Electronic Neural Bridge Makes Paralyzed Rats Walk Again

As we reported last year, researchers at the University of California, Los Angeles, are working on spinal neurostimulation to make spinal cord injured persons walk again. They have advanced a bit further and now use a “neural bridge” that carries neural signals across spinal cord injury lesions. Currently the researchers are in a stage where they can make rats with severed spinal cords and completely paralyzed hind legs run on all four legs again. One of the tricks exploited here is the fact that walking is controlled in a big part by spinal cord reflexes. Thus, only a simple signal needs to be transferred to the spinal cord part distal of the lesions to set the walking reflex in motion. This also means that the neural bridge only needs to be attached to electrodes on the outside membrane of the severed spinal cord, avoiding the complexity of connecting individual nerve bundles. Slow neural pulses invoke a stepping pattern and once the legs bear weight the movement pattern is automatically continued without the need for additional pulses. This produces better walking patterns than what complicated muscle stimulation devices have achieved so far.
Rats are at an advantage here however, in that they walk on four legs, which enables the researchers to detect walking activity using implanted EMG wires into the front legs. The wires are connected to a small device on the back of the rat, seen in the picture above, which sends out pulses to the spinal cord when walking activity is detected on the EMG. So far the technique works fine with rats in a treadmill, however there will still be much work ahead before it will be usable in two-legged humans walking on flat surfaces.
More: MIT Technology Review: Device Helps Paralyzed Rats Walk Again…
Image credit: Parad Gad