Development and evaluation of a non-invasive brain-spine interface using transcutaneous spinal cord stimulation

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Science

Background:

• Motor rehabilitation aids functional recovery post-spinal cord injury (SCI), but is limited by remaining sensorimotor function.
• Spinal cord stimulation (SCS) may enhance rehabilitation for severe SCI by creating a prosthetic effect.
• Developing non-invasive brain-spine interfaces (BSIs) is crucial for extending rehabilitation's reach.

Purpose of the Study:

• To identify electroencephalography (EEG)-based neural correlates of lower limb movement in the sensorimotor cortex.
• To assess the performance of a linear discriminant analysis (LDA) decoder in detecting movement onset.
• To evaluate a non-invasive BSI combining EEG and transcutaneous spinal cord stimulation (tSCS) for SCI rehabilitation.

Main Methods:

• Recorded EEG from unimpaired individuals during cued lower limb movement tasks.
• Identified event-related desynchronization in specific frequency bands (4-44 Hz) associated with movement initiation.
• Developed and tested an LDA neural decoder, integrating it with real-time tSCS modulation.

Main Results:

• Movement onset correlated with event-related desynchronization in central-medial cortical regions (4-44 Hz).
• The neural decoder achieved an AUC of 0.83 ± 0.06 for cued movement offline.
• Real-time BSI with tSCS showed an AUC of 0.81 ± 0.05 for cued and 0.68 ± 0.12 for uncued movements.

Conclusions:

• The non-invasive BSI effectively detects neural correlates of lower limb movement.
• Decoder performance decreased in uncued movements, possibly due to altered cortical strategies.
• This BSI technology could enable precisely timed tSCS during voluntary effort, enhancing motor rehabilitation outcomes for SCI.