Functional near-infrared spectroscopy (fNIRS) of posterolateral cerebellum and prefrontal cortex for fNIRS-driven cerebellar tES

Abstract —Cerebellar transcranial direct current stimulation (ctDCS) has been shown to facilitate standing balance in stroke survivors where a good general linear model fit was found in the latent space between the mean lobular ctDCS electric field strength with the oxy-hemoglobin concentrations (HbO) from functional near-infrared spectroscopy (fNIRS) and log10-transformed electroencephalogram (EEG) bandpower at the prefrontal cortex (PFC) and the sensorimotor cortex in the responders. Recent works have also found that the infra-slow activity (0.01–0.10 Hz) and delta band (0.5–4 Hz) activity propagated in opposite directions between the cerebellum and cerebral cortex. Therefore, in this study, we tested the feasibility of fNIRS of cerebellum and PFC where infra-slow (0.01–0.10 Hz) PFC HbO activity was used to drive (phase amplitude coupling) 4Hz cerebellar transcranial alternating current stimulation (ctACS) at right lobules VI-CrusI/II-VIIb. We found that 2mA ctDCS evoked similar HbO response across cerebellum and PFC brain regions (a=0.01); however, 2mA ctACS evoked HbO across brain regions that was statistically different (a=0.01). Clinical Relevance —We showed the feasibility of fNIRS of cerebellum and PFC, and fNIRS-driven ctACS at 4Hz that may facilitate cognitive function via the frontoparietal network in cerebellar cognitive affective/Schmahmann syndrome.