Simultaneous tDCS-fMRI reveals limited and inconsistent changes in functional connectivity: Insights from a temporal...

Area of Science:

• Neuroscience
• Neuromodulation
• Brain Imaging

Background:

• Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique.
• Previous studies assessed tDCS effects on functional connectivity using pre- and post-intervention resting-state functional MRI (rs-fMRI).
• The temporal dynamics of functional connectivity during tDCS remain less understood.

Purpose of the Study:

• To investigate the temporal dynamics of functional connectivity during tDCS.
• To explore the mechanism of action by incorporating electric field simulations.
• To analyze functional connectivity changes at whole-brain and network levels.

Main Methods:

• Forty-seven healthy females underwent a randomized, sham-controlled, cross-over tDCS study.
• rs-fMRI data were collected before, during (three time windows), and after tDCS targeting the left dorsolateral prefrontal cortex.
• Functional connectivity analyses used seed regions based on electrode placement and electric field strength.

Main Results:

• tDCS did not consistently change functional connectivity over time.
• No significant whole-brain functional connectivity changes were observed during active tDCS.
• Increased connectivity between the cathode and postcentral gyrus was noted after active tDCS; network changes were observed for both sham and active tDCS.

Conclusions:

• tDCS effects on functional connectivity are not consistently dynamic during stimulation.
• Observed network changes may not be solely attributable to active tDCS.
• Further research is needed to link tDCS-induced functional connectivity changes to clinical outcomes.