My PhD was supervised by Fabien Lotte, within the National Institute of Computer Science and Technology — Inria, team Potioc in Bordeaux, France; and Jeremie Mattout, within the National Institute of Health and Medical Sciences — Inserm, team DyCog as part of CRNL (Centre for Research in Neuroscience in Lyon, France). Within the BCI-LIFT project, the goal was to improve Brain-Computer Interfaces (BCIs) of Motor Imagery and P300, by using user centered design and adapting online the BCI task (environment, feedback and instructions) according to user states and performances.