CSF production rate was quantified as previously described in rats(70 (link), 71 (link)). Anesthetized mice were fixed on a stereotactic apparatus and a 0.5mm burr hole was made over the left lateral ventricle (AP=−0.1mm, ML= −0.85mm). A 30-gauge needle connected to PE-10 tubing was lowered through the burr hole to −2.00 mm DV. The mouse then received a MCAO as before. The rCBF drop was confirmed with laser Doppler flowmetry for five minutes and then the mouse was placed back in a stereotactic head frame and the cisterna magna was surgically exposed with the mouse’s neck flexed at 90 degrees. A 30-gauge needle connected to PE10 tubing filled with mineral oil (Sigma Aldrich, M5904) was inserted into the cisterna magna and advanced gently 2mm through the foramen of Magendie into the 4th ventricle. One microliter of mineral oil was infused at a rate of 1μl/min for 1 min with a syringe pump (Harvard Apparatus) to block outflow from the ventricular system. The location of CSF within the intraventricular PE-10 tubing was marked at 10 min intervals. The volume of CSF was calculated as: CSF volume=π x (internal radius: 0.14mm)2 x length. The rate of CSF production (μl/min) was calculated as the slope of the linear regression from each mouse.