While some patients with spinal cord injuries recover full movement, others suffer permanent paralysis, ranging from partial to full-body. Despite recent progress in medicine and technology, a surgical solution does not yet exist, and physical therapy remains the dominant therapy for spinal cord injury. At the beginning of October, Brown University announced a $6.3 million grant from DARPA to develop and test an intelligent read-write link for the spinal cord. The two-year project aims to connect the neurological signals from above and below spinal cord injuries and restore two-way communication in the spine, without having to tap brain signals with implants as in other approaches.
“Recent studies have demonstrated that we can use electrical pulses to write into the spinal cord for motor control, and we are starting to learn how to write into the spinal cord for sensory restoration, to some degree," explains David Borton, assistant professor of engineering at Brown University School of Engineering and the Carney Institute for Brain Science.
"We are now attempting to address the question that's always been there tantalizing us: can we ‘bridge the gap' in a spinal cord injury?"
As far back as 2006, the BrainGate project demonstrated that the acquired signals from implanted brain-recording electrodes could be used to drive a cursor on a computer screen, enabling paralyzed patients to type an email or play a virtual piano using their minds. Borton's thesis work focused on the development of next-generation neural recording systems that were fully implanted, using wireless power and data telemetry.
The upcoming intelligent spine interface project builds on Borton's 2016 postdoctoral work with Gregoire Courtine at the Center for Neuroprosthetic and Brain Mind Institute at the Swiss Federal Institute of Technology Lausanne, where they developed a brain-spine interface. In that study, they were able to record from the brain and use those signals to stimulate the spinal cord, bypassing a spinal injury. Here the system receives data from the leg area of the motor cortex and, similar to the computer-in-the-loop BrainGate system, relays that signal to a computer, which interprets whether the person wants to lift up the leg or put it down, and then relays that information to a Medtronic spinal cord stimulator that stimulates the nonfunctional limb.
But the new project aims to bypass the invasive brain surgery, limiting the medical intervention to the spine. An intelligent spinal interface would sit above and below the spinal cord lesion and stimulate across that gap, utilizing an AI-trained computer chip to decode signals recorded from the spinal cord, retrain the remaining biological networks, and initiate the correct intended behaviors.