Predictor of BCI performance.

<p>The predictor is calculated from 2.5 minutes of recording of the brain in resting state with eyes open and correlated with the mean feedback accuracy for each participant (blue dots). The back dashed line pictures the linear regression between the predictors and the accuracies (r = 0.53). The magenta dots are the values detected as outliers. After the exclusion of the outliers, a higher correlation of 0.66 is reached (magenta line).</p

Grand average ERD/ERS for class combination. <i>left-right</i> and intervention groups in Berlin.

<p>‘N’ is the number of participants of each group. From left to right: runs 1–3, runs 4–5, runs 6–7. The time plots in the first rows picture the evolution of the ERD/ERS for about 6000 ms at C3 (thick lines) and C4 (thin lines). At time 0 is the onset of the cue, at times 1000–4000 the display of the feedback. Magenta lines refer to <i>left</i> MI trials, green lines to <i>right</i> MI trials. The scalp plots underneath refer to the shaded areas of the time plots and show the distribution of the ERD/ERS. In the second rows, the scalp plots of the <i>left</i> MI trials, in the third rows the scalp plots of the <i>right</i> MI trials and in the fourth the scalp plots of the sign-r².</p

Mean BCI feedback accuracies for each intervention group (Control, PMR, 2HAND) over runs 4–7 (left) and run-wise (right).

<p>‘B’ refers to participants of Berlin and ‘W’ to participants of Würzburg. PMR W has significantly higher mean BCI performance compared to Control W (p<0.05), marked with a star in the bar plot.</p

Grand average ERD/ERS for class combination <i>left-right</i> and intervention groups in Würzburg.

<p>‘N’ is the number of participants of each group. From left to right: runs 1–3, runs 4–5, runs 6–7. The time plots in the first rows picture the evolution of the ERD/ERS for about 6000 ms at C3 (thick lines) and C4 (thin lines). At time 0 is the onset of the cue, at times 1000–4000 the display of the feedback. Magenta lines refer to <i>left</i> MI trials, green lines to <i>right</i> MI trials. The scalp plots underneath refer to the shaded areas of the time plots and show the distribution of the ERD/ERS. In the second rows, the scalp plots of the <i>left</i> MI trials, in the third rows the scalp plots of the <i>right</i> MI trials and in the fourth the scalp plots of the sign-r².</p

Schematic flowchart of the online protocol.

<p>The EEG processing and adaptation protocol during runs 1–3 with positive biased feedback are depicted in blue, in yellow the processing and adaptation during runs 4–5 with real feedback, in green the processing and adaptation during runs 6–7 also with real feedback. The adaptation applied in runs 1–3 and 4–5 uses supervised methods, the adaptation of runs 6–7 uses unsupervised methods. In magenta are depicted the phases of subject-specific features selection (e.g. frequency band, CSP filters, etc) and training of the classifier that happened two times, i.e. after runs 1–3 and after runs 4–5.</p

Overview of BCI performances sorted in ascendent order.

<p>For each participant, the black crosses indicate the overall mean feedback accuracy and the colored stars the accuracies of the four feedback runs (4–7). The participants of Berlin are displayed in magenta and the ones of Würzburg in green. The accuracies of each participant are connected by colored lines that emphasize the variance of the accuracies between runs. The dotted gray lines represent the accuracy considered necessary for BCI control (70%) and the threshold for accuracy significantly higher than chance (54.69%).</p