Dynamic Influence of Ongoing Brain Stimulation on Resting State fMRI Connectivity: A Concurrent tDCS-fMRI Study.

Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique that serves as treatment tool to neurological disorders. However, the mechanism of how the stimulation modulates ongoing brain activity and connectivity is still not fully understood. Simultaneous acquisition of neuroimaging data together with brain stimulation could allow a noninvasive examination of the brain dynamic changes during the process. In this pilot study, concurrent tDCS and fMRI was conducted in a healthy subject. Dynamic functional connectivity and effective connectivity were used to reveal the information flow. The results demonstrated that tDCS duration has important effects on the brain connectivity and the causal relationships among the brain regions. These results might reflect the fundamental mechanism of brain processing under the external stimulation.