Effects of Transcranial Direct Current Stimulation Rapid Automatized Naming Performance in Healthy Individuals

Purpose: This study investigated the effects of anodal, cathodal, and shatranscranial direct current stimulation (tDCS) on rapid automatized naming (RAN) performance, a task assessing accuracy and speed in naming visual stiuli, closely linked to phonological processing and language production. Method: Sixty healthy, right-handed young adults were randomly assigned tanodal, cathodal, or sham tDCS groups. RAN performance was evaluated usinmeasures of accuracy, vocal reaction time (vRT), and task completion tim(TCT) before and after 20-min tDCS targeting the left temporo–parieto–occipitjunction. Each RAN subtask (color, number, letter, and combination) include36 stimuli. Results: Anodal tDCS significantly reduced vRT in the color subtask (d = 0.and significantly reduced TCT across all subtasks: color (d = 0.85), number (0.68), letter (d = 0.79), and combination (d = 0.62). Cathodal tDCS significanincreased vRT in the color subtask (d = −0.65) and significantly increased Tin the letter (d = −0.62) and combination (d = −0.84) subtasks. Sham stimulahad no significant effects. Conclusions: Anodal tDCS enhances RAN performance in healthy adults, prmarily by reducing TCT across all categories and selectively shortening vRT color naming. In contrast, cathodal tDCS slowed performance in specific sutasks. These findings indicate that temporal measures—particularly TCT—are more sensitive than accuracy for detecting neurostimulation effects in healthpopulations. Beyond its established role in addressing reading difficulties, RAmay also provide early insights into broader cognitive–linguistic disordersunderscoring its potential value for future clinical and therapeutic applications.