Systematic review of combined functional near-infrared spectroscopy and transcranial direct-current stimulation studies

Abstract

Significance: Combining transcranial direct-current stimulation (tDCS) with functional nearinfrared spectroscopy (fNIRS) is a recent approach to exploring brain activation evoked by neurostimulation. Aim: To critically evaluate studies combining tDCS and fNIRS and provide a consolidated overview of cortical hemodynamic responses to neurostimulation. Approach: Key terms were searched in three databases (MEDLINE, EMBASE, and PsycINFO) with cross-referencing and works from Google Scholar also evaluated. All studies reporting on fNIRS-derived hemoglobin changes evoked by tDCS were included. Results: Literature searches revealed 474 articles, of which 28 were included for final review (22 in healthy individuals: 9 involving rest and 13 with tasks; 6 in the clinical setting). At rest, an overall increase in cortical activation was observed in fNIRS responses at the site of stimulation, with evidence suggesting nonstimulated brain regions are also similarly affected. Conversely, during tasks, reduced cortical activation was observed during online stimulation. Offline and poststimulation effects were less consistent, as is the impact on clinical populations and their symptom correlation. Conclusion: This review explores the methodological frameworks for fNIRS-tDCS evaluations and summarizes hemodynamic responses associated with tDCS in all populations. Our findings provide further evidence of the impact of tDCS on neuronal activation within functionally connected networks.

Acupuncture With deqi Modulates the Hemodynamic Response and Functional Connectivity of the Prefrontal-Motor Cortical Network

“…Moreover, compared to fMRI, fNIRS is both portable and less sensitive to motion artifacts. As a useful neuroimaging tool, fNIRS is widely used to investigate the high-level cerebral cortex's hemodynamic activities and the related functional network in various neuromodulation studies, such as TMS (Park et al, 2017;Curtin et al, 2019b), tES (Patel et al, 2020), and acupuncture (Takamoto et al, 2010;Ghafoor et al, 2019;Rojas et al, 2019). Previous acupuncture studies also showed the prospect of applying fNIRS to study acupuncture's neural mechanism (Takamoto et al, 2010;Ghafoor et al, 2019;Rojas et al, 2019).…”

Effects of Transcranial Direct Current Stimulation (tDCS) on Cognitive Performance and Cerebral Oxygen Hemodynamics: A Systematic Review

“…However, the interaction between tDCS induced effects on cognition and cerebral perfusion across aging remains widely unknown. Post-tDCS cerebral perfusion changes have been measured using neuroimaging techniques such as functional magnetic resonance imaging (fMRI) (Antal et al, 2011 ) and functional near-infrared spectroscopy (fNIRS) (Patel et al, 2020 ). Widespread decreases in cerebral perfusion after cathodal and anodal tDCS have been reported using arterial spin labeling (Stagg et al, 2013 ).…”

“…Furthermore, regional decreases in blood-oxygen-level-dependent signals have been reported beyond, but not within, the region of stimulation (Antal et al, 2011 ). Regarding fNIRS, significant interindividual and methodological variability on reported tDCS effects exists in tDCS-fNIRS study designs (Patel et al, 2020 ). However, increases in cortical activation are reported during resting state; interestingly, a decreased level of cortical activation has also been reported during online tasks (Patel et al, 2020 ).…”

“…Previous studies have successfully utilized fMRI with tDCS during cognitive tasks, though only a handful have implemented fNIRS with tDCS [see Patel et al ( 2020 ) for a review]. As methodological and perfusional considerations differ between fNIRS protocols and other types of neuroimaging, this study will solely review tDCS-fNIRS protocols targeting cognition.…”

Functional Near‐Infrared Spectroscopy to Assess Central Pain Responses in a Nonpharmacologic Treatment Trial of Osteoarthritis

“…In the last decade, fNIRS has been used to investigate pain perception and its therapeutic interventions, as well as to measure the effect of tDCS on cortical activation. [21][22][23][24] Recently, we explored the longitudinal effect of tDCS on the hemodynamic response to thermal pain in knee OA patients using fNIRS 25 and found that cortical activity increased over time. However, to our knowledge, no study has yet investigated the neuromodulatory effect of a combination of tDCS and MBM on the same population.…”