Transcranial alternating current stimulation attenuates BOLD adaptation and increases functional connectivity.

Area of Science:

• Neuroscience
• Cognitive Science
• Neuroimaging

Background:

• Transcranial alternating current stimulation (tACS) is a noninvasive brain stimulation technique used for cognitive enhancement and clinical purposes.
• The precise physiological mechanisms of tACS remain incompletely understood, with most research focusing on brain oscillation entrainment.

Purpose of the Study:

• To investigate the hypothesis that 10 Hz tACS modulates brain function by reducing sensory adaptation.
• To examine the effects of tACS on brain activity and connectivity using concurrent functional magnetic resonance imaging (fMRI).

Main Methods:

• Concurrent application of tACS and fMRI in human subjects.
• Utilized a motion adaptation paradigm to quantify blood oxygen level-dependent (BOLD) adaptation.
• Employed individualized head models to estimate tACS-induced electric fields.

Main Results:

• tACS significantly attenuated sensory adaptation in the human motion area (hMT+).
• tACS increased functional connectivity between hMT+ and other brain regions, including the dorsal attention network.
• The increase in functional connectivity was proportional to the strength of the tACS-induced electric field.

Conclusions:

• tACS at 10 Hz modulates local brain activity by reducing sensory adaptation.
• tACS enhances global brain function by increasing functional connectivity in a dose-dependent manner.
• These findings provide a more comprehensive understanding of tACS mechanisms, crucial for optimizing its therapeutic applications.