High-definition tDCS to the right temporoparietal junction modulates slow-wave resting state power and coherence in healthy adults

The right temporoparietal junction (rTPJ) is a multisensory integration hub that is increasingly utilised as a target of stimulation studies exploring its rich functional network roles and potential clinical applications. Whilst transcranial direct current stimulation (tDCS) is frequently employed in such studies, there is still relatively little known regarding its local and network neurophysiological effects, particularly at important non-motor sites such as the rTPJ. The current study applied either anodal, cathodal, or sham high-definition tDCS (HD-tDCS) to the rTPJ of 53 healthy participants and used offline electroencephalography (EEG) to assess the impacts of stimulation on resting state (eyes open and eyes closed) band power and coherence. Temporoparietal and central region delta power was increased after anodal stimulation (the latter trend only), whereas cathodal stimulation increased frontal region delta and theta power. Increased coherence between right and left temporoparietal regions was also observed after anodal stimulation. All significant effects occurred in the eyes open condition. These findings are discussed with reference to domain general and mechanistic theories of rTPJ function. Low frequency oscillatory activity may exert long-range inhibitory network influences that enable switching between and integration of endogenous/exogenous processing streams.