Do Progressive Intensities of Transcranial Direct Current Stimulation with and Without 40 Hz Binaural Beats Change...

Area of Science:

• Neuroscience
• Cognitive Science
• Biomedical Engineering

Background:

• Transcranial direct current stimulation (tDCS) and binaural beats (BBs) are non-invasive techniques explored for enhancing cognitive function and brain hemodynamics.
• Previous research indicates potential benefits of both tDCS and BBs individually, but limited studies have investigated their combined effects on prefrontal hemodynamics.
• The impact of varying tDCS intensities (2 mA and 3 mA) on hemodynamic responses, especially when combined with BBs, remains underexplored.

Purpose of the Study:

• To compare the immediate hemodynamic responses to tDCS at 2 mA and 3 mA, both with and without concurrent 40 Hz binaural beats (BBs).
• To investigate the effects of these combined interventions on prefrontal cortex oxygen saturation (SatO2) and oxygenated hemoglobin (HbO) levels.

Main Methods:

• Sixty-eight healthy young participants were divided into four groups: tDCS 2 mA, tDCS 3 mA, tDCS 2 mA + BB, and tDCS 3 mA + BB.
• Each group received 20 minutes of tDCS (F3-Fp2) either alone or combined with BBs.
• Hemodynamic changes were assessed using functional near-infrared spectroscopy (fNIRS) measuring SatO2 and HbO at the left supraorbital region (Fp1) before, during, and after stimulation.

Main Results:

• No significant differences in hemodynamic responses were observed between the different groups (between-group analysis).
• While the time factor showed significant within-group differences in SatO2, the interaction between time and groups was not significant.
• No significant differences were found in oxygenated hemoglobin (HbO) rates across any conditions.
• tDCS at both 2 mA and 3 mA demonstrated an effect on prefrontal cortex SatO2, but the addition of BBs did not yield different SatO2 levels compared to tDCS alone.

Conclusions:

• Both 2 mA and 3 mA tDCS influence prefrontal cortex oxygen saturation in healthy young individuals.
• The concurrent application of 40 Hz binaural beats does not appear to modulate the immediate hemodynamic effects of tDCS on prefrontal SatO2.
• Further research is needed to explore potential synergistic or differential effects of combined tDCS and BBs on cognitive performance and brain activity.