PMC6306452_01
(A) photo of the left exoskeleton attached to the chair arm pad; the right exoskeleton has symmetrical construction. (B) visual cues of the BCI system; the upper arrow corresponds to relaxation, the left and right arrows correspond to the left and right hand extension imagery; the blue arrow signals the patient to prepare for performing the corresponding task; the green arrow signals the patient to start performing the task; circle in the middle of the screen serves both as a gaze fixation point and for additional visual feedback, it becomes green when the BCI classifier recognizes that the cued task is executed. (C) schematic illustration of the BCI classification algorithm. After several presentations of each task the corresponding EEG covariance matrices (CR for Relaxation, CLH and CRH for the left and hand motor imagery) are estimated. Then for each sliding 1 s EEG window, X, the probability of its corresponding to each task is estimated using the Bayesian approach. The command is generated based on the maximal probability, and the window is shifted as new EEG data are acquired. The more correct answers the BCI provides, the more is the exoskeleton extended.
fneur-09-01135-g0001.jpg
PMC6306452_01_fneur-09-01135-g0001.jpg
F1
She controlled extension of two hand exoskeletons (Figure 1A) by performing motor imagery tasks, following visual cues presented on the monitor (Figure 1B). The BCI classified ongoing EEG signal by comparing its covariance matrix obtained for the last second epoch with the three EEG covariance matrices corresponding to the R, LH, and RH tasks (Figure 1C).
(A) T2 contrasted image of the lesion in the left motor and premotor areas; (B) results of the task-specific EEG source localization. The SIR source (red) is located in the primary somatosensory area of the right (intact) hemisphere, the SILa,b sources (green and magenta) are located in the primary somatosensory area of the left hemisphere, near the lesion edge, the PRC source (blue) is located in the precuneus. (C) voxels with BOLD response significantly higher during LH MI than during relaxation (p < 0.001) before the treatment; (D) voxels with BOLD response significantly higher during RH MI than during relaxation (p < 0.001) before the treatment; (E) voxels with BOLD response significantly higher during LH MI than during relaxation (p < 0.001) after the treatment; (F) voxels with BOLD response significantly higher during RH MI than during relaxation (p < 0.001) after the treatment. All images are presented in the neurological convention. The left and the right hemispheres are marked by L and R, respectively.
fneur-09-01135-g0003.jpg
PMC6306452_01_fneur-09-01135-g0003.jpg
F3
Following the MRI data the lesion was located in cortical-subcortical areas of the frontal lobe in the left hemisphere (Figure 3A).