2. History of the collaboration

Prior to this project, several informal collaborations took place between the two teams, like the evaluation of an histological slices registration method developped at Epidaure thanks to an atlas of a rat brain acquired at the LONI, or the participation of Epidaure to the redaction of of the "brain warping" book editer by A. Toga on digital techniques for the analysis of the human brain.

During the first three years of this joint-team project, the PhD thesis of Alain Pitiot, jointly supervised by N. Ayache and P. Thompson, strengthened the scientific exchanges between the two teams. This thesis was devoted to the segmentation of anatomical structures of the brain for the creation of atlases, and was successfully defended on November 26, 2003. Since then, Vincent Arsigny and Pierre Fillard dedicate part of their PhD to the study of the brain variability using the massive database of images and delineated cerebral structures acquired by P. Thompson at the LONI.

The constitution of EPIDAURE and LONI as associated teams brings a formal framework to an already existing collaboration with concrete projects and the joint supervision of PhD students. EPIDAURE's strength principally resides in the methodological expertise developped for the robust analysis of medical images, while the strength of the LONI lies in the experiences accumulated through multiple international collaborations on the development of brain atlases (e.g. the Human Brain Mapping project) and the amount of data and knowledge acquired to validate these methods. This collaboration allows to factor the image analysis algorithms and the clinical databases of a sufficient size (typically several hundreds of images) need to validate them, in order to develop more robust and more accurate brain atlases. Thanks to the combined power of the databases sizes and the precision of the image analysis algorithms, we expect to be able to infer new hypotheses about the underlying structural organization of the brain.