not-yet-known not-yet-known not-yet-known unknown Results: The demographic details and baseline data for the participants in each group are listed in Table 1. There were no significant differences among groups in age, gender, MMSE, and baseline RT and ER (Pre 2) (P > 0.05). <<<Please insert Table 1 here>>> Table 2 presents the results of general linear repeated measures ANOVA. The between-subjects main effect of “Group” and the within-subjects main effect of “Time” were significant for both RT and ER (P < 0.001). The analysis also showed that there was a significant interaction effect between “Group” and “Time” (P < 0.001) for both RT and ER (Table 2). <<<Please insert Table 2 here>>> Post hoc paired T-test using Bonferroni correction showed significant reduction in RT between Train3 and Train10, between Pre 2 and Post 12 in M1 a-tDCS (1mA), M1 a-tDCS (2mA), M1 c-tDCS (2 mA) and sham groups (P < 0.01), which indicated online improvement and offline learning (Figure 3). In addition, post hoc analysis indicated that the amount of decreasing RT of Train 10, as online learning, in M1 a-tDCS (1 mA) and M1 a-tDCS (2mA) groups was more than M1 c-tDCS (2 mA) and sham groups (P<0.01, Figure 4, A). However, a significant reduction in ER between Train 3 and Train 10 and between Pre 2 and Post 12 was only shown in M1 a-tDCS (1mA) and M1 a-tDCS (2mA) groups (P<0.001) (Figure 3). Moreover, one-way ANOVA analysis indicated that there were significant differences in online and offline learning (RT and ER reduction) among groups (P < 0.001, Table 3). Figure 4 also indicates more offline learning, based on RT reduction, in M1 a-tDCS (1mA) than M1 c-tDCS (1mA) (p=0.01) and sham M1 a-tDCS groups (p=0.02). There was more offline learning, based on ER reduction, in M1 a-tDCS (1 mA), M1 a-tDCS (2mA) and M1 c-tDCS (2 mA) groups as compared to M1 c-tDCS (1mA) and sham M1 a-tDCS groups (p<0.03). In contrast, there were no significant decreases in RT and ER between Train 3 and Train 10 (P>0.05) and Pre 2 and Post 2 (P>0.05) in M1 c-tDCS (1 mA) group, which indicated deficits in online and offline learning (Figure 3, 4). In addition, there was a consolidation effect of learning in all groups, except in M1 c-tDCS (1 mA) group (Figure 4). The results show a reduction in RT and ER, which lasted and even shows a trend toward more reduction offline, between Train10 and Post2 in the M1 a-tDCS (2mA) and M1 c-tDCS (2 mA) groups (fig. 4 a, b). On the other hand, the M1 c-tDCS (1 mA) group did not show any offline effect and even showed a trend toward negative offline learning (comparison between Train10 and Post12, Fig. 4, a, b). This study indicated that 20-minute M1 a-tDCS (1 &2 mA) and M1 c-tDCS (1 & 2 mA) intervention was tolerated well with minimal adverse or side effects by all participants. The participants of all groups did not report any burning sensation or pain during or after stimulation. However, the majority of participants reported having itching during stimulation, which indicated a common side effect of the intervention.