scholarly journals PHASE DIFFERENCE BETWEEN LOW-FREQUENCY OSCILLATIONS OF CEREBRAL DEOXY- AND OXY-HEMOGLOBIN CONCENTRATIONS DURING A MENTAL TASK

2011 ◽  
Vol 04 (02) ◽  
pp. 151-158 ◽  
Author(s):  
ANGELO SASSAROLI ◽  
FENG ZHENG ◽  
MICHELE PIERRO ◽  
PETER R. BERGETHON ◽  
SERGIO FANTINI
Keyword(s):  
Near Infrared ◽  
Phase Synchronization ◽  
Mental Workload ◽  
Low Frequency ◽  
Phase Lag ◽  
Low Frequency Oscillations ◽  
Potential Applications ◽  
Rest Condition ◽  
The Brain ◽  
Initial Results

Hemodynamic low-frequency (~0.1 Hz) spontaneous oscillations as detected in the brain by near-infrared spectroscopy have potential applications in the study of brain activation, cerebral autoregulation, and functional connectivity. In this work, we have investigated the phase lag between oscillations of cerebral deoxy- and oxy-hemoglobin concentrations in the frequency range 0.05–0.10 Hz in a human subject during a mental workload task. We have obtained a measure of such phase lag using two different methods: (1) phase synchronization analysis as used in the theory of chaotic oscillators and (2) a novel cross-correlation phasor approach. The two methods yielded comparable initial results of a larger phase lag between low-frequency oscillations of deoxy- and oxy-hemoglobin concentrations during mental workload with respect to a control, rest condition.

scholarly journals Anesthesia enhances spontaneous low-frequency oscillations in the brain

Neuroreport ◽  
2020 ◽  
Vol 31 (5) ◽  
pp. 394-398
Author(s):  
Zhuo Zhang ◽  
Fuquan Li ◽  
Ming Li ◽  
Dewen Hu
Keyword(s):  
Low Frequency ◽  
Low Frequency Oscillations ◽  
The Brain

scholarly journals Spontaneous Low-Frequency Oscillations Decline in the Aging Brain

2004 ◽  
Vol 24 (10) ◽  
pp. 1183-1191 ◽  
Author(s):  
Matthias L. Schroeter ◽  
Ole Schmiedel ◽  
D. Yves von Cramon
Keyword(s):  
Near Infrared ◽  
Visual Stimulation ◽  
Vascular System ◽  
Low Frequency ◽  
Aging Brain ◽  
Functional Near Infrared Spectroscopy ◽  
Low Frequency Oscillations ◽  
Total Hemoglobin ◽  
Power Spectral ◽  
Spontaneous Oscillations

It is well known that aging leads to a degeneration of the vascular system. Hence, one may hypothesize that spontaneous oscillations decrease in the cerebral microvasculature with aging. Accordingly, the authors investigated the age dependency of spontaneous oscillations in the visual cortex during rest and functional activation. Functional near-infrared spectroscopy was used because it is particularly sensitive to the microvasculature. Visual stimulation led to an increase of oxyhemoglobin, total hemoglobin, and a decrease of deoxyhemoglobin, without any influence of age. Peaks of normalized power spectral density were detected for spontaneous low-frequency (0.07 to 0.11 Hz) and very-low-frequency (0.01 to 0.05 Hz) oscillations, with a higher amplitude for oxyhemoglobin than for deoxyhemoglobin. Spontaneous low-frequency oscillations of oxyhemoglobin and deoxyhemoglobin declined strongly with aging during both rest and visual stimulation. Reduction of spontaneous low-frequency oscillations might indicate a declining spontaneous activity in microvascular smooth muscle cells, in conjunction with an increased vessel stiffness with aging.

scholarly journals The resting-state fMRI arterial signal predicts differential blood transit time through the brain

2018 ◽  
Vol 39 (6) ◽  
pp. 1148-1160 ◽  
Author(s):  
Yunjie Tong ◽  
Jinxia (Fiona) Yao ◽  
J Jean Chen ◽  
Blaise deB Frederick
Keyword(s):  
Transit Time ◽  
Resting State ◽  
Time Delays ◽  
Carotid Arteries ◽  
Near Infrared ◽  
Low Frequency ◽  
Hemoglobin Concentration ◽  
Resting State Fmri ◽  
Single Subject ◽  
The Brain

Previous studies have found that aperiodic, systemic low-frequency oscillations (sLFOs) are present in blood-oxygen-level-dependent (BOLD) data. These signals are in the same low frequency band as the “resting state” signal; however, they are distinct signals which represent non-neuronal, physiological oscillations. The same sLFOs are found in the periphery (i.e. finger tips) as changes in oxy/deoxy-hemoglobin concentration using concurrent near-infrared spectroscopy. Together, this evidence points toward an extra-cerebral origin of these sLFOs. If this is the case, it is expected that these sLFO signals would be found in the carotid arteries with time delays that precede the signals found in the brain. To test this hypothesis, we employed the publicly available MyConnectome dataset (a two-year longitudinal study of a single subject) to extract the sLFOs in the internal carotid arteries (ICAs) with the help of the T1/T2-weighted images. Significant, but negative, correlations were found between the LFO BOLD signals from the ICAs and (1) the global signal (GS), (2) the superior sagittal sinus, and (3) the jugulars. We found the consistent time delays between the sLFO signals from ICAs, GS and veins which coincide with the blood transit time through the cerebral vascular tree.

scholarly journals Motor Training Using Mental Workload (MWL) With an Assistive Soft Exoskeleton System: A Functional Near-Infrared Spectroscopy (fNIRS) Study for Brain–Machine Interface (BMI)

2021 ◽  
Vol 15 ◽  
Author(s):  
Umer Asgher ◽  
Muhammad Jawad Khan ◽  
Muhammad Hamza Asif Nizami ◽  
Khurram Khalil ◽  
Riaz Ahmad ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Mental Workload ◽  
Assistive Technologies ◽  
Brain Machine Interface ◽  
Functional Near Infrared Spectroscopy ◽  
Robotic Exoskeleton ◽  
Machine Interface ◽  
The Brain

Mental workload is a neuroergonomic human factor, which is widely used in planning a system's safety and areas like brain–machine interface (BMI), neurofeedback, and assistive technologies. Robotic prosthetics methodologies are employed for assisting hemiplegic patients in performing routine activities. Assistive technologies' design and operation are required to have an easy interface with the brain with fewer protocols, in an attempt to optimize mobility and autonomy. The possible answer to these design questions may lie in neuroergonomics coupled with BMI systems. In this study, two human factors are addressed: designing a lightweight wearable robotic exoskeleton hand that is used to assist the potential stroke patients with an integrated portable brain interface using mental workload (MWL) signals acquired with portable functional near-infrared spectroscopy (fNIRS) system. The system may generate command signals for operating a wearable robotic exoskeleton hand using two-state MWL signals. The fNIRS system is used to record optical signals in the form of change in concentration of oxy and deoxygenated hemoglobin (HbO and HbR) from the pre-frontal cortex (PFC) region of the brain. Fifteen participants participated in this study and were given hand-grasping tasks. Two-state MWL signals acquired from the PFC region of the participant's brain are segregated using machine learning classifier—support vector machines (SVM) to utilize in operating a robotic exoskeleton hand. The maximum classification accuracy is 91.31%, using a combination of mean-slope features with an average information transfer rate (ITR) of 1.43. These results show the feasibility of a two-state MWL (fNIRS-based) robotic exoskeleton hand (BMI system) for hemiplegic patients assisting in the physical grasping tasks.

scholarly journals The Validation of a Portable Functional NIRS System for Assessing Mental Workload

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3810
Author(s):  
Manob Jyoti Saikia ◽  
Walter G. Besio ◽  
Kunal Mankodiya
Keyword(s):  
Cognitive Load ◽  
Near Infrared ◽  
Mental Workload ◽  
Brain Area ◽  
Experimental Studies ◽  
Functional Near Infrared Spectroscopy ◽  
Naturalistic Environment ◽  
The Right ◽  
User Friendly ◽  
The Brain

Portable functional near-infrared spectroscopy (fNIRS) systems have the potential to image the brain in naturalistic settings. Experimental studies are essential to validate such fNIRS systems. Working memory (WM) is a short-term active memory that is associated with the temporary storage and manipulation of information. The prefrontal cortex (PFC) brain area is involved in the processing of WM. We assessed the PFC brain during n-back WM tasks in a group of 25 college students using our laboratory-developed portable fNIRS system, WearLight. We designed an experimental protocol with 32 n-back WM task blocks with four different pseudo-randomized task difficulty levels. The hemodynamic response of the brain was computed from the experimental data and the evaluated brain responses due to these tasks. We observed the incremental mean hemodynamic activation induced by the increasing WM load. The left-PFC area was more activated in the WM task compared to the right-PFC. The task performance was seen to be related to the hemodynamic responses. The experimental results proved the functioning of the WearLight system in cognitive load imaging. Since the portable fNIRS system was wearable and operated wirelessly, it was possible to measure the cognitive load in the naturalistic environment, which could also lead to the development of a user-friendly brain–computer interface system.

scholarly journals Increase in Low-Frequency Oscillations in fNIRS as Cerebral Response to Auditory Stimulation with Familiar Music

2021 ◽  
Vol 12 (1) ◽  
pp. 42
Author(s):  
Giulio Bicciato ◽  
Emanuela Keller ◽  
Martin Wolf ◽  
Giovanna Brandi ◽  
Sven Schulthess ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Power ◽  
Low Frequency ◽  
Signal Recognition ◽  
Brain Response ◽  
Cognitive Response ◽  
Low Frequency Oscillations ◽  
Environmental Stimulation ◽  
Frequency Domain Approach ◽  
External Stimuli

Recognition of typical patterns of brain response to external stimuli using near-infrared spectroscopy (fNIRS) may become a gateway to detecting covert consciousness in clinically unresponsive patients. This is the first fNIRS study on the cortical hemodynamic response to favorite music using a frequency domain approach. The aim of this study was to identify a possible marker of cognitive response in healthy subjects by investigating variations in the oscillatory signal of fNIRS in the spectral regions of low-frequency (LFO) and very-low-frequency oscillations (VLFO). The experiment consisted of two periods of exposure to preferred music, preceded and followed by a resting phase. Spectral power in the LFO region increased in all the subjects after the first exposure to music and decreased again in the subsequent resting phase. After the second music exposure, the increase in LFO spectral power was less distinct. Changes in LFO spectral power were more proGfirst music exposure and the repetition-related habituation effect strongly suggest a cerebral origin of the fNIRS signal. Recognition of typical patterns of brain response to specific environmental stimulation is a required step for the concrete validation of a fNIRS-based diagnostic tool.

Incoherent oscillations of respiratory sinus arrhythmia during acute mental stress in humans

2012 ◽  
Vol 302 (1) ◽  
pp. H359-H367 ◽  
Author(s):  
Kyuichi Niizeki ◽  
Tadashi Saitoh
Keyword(s):  
Heart Rate ◽  
Respiratory Sinus Arrhythmia ◽  
Mental Stress ◽  
Phase Synchronization ◽  
Mental Arithmetic ◽  
Recovery Period ◽  
Low Frequency ◽  
Phase Lag ◽  
Arithmetic Task ◽  
Sinus Arrhythmia

Respiratory sinus arrhythmia (RSA) has been widely used as a measure of the cardiac vagal control in response to stress. However, RSA seems not to be a generalized indicator because of its dependency on respiratory parameter and individual variations of RSA amplitude (ARSA). We hypothesized that phase-lag variations between RSA and respiration may serve as a normalized index of the degree of mental stress. Twenty healthy volunteers performed mental arithmetic task (ART) after 5 min of resting control followed by 5 min of recovery. Breathing pattern, beat-to-beat R-R intervals, and blood pressure (BP) were determined using inductance plethysmography, electrocardiography, and a Finapres device, respectively. The analytic signals of breathing and RSA were obtained by Hilbert transform and the degree of phase synchronization (λ) was quantified. With the use of spectral analysis, heart rate variability (HRV) was estimated for the low-frequency (LF) and high-frequency (HF) bands. A steady-state 3-min resting period (REST), the first 3 min (ART1), and the last 3 min (ART2) of the ART period (ranged from 6- to 19 min) and the last 3 min of the recovery period (RCV) were analyzed separately. Heart rate, systolic BP, and breathing frequency (fR) increased and λ, ARSA, and HF power decreased from REST to ART ( P < 0.01). The λ was correlated with normalized ARSA and the HF power. The decrease in λ could not be explained solely by the increase in fR. We conclude that mental stress exerts an influence on RSA oscillations, inducing incoherent phase lag with respect to breathing, in addition to a decrease in RSA.

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