Transcranial direct current stimulation over medial prefrontal cortex reduced alpha power and functional connectivity...

Area of Science:

• Neuroscience
• Cognitive Science
• Brain Stimulation

Background:

• Previous studies on medial prefrontal cortex (mPFC) transcranial direct current stimulation (tDCS) for self-referential processing (SRP) have shown inconsistent results.
• Electroencephalography (EEG) studies suggest alpha oscillations are involved in semantic and somatic SRP, but tDCS effects on alpha-EEG during SRP are unknown.

Purpose of the Study:

• To investigate the effects of mPFC-tDCS on EEG and subjective experiences during semantic and somatic self-referential processing (SRP).
• To examine how tDCS influences alpha oscillations and their connectivity during different types of SRP.

Main Methods:

• Fifty-two young adults received 2 mA tDCS over the mPFC or sham stimulation.
• Participants performed semantic and somatic SRP tasks, a resting state task, and an external attention memory task.
• EEG data were analyzed using source analysis to assess power and functional connectivity, alongside subjective reports.

Main Results:

• mPFC-tDCS did not significantly alter mood, attention, or pleasantness during the SRP task.
• Compared to sham, tDCS reduced alpha power in the posterior cingulate cortex (PCC) and other brain regions during somatic SRP.
• tDCS reduced functional connectivity between the left inferior parietal lobule and ventral PCC during the second session of somatic SRP.

Conclusions:

• mPFC-tDCS may not be sufficient to change immediate subjective experiences during SRP.
• mPFC-tDCS can modulate alpha oscillation power and functional connectivity, particularly during somatic SRP.
• Findings suggest tDCS effects on brain activity during SRP may depend on the type of self-reference and experimental session.