Transcranial photobiomodulation changes topology, synchronizability, and complexity of resting state brain networks

Abstract

Objective. Transcranial photobiomodulation (tPBM) is a recently proposed non-invasive brain stimulation approach with various effects on the nervous system from the cells to the whole brain networks. Specially in the neural network level, tPBM can alter the topology and synchronizability of functional brain networks. However, the functional properties of the neural networks after tPBM are still poorly clarified. Approach. Here, we employed electroencephalography and different methods (conventional and spectral) in the graph theory analysis to track the significant effects of tPBM on the resting state brain networks. The non-parametric statistical analysis showed that just one short-term tPBM session over right medial frontal pole can significantly change both topological (i.e. clustering coefficient, global efficiency, local efficiency, eigenvector centrality) and dynamical (i.e. energy, largest eigenvalue, and entropy) features of resting state brain networks. Main results. The topological results revealed that tPBM can reduce local processing, centrality, and laterality. Furthermore, the increased centrality of central electrode was observed. Significance. These results suggested that tPBM can alter topology of resting state brain network to facilitate the neural information processing. On the other hand, the dynamical results showed that tPBM reduced stability of synchronizability and increased complexity in the resting state brain networks. These effects can be considered in association with the increased complexity of connectivity patterns among brain regions and the enhanced information propagation in the resting state brain networks. Overall, both topological and dynamical features of brain networks suggest that although tPBM decreases local processing (especially in the right hemisphere) and disrupts synchronizability of network, but it can increase the level of information transferring and processing in the brain network.

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

“…However, even with room for improvement of accuracy, our reported results and conclusions in this study are in good agreement with a recent fMRI-driven report, showing that increases in brain-wide FC of the human brain were observed with connections involving the stimulated hemisphere having a significantly larger increase than those in the contralateral hemisphere (Dmochowski et al, 2020). Several independent studies also confirmed that tPBM enables to stimulate electrophysiological oscillation powers and enhance functional connectivity based on whole-head electroencephalogram (Berman et al, 2017;Zomorrodi et al, 2019;Ghaderi et al, 2021).…”

“…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).…”

“…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?…”

Combination of Group Singular Value Decomposition and eLORETA Identifies Human EEG Networks and Responses to Transcranial Photobiomodulation

“…However, research on the mechanism of tPBM-evoked electrophysiological effects in the human brain is on its early stage with only a handful of publications ( Berman et al, 2017 ; Vargas et al, 2017 ; Zomorrodi et al, 2019 ; Ghaderi et al, 2021 ; Spera et al, 2021 ), besides ours ( Wang et al, 2017 , 2019 ), in the last 4–5 years. Most of these studies have reported alterations of electroencephalography (EEG) powers by tPBM compared to sham stimulation.…”

The effect of photobiomodulation on the brain during wakefulness and sleep

“…In addition, photobiomodulation has been reported to influence the global, large scale networks of the brain ( Ghaderi et al, 2021 ). These large scale networks involve the coordination and intercommunication of a number of different regions of the cortical areas involved in the processing and integration of information that is necessary to generate a number of higher-order cognitive functions, such as perception, attention, memory and emotion.…”