Effects of Transcranial Direct Current Stimulation on Baseline and Slope of Prefrontal Cortex Hemodynamics During a...

Area of Science:

• Neuroscience
• Cognitive Science
• Neuroimaging

Background:

• Transcranial direct current stimulation (tDCS) is a safe and effective method for cognitive enhancement.
• Concurrent neuroimaging during tDCS is advancing, but findings on brain activity effects are conflicting.
• Previous studies showed inconsistent results regarding tDCS effects on brain activity and behavior.

Purpose of the Study:

• To investigate tDCS effects on hemodynamic activity and behavioral changes during a spatial memory task.
• To differentiate tDCS effects on hemodynamic amplitude and baseline during active stimulation.
• To address questions about within- and between-participant designs in tDCS research.

Main Methods:

• Functional near-infrared spectroscopy (fNIRS) measured prefrontal cortex hemodynamics during a spatial memory task.
• Participants received either sham stimulation (n=10) or tDCS (n=11) targeting the right ventral lateral prefrontal cortex.
• fNIRS monitored cortical oxygenated and deoxygenated hemoglobin changes non-invasively.

Main Results:

• tDCS significantly improved spatial memory performance.
• tDCS induced changes in hemodynamic response (HbO-HbR) in dorsolateral and ventromedial prefrontal cortex.
• Neural processing efficiency improved, indicated by reduced oxygenation and increased performance over time.

Conclusions:

• tDCS primarily modulates neuronal propensity for activity rather than activity strength.
• tDCS enhances task-relevant processing efficiency and alters hemodynamic resource utilization.
• Findings suggest tDCS can optimize cognitive function through neurophysiological changes.