A tough question to address would be who can be considered the inventor of the Brain-computer interface. Many researchers have contributed to the evolution of this concept, from the basis conception of the neurons, synaptic connections and rudimentary EEG measurement systems up to the use of virtual reality environments with modern wireless devices. In the middle, series of devoted people with the honourable aim of provide a better quality of life to disabled patients. In the course of this evolution a key point is the use of efficient techniques of mutual training for both the patient and the system. In this paper we introduce the multi-disciplinary nature of the Brain-computer interfaces, for later focus on training techniques used in those based in the sensorimotor rhythm.