A estimulação transcraniana por corrente contínua de diferentes intensidades com e sem batidas binaurais de 40 Hz altera a hemodinâmica do córtex pré-frontal? Um ensaio controlado randomizado

Abstract

Introduction: Positive effects of transcranial direct current stimulation (tDCS) on brain hemodynamics as well as to cognitive performance are often reported. The binaural beat (BB) also showed potential to provoke improvements in cognitive performance. However, no study assessing the prefrontal hemodynamics was found using the combination of those techniques nor assessing the effects on hemodynamic response at different intensity levels of tDCS (2 and 3 mA). Objective: To compare the immediate hemodynamic responses to tDCS at different intensities (2 and 3 mA) with and without 40 Hz BB. Materials and Methods: Sixty-eight healthy young individuals of both sexes were split into 4 groups: tDCS 2 mA group; tDCS 3 mA group; tDCS 2 mA + BB group; tDCS 3 mA + BB group. All groups received 20-minute tDCS (F3-Fp2) alone or combined to BB. The hemodynamic effect was assessed using a near-infrared intracranial spectroscopy (NIRS) positioned on the left supraorbital region (Fp1). The mean values of rates of oxygen saturation (SatO2) were recorded at baseline, during intervention period and post-stimulation. The oxygenated hemoglobin rates (HbO) were also extracted. Results: No between-group differences were observed. The within-group analysis did not show significant differences comparing the time*groups factor. However, the time factor showed significant within-group differences for all groups. No differences were found for any HbO. Conclusion: The present findings showed that 2 and 3 mA tDCS had effects over pre-frontal cortex SatO2, however additional BB did not change the SatO2 levels compared to tDCS alone.