Bypass Commands From the Brain to Legs Through a Computer

Potential rehabilitation of volitional walking in individuals with spinal cord injury.

Gait disturbance in individuals with spinal cord injury is attributed to the interruption of neural pathways from brain to the spinal locomotor center, whereas neural circuits locate below and above the lesion maintain most of their functions. An artificial connection that bridges the lost pathway and connects brain to spinal circuits has potential to ameliorate the functional loss. A Japanese research group led by Shusaku Sasada, research fellow and Yukio Nishimura, associate professor of the National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS) has successfully made an artificial connection from the brain to the locomotion center in the spinal cord by bypassing with a computer interface. This allowed subjects to stimulate the spinal locomotion center using volitionally-controlled muscle activity and to control walking in legs. This result was published online in the Journal of Neuroscience on August 13, 2014.

The image is a diagram of a person with the spinal cord bypass switched off and on.

When turning off the computer-aided spinal cord bypass, the lower extremities which were in a relaxed state did not move even if the subject was swinging his/her arms. With the bypass turned on, when the subject swung his/her arms by his/her own will and a walking motion of the lower extremities began in rhythm to the motion of the arms. Credit Yukio Nishimura.

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 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.

The research group came up with bypassing the functioning brain and locomotion center with the computer to compensate lost pathways as a way to enable individuals with spinal cord injury to regain walking ability.

Since the arm movement associte with leg movement when we walk they used muscle activity of arm to sarogate the brain activity. The computer interface allowed subjects to control magnetic stimulator that drive to the spinal locomotion center non-invassively using volitionally-controlled muscle activity and to control walking in legs. As a results of experiments in people who are neurologically intact, the subjects were asked to make own legs relaxed and passively controlled via computer interface that was controlled by arm muscle, walking behavior in legs was induced and subjects could control the step cycle volitionally as well. However without bypassing with the computer interface, the legs did not move even if the arms muscle was volitionally acivated.

The right arm muscles and the locomotion center of the man are artificially connected through a computer. His legs are in a relaxed state. When he moves his right hand, the computer catches the signal from his arm and produces signals to his locomotion center to move his legs.

“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 indviduals with paraplegia. 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”, Nishimura said.

Notes about this psychiatry research

Source Yukio Nishimura – National Institutes of Natural Sciences
Contact: National Institutes of Natural Sciences press release
Image Source: The imag is credited to Yukio Nishimura and is adapted from the National Institute of Natural Sciences press release
Video Source: The video is credited to Yukio Nishimura/National Institute of Natural Sciences and adapted from the press release
Original Research Abstract for “Volitional Walking via Upper Limb Muscle-Controlled Stimulation of the Lumbar Locomotor Center in Man” by Syusaku Sasada, Kenji Kato, Suguru Kadowaki, Stefan J. Groiss, Yoshikazu Ugawa, Tomoyoshi Komiyama, and Yukio Nishimura in Journal of Neuroscience. Published online August 14 2014 doi:10.1523/JNEUROSCI.4674-13.2014

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