Assessment of the Effect of Transcranial Direct Current Stimulations (tDCS) in Focused Attention Enhancement Using Event-Related Potentials

Attention is a multi-dimensional cognitive process. Transcranial direct current stimulation (tDCS) is an effective approach for the improvement of attention. Using Event-related potentials (ERP) frequency components, the main goal of this study was to develop an attention index to assess improvement of attention in healthy people by applying tDCS.

13 subjects (6 males and 7 females, with mean age 24.53±4.5 years) participated in this study. First, participants were asked to fill out the Adult ADHD self-report scale, Beckchr('39')s depression, and Spielberger anxiety questionnaires. Simultaneous to recording their brain signals (19 channels), subjects were asked to participate in the Integrated visual and auditory (IVA) test. This test entails 500 stimulations, which include 125 auditory targets, 125 visual targets, 125 auditory non-target, and 125 visual non-target stimulations lasting for 13 minutes, after recording the electroencephalogram (EEG), the Dorsolateral Prefrontal Cortex (DLPFC) in subjectschr('39') left hemisphere is stimulated using tDCS, with 1mA current for 20 minutes. The stimulation period was 5 consecutive days. To analyze the data, after removing noise and artifacts, ERP components were extracted using synchronous averaging. Then frequency domains feature in every stimulation type were extracted from ERP components. Correlation between percentage changes and the subjectchr('39')s IVA test results were calculated before and after applying tDCS.

The result showed that Beta energy significantly increased after applying tDCS. Furthermore, a significant correlation was observed between beta energy and auditory omission error in FP1 channel.

  tDCS decreases omission error and increases beta energy in auditory stimulation, which then leads to the improvement of focus attention. Further studies are needed to assess the effect of tDCS on the improvement of attention in auditory attention deficit.