Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation

Area of Science:

• Neuroscience
• Motor Control
• Rehabilitation Medicine

Background:

• Previous research explored corticospinal excitability changes post-contraction with electrical stimulation (ES).
• Real-time assessment of these changes remained largely uninvestigated.
• Understanding these dynamic neural adaptations is crucial for optimizing therapeutic interventions.

Purpose of the Study:

• To investigate real-time changes in corticospinal excitability during voluntary wrist flexion combined with median nerve electrical stimulation.
• To determine the effects of simultaneous electrical stimulation on agonist (flexor carpi radialis - FCR) and antagonist (extensor carpi radialis - ECR) muscle excitability.
• To explore the potential of this combined approach for neurorehabilitation.

Main Methods:

• Transcranial magnetic stimulation (TMS) was used to elicit motor evoked potentials (MEPs).
• MEPs were recorded using a mechanomyogram to minimize electrical artifacts.
• Participants performed voluntary wrist flexion at varying intensities (0%, 5%, 20% MVC) with or without 10 Hz median nerve ES.

Main Results:

• Voluntary contraction with median nerve ES significantly increased corticospinal excitability in the FCR compared to contraction alone (p<0.01).
• Corticospinal excitability in the antagonist ECR significantly decreased with median nerve ES during FCR contraction (p<0.05).
• Mental imagery of the combined task also induced similar reciprocal changes in cortical excitability.

Conclusions:

• Median nerve stimulation during voluntary contraction induces reciprocal changes in cortical excitability in agonist and antagonist muscles.
• These findings support the use of voluntary contraction coupled with electrical stimulation in neurorehabilitation.
• Real-time modulation of corticospinal excitability offers a promising avenue for therapeutic strategies.