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Afferent control of locomotor CPG: insights from a simple neuromechanical model
Author(s) -
Markin Sergey N.,
Klishko Alexander N.,
Shevtsova Natalia A.,
Lemay Michel A.,
Prilutsky Boris I.,
Rybak Ilya A.
Publication year - 2010
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2010.05435.x
Subject(s) - afferent , neuroscience , simple (philosophy) , cpg site , physical medicine and rehabilitation , biology , medicine , gene expression , biochemistry , gene , dna methylation , philosophy , epistemology
A simple neuromechanical model has been developed that describes a spinal central pattern generator (CPG) controlling the locomotor movement of a single‐joint limb via activation of two antagonist (flexor and extensor) muscles. The limb performs rhythmic movements under control of the muscular, gravitational and ground reaction forces. Muscle afferents provide length‐dependent (types Ia and II) and force‐dependent (type Ib from the extensor) feedback to the CPG. We show that afferent feedback adjusts CPG operation to the kinematics and dynamics of the limb providing stable “locomotion.” Increasing the supraspinal drive to the CPG increases locomotion speed by reducing the duration of stance phase. We show that such asymmetric, extensor‐dominated control of locomotor speed (with relatively constant swing duration) is provided by afferent feedback independent of the asymmetric rhythmic pattern generated by the CPG alone (in “fictive locomotion” conditions). Finally, we demonstrate the possibility of reestablishing stable locomotion after removal of the supraspinal drive (associated with spinal cord injury) by increasing the weights of afferent inputs to the CPG, which is thought to occur following locomotor training.