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 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. 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 associate 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 activated.
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