioRobotics Institute, Scuola Superiore Sant'Anna, Pontedera, Pisa, Italy; Department of Mechanical Engineering, Columbia University, New York, New York;
authors.forename: Dario
authors.initials: D
authors.lastname: Martelli
authors.affiliation: The BioRobotics Institute, Scuola Superiore Sant'Anna, Pontedera, Pisa, Italy; Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; and.
authors.forename: Silvestro
authors.initials: S
authors.lastname: Micera
authors.affiliation: The BioRobotics Institute, Scuola Superiore Sant'Anna, Pontedera, Pisa, Italy; MARE Lab, Don Carlo Gnocchi Foundation, Florence, Italy v.monaco@sssup.it.
authors.forename: Vito
authors.initials: V
authors.lastname: Monaco
mesh_terms: D000328:Adult; D005121:Extremities / Q000294:innervation / Q000502:physiology; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D007596:Joints / Q000294:innervation / Q000502:physiology; D008297:Male; D009949:Orientation; D011597:Psychomotor Performance; D016138:Walking / Q000502:physiology*
keywords: intersegmental coordination; motor control; reactive response; unexpected multidirectional slipping-like perturbations; walking