Abstract
During the nineteenth century, neuroanatomical knowledge and the clinical practice of treating mental illnesses develop at the same time. Some practitioners of mental medicine try to combine the clinical practice of treating mental diseases with neuroanatomical knowledge using the idea of cerebral localisations. This point of view is advocated by Gall and the field of phrenology. But there is no obvious success of such a localisationist project before Broca and Wernickeâs works on aphasia. This discovery will provoke a revival of the desire to localise the cerebral zones involved in mental diseases. However, the cerebral localisation project progressively decreases during the end of the nineteenth century while neurological clinical practice emerges. Moreover, neurological clinical practice aims to localise anatomical lesions through clinical examination. From a philosophy of science point of view, this segment of history brings into question the relation between a scientific object (the cerebral localisation of zones involved in diseases) and a scientific subject (psychiatry and neurology). It stresses how a scientific project can migrate from one subject to another