RESUMEN
Purpose: Attention, a complex cognitive process, is linked to the functional activities of the brain's dorsal attention network (DAN) and default network (DN). This study aimed to investigate the feasibility, safety, and blinding efficacy of a transcranial direct current stimulation (tDCS) paradigm designed to increase the excitability of the DAN while inhibiting the DN (DAN+/DN-tDCS) on attention function in healthy young adults. Methods: In this randomized controlled experiment, participants were assigned to either the DAN+/DN-tDCS group or the sham group. A single intervention session was conducted at a total intensity of 4 mA for 20 min. Participants completed the Attention Network Test (ANT) immediately before and after stimulation. Blinding efficacy and adverse effects were assessed post-stimulation. Results: Forty participants completed the study, with 20 in each group. Paired-sample t-test showed a significant post-stimulation improvement in executive effect performance (t = 2.245; p = 0.037) in the DAN+/DN-tDCS group. The sham group did not exhibit any significant differences in ANT performance. Participants identified the stimulation type with 52.50% accuracy, indicating no difference in blinding efficacy between groups (p = 0.241). Mild-to-moderate adverse effects, such as stinging, itching, and skin reddening, were reported in the DAN+/DN-tDCS group (p < 0.05). Conclusion: DAN+/DN-tDCS enhanced attention function in healthy young individuals, particularly in improving executive effect performance. This study presents novel strategies for enhancing attentional performance and encourages further investigation into the mechanisms and outcomes of these interventions across diverse populations.
RESUMEN
BACKGROUND: Temporal interference (TI) stimulation, an innovative non-invasive brain stimulation technique, has the potential to activate neurons in deep brain regions. The objective of this study was to evaluate the effects of repetitive TI stimulation targeting the lower limb motor control area (i.e., the M1 leg area) on lower limb motor function in healthy individuals, which could provide evidence for further translational application of non-invasive deep brain stimulation. METHODS: In this randomized, double-blinded, parallel-controlled trial, 46 healthy male adults were randomly divided into the TI or sham group. The TI group received 2 mA (peak-to-peak) TI stimulation targeting the M1 leg area with a 20 Hz frequency difference (2 kHz and 2.02 kHz). Stimulation parameters of the sham group were consistent with those of the TI group but the current input lasted only 1 min (30 s ramp-up and ramp-down). Both groups received stimulation twice daily for five consecutive days. The vertical jump test (countermovement jump [CMJ], squat jump [SJ], and continuous jump [CJ]) and Y-balance test were performed before and after the total intervention session. Two-way repeated measures ANOVA (group × time) was performed to evaluate the effects of TI stimulation on lower limb motor function. RESULTS: Forty participants completed all scheduled study visits. Two-way repeated measures ANOVA showed significant group × time interaction effects for CMJ height (F = 8.858, p = 0.005) and SJ height (F = 6.523, p = 0.015). The interaction effect of the average CJ height of the first 15 s was marginally significant (F = 3.550, p = 0.067). However, there was no significant interaction effect on the Y balance (p > 0.05). Further within-group comparisons showed a significant post-intervention increase in the height of the CMJ (p = 0.004), SJ (p = 0.010) and the average CJ height of the first 15 s (p = 0.004) in the TI group. CONCLUSION: Repetitive TI stimulation targeting the lower limb motor control area effectively increased vertical jump height in healthy adult males but had no significant effect on dynamic postural stability.