A wireless optogenetic stimulation system for long-term function evaluation of mice forelimb with sub-nerve resolution.

Peripheral nerve transfer is an effective surgical method in restoring motor functions of upper limb after peripheral nerve injuries. However, the outcome of individual function recovery is less predictable. It is crucial to access the long-term evaluation of function improvement. Here, we developed a fully implantable multisite optogenetic stimulation system, which is tailored for wireless, reprogrammable and long-term function evaluation of peripheral nerve plexus with sub nerve resolution. In Thy1-ChR2-EYFP mice, our system induced distinct compound muscle action potentials and forelimb movements when illuminating different nerve fascicles. Furthermore, we applied the system on a nerve transfer mice model after traumatic brain injury and discovered innervation pattern of the transferred and adjacent nerves to multiple muscles consecutively within 12 weeks after surgery. Our system enabled refined evaluation of electrophysiological and motor functions of peripheral nerve plexus, shining light upon personalized diagnosis and treatment after nerve injuries or surgeries.