Optimization of mirror therapy to excite ipsilateral primary motor cortex

Area of Science:

• Neuroscience
• Motor Control
• Rehabilitation Science

Background:

• Mirror therapy utilizes visual illusions of hand movement to stimulate the ipsilateral primary motor cortex (iM1).
• Understanding factors that modulate iM1 excitability during mirror therapy is crucial for optimizing its clinical application.

Purpose of the Study:

• To investigate whether iM1 excitability can be modulated by controlling visual feedback of the active hand during mirror therapy.
• To compare the effects of enabling versus disabling vision of the active hand on iM1 responses.

Main Methods:

• Magnetoencephalography (MEG) was used to record motor cortical activations in healthy participants.
• Participants performed index finger extensions with either their dominant or non-dominant hand under two conditions: vision of the active hand (uncovered) and no vision (covered).
• A questionnaire assessed the clarity of the visual illusion experienced by participants.

Main Results:

• Disabling vision of the active hand (covered condition) consistently excited iM1 in all participants, regardless of hand dominance.
• Enabling vision (uncovered condition) resulted in iM1 excitation in fewer participants.
• The covered viewing condition reported a clearer visual illusion compared to the uncovered condition.

Conclusions:

• Disabling vision of the active hand during mirror therapy is a more effective strategy for exciting iM1 responses.
• Creating a more immersive visual illusion by obscuring the active hand enhances the therapeutic potential of mirror therapy.
• These findings suggest a refined approach to mirror therapy for neurological rehabilitation.