Brain State-Dependent Closed-Loop Modulation of Paired Associative Stimulation Controlled by Sensorimotor...

Area of Science:

• Neuroscience
• Motor Control
• Rehabilitation Technology

Background:

• Pairing electrical stimulation (ES) and transcranial magnetic stimulation (TMS) enhances corticospinal excitability.
• Motor imagery (MI)-related brain activity amplifies effects of ES and TMS individually.
• The impact of brain self-regulation on combined ES and TMS is not well understood.

Purpose of the Study:

• Investigate the influence of MI-related event-related desynchronization (ERD) during associative ES and TMS on corticospinal excitability.
• Explore brain state-dependent effects of paired stimulation.

Main Methods:

• Paired functional electrical stimulation (FES) of the extensor digitorum communis (EDC) muscle and single-pulse TMS applied to the motor cortex.
• Beta-band (16-22 Hz) ERD during MI controlled the timing of paired stimulation within a brain-machine interface.
• Stimulus-response curves (SRCs) of motor-evoked potentials (MEPs) measured before and after intervention.

Main Results:

• Approximately 150 pairs of FES and TMS significantly increased MEP amplitude and area under the curve (AUC).
• Increased corticospinal excitability was linked to recruitment of additional neuronal pools.
• MEP increases were dependent on brain state (beta-band ERD) and not background muscle activity.

Conclusions:

• Brain state-dependent paired associative stimulation (PAS) shows promise for neurorehabilitation.
• Findings support the development of closed-loop therapeutic approaches.
• The study highlights the role of self-regulated brain states in modulating stimulation efficacy.