Theta tACS Over the Medial Frontal Cortex Modulates Executive Function in Parkinson's Disease: A Randomized,...

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Executive dysfunction is a common non-motor symptom in Parkinson's disease (PD).
• Medial frontal cortex (MFC) dysfunction is linked to executive dysfunction in PD.
• This study investigates non-invasive brain stimulation for PD-related cognitive deficits.

Purpose of the Study:

• To assess the efficacy of high-definition transcranial alternating current stimulation (HD-tACS) over the MFC for improving executive function in PD patients.
• To explore the neurophysiological effects of HD-tACS on prefrontal cortex activity during cognitive tasks.
• To provide evidence for the potential of oscillatory neuromodulation in PD cognitive rehabilitation.

Main Methods:

• Randomized, sham-controlled study with 28 PD patients.
• 10 daily sessions of 6-Hz HD-tACS or sham stimulation over the MFC.
• Executive functions assessed via Digit Span Test, Trail Making Test, Verbal Fluency Test, Simon task, and stop-signal task.
• Functional near-infrared spectroscopy (fNIRS) measured prefrontal hemodynamic responses.

Main Results:

• Active 6-Hz HD-tACS significantly improved performance on TMT-A, TMT-B, and semantic VFT compared to sham.
• Reduced VFT-evoked oxyhemoglobin responses in the right dorsolateral prefrontal cortex were observed with active HD-tACS.
• Active HD-tACS led to a smaller Simon effect and higher inhibition rate, indicating improved cognitive control.

Conclusions:

• 6-Hz HD-tACS over the MFC selectively enhances specific executive functions in PD.
• HD-tACS demonstrates potential as a non-invasive neuromodulation technique for cognitive rehabilitation in Parkinson's disease.
• This study provides neurobehavioral evidence supporting oscillatory stimulation for PD cognitive deficits.