Advances in BCI: A Neural Bypass Technology to Reconnect the Brain to the Body

Abstract

Millions of people worldwide suffer from diseases that lead to paralysis through disruption of signal pathways between the brain and the muscles. Neuroprosthetic devices are designed to restore lost function and could be used to form an electronic neural bypass to circumvent disconnected pathways in the nervous system. We have shown that intracortically-recorded signals can be linked in real-time to muscle activation to restore movement in a paralyzed human. The system provided cortical control of isolated finger and hand movements and the participant was also able to use the system to complete functional tasks relevant to daily living. The investigational system has been demonstrated during an FDA-approved study (Nature, 533:247 250, 2016). We utilized a chronically-implanted microelectrode array to record multiunit activity from the motor cortex in a study participant with C5/C6 quadriplegia from cervical spinal cord injury (SCI). We applied machine-learning algorithms to decode the neuronal activity and control activation of the participant s forearmmuscles through a custom-built high-resolution neuromuscular electrical stimulation system. Using the system, the subject achieved multiple voluntary movements of the wrist and hand. The neural signal quality remained suitable for decoding and facilitation of movement over a two-year period. The system provided isolated finger movements and the participant achieved continuous cortical control of six different wrist and hand motions. Clinical assessment showed that when using the system, his motor impairment level improved from C5-C6 to a C7-T1 level unilaterally, conferring on him the critical abilities to grasp, manipulate and release objects. This improvement in function is meaningful for reducing the burden of care in patients with SCI as most C5 and C6 patients require assistance for activities of daily living, while C7-T1 level patients can live more independently. The system also enabled volitional control of rhythmic finger movements that are typically coordinated in the spinal cord. This is the first demonstration of successful control of muscle activation utilizing intracortically-recorded signals in a paralyzed human. In the future, the technology could allow brain-to-body interfacing and bridging of injured portions of the nervous system and have applications in SCI, stroke, traumatic brain injury, and motor neuron disease.