Fig. 5

Real-time, closed-loop control of tSCS using predictions of movement intention in a non-invasive BSI. (a) Technological framework for non-invasive BSI. Desynchronization in the sensorimotor cortex was identified using a 32-channel EEG system in real-time as participants extended their right knee. The predicted movement intention was used to trigger the delivery of tSCS at a higher amplitude. (b) Illustration of a cued movement block used in the training set. Stimulation was ramped up to a baseline of 10 mA and was increased to 15 mA during the movement phases using the task’s movement cue. (c) EEG spectrograms of selected sensorimotor channels, kinematics, movement probability, and real-time closed-loop stimulation for a single block for a representative participant (thin lines) and averaged across trials (thick line). Note that there is event-related desynchronization before and after movement onset. Stimulation onset was generally timed with movement onset as shown by the stimulation averaged across trials. (d) ROC curve for individual participants (thin lines) and averaged across participants (thick line) when testing on cued movement with stimulation. (e) Same as (d) but for a decoder tested on uncued movement with stimulation. (f) Paired comparison of average AUC across participants for cued and uncued movement and comparison to chance. (g) Confusion matrix calculated according to the stimulation administered during the trial and averaged across participants. (h) Same as g but for a decoder tested on uncued movement. Bars in f represent mean ± s.d., with each circle representing the average AUC for one participant. The asterisks on the right of each bar represent the results of the paired samples Wilcoxon signed test for each decoder’s AUC against chance; the asterisks between bars represent one-sample Wilcoxon signed test between two decoders’ average AUCs. ∗ p < 0.05; ∗∗ p < 0.01; ∗∗∗ p < 0.001. Abbreviations: rectus femoris (RF), vastus lateralis (VL), tibialis anterior (TA), medial gastrocnemius (MG). EEG map and brain region division modified from [29]