Optical Fiber Implantation Procedure

The optical fiber implantation procedure was carried out under anesthesia using a stereotactic frame, as mentioned previously. An optical fiber (200-μm-diameter core and 0.39 numerical aperture; Newdoon Technology) was held by a stereotaxic manipulator and inserted into the brain. The tip of the optical fiber was located slightly on top (∼200 μm dorsoventral) of the targeted region. A custom-designed headpost was attached to the skull with four screws for head fixation. The optical fiber cannula and headpost were fixed with dental cement for later stimulation and recording. After surgery, the mice were allowed to recover for 2–3 weeks before experiments began. Analgesic (carprofen, 5 mg/kg, i.p.) was injected with carprofen immediately after the surgery for consecutive 3 days.