Metal ferrule

All experiments were conducted in an open arena in freely moving mice. Beginning 1 week post GCaMP injection, mice were habituated to the arena with fiber optic cable connected, and were administered 0.3 mL intraperitoneal (i.p.) injection of saline for habituation purposes.
In vivo fiber photometry was conducted as previously described (Chen et al., 2015 (link)). A fiber optic cable (“patch cord,” 1.5 m long, metal ferrule, 400 μm diameter; Doric Lenses) was firmly attached to the implanted fiber optic cannula with zirconia sleeves (Doric Lenses). Laser light (473 nm) was adjusted such that a light intensity of less than 0.05 mW entered the brain; emission light was passed through a dichroic mirror (Di02-R488-25x36, Semrock) and GFP emission filter (FF03-525/50-25, Semrock), before being collected by a sensitive photodetector (Newport part #2151). The signal was digitized at 1019 Hz using a TDT data acquisition software.

Mice were anesthetized using isoflurane in 100% oxygen (induction, 3%; maintenance, 1–2%) and placed into a stereotaxic apparatus (Kopf, Model 940 10 Small Animal Stereotaxic Instrument with Digital Display Console) on a temperature-controlled heating pad. Ophthalmic ointment was applied to the eyes. A 0.5 mm diameter burr hole was drilled over the mouse barrel cortex. To selectively record calcium induced fluorescence from pyramidal neurons in the projected infarct area, we injected 300 nL of AAV9-CAMKII-GCaMP6m (10^13 GC/ml, Vector Bio labs) into the barrel cortex using the following stereotaxic coordinates: (anterior-posterior for core area: 0.4 mm, for peri-infarct: −1.6 mm; dorsal-ventral, 0.7 mm; medial-lateral, 3 mm) of wildtype C57BL6 mice. Following the injection, an optic fiber (1 mm length, 400 μm diameter, NA = 0.48, metal ferrule, DORIC) was implanted 0.2 mm above injection area and secured to the skull with dental cement (Metabond dental cement. JAX_C57N = 23 core, CRL_C57N = 12 core, N = 8 peri-infarct). Additionally, a subset of mice had two implants to simultaneously record both from the core and the peri-infarct regions (CRL_C57N = 12, of which 6 were administered vehicle and MK-801).