The DARPA ElectRx program seeks innovative research proposals for creating closed-loop neuromodulation systems that utilize innate neurophysiological circuits to achieve therapeutic benefits. To achieve this goal, ElectRx will simultaneously drive biological understanding and technology development. Specifically, ElectRx is looking to develop and leverage fundamental understanding of the anatomy and physiology of neural circuits in the spinal cord or peripheral nerves that mediate health status. This knowledge will be leveraged to design and demonstrate feedback-controlled neuromodulation systems for the direct regulation of immune system functions and CNS disorders. In parallel, technology development focused on next-generation minimally-invasive neural interfaces and biosensors will enable interaction with the neurophysiology of interest at unmatched spatiotemporal resolution, precision, and specificity. These neuromodulation treatments will be tuned automatically and continuously to the unique physiology of each individual and will produce no off-target effects. Additional information set forth in attached BAA.