Brain activation induced a local transient increase in cerebral blood flow (CBF). This phenomenon is known as the 'neurovascular coupling' in which the neurons and vascular cells are closely cooperated to maintain the adequate supply of CBF. In this talk, I will summarize the optical imaging techniques to visualize the cellular activity of the neurovascular coupling in in vivo rodent brains using two-photon laser scanning microscopy and a variety of fluorescent probes and proteins. To link these microscopic observations to the macroscopic diagnostic measures, it is also important to quantify the morphological and functional parameters of the cells. To test the hypothesis and to probe the casual link in the signaling mechanism of the neurovascular coupling, optogenetic techniques that enable us to modulate the cellular activity specifically with photostimulation, were introduced. The results of these experiments showed that the both neurogenic and astrogliogenic mechanisms participate in the CBF regulation of the neurovascular coupling.