Abstract
Transcranial alternating current stimulation (tACS) is a noninvasive method to modulate brain oscillation and cognitive functions. Considering the important roles of alpha- and gamma-band neural oscillations in spatial attention, we aimed to investigate whether and how the application of tACS in the alpha and gamma bands could modify the distraction of a task-irrelevant but salient stimulus during visual search. In the current study, fourteen participants received three kinds of 2 mA alternating current stimulation (Sham, 10Hz or 40Hz) at either the left or right inferior parietal area (P5 or P6) on six different days, with an at least two-day interval between stimulation conditions. The stimulation order was randomized across participants. Each stimulation condition consisted of 3 consecutive sessions and each session took approximately 12 min. Participants performed an additional singleton task (Theeuwes, Perception & Psychophysics, 1992). Note that participants only received tACS during the first session. There was no tACS in sessions 2 and 3. Distractor effect (DE = RT_distractor – RT_non-distractor) was calculated as an index of attention captured by a colored singleton, and then submitted to a repeated-measures ANOVA with within-participants factors of time (sessions 1 to 3), hemisphere (left vs. right) and treatment (10Hz vs. 40Hz vs. sham). We found a significant interaction between time and treatment. Compared to the sham condition, DE in the 10Hz condition was significantly lower in session 1. Interestingly, this effect disappeared in sessions 2 and 3. The 40Hz tACS made no difference in all the 3 sessions. These findings demonstrated that the 10Hz tACS could decrease visual distraction from a colored singleton. However, this effect was short-lived and it no longer manifested when the tACS was terminated. These findings also help to explore the possibility of modulating visual search performance by tACS.
Meeting abstract presented at VSS 2018