Left parietal tACS at alpha frequency induces a shift of visuospatial attention

However, spatial attention shifts not only occur voluntarily (endogenous), but also stimulus-driven (exogenous). In order to study the task-specificity of the potential effects of tACS on attentional processes, we administered three conceptually different spatial attention tasks. Methods: 36 healthy volunteers were recruited from an academic environment.

In two seperate sessions, we applied either high-density tACS at 10Hz, or sham tACS, for 35-40 minutes to their left parietal cortex. We systematically compared performance on endogenous attention, exogenous attention, and stimulus detection tasks. Results: In the Endogenous attention task, we found a greater leftward bias in reaction times during left parietal 10Hz tACS as compared to sham.

There were no stimulation effects in the exogenous attention or stimulus detection task. Conclusion: The study shows that high-density tACS at 10Hz can be used to modulate visuospatial attention performance. The tACS effect is task-specific, indicating that not all forms of attention are equally susceptible to the stimulation.