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Beta Changes Induced by Acute Hand Loss Model during NMES
Summary
Neuromuscular electrical stimulation (NMES) alters sensorimotor cortex activity after simulated hand loss. NMES causes ipsilateral brain activity dominance, suggesting compensatory changes important for prosthetic limb development.
Area of Science:
- Neuroscience
- Rehabilitation Engineering
- Motor Control
Background:
- Neuromuscular electrical stimulation (NMES) effectively aids motor rehabilitation by inducing muscle contractions and modulating cortical activity.
- Hand amputation leads to cortical reorganization, making the sensorimotor cortex's response to NMES-evoked contractions in amputation stumps unclear.
- Understanding these neural responses is crucial for developing effective neuroprosthetics and rehabilitation strategies.
Purpose of the Study:
- To investigate how sensorimotor cortical activity changes in response to NMES-evoked muscle contractions during acute simulated hand loss.
- To quantify alterations in Beta-band event-related desynchronization (Beta ERD) and functional connectivity.
- To explore the compensatory mechanisms in the sensorimotor cortex following proprioceptive loss.
Main Methods:
- An acute hand loss model was created using the ischemic nerve block (INB) technique in 11 healthy subjects.
- 64-channel EEG signals were recorded during a 2x2 factorial design, varying INB state and NMES current intensity.
- Beta ERD patterns and adaptive directed transfer function (ADTF) were used to analyze cortical activity and functional connectivity.
Main Results:
- Simulated hand loss (INB) induced ipsilateral dominance in NMES-evoked Beta ERD, contrasting with contralateral dominance before INB.
- Before INB, NMES above motor threshold elicited significantly higher contralateral Beta ERD than ipsilateral.
- Functional connectivity analysis revealed temporal dynamics, with lower clustering coefficients during INB compared to before INB.
Conclusions:
- Loss of hand proprioception degrades contralateral sensorimotor cortical activity and induces compensatory increases in ipsilateral activity in response to NMES.
- These findings highlight adaptive neural plasticity following limb loss.
- This research provides valuable insights for improving proprioceptive function reconstruction in hand prosthetics.
