Browsing by Subject "Neurovasculature"

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Tools to improve large-volume longitudinal evaluation of the neurovascular system through in vivo two-photon microscopy
(2023-04-21) Engelmann, Shaun Alan; Dunn, Andrew Kenneth, 1970-; Tunnell, James W; Parekh, Sapun H; Jones, Theresa A
Two-photon microscopy is often used to image in vivo neural structural due to the excellent contrast, resolution, and penetration depth available through the technique. While brain tissue can be imaged down to 500 µm routinely, there is a desire to push this even further given that the cerebral cortex extends to a 1 mm depth in mice. In this work we introduce a custom ytterbium fiber amplifier and diamond Raman laser that operate at wavelengths more suitable for deep imaging (1060 nm, 1250 nm) as compared to more traditional Ti:sapphire lasers (700-1000 nm). We prove their utility for two-photon excitation of multiple fluorophores that commonly serve as vascular and neuronal labels. Our custom oscillators are well suited for rapid imaging strategies as well given their high repetition rate (80 MHz), so additionally we present a methodology to increase our lateral imaging field of view which makes use of a resonant scanning mirror. Finally, we demonstrate a pulse gating strategy that can either increase signal generation or reduce average excitation power when imaging as to avoid excessive tissue heating. Many of the tools and strategies we present can be used in parallel to image larger tissue volumes for more comprehensive longitudinal study of neurovascular structure.