Locomotion restored after spinal cord injury in a primate

Grégoire Courtine and colleagues show that a fully implantable, wireless brain–spine interface can be used to improve locomotion after a unilateral spinal lesion in monkeys without training. The authors implanted monkeys with an electrode array in the leg area of the motor cortex and a stimulator in the lumbar spinal cord, enabling real-time decoding and stimulation. Decoded activity from the motor cortex was used to stimulate ‘hotspot’ locations in the lumbar spinal cord that control hindlimb flexion and extension during locomotion. Stimulating these hotspots enhanced flexion and extension of the target muscles during locomotion in intact monkeys and restored weight-bearing locomotion of the paralysed leg in monkeys with a unilateral spinal cord lesion six days after the injury. This proof-of-principle study shows that a similar system may improve or restore locomotion in people with spinal cord injury.