Preface to an editorial controversy on α-synuclein: How good are cellular models?: This is a Preface for an Editorial controversy between Hilal A. Lashuel "Monitoring alpha-synuclein oligomerization and aggregation using bimolecular fluorescence complementation assays: What you see is not always what you get" and Tiago F. Outeiro "Alpha-synuclein oligomerization and aggregation: A model will always be a model" Read Hilal A. Lashuel's reply "Alpha-Synuclein oligomerization and aggregation: All models are useful but only if we know what they model".

In many scientific disputes, research evidence may support one side or the other of a working hypothesis, and even in case of largely coherent hypotheses, arguments may be in favor of discrepant points of view. In the case of α-synuclein pathology and specific mechanisms of disease progression, various animal and cellular models have been established to pinpoint the physiological and pathological mechanisms. In the present 'Editorial controversy', two well-reputed researchers, Hilal Lashuel and Tiago F. Outeiro, discuss-with view to findings from their own and others' groups in the context of current status of knowledge-the question of how well models on α-synuclein pathology can reflect actual pathomechanisms, and derive recommendations for future research from it that shall help advance our understanding not only of α-synuclein-related pathologies and its role in the formation of Lewy bodies in particular, but of cellular or animal models in general.