In recent years, the structural understanding of amyloid-like pathological tau, α-synuclein, and TDP-43 extracted from the brains of patients with neurodegenerative diseases such as tauopathy, synucleinopathy, and TDP-43 proteinopathy has greatly expanded. This research project aims to establish an experimental and technological platform for the structure determination of pathogenic protein filaments using cryo-electron microscopy installed in Japan. Based on structural insights obtained from this platform, we elucidate pathogenesis in human brains from various perspectives.