As the interface between brain and body, the spinal cord contains interconnected modular elements serving sensory, motor, and autonomic function with anatomical segregation of functionally distinct ascending and descending pathways. The epidural space provides an anatomically accessible and low-risk site for chronic placement of epidural stimulation (ES) electrodes for the therapeutic modulation of these circuits, particularly for the control of pain. Commercially-available technologies now offer multi-electrode containing paddles, and Boston Scientific also utilizes sophisticated current-steering technologies in their programmable control over implanted devices.
While ES has been used for decades to control chronic pain specific use for the control of chronic pain after spinal cord injury has not been generally considered, though a high success rate seems likely and relevant given that neuropathic pain is experienced by greater than 1/3 of spinal cord injured patients. Thus, furthering our mechanistic understanding of ES-based sensory modulation is important.
Interrogating ES mechanisms of action require animal models and circuit-based experimental approaches. To probe ES-based sensory modulation, we will first answer the most fundamental questions on neuronal recruitment. We propose to use mouse for rigorously controlled experiments that include; (i) realistic modeling-based dimensional electrode scaling, (ii) manipulable control of epidural electrode distance from cord, and (iii) physiological approaches amenable to circuit dissection including optogenetics for selective afferent activation.