MAPT and tauopathy: While the bulk of current research on tau is focused on toxicity questions such as elucidating the causes of de novo tau aggregation, as well as understanding mechanisms of seeding further aggregation, release and uptake in neuronal cells, studying the fibrillar structure of tau aggregates isolated from post-mortem brain may also allow insight into differences between individual tauopathies and facilitate improved diagnostics such fluid biomarkers or as tracer ligands for neuroimaging.