Abstract

We present all-optical imaging system for studying cerebral blood flow regulation. To investigate changes in blood flow in the brain, it is necessary to visualize the vascular microstructure between neurons, astrocytes, and vascular cells and monitor changes in vessel diameter and blood flow velocity. Optogenetics is an excellent technology that can be applied to cerebral blood flow regulation studies that require superior spatial and temporal resolution and individual control of cellular activity. The developed optical system is a new integrated optical imaging system that can apply all of the techniques mentioned above for cerebral blood flow regulation research. The optical system includes a dual-color fluorescence imaging system and a laser stimulation system. The system successfully performed dual-color fluorescence imaging with a 50 μm grid pattern in the two wavelength ranges of 515-545 nm and 608-631 nm. It also performed laser stimulation with a minimum output laser pattern size of 2 × 2 μm² and a maximum intensity of up to 120 mW/mm². In addition, the optical system measured the fast flow velocity of fluorescent microbeads up to 1.9 μm/ms. Experimental results show that the system can be a promising tool for cerebral blood flow regulation studies that require optogenetic stimulation and dual-fluorescence imaging while measuring blood flow velocity. In the future, the all-optical imaging system will be applied to fiber bundle-based endoscopic systems developed to study cerebral blood flow regulation using optogenetics in living animal brains.

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