Training sessions
During training sessions, all participants will be seated on a comfortable chair (or on their wheelchair) in a dimly lit room with their hands and forearms resting under the BCI station screen (Fig. Participants will be instructed by the therapists to perform the kinesthetic MI of both hands movements either closing or opening in separate runs randomly ordered. Each training session will consist of 4 runs (20 trials each). In the case of BCI-MI training, each trial will consist of constant baseline period of 4 s and MI task period of maximally 10 s in case of unsuccessful trial, whereas for the Control-MI training the trial length is fixed and randomly choose in the range 4-6 s. In both intervention trainings, EEG data will be collected from 16 EEG electrodes, assembled on an electrode cap according to an extension of the 10–20 International System (ground: left mastoid). Electrode positions will cover the bilateral sensorimotor area (FC3, FC1, FCz, FC2, FC4, C3, C1, Cz, C2, C4, CP3, CP1, CPz, CP2, CP4, Pz). For each participant in BCI-MI group the individual significant EEG features (extracted as described in 