Altered modulation of sensorimotor rhythms with chronic paralysis.

Area of Science:

• Neuroscience
• Motor Control
• Neurophysiology

Background:

• Paralysis disconnects the cortex from peripheral targets, inducing neuroplasticity.
• The impact of chronic paralysis on cortical oscillations during attempted movement remains unclear.
• Event-related desynchronization (ERD) in μ (8-13 Hz) and β (15-30 Hz) bands is crucial for motor control.

Purpose of the Study:

• To investigate how chronic paralysis affects cortical oscillations (ERD) during attempted and imagined hand grasping.
• To compare ERD modulation in individuals with cervical spinal cord injury (SCI) and able-bodied controls.
• To determine if the capacity for volitional muscle activity influences ERD characteristics post-SCI.

Main Methods:

• Magnetoencephalography (MEG) was used to measure source space cortical oscillations.
• Participants with cervical SCI (n=12) and able-bodied controls (n=13) performed attempted and imagined grasping tasks.
• Electromyography (EMG) recorded muscle activity during attempted movements.

Main Results:

• Individuals with SCI and no volitional EMG activity exhibited significantly decreased peak and area of ERD during attempted grasping compared to controls and SCI individuals with residual EMG.
• No significant differences in ERD were observed between groups during motor imagery tasks.
• ERD modulation during attempted movement is dependent on the presence of intact muscle activity post-SCI.

Conclusions:

• Individuals with SCI incapable of muscle activation can generate ERD during attempted movements, but its characteristics are altered.
• Individuals with SCI who retain some volitional muscle activity show no significant differences in ERD compared to able-bodied controls.
• These findings highlight the role of residual muscle activity in maintaining normal sensorimotor cortical oscillation patterns after SCI and inform therapeutic interventions like motor imagery and neurofeedback.