Electrical Stimulation of a Spinal Central Pattern Generator for Locomotion

We present data illustrating the effects of direct electrical stimulation on the spinal central pattern generator (CPG) for locomotion. Discrete current pulses were applied to isolated lamprey spinal cords during "fictive swimming", resulting in phase shifts in the underlying CPG rhythm. The impact of a given stimulus is shown to be a function of the phase at which it is applied, so effects are characterized by phase-transition curves (PTCs). Additionally, the shape and amplitude of the stimulus pulses are shown to control different aspects of the response. These preliminary results represent the first stage of a project to develop a neuroprosthetic device for restoring locomotion after severe spinal cord injury. The implication of these data is that a smart, closed-loop neuroprosthesis could control locomotion by monitoring the state of the CPG and applying the appropriate stimuli at appropriate times to effect a desired locomotor pattern