Neurovascular Coupling Studies in Awake-Behaving Mice

The mechanism regulating cerebral blood fl ow (CBF) during brain function (neurovascular coupling)has been widely investigated in animals under anesthetized conditions, though anesthesia is known to greatly aff ectneurovascular physiology. The present study aims to develop a novel model for neurovascular coupling studies inawake-behaving mice. Male C57BL/6J mice were initially anesthetized with isofl urane in preparation for attachingthe study apparatus to the head. The animal was tethered to the study apparatus but allowed to move spontaneouslyon a fl oated ball. The animal behavior and regional CBF in the somatosensory barrel cortex were simultaneouslymeasured with optical motion sensor and laser-Doppler fl owmetry (LDF), respectively. Anesthesia was discontinuedduring recovery, while whisker stimulation (frequency 10 Hz and duration 10 or 20 sec) was induced at either thecontralateral or ipsilateral side of the LDF recording site. During the experiments, the animals showed no signs ofstruggling against the head restraint. The intensity of baseline CBF was higher while the animal was under 2%isofl urane aesthesia than it was after anesthesia was stopped. CBF response to stimulation was not observed underanesthesia. After the animal was recovered from anesthesia, an increase in CBF (34 +- 18%) was observed duringcontralateral stimulation but not during ipsilateral stimulation. The fl uctuation levels of CBF baseline during restingand walking conditions were +-2.7% and +-3.5%, respectively. We observed that these fl uctuations were not due tovibration noises caused by such as air-puff and animal motion in our experimental conditions