Inconsistent results are observed in the effects of transcranial direct current stimulation (tDCS) with different montages on motor learning. This study aimed to compare the effects of anodal and cathodal tDCS over primary motor cortex (M1) at different intensities (1 and 2 mA) on motor learning in healthy young adults. The participants were randomly divided to five groups: 1) 1mA M1 c-tDCS, 2) 1mA M1 a-tDCS, 3) 2 mA M1 c-tDCS, 4) 2 mA M1 a-tDCS and 5) M1 sham tDCS. The groups received 20-minute stimulation concurrent with serial response time test (SRTT) implicitly, while the tDCS was turned off after 30 seconds in the sham tDCS group. Response time (RT) and error rate (ER) during SRTT were assessed prior, during and 72 hours after the intervention. The results indicated that online learning occurred in all groups (P < 0.05), except in M1 c-tDCS (1 mA) (P>0.05). In addition, offline learning was observed in 1 mA M1 a-tDCS, 2mA M1 a-tDCS and 2 mA M1 c-tDCS as compared to sham tDCS and M1 c-tDCS (1 mA) groups (P < 0.05). On the other hand, 1 mA M1 c-tDCS group did not indicate any consolidation effect and even a trend toward negative offline learning. M1 a-tDCS with different intensities and also 2 mA M1 c-tDCS may be helpful for the enhancement of motor learning in young adults. Considering the deterioration effect of 1 mA M1 c-tDCS, it seems that caution should be applied in using it to improve motor learning.

Introduction: The rating of perceived exertion (RPE) is a widely used method for monitoring the load during training, as it provides insight into the subjective intensity of effort experienced during exercises. Considering the role of brain in monitoring and perception of the effort, several studies explored the effect of transcranial direct current stimulation (tDCS) on RPE in different populations. The aim of current study is to review the studies investigated the effect of tDCS on RPE in three groups including healthy untrained people, physically active persons and athletes. Method: Nine databases were searched for papers assessing the effect of tDCS on RPE. The data of included studies were extracted and methodological quality examined using the risk of bias 2 (ROB2) tool. Thirty-three studies met the inclusion criteria. Results: According to the meta-analysis, active a-tDCS significantly decreased the RPE compared to the sham-stimulation. The a-tDCS could decrease the RPE when it was applied over M1 or DLPF. Regarding the measurement tool, Borg’s scale 6-20 and OMNI scale could show an improvement in RPE scale. Conclusion: A-tDCS is a promising technique that can decrease improve the RPE. M1 and DLPFC are suggested as the target area of stimulation. From the tools that measure the RPE, Borg’s RPE 6-20 and OMNI scale could better show the effect of a-tDCS.

Transcranial pulsed current stimulation (tPCS) is a promising non-invasive brain stimulation technique that has gained considerable attention in recent years. The purpose of this review is to provide an overview of the existing literature on tPCS, examine the scope and nature of previous research, investigate its underlying mechanisms, and identify gaps in the literature. A search of online databases resulted in 36 published tPCS studies from inception until May 2023. These studies were categorized into three groups: human studies on healthy individuals, patient studies with pathological conditions, and animal studies. The findings suggest that tPCS has the potential to modulate brain excitability by entraining neural oscillations and utilizing stochastic resonance. However, the mechanisms underlying the effects of tPCS are not yet fully understood and require further investigation. Furthermore, the included studies indicate that tPCS may have therapeutic potential for neurological diseases. However, before tPCS can be applied in clinical settings, a better understanding of its mechanisms is crucial. In this regard, the tPCS studies were categorized into four types of research: basic, strategic, applied, and experimental research, to identify the nature of the literature and gaps. Analysis of these categories revealed that tPCS, with its diverse parameters, effects, and mechanisms, presents a wide range of research opportunities for future investigations.