Concurrent fNIRS and EEG for Brain Function Investigation: A Systematic, Methodology-Focused Review

Abstract

Electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) stand as state-of-the-art techniques for non-invasive functional neuroimaging. On a unimodal basis, EEG has poor spatial resolution while presenting high temporal resolution. In contrast, fNIRS offers better spatial resolution, though it is constrained by its poor temporal resolution. One important merit shared by the EEG and fNIRS is that both modalities have favorable portability and could be integrated into a compatible experimental setup, providing a compelling ground for the development of a multimodal fNIRS–EEG integration analysis approach. Despite a growing number of studies using concurrent fNIRS-EEG designs reported in recent years, the methodological reference of past studies remains unclear. To fill this knowledge gap, this review critically summarizes the status of analysis methods currently used in concurrent fNIRS–EEG studies, providing an up-to-date overview and guideline for future projects to conduct concurrent fNIRS–EEG studies. A literature search was conducted using PubMed and Web of Science through 31 August 2021. After screening and qualification assessment, 92 studies involving concurrent fNIRS–EEG data recordings and analyses were included in the final methodological review. Specifically, three methodological categories of concurrent fNIRS–EEG data analyses, including EEG-informed fNIRS analyses, fNIRS-informed EEG analyses, and parallel fNIRS–EEG analyses, were identified and explained with detailed description. Finally, we highlighted current challenges and potential directions in concurrent fNIRS–EEG data analyses in future research.

Current opinions on the present and future use of functional near-infrared spectroscopy in psychiatry

“…For instance, concurrent imaging of fNIRS and EEG has provided high spatiotemporal information for investigating brain activity. 20,[98][99][100][101][102] Concurrent fNIRS and eye tracking measurement has been adopted to investigate aberrant neural response and associated eye movements in children with genetic risk factors for ASD (e.g., FXS 75 ). Physiological or auxiliary signals, such as blood pressure, respiration, and head movement, have been proven to greatly improve the filtering of physiological interference and motion artifacts during the fNIRS signal processing.…”

Psychedelics and fNIRS neuroimaging: exploring new opportunities

“…As far as current trends in fNIRS neuroimaging are concerned, there is a development toward using fNIRS in combination with the measurement of systemic signals [an approach termed “systemic physiology augmented functional near-infrared spectroscopy” (SPA-fNIRS); 92 , 120 for a review see Ref. 108 ], or combining fNIRS with other neuroimaging techniques, such as EEG, 121 – 123 fMRI, 121 , 124 or PET. 125 – 128 Ideally, both approaches can then be combined [ Fig.…”

Interdisciplinary views of fNIRS: Current advancements, equity challenges, and an agenda for future needs of a diverse fNIRS research community

“…Both fNIRS and fMRI measure changes in blood flow in the brain, however fNIRS has emerged as a popular approach as it is portable, captures both oxygenated and deoxygenated hemoglobin concentrations (Hoshi and Michael, 2005), has a higher tolerance to motion, and is much less expensive to operate than fMRI (Scarapicchia et al, 2017). As compared to Electroencephalogram (EEG), fNIRS, and EEG are complementary neuroimaging techniques; EEG measures changes in electrical changes in the brain while fNIRS measures changes in blood flow (Li et al, 2022). EEG lacks spatial resolution however presents higher temporal solution, whereas fNIRS has better spatial resolution and is restricted by its lower temporal solution caused by the slower hemodynamic response (Li et al, 2022).…”

“…As compared to Electroencephalogram (EEG), fNIRS, and EEG are complementary neuroimaging techniques; EEG measures changes in electrical changes in the brain while fNIRS measures changes in blood flow (Li et al, 2022). EEG lacks spatial resolution however presents higher temporal solution, whereas fNIRS has better spatial resolution and is restricted by its lower temporal solution caused by the slower hemodynamic response (Li et al, 2022). EEG is substantially lower in cost compared to fNIRS, however many manufacturers encourage and support the concurrent use of both technologies due to their complementary features (see Li et al, 2022 for a full comparison).…”

“…EEG lacks spatial resolution however presents higher temporal solution, whereas fNIRS has better spatial resolution and is restricted by its lower temporal solution caused by the slower hemodynamic response (Li et al, 2022). EEG is substantially lower in cost compared to fNIRS, however many manufacturers encourage and support the concurrent use of both technologies due to their complementary features (see Li et al, 2022 for a full comparison).…”