Lidocaine hydrochloride jelly

Details of the surgical procedure are provided in Thompson and Felsen (2013) (link). Briefly, once the mouse was fully trained on the task, it was anesthetized with isoflurane and secured in a stereotaxic device, the scalp was incised and retracted, 2 small screws were attached to the skull, and a craniotomy targeting the left SNr was performed, centered at 3.27 mm posterior from bregma and 1.4 mm lateral from the midline (Paxinos and Franklin, 2004 ). A VersaDrive 4 microdrive (Neuralynx), containing 4 independently adjustable tetrodes, was affixed to the skull via the screws, luting (3M), and dental acrylic (A-M Systems). A second small craniotomy was performed in order to place the ground wire in direct contact with the brain. After the acrylic hardened, a topical triple antibiotic ointment (Major) mixed with 2% lidocaine hydrochloride jelly (Akorn) was applied to the scalp, the mouse was removed from the stereotaxic device, the isoflurane was turned off, and oxygen alone was delivered to the animal to gradually alleviate anesthetic state. Mice were administered sterile isotonic saline (0.9%) for rehydration and an analgesic (Ketofen; 5 mg/kg) for pain management. Analgesic and topical antibiotic administration was repeated daily for up to 5 days, and animals were closely monitored for any signs of distress.

Following hair removal and sterilization with Povidone-iodine, the scalp was covered in topical 2% lidocaine hydrochloride jelly (Akorn) for at least 5 min. The scalp and underlying connective tissue were removed to expose the parietal and interparietal bone. Lidocaine hydrochloride (1%) was injected into the right temporalis which was subsequently detached (posterior half) from the skull. The skull was dried using ethanol (70% in DI water) and a thin layer of the tissue adhesive Vetbond (3 M) was applied. Custom-printed titanium headplates (Star Rapid) were attached to the skull using the acrylic resin Ortho-Jet BCA (Lang Dental).