A Comparison Between Movement-Related Brain Activity Modalities for Increasing Corticospinal Excitability Using an Associative Brain-Computer Interface

Brain-computer interfaces (BCIs) have been shown to increase corticospinal excitability and promote motor recovery in patients with stroke when pairing efferent activity associated with either executed or imagined movements with congruent afferent somatosensory feedback from, for example, electrical stimulation. However, direct comparisons between motor execution and motor imagery within associative BCI paradigms remain lacking. This study investigated how corticospinal excitability was modulated by two associative BCI interventions that paired motor execution and motor imagery with peripheral electrical stimulation (PES).

Seventeen able-bodied participants completed two interventions: 1) executed wrist extension paired with PES to the radial nerve, and 2) imagined wrist extension paired with PES. During each intervention, 100 executed or imagined visually cued wrist extensions were paired with PES. The timing of the PES was determined based on the peak negativity of the movement-related cortical potential associated with the visually cued movements. Before, immediately after, and 30 minutes after the intervention, transcranial magnetic stimulation was used to elicit motor-evoked potentials (MEPs) to assess changes in corticospinal excitability.

Both executed and imagined movements paired with PES significantly increased the maximal MEP amplitudes by 45 ± 63% and 41 ± 63%, respectively, immediately after the intervention, and by 35 ± 54% and 55 ± 83%, respectively, 30 minutes after the intervention, compared with preintervention measurements (all p's ≤ 0.03). No significant differences were observed between the two interventions.

An associative BCI using either motor execution or motor imagery effectively increases corticospinal excitability. These findings suggest that both forms of efferent activity are viable, allowing flexibility in selecting the modality based on user capability or clinical context.