The right dorsolateral prefrontal cortex is essential in seconds range timing, but not in milliseconds range timing: An investigation with transcranial direct current stimulation.

It is unclear whether altering the activity of the right dorsolateral prefrontal cortex (right DLPFC) affects an individual's timing performance in milliseconds- and seconds range timing. Here we investigated the causal role of right DLPFC in milliseconds- and seconds range timing with a temporal bisection task under the application of transcranial direct current stimulation (tDCS) that altered the neural activities of the right DLPFC. The tDCS conditions consisted of anodal, cathodal, and sham conditions. The electrodes were placed over the F4 position (10-20 system) and on the left supraorbital forehead. In current study, participants completed two blocks of trials involving short ("Short blocks": 200-800 ms) or longer ("Long blocks": 1400-2600 ms) durations. The results showed that no significant differences in the bisection point (BP) were found among anodal condition, sham condition and cathodal condition in "Short blocks". However, in "Long blocks", the BP were found to be shifted toward the left for the anodal condition, sham condition, compared to cathodal condition, suggesting that the stimulus duration was judged to last longer for anodal condition compared to sham condition, whereas shorter for cathodal condition compared to sham condition. The results demonstrated that the right DLPFC played a causal role in seconds range timing (average duration 2000 ms), but not in milliseconds range timing (average duration 500 ms), which is shown it might be involved in the cognitive processing (for example, working memory process) based on dual-timing system and scalar timing theory.