Effects of transcranial direct current stimulation on reading processes: a pilot study

BACKGROUND: tDCS is a noninvasive brain stimulation technique which is gaining interest in clinical field, especially for rehabilitation purposes. The aim of this pilot study was to test the effects of tDCS over the left posterior temporal cortex, on reading processes in good readers and in dyslexics performing a words and nonwords reading task. We hypothesized that anodic stimulation facilitates the reading performance. METHOD: One group of 30 good readers and one group of 15 dyslexics were tested in 3 sessions (sham, anodal, cathodal). tDCS was applied over posterior temporal lobe, with a current of 1,5 mA, lasting for 20 minutes. Subjects task was to read aloud lists of words or nonwords, before and after stimulation. During the stimulation participants read a book. We recorded reading times and accuracy of every single lists (words and nonwords) before and after the stimulation. RESULTS: Regarding reading times, we found a faster performance after tDCS. We couldn’t discriminate between different types of stimulation, maybe because of task simplicity. Similarly we found an improvement in reading accuracy for nonwords after tDCS and a better performance after anodal stimulation. Concerning the dyslexic group, we found a significant improvement in reading times for nonwords after anodal stimulation. Further experiments are necessary to prove the benefits of tDCS for reading processes and more generally for rehabilitation purposes.