Spinal Circuits for Sensorimotor Integration During Locomotion at Different Speeds: A Computational Model

Simon Danner, Ph.D.
College of Medicine
Drexel University

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ABSTRACT
To effectively move in complex and changing environments, animals must control locomotor speed and gait, while precisely coordinating and adapting limb movements to the terrain. The underlying neural control involves dynamic interactions between neural circuits at different levels of the nervous system, biomechanical properties of the musculoskeletal system, and afferent feedback signals from the periphery. Here, we present a computational neuromechanical model of mouse hindlimb locomotion to study the mechanisms of sensorimotor integration and the role of different afferent pathways in the stabilization of locomotion at different speeds and under different environmental conditions. The model closely reproduced characteristics of mouse locomotion at different speeds, while being able to adapt to changes in the environment. With increasing speed, the model exhibited walking, running and hopping gaits. By systematically manipulating feedback gains, we found that feedback pathways serve different roles depending on speed. We suggest that supraspinal control of locomotor speed, besides tonic drive to the rhythm generators and commissural interneurons, includes task-dependent (slow, exploratory, vs. fast, escape-type locomotion) modulation of the gain of sensory afferent pathways to the spinal locomotor circuitry.

Host: Boris Prilutsky, Ph.D.