Cortical Activity During Active Walking and Kinesthetic Motor Imagery with Proprioceptive Feedback for Lower-Limb BCI in Stroke Survivors

A stroke can affect postural control, balance, and walking, thereby limiting the ability to perform activities of daily living. Although conventional physical therapy supports motor recovery through active walking, researchers have increasingly investigated advanced modalities, such as integrating motor-imagery-based brain–computer interfaces (BCIs) with proprioceptive feedback (PF). This combination aims to engage both the peripheral and central nervous systems. However, this integrated approach remains underexplored, particularly in the domain of lower-limb rehabilitation. To address this gap, this study developed and evaluated a BCI with five stroke survivors. The BCI provided treadmill-based PF at three different speeds, controlled by relative power changes detected in the participants’ brain signals during kinesthetic motor imagery (KMI). Cortical activity was analyzed across three states: baseline period, active walking, and KMI + PF. Specifically, active walking exhibited lower event-related desynchronization values compared to the KMI state combined with feedback. These findings suggest that the detection of relative power changes may provide a basis for establishing a common threshold in future MI classification strategies. In terms of clinical outcomes, preliminary improvements were observed across all five participants. However, the functional ambulation category metric, which reflects the level of assistance required for walking, remained the same in two out of the five participants. In addition, the lack of a control group limits our analysis to a pilot study rather than determining clinical improvement. These results support the potential of integrating brain signals with PF and provide a basis for exploring classification strategies that could reduce calibration time and improve the applicability of BCI systems in clinical settings.