Spinal cord injuries that result in paraplegia may one day be treatable using a technique that bypasses the damaged neural pathways that connect the brain to the spinal locomotor center. The researchers, from the National Institute for Physiological Sciences in Japan, have demonstrated how the computer-controlled bypass circuit allowed a subject to use hand movements to initiate walking.
The technique, detailed in The Journal of Neuroscience, allows subjects to stimulate the spinal locomotion center using volitionally-controlled muscle activity – in this case, rhythmic hand movements. This upper limb muscle activity was converted to magnetic stimulii delivered non-invasively over the lumbar vertebra. The subjects were able to initiate and terminate walking-like behavior and to control the step cycle solely via their arm activity. The researchers say the kinematics of the induced gait were identical to those observed in voluntary walking.
“Neural networks in the spinal cord locomotion center are capable of producing rhythmic movements – such as swimming and walking – even when isolated from the brain. The brain controls the spinal locomotion center by sending command to the spinal locomotion center to start, stop and change waking speed. In most cases of spinal cord injury, the loss of this link from the brain to the locomotion center causes problems with walking,” explained lead researcher Shusaku Sasada.
“We hope that this technology would compensate for the interrupted pathways’ function by sending an intentionally encoded command to the preserved spinal locomotor center and regain volitionally-controlled walking in individuals with paraplegia,” added co-researcher Yukio Nishimura. “However, the major challenge that this technology does not help them to dodge obstacles and to maintain posture. We are carefully working toward clinical application in near future.”
by Will Parker