High-definition transcranial direct current stimulation of the right inferior parietal modulates oscillatory activity in higher-

Attentional reorientation is crucial to navigating the world and relies heavily on the parietal cortex. Several studies have shown that transcranial direct current stimulation (tDCS) has an effect on attentional reorientation; however, these studies mainly focused on the difference between anodal and cathodal stimulation. In this study, we investigated the role of left versus right inferior parietal cortices in attention reorientation by applying high-definition tDCS (HD-tDCS) to these regions in 39 healthy adults (age 19-33 years) for 20 minutes in 3 separate sessions (left active, right active, and sham). Following stimulation, participants completed a modified Posner task during magnetoencephalography (MEG). Significant neural responses at the sensor level across all conditions were then imaged using a beamformer, and the whole-brain, voxel-wise maps were probed for task condition and stimulation montage effects. Our neural findings showed significant stimulation montage by task condition interactions that were multispectral and involved the left frontal eye fields, right inferior parietal cortex, and left anterior prefrontal cortex. We also observed main effects of stimulation montage in the theta and beta ranges, main effects of task condition that were consistent with previous studies of attentional reorienting, and a significant neurobehavioral relationship between theta oscillations in the left frontal eye fields and accuracy. Overall, our findings indicate that HD-tDCS of the inferior parietal cortices modulates several brain regions that are important for attentional reorientation.