To bring movement back to Rob Summers' paralyzed lower body, scientists and doctors surgically implanted a package of 16 small electrodes, just a few centimeters long, above the protective membrane layers of his spinal cord. Wires lead from the electrodes to a small rectangular neurostimulator device inserted in Summers' lower back. Summers uses a remote control to send an electrical current from the neurostimulator to the array and a group of neurons - called interneurons - in the spinal cord. Interneurons in the lower spine send tailored messages to specific muscles via another type of neuron called motor neurons. Excited into action by the electrical charge, neurons communicate with each other and with muscles to create movement.
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