scholarly journals Modifying resting-state EEG microstates with pulsed near-infrared transcranial photobiomodulation: a randomized sham-controlled crossover study

2021 ◽  
Vol 14 (6) ◽  
pp. 1697
Author(s):  
Reza Zomorrodi ◽  
Neda Rashidi-Ranjbar ◽  
Genane Loheswaran ◽  
Lew Lim
Keyword(s):  
Crossover Study ◽  
Resting State ◽  
Near Infrared

scholarly journals Amplitude of fNIRS Resting-State Global Signal Is Related to EEG Vigilance Measures: A Simultaneous fNIRS and EEG Study

2020 ◽  
Vol 14 ◽  
Author(s):  
Yuxuan Chen ◽  
Julia Tang ◽  
Yafen Chen ◽  
Jesse Farrand ◽  
Melissa A. Craft ◽  
...  
Keyword(s):  
Human Brain ◽  
Resting State ◽  
Near Infrared ◽  
Low Frequency ◽  
Temporal Correlation ◽  
Frequency Range ◽  
Functional Near Infrared Spectroscopy ◽  
Physical Constraints ◽  
Global Signal ◽  
Eeg Data

Recently, functional near-infrared spectroscopy (fNIRS) has been utilized to image the hemodynamic activities and connectivity in the human brain. With the advantage of economic efficiency, portability, and fewer physical constraints, fNIRS enables studying of the human brain at versatile environment and various body positions, including at bed side and during exercise, which complements the use of functional magnetic resonance imaging (fMRI). However, like fMRI, fNIRS imaging can be influenced by the presence of a strong global component. Yet, the nature of the global signal in fNIRS has not been established. In this study, we investigated the relationship between fNIRS global signal and electroencephalogram (EEG) vigilance using simultaneous recordings in resting healthy subjects in high-density and whole-head montage. In Experiment 1, data were acquired at supine, sitting, and standing positions. Results found that the factor of body positions significantly affected the amplitude of the resting-state fNIRS global signal, prominently in the frequency range of 0.05–0.1 Hz but not in the very low frequency range of less than 0.05 Hz. As a control, the task-induced fNIRS or EEG responses to auditory stimuli did not differ across body positions. However, EEG vigilance plays a modulatory role in the fNIRS signals in the frequency range of less than 0.05 Hz: resting-state sessions of low EEG vigilance measures are associated with high amplitudes of fNIRS global signals. Moreover, in Experiment 2, we further examined the epoch-to-epoch fluctuations in concurrent fNIRS and EEG data acquired from a separate group of subjects and found a negative temporal correlation between EEG vigilance measures and fNIRS global signal amplitudes. Our study for the first time revealed that vigilance as a neurophysiological factor modulates the resting-state dynamics of fNIRS, which have important implications for understanding and processing the noises in fNIRS signals.

Can Hyperoxic Preconditioning in Normobaric Hypoxia (3500 m) Improve All-Out Exercise Performance in Highly Skilled Skiers? A Randomized Crossover Study

2020 ◽  
Vol 15 (3) ◽  
pp. 346-353
Author(s):  
David Morawetz ◽  
Tobias Dünnwald ◽  
Martin Faulhaber ◽  
Hannes Gatterer ◽  
Lukas Höllrigl ◽  
...  
Keyword(s):  
Crossover Study ◽  
Exercise Performance ◽  
Near Infrared ◽  
Acute Hypoxia ◽  
Normobaric Hypoxia ◽  
Pure Oxygen ◽  
Adaptation To Hypoxia ◽  
Short Period ◽  
Highly Skilled ◽  
Randomized Crossover Study

Background: The altering effects of hypoxia on aerobic/anaerobic performance are well documented and form the basis of this study. Application of hyperoxic gases (inspiratory fraction of oxygen [FiO2] > 0.2095) prior to competition or training (hyperoxic preconditioning) can compensate for the negative influence of acute hypoxia. Purpose: To investigate whether oxygen supplementation immediately prior to exercise (FiO2 = 1.0) improves all-out exercise performance in normobaric hypoxia (3500 m) in highly skilled skiers. Methods: In this single-blind, randomized, crossover study, 17 subjects performed a 60-second constant-load, all-out test in a normobaric hypoxic chamber. After a short period of adaptation to hypoxia (60 min), they received either pure oxygen or chamber air for 5 minutes prior to the all-out test (hyperoxic preconditioning vs nonhyperoxic preconditioning). Capillary blood was collected 3 times, and muscle oxygenation was assessed with near-infrared spectroscopy. Results: Absolute and relative peak power (P = .073 vs P = .103) as well as mean power (P = .330 vs P = .569) did not significantly differ after the hyperoxic preconditioning phase. PaO2 increased from 51.3 (3) to 451.9 (89.0) mm Hg, and SaO2 increased from 88.2% (1.7%) to 100% (0.2%) and dropped to 83.8% (4.2%) after the all-out test. Deoxygenation (P = .700) and reoxygenation rates (P = .185) did not significantly differ for both preconditioned settings. Conclusions: Therefore, the authors conclude that hyperoxic preconditioning did not enhance 60-second all-out exercise performance in acute hypoxia (3500 m).

scholarly journals Median Nerve Electrical Stimulation–Induced Changes in Effective Connectivity in Patients With Stroke as Assessed With Functional Near-Infrared Spectroscopy

2019 ◽  
Vol 33 (12) ◽  
pp. 1008-1017 ◽  
Author(s):  
Congcong Huo ◽  
Xinglou Li ◽  
Jing Jing ◽  
Yanping Ma ◽  
Wenhao Li ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Infrared Spectroscopy ◽  
Median Nerve ◽  
Near Infrared Spectroscopy ◽  
Resting State ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Effective Connectivity ◽  
Stroke Patients ◽  
Functional Near Infrared Spectroscopy

Background. The cortical plastic changes in response to median nerve electrical stimulation (MNES) in stroke patients have not been entirely illustrated. Objective. This study aimed to investigate MNES-related changes in effective connectivity (EC) within a cortical network after stroke by using functional near-infrared spectroscopy (fNIRS). Methods. The cerebral oxygenation signals in the bilateral prefrontal cortex (LPFC/RPFC), motor cortex (LMC/RMC), and occipital lobe (LOL/ROL) of 20 stroke patients with right hemiplegia were measured by fNIRS in 2 conditions: (1) resting state and (2) MNES applied to the right wrist. Coupling function together with dynamical Bayesian inference was used to assess MNES-related changes in EC among the cerebral low-frequency fluctuations. Results. Compared with the resting state, EC from LPFC and RPFC to LOL was significantly increased during the MNES state in stroke patients. Additionally, MNES triggered significantly higher coupling strengths from LMC and LOL to RPFC. The interregional main coupling direction was observed from LPFC to bilateral motor and occipital areas in responding to MNES, suggesting that MNES could promote the regulation function of ipsilesional prefrontal areas in the functional network. MNES can induce muscle twitch of the stroke-affected hand involving a decreased neural coupling of the contralesional motor area on the ipsilesional MC. Conclusions. MNES can trigger sensorimotor stimulations of the affected hand that sequentially involved functional reorganization of distant cortical areas after stroke. Investigating MNES-related changes in EC after stroke may help further our understanding of the neural mechanisms underlying MNES.

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