Begin by securing the anesthetized mouse onto a stereotaxic frame with ear bars. Apply ophthalmic ointment on the mouse's eyes to prevent drying, and maintain the body temperature of the mouse at 37 degrees Celsius with a thermostatic heating pad. After shaving the fur and sterilizing the surgical site, inject lidocaine, tilidine, and meloxicam.
Once the skin over the SC is removed, clean the skull with a cotton swab. Adjust the stereotaxic frame until the skull surface is flat. Using a drill, create a whole 0.5 millimeter lateral, and 0.42 millimeter anterior to the lambda, until the dura is exposed.
Inject an adeno-associated virus, or AAV, expressing GCaMP6m, at depths of one millimeter and 1.6 millimeters from the Lambda using a beveled glass micro-pipette. After the injection, slowly withdraw the injector and proceed with the implantation of the head plate.
