We aimed to build on research using transcranial alternating current stimulation (tACS) to modulate visuospatial attention. The goal was to replicate previous findings that lateralized parietal tACS at alpha frequency induces a change in attention bias away from the contra- towards the ipsilateral visual hemifield. 40 healthy participants underwent tACS in two separate sessions where either 10 Hz tACS or sham was applied via a high-density montage over the left parietal cortex at 1.5 mA for 20 min, while performance was assessed in an endogenous attention task. Resting electroencephalography was recorded offline immediately after each session.It is well established that domain specific brain functions (such as perception, language, speech, declarative memory etc.) do not only depend on the corresponding, specialized systems, but are also modulated dynamically by regulatory brain networks, such as the "attention" system. It has become apparent that brain oscillations may subserve some of these regulatory (domain-general) processes. Importantly, a growing body of evidence suggests that brain oscillations do not only correlate but are likely causally involved in shaping brain function and that these oscillations change as a function of age and several neurological conditions. We aim to test how attention-related brain oscillations regulate performance using electroencephalography (EEG) and non-invasive brain stimulation techniques (NIBS). Insights from this project will help to more firmly link specific brain oscillations (such as alpha activity) to domain general processes that likely impact on several specialised functions. This could inform related studies on brain oscillations as targets for interventions (i.e. with a clinical scope), and add to new quantitative approaches for linking oscillatory EEG signatures to performance.

A total of 40 right-handed participants with no contraindication to undergo transcranial alternating current stimulation (tACS) took part in this study. Each participant underwent two sessions at least 2 days apart, in which they have received 10 Hz or sham tACS over the left parietal cortex for 20 minutes, while performing a visually cued target discrimination task. The target stimulus was a Gabor patch and participants had to judge whether the gratings were tilted to the left or right. After task completion and tACS cessation, 4 minutes of resting EEG were recorded from three occipital electrodes.