Motor system modulation by transcranial alternating current stimulation: insights from functional MRI-a scoping...

Area of Science:

• Neuroscience
• Neuromodulation
• Motor Control

Background:

• Transcranial alternating current stimulation (tACS) is a non-invasive technique for modulating brain rhythms.
• Understanding the neural mechanisms of tACS on motor function requires further investigation.
• Functional magnetic resonance imaging (fMRI) offers insights into tACS-induced brain activity and connectivity.

Purpose of the Study:

• To review functional MRI (fMRI) evidence on how tACS affects motor-related brain activity and connectivity.
• To synthesize findings in both healthy individuals and patients with neurological conditions.
• To explore frequency-specific effects of tACS on motor networks.

Main Methods:

• Systematic literature search for studies using fMRI to investigate tACS effects on motor function.
• Included studies with healthy participants and individuals with chronic stroke.
• Analyzed data from six eligible studies involving 108 participants.

Main Results:

• Gamma-band tACS (≥50 Hz) increased activation and connectivity in healthy participants' sensorimotor networks.
• Alpha- and beta-band stimulation showed variable or region-specific effects.
• In chronic stroke, 10 Hz tACS enhanced localized activation, while 20 Hz tACS improved network integration.

Conclusions:

• tACS modulates motor networks in a frequency- and site-dependent manner.
• Findings suggest potential applications for tACS in post-stroke rehabilitation.
• Standardized protocols and larger trials are needed to optimize tACS for motor recovery.