ERD Full-process Longitudinal Trend and Pre-post Motor Recovery Under BCI-controlled Sixth-finger Neurofeedback Intervention in Stroke Patients

Background Brain-computer interface (BCI) is used in stroke rehabilitation to match brain activity with contingent feedback to establish closed-loop pathways and provide a measure of neuroplasticity changes of patients. However, most studies assessed neural function only at pre- and post-intervention, thereby longitudinal trends of neural patterns and mechanismsduring full-process of intervention remain unclear. Methods Forty stroke patients were recruited to receive a total of 8 sessions motor imagery-based (MI-based) BCI-controlled “sixth-finger” neurofeedback intervention, 4 sessions per week for 2 weeks. Electroencephalography (EEG) measure and clinical scales were assessed at three time points: baseline, post-train and 1month follow-up period, and EEG data of each intervention sessions were also tracked. ERD phenomenon induced by MI and resting-state functional connectivity were used to reflect the longitudinal trends and pre-post changes in neural activity. The upper extremity Fugl-Meyer assessment (FMA-UE) and Barthel index (BI) were used to reflect the motor improvement. Results EEG longitudinal trend shows three phases over full-process of intervention: ERD gradually increased in the first week of training, weakened and focused on the contralateral sensorimotor area in the second week, and showed a significant correlation over sessions, remaining focused and contralateral pattern in the follow-up period. And resting-state functional connectivity increased after intervention. Motor function between pre-post intervention showed significant improvement by clinical metrics, with + 7.9 in FMA-UE and + 7.1 in BI. More than half of patients (9/14) reached the minimally clinically important difference (MCID) of 6.6 points change for FMA-UE after therapy. Meanwhile the improvement was maintained until the one-month follow-up after the end of therapy. In addition, improvement of motor function is associated with the enhancement of resting-state functional connectivity. Conclusions This work reveals longitudinal trend of neural patterns over full-process of intervention and its correlation with motor recovery, so as to provide more evidence for a detailed understanding of the mechanism of neural plasticity.