Using an In Vitro Spinal Cord-Hindlimb Rat Model to Address the Role of Sensory Feedback in Spinally Generated Locomotion

Understanding how sensory feedback can be used to facilitate locomotion is vital for designing effective locomotor rehabilitation strategies for spinal cord injury. Here we describe an in vitro spinal cord-hindlimb preparation (SCHP) that can be used to answer clinically relevant questions about the interaction of sensory feedback and spinal locomotor circuitry. The SCHP, composed of the exposed rodent spinal cord with hindlimbs intact, combines the neural accessibility and manipulability of classic in vitro isolated cord preparations with intact sensory feedback and many of the behavioral analysis techniques used in the clinic, such as kinematics, treadmill walking, and electromyography. Using the SCHP, we demonstrate the importance of task-appropriate limb loading and posture for establishing intact rat-like kinematic trajectories and muscle activation patterns. We also show that applying stepping-like movements to the limbs, similar to those applied during physical therapist-assisted or robot-guided bo...