Chronic in vivo imaging of tau-induced neurodegeneration and microglial response using two-photon microscopy

Investigations into neurodegenerative progression have traditionally relied on pathological sectioning and intergroup analysis, with outcomes heavily dependent on sample size. Emerging in vivo imaging techniques now enable dynamic, long-term tracking of the same subjects, enhancing comparability and reducing variability. In this study, we use two-photon microscopy to visualize neurons and microglia through fluorescent markers introduced by adeno-associated virus (AAV) labeling and transgenic mice. Additionally, AAV-driven tau pathology induces neurodegeneration in the brain. A head ring is attached to the mouse’s skull for reversible mounting on a head-fixed treadmill. This setup allows us to image neurodegeneration progression without anesthesia, quantifying changes in the number, morphology, and spatial positioning of tau-overexpressing neurons and microglia. This approach provides spatiotemporal insights into neurodegeneration previously unattainable.