Completely locked-in patients have lost the ability to interact with their environment through behavioral means. They are unable to control muscle movements to produce speech, gestures, or even eye-movements to indicate yes-no answers to questions. Yet, there is no reason to assume that their cognitive system is impaired. One potential way to enable these kinds of patients to interact with their surroundings is the creation of brain-computer interfaces through which a patient can learn to communicate with the external world without having to go through any overt behavioral channels. Dr. Niels Birbaumer at the University of Tuebingen is one of the leaders in this field. Drawing on old techniques of bio-feedback, Dr. Birbaumer and his colleagues are working on ways to meaningfully interpret brain activity in response to simple questions and to train locked in patients to use such BCIs. Other applications, such as neuro-rehabilitation after stroke are also addressed.