Dr. Northoff's comprehensive comparison of clinical symptoms and neurobiological findings in catatonia with that of Parkinson's disease through integration of various levels of investigation, from neurochemistry up to the subjective experience, is a good example of the new strategies we need to improve our understanding of psychiatric disorders. His multimodal approach, leading to the hypothesis that different pathophysiologies of transcortical “horizontal modulation” and “bottom-up/top-down” – orbitofrontal/basal ganglia – “vertical modulations,” may explain many clinical aspects of catatonia and Parkinson's disease, and thereby fills an important gap in current theories of psychomotor syndromes. However, to analyze more specifically the pathophysiology of catatonia, comparison not only with Parkinson's disease, but also with schizophrenia and anxiety disorders would be helpful. As long as the pathohistological and molecular basis of catatonic syndromes is unknown, theories based mainly on functional considerations remain preliminary.