Laser doppler monitor

Two weeks after virus injection, mice underwent a 60-minute tMCAO surgery. The protocol of tMCAO surgery was described in the previous study [18 (link)]. Briefly, the middle cerebral artery (MCA) was occluded by a 6–0 suture (Covidien, Mansfield, MA) with a silicone-coated round tip. During the surgery, mice body temperature was maintained at 37 ± 0.5°C using a heating pad (RWD Life Science) with a feedback control. The blood flow in MCA was measured by Laser Doppler monitor (Moor instruments, Devon, U.K.) before MCAO, at the beginning of occlusion and 1 minute after reperfusion. Animals whose MCA blood flow did not decrease to 10%~20% of baseline during occlusion or did not recover to 40%~60% of baseline after reperfusion were excluded from this study.

Systemic physiological monitoring data were collected simultaneously with NIRS measurements. Arterial blood pressure (ABP) was measured with a Portapres® system (Finapres Medical Systems, the Netherlands); scalp blood flow was measured by Laser Doppler Monitor (Moor Instruments); and end-tidal carbon dioxide (EtCO₂), arterial oxygen saturation and heart rate were measured with a clinical monitor IntelliVue (Philips, the Netherlands). Systemic changes were block-averaged according to epoch and averaged across nine subjects. For each systemic variable, the response for each subject was defined as the difference between the mean of the first 10s window of activation and the mean of the first 10s window during the black screen period. Paired t-tests were used to compare the responses across nine subjects to zero, identical to the statistical analysis done for the NIRS signals.