Near-Infrared Light Increases Functional Connectivity with a Non-thermal Mechanism

Dmochowski, Grzegorz M.; Shereen, A. Duke; Berisha, Destiny; Dmochowski, Jacek

doi:10.1093/texcom/tgaa004

Cited by 35 publications

(28 citation statements)

References 52 publications

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“…Since the thermo_stim given in this study generated equivalent heating on the subject’s forehead, it does not rule out heating of the brain as a mechanism. However, a recent study by Dmochowski et al employed magnetic resonance thermometry to measure brain temperature during 10-min tPBM ( n = 20) with 808-nm laser and found no significant temperature differences between active and sham stimulation 62 . Another group conducted computer simulations of motor cortex tPBM with 500 mW/cm 2 at three wavelengths (630 nm, 700 nm, and 810 nm) 63 .…”

Section: Discussionmentioning

confidence: 99%

Transcranial photobiomodulation and thermal stimulation induce distinct topographies of EEG alpha and beta power changes in healthy humans

Wang

Wanniarachchi

et al. 2021

Sci Rep

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Our recent study demonstrated that prefrontal transcranial photobiomodulation (tPBM) with 1064-nm laser enables significant changes in EEG rhythms, but these changes might result from the laser-induced heat rather than tPBM. This study hypothesized that tPBM-induced and heat-induced alterations in EEG power topography were significantly distinct. We performed two sets of measurements from two separate groups of healthy humans under tPBM (n = 46) and thermal stimulation (thermo_stim; n = 11) conditions. Each group participated in the study twice under true and respective sham stimulation with concurrent recordings of 64-channel EEG before, during, and after 8-min tPBM at 1064 nm or thermo_stim with temperature of 33–41 °C, respectively. After data preprocessing, EEG power spectral densities (PSD) per channel per subject were quantified and normalized by respective baseline PSD to remove the power-law effect. At the group level for each group, percent changes of EEG powers per channel were statistically compared between (1) tPBM vs light-stimulation sham, (2) thermo_stim vs heat-stimulation sham, and (3) tPBM vs thermo_stim after sham exclusion at five frequency bands using the non-parametric permutation tests. By performing the false discovery rate correction for multi-channel comparisons, we showed by EEG power change topographies that (1) tPBM significantly increased EEG alpha and beta powers, (2) the thermal stimulation created opposite effects on EEG power topographic patterns, and (3) tPBM and thermal stimulations induced significantly different topographies of changes in EEG alpha and beta power. Overall, this study provided evidence to support our hypothesis, showing that the laser-induced heat on the human forehead is not a mechanistic source causing increases in EEG power during and after tPBM.

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Section: Discussionmentioning

confidence: 99%

Transcranial photobiomodulation and thermal stimulation induce distinct topographies of EEG alpha and beta power changes in healthy humans

Wang

Wanniarachchi

et al. 2021

Sci Rep

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“…We showed in our previous studies that tPBM promoted both con-centrations of ∆[oxCCO] and ∆[HbO] linearly in amplitude [34,36], without knowing their coherent or coherence relationship. It is also known that tPBM would release nitric oxide (NO) which stimulates vessel dilation [78]. Accordingly, we speculated two sources contributing to our measured ∆[HbO] by bbNIRS: one was a ∆[oxCCO]-driven component [34] and the other a vessel-dilation-driven component.…”

Section: Tpbm-induced Alteration In Bilateral Functional Connectivity and Unilateral Coherence In Iso Of [Hbo] And [Oxcco]mentioning

confidence: 93%

Metabolic Connectivity and Hemodynamic-Metabolic Coherence of Human Prefrontal Cortex at Rest and Post Photobiomodulation Assessed by Dual-Channel Broadband NIRS

Wang

Shahdadian

et al. 2022

Metabolites

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Billions of neurons in the human brain form neural networks with oscillation rhythms. Infra-slow oscillation (ISO) presents three main physiological sources: endogenic, neurogenic, and myogenic vasomotions. Having an in vivo methodology for the absolute quantification of ISO from the human brain can facilitate the detection of brain abnormalities in cerebral hemodynamic and metabolic activities. In this study, we introduced a novel measurement-plus-analysis framework for the non-invasive quantification of prefrontal ISO by (1) taking dual-channel broadband near infrared spectroscopy (bbNIRS) measurements from 12 healthy humans during a 6-min rest and 4-min post transcranial photobiomodulation (tPBM) and (2) performing wavelet transform coherence (WTC) analysis on the measured time series data. The WTC indexes (IC, between 0 and 1) enabled the assessment of ipsilateral hemodynamic-metabolic coherence and bilateral functional connectivity in each ISO band of the human prefrontal cortex. At rest, bilateral hemodynamic connectivity was consistent across the three ISO bands (IC ≅ 0.66), while bilateral metabolic connectivity was relatively weaker. For post-tPBM/sham comparison, our analyses revealed three key findings: 8-min, right-forehead, 1064-nm tPBM (1) enhanced the amplitude of metabolic oscillation bilaterally, (2) promoted the bilateral metabolic connectivity of neurogenic rhythm, and (3) made the main effect on endothelial cells, causing alteration of hemodynamic-metabolic coherence on each side of the prefrontal cortex.

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“…Different imaging modalities have been utilized concurrently with tPBM administration to investigate its effects on the brain, such as electroencephalography (EEG) (Wang et al, 2019;Ghaderi et al, 2021), functional magnetic resonance imaging (fMRI) (Vargas et al, 2017;Dmochowski et al, 2020), broadband near-infrared spectroscopy (bbNIRS) (Tian et al, 2016;Wang et al, 2017b;Pruitt et al, 2020;Saucedo et al, 2021), or functional near-infrared spectroscopy (fNIRS) (Holmes et al, 2019;Urquhart et al, 2020b). Among them, NIRS (both fNIRS and bbNIRS) has been considered as an effective and noninvasive tool for assessing the hemodynamic (Villringer et al, 1993;Boas and Franceschini, 2011;Quaresima et al, 2012;Boas et al, 2014;Scholkmann et al, 2014) and metabolic state of the brain (Villringer et al, 1993;Smith, 2011;Tian et al, 2016;Wang et al, 2017b).…”

Section: Introductionmentioning

confidence: 99%

“…The novel findings of this publication included (1) quantification of ISO powers of [HbO], (2) ISOspecific functional connectivity (FC) across the whole cortex, and (3) global topographical network metrics at three ISO frequency bands. A few existing tPBM-related studies assessed FC computed from EEG (Zomorrodi et al, 2019;Ghaderi et al, 2021), fMRI (Dmochowski et al, 2020;Naeser et al, 2020), or broad-frequency fNIRS (Urquhart et al, 2020b), but not frequency-specific fNIRS. Therefore, the current work would help answer two key questions: Does tPBM modulate FC differently at different ISO frequencies?…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Frequency-Specific Hemodynamic Power and Functional Connectivity by Transcranial Photobiomodulation in Healthy Humans

et al. 2022

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Transcranial photobiomodulation (tPBM) has been considered a safe and effective brain stimulation modality being able to enhance cerebral oxygenation and neurocognitive function. To better understand the underlying neurophysiological effects of tPBM in the human brain, we utilized a 111-channel functional near infrared spectroscopy (fNIRS) system to map cerebral hemodynamic responses over the whole head to 8-min tPBM with 1,064-nm laser given on the forehead of 19 healthy participants. Instead of analyzing broad-frequency hemodynamic signals (0–0.2 Hz), we investigated frequency-specific effects of tPBM on three infra-slow oscillation (ISO) components consisting of endogenic, neurogenic, and myogenic vasomotions. Significant changes induced by tPBM in spectral power of oxygenated hemoglobin concentration (Δ[HbO]), functional connectivity (FC), and global network metrics at each of the three ISO frequency bands were identified and mapped topographically for frequency-specific comparisons. Our novel findings revealed that tPBM significantly increased endogenic Δ[HbO] powers over the right frontopolar area near the stimulation site. Also, we demonstrated that tPBM enabled significant enhancements of endogenic and myogenic FC across cortical regions as well as of several global network metrics. These findings were consistent with recent reports and met the expectation that myogenic oscillation is highly associated with endothelial activity, which is stimulated by tPBM-evoked nitric oxide (NO) release.

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Near-Infrared Light Increases Functional Connectivity with a Non-thermal Mechanism

Cited by 35 publications

References 52 publications

Transcranial photobiomodulation and thermal stimulation induce distinct topographies of EEG alpha and beta power changes in healthy humans

Transcranial photobiomodulation and thermal stimulation induce distinct topographies of EEG alpha and beta power changes in healthy humans

Metabolic Connectivity and Hemodynamic-Metabolic Coherence of Human Prefrontal Cortex at Rest and Post Photobiomodulation Assessed by Dual-Channel Broadband NIRS

Enhancement of Frequency-Specific Hemodynamic Power and Functional Connectivity by Transcranial Photobiomodulation in Healthy Humans

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