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

Abstract

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.

Neuroimaging Guided Transcranial Electrical Stimulation in Enhancing Surgical Skill Acquisition. Comment on Hung et al. The Efficacy of Transcranial Direct Current Stimulation in Enhancing Surgical Skill Acquisition: A Preliminary Meta-Analysis of Randomized Controlled Trials. Brain Sci. 2021, 11, 707

“…Human functional neuroimaging has shown segregated fronto-cerebellar circuits [27], e.g., dorsolateral PFC (DLPFC)-correlated activity was shown to span cerebellar Crus I/II lobules in its lateral and ventral extent while medial PFC (MPFC)-correlated activity spanned cerebellar Crus I lobule. Crus I preferentially correlated with MPFC, while Crus II preferentially correlated with DLPFC that can be targeted with tES in an age-specific manner [28] where posterolateral cerebellum and cerebrum is feasible for fNIRS monitoring [29]. Then, fNIRS-based monitoring of the functional brain connectivity may be crucial to capture neural correlates of learning during surgical training where wavelet coherence between the medial PFC and the supplementary motor area was found lower in experts than untrained subjects in FLS physical simulators [30]-a postulated marker of skill dexterity.…”