Simultaneous functional near-infrared spectroscopy (fNIRS) and electroencephalogram (EEG) to elucidate neurovascular modulation by transcranial electrical stimulation (tES)

I read with great interest the review by Mersedeh Bahr-Hosseini and Marom Bikson [1] focused on elucidating vascular responses to transcranial electrical stimulation (tES). Indeed, a mechanistic understanding of tES effects on cerebral blood flow (CBF) is essential for innovations in its therapeutic interventions. Here, tES, particularly transcranial direct current (tDCS), is a promising therapeutic method that can evoke regional CBF; however, the physiological mechanisms of tDCS-evoked CBF response are unknown.