Surgical Procedure

All surgical procedures were performed under aseptic conditions. Adult rats (200 – 280 g) were deeply anesthetized with a ketamine (80 mg/kg) and Dexmedetomidine (0.5 mg/kg) cocktail, administered through intraperitoneal injection. After confirming the loss of toe pinch reflex, the surgical site was shaved and sterilized with iodine and alcohol. The skin over the lower thoracic/upper lumbar area was incised to expose the underlying fascia, which served as a region to secure the connector mount. The right sciatic nerve was exposed using blunt dissection methods, followed by exposure of gastrocnemius and tibialis anterior muscles through skin incision between the muscles. The suture tabs of the connector mount were sutured to the lumbar fascia using 4-0 Polypropylene sutures (Oasis, U.S.A.) and the electrodes were carefully tunneled under the skin to the implant site as show in figure 1A. For FMA implantation, a 2 mm long incision of the epineurium was made 5 mm proximal to the sciatic trifurcation. The base of the FMA electrode was carefully handled using fine forceps and the shanks were manually inserted through the epineurium incision, until the base was flush with the nerve (Fig 1A). To secure the FMA, fibrin sealant (Tisseel, Baxter, U.S.A.) was applied around the implant site, and then further secured by 4 mm long, 3.2 mm (ID) silicone tubing placed around the implant/fibrin glue construct and filled with additional fibrin sealant. The ground wire was inserted into the muscles next the FMA electrode implant (Fig 1A). Two EMG wires per muscle (placed 2 mm apart) were implanted in the gastrocnemius and tibialis anterior muscles using an 18 G needle, followed by removal of ~1 mm Teflon insulation using a scalpel to create a recording site, as described elsewhere (Courtine et al., 2009). The wires were bundled at the proximal EMG wire entry point and distal end (EMG wire exit) and secured by suture. Wounds were closed in layers and at the end of surgery, animals were administered Atipamezole (0.5 mg/kg) for reversal, Gentamycin (8 mg/kg) for antibiotics and Meloxicam (2 mg/kg) for analgesia. Animals were further administered Meloxicam (1 mg/kg) for the two days post-surgery. For sham procedures, a connector mount was implanted as following identical procedures, the sciatic nerve and muscles were exposed, and then the wounds were closed in layers, followed by post-surgery drug administration as mentioned for the FMA implanted animals.