Motor excitability changes during action observation in stroke patients

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Motor Control

Background:

• Stroke often impairs motor function, necessitating effective rehabilitation strategies.
• Action observation therapy (AOT) is a promising, non-invasive approach to enhance motor recovery.
• Understanding the neurophysiological underpinnings of AOT in stroke patients is crucial for optimizing its application.

Purpose of the Study:

• To investigate changes in motor excitability in stroke patients during action observation.
• To determine if motor excitability differs between the affected and unaffected limbs.
• To compare these effects in patients with pure motor strokes versus predominantly sensory strokes.

Main Methods:

• Utilized transcranial magnetic stimulation (TMS) to assess motor excitability in 18 stroke patients (10 pure motor, 8 sensory).
• Patients observed a video of hand performing pinch grips while TMS pulses were applied.
• Recorded motor evoked potentials (MEPs) from the first dorsal interosseous muscle of both hands at rest and during action observation.

Main Results:

• Motor excitability significantly increased during action observation compared to rest for both affected (p=0.024) and unaffected sides (p=0.004).
• The increase in motor excitability was more pronounced when observing the hand ipsilateral to the stimulated hemisphere (p=0.019).
• No significant differences in motor excitability changes were observed between motor and sensory stroke types.

Conclusions:

• Action observation enhances motor excitability in stroke patients, suggesting a neurophysiological basis for AOT.
• The findings indicate that AOT may engage both affected and unaffected motor pathways.
• Results support the potential of action observation as a therapeutic intervention for improving motor function post-stroke.