Accumulation of assembled tau protein in the central nervous system is characteristic of Alzheimer’s disease and several other neurodegenerative diseases, called tauopathies. Researchers have now established a new mouse model of tau accumulation and propagation in brain. Single intracerebral injection of synthetic tau filaments induced by dextran sulphate into wild-type mice caused seeding of endogenous tau, followed by spreading to distinct areas in a time-dependent manner.