scholarly journals Cortical Network Response to Acupuncture and the Effect of the Hegu Point: An fNIRS Study

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 394 ◽  
Author(s):  
Raul Fernandez Rojas ◽  
Mingyu Liao ◽  
Julio Romero ◽  
Xu Huang ◽  
Keng-Liang Ou
Keyword(s):  
Functional Connectivity ◽  
Analgesic Effect ◽  
Mixed Model ◽  
Low Frequency ◽  
Hemodynamic Response ◽  
The Body ◽  
Cortical Networks ◽  
Functional Near Infrared Spectroscopy ◽  
Frequency Bands ◽  
Low Frequency Oscillations

Acupuncture is a practice of treatment based on influencing specific points on the body by inserting needles. According to traditional Chinese medicine, the aim of acupuncture treatment for pain management is to use specific acupoints to relieve excess, activate qi (or vital energy), and improve blood circulation. In this context, the Hegu point is one of the most widely-used acupoints for this purpose, and it has been linked to having an analgesic effect. However, there exists considerable debate as to its scientific validity. In this pilot study, we aim to identify the functional connectivity related to the three main types of acupuncture manipulations and also identify an analgesic effect based on the hemodynamic response as measured by functional near-infrared spectroscopy (fNIRS). The cortical response of eleven healthy subjects was obtained using fNIRS during an acupuncture procedure. A multiscale analysis based on wavelet transform coherence was employed to assess the functional connectivity of corresponding channel pairs within the left and right somatosensory region. The wavelet analysis was focused on the very-low frequency oscillations (VLFO, 0.01–0.08 Hz) and the low frequency oscillations (LFO, 0.08–0.15 Hz). A mixed model analysis of variance was used to appraise statistical differences in the wavelet domain for the different acupuncture stimuli. The hemodynamic response after the acupuncture manipulations exhibited strong activations and distinctive cortical networks in each stimulus. The results of the statistical analysis showed significant differences ( p < 0.05 ) between the tasks in both frequency bands. These results suggest the existence of different stimuli-specific cortical networks in both frequency bands and the anaesthetic effect of the Hegu point as measured by fNIRS.

scholarly journals Low Frequency Oscillations drive EEG's complexity changes during wakefulness and sleep

2021 ◽  
Author(s):  
Joaquin Gonzalez ◽  
Diego M. Mateos ◽  
Matias Cavelli ◽  
Alejandra Mondino ◽  
Claudia Pascovich ◽  
...  
Keyword(s):  
Slow Wave Sleep ◽  
Low Frequency ◽  
Neuronal Population ◽  
Complexity Measures ◽  
Low Frequencies ◽  
New Approach ◽  
Frequency Bands ◽  
Cortical Oscillations ◽  
Brain Signals ◽  
Low Frequency Oscillations

Recently, the sleep-wake states have been analysed using novel complexity measures, complementing the classical analysis of EEGs by frequency bands. This new approach consistently shows a decrease in EEG's complexity during slow-wave sleep, yet it is unclear how cortical oscillations shape these complexity variations. In this work, we analyse how the frequency content of brain signals affects the complexity estimates in freely moving rats. We find that the low-frequency spectrum - including the Delta, Theta, and Sigma frequency bands - drives the complexity changes during the sleep-wake states. This happens because low-frequency oscillations emerge from neuronal population patterns, as we show by recovering the complexity variations during the sleep-wake cycle from micro, meso, and macroscopic recordings. Moreover, we find that the lower frequencies reveal synchronisation patterns across the neocortex, such as a sensory-motor decoupling that happens during REM sleep. Overall, our works shows that EEG's low frequencies are critical in shaping the sleep-wake states' complexity across cortical scales.

scholarly journals Resting-state brain function in schizophrenia and psychotic bipolar probands and their first-degree relatives

2014 ◽  
Vol 45 (1) ◽  
pp. 97-108 ◽  
Author(s):  
S. Lui ◽  
L. Yao ◽  
Y. Xiao ◽  
S. K. Keedy ◽  
J. L. Reilly ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Low Frequency ◽  
Network Connectivity ◽  
Orbital Frontal Cortex ◽  
Cortical Networks ◽  
First Degree Relatives ◽  
Family Associations ◽  
Brain Functional Connectivity ◽  
Psychotic Bipolar Disorder

BackgroundSchizophrenia (SCZ) and psychotic bipolar disorder (PBD) share considerable overlap in clinical features, genetic risk factors and co-occurrence among relatives. The common and unique functional cerebral deficits in these disorders, and in unaffected relatives, remain to be identified.MethodA total of 59 healthy controls, 37 SCZ and 57 PBD probands and their unaffected first-degree relatives (38 and 28, respectively) were studied using resting-state functional magnetic resonance imaging (rfMRI). Regional cerebral function was evaluated by measuring the amplitude of low-frequency fluctuations (ALFF). Areas with ALFF alterations were used as seeds in whole-brain functional connectivity analysis. We then tested whether abnormalities identified in probands were present in unaffected relatives.ResultsSCZ and PBD probands both demonstrated regional hypoactivity in the orbital frontal cortex and cingulate gyrus, as well as abnormal connectivity within striatal-thalamo-cortical networks. SCZ probands showed greater and more widely distributed ALFF alterations including the thalamus and bilateral parahippocampal gyri. Increased parahippocampal ALFF was related to positive symptoms and cognitive deficit. PBD patients showed uniquely increased functional connectivity between the thalamus and bilateral insula. Only PBD relatives showed abnormal connectivity within striatal-thalamo-cortical networks seen in both proband groups.ConclusionsThe present findings reveal a common pattern of deficits in frontostriatal circuitry across SCZ and PBD, and unique regional and functional connectivity abnormalities that distinguish them. The abnormal network connectivity in PBD relatives that was present in both proband groups may reflect genetic susceptibility associated with risk for psychosis, but within-family associations of this measure were not high.

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 timing of hemodynamic changes reliably reflects spiking activity

2018 ◽  
Author(s):  
Ali Danish Zaidi ◽  
Niels Birbaumer ◽  
Eberhard Fetz ◽  
Nikos Logothetis ◽  
Ranganatha Sitaram
Keyword(s):  
Functional Neuroimaging ◽  
Field Potential ◽  
Low Frequency ◽  
Hemodynamic Response ◽  
Blood Oxygenation ◽  
Peak Time ◽  
Hemodynamic Changes ◽  
Functional Near Infrared Spectroscopy ◽  
Initial Dip ◽  
Spiking Activity

AbstractFunctional neuroimaging is a powerful non-invasive tool for studying brain function, using changes in blood-oxygenation as a proxy for underlying neuronal activity. The neuroimaging signal correlates with both spiking, and various bands of the local field potential (LFP), making the inability to discriminate between them a serious limitation for interpreting hemodynamic changes. Here, we record activity from the striate cortex in two anesthetized monkeys (Macaca mulatta), using simultaneous functional near-infrared spectroscopy (fNIRS) and intra-cortical electrophysiology. We find that low-frequency LFPs correlate with hemodynamic signal’s peak amplitude, whereas spiking correlates with its peak-time and initial-dip. We also find spiking to be more spatially localized than low-frequency LFPs. Our results suggest that differences in spread of spiking and low-frequency LFPs across cortical surface influence different parameters of the hemodynamic response. Together, these results demonstrate that the hemodynamic response-amplitude is a poor correlate of spiking activity. Instead, we demonstrate that the timing of the initial-dip and the hemodynamic response are much more reliable correlates of spiking, reflecting bursts in spike-rate and total spike-counts respectively.

scholarly journals Narrowband Resting-State fNIRS Functional Connectivity in Autism Spectrum Disorder

2021 ◽  
Vol 15 ◽  
Author(s):  
Weiting Sun ◽  
Xiaoyin Wu ◽  
Tingzhen Zhang ◽  
Fang Lin ◽  
Huiwen Sun ◽  
...  
Keyword(s):  
Autism Spectrum Disorder ◽  
Functional Connectivity ◽  
Resting State ◽  
Near Infrared ◽  
Low Frequency ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Resting State Functional Connectivity ◽  
Characteristic Analysis ◽  
Functional Near Infrared Spectroscopy

Hemispheric asymmetry in the power spectrum of low-frequency spontaneous hemodynamic fluctuations has been previously observed in autism spectrum disorder (ASD). This observation may imply a specific narrow-frequency band in which individuals with ASD could show more significant alteration in resting-state functional connectivity (RSFC). To test this assumption, we evaluated narrowband RSFC at several frequencies for functional near-infrared spectroscopy signals recorded from the bilateral temporal lobes on 25 children with ASD and 22 typically developing (TD) children. In several narrow-frequency bands, we observed altered interhemispheric RSFC in ASD. However, in the band of 0.01–0.02 Hz, more mirrored channel pairs (or cortical sites) showed significantly weaker RSFC in the ASD group. Receiver operating characteristic analysis further demonstrated that RSFC in the narrowband of 0.01–0.02 Hz might have better differentiation ability between the ASD and TD groups. This may indicate that the narrowband RSFC could serve as a characteristic for the prediction of ASD.

scholarly journals Bispectrum-based Cross-frequency Functional Connectivity: A Study of Alzheimer's Disease

2021 ◽  
Author(s):  
Dominik Klepl ◽  
Fei He ◽  
Min Wu ◽  
Daniel J Blackburn ◽  
Ptolemaios G Sarrigiannis
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
High Frequency ◽  
Neurodegenerative Disorder ◽  
Low Frequency ◽  
Brain Regions ◽  
Frequency Bands ◽  
Frequency Coupling ◽  
Eeg Recordings

Alzheimer's disease (AD) is a neurodegenerative disorder known to affect functional connectivity (FC) across many brain regions. Linear FC measures have been applied to study the differences in AD by splitting neurophysiological signals such as electroencephalography (EEG) recordings into discrete frequency bands and analysing them in isolation from each other. We address this limitation by quantifying cross-frequency FC in addition to the traditional within-band approach. Cross-bispectrum, a higher-order spectral analysis approach, is used to measure the nonlinear FC and is compared with the cross-spectrum, which only measures the linear FC within bands. This work reports the first use of cross-bispectrum to reconstruct a cross-frequency FC network where each frequency band is treated as a layer in a multilayer network with both inter- and intra-layer edges. An increase of within-band FC in AD is observed in low-frequency bands using both methods. Bispectrum also detects multiple cross-frequency differences, mainly increased FC in AD in delta-theta coupling. An increased importance of low-frequency coupling and decreased importance of high-frequency coupling is observed in AD. Integration properties of AD networks are more vulnerable than HC, while the segregation property is maintained in AD. Moreover, the segregation property of γ is less vulnerable in AD, suggesting the shift of importance from high-frequency activity towards low-frequency components. The results highlight the importance of studying nonlinearity and including cross-frequency FC in characterising AD. Moreover, the results demonstrate the advantages and limitations of using bispectrum to reconstruct FC networks.

Vascular resistance and arterial pressure low-frequency oscillations in the anesthetized dog

1995 ◽  
Vol 268 (1) ◽  
pp. H7-H16 ◽  
Author(s):  
A. Cevese ◽  
R. Grasso ◽  
R. Poltronieri ◽  
F. Schena
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Low Frequency ◽  
Peripheral Vascular Resistance ◽  
Common Mechanism ◽  
Peripheral Vascular ◽  
Frequency Range ◽  
Frequency Bands ◽  
Low Frequency Oscillations

The spontaneous variability of heart rate and arterial blood pressure was investigated in chloralose-anesthetized dogs with the left iliac vascular bed mechanically uncoupled from the central circulation. Electrocardiogram, mean arterial pressure (ABP), iliac perfusion and venous pressures, and flow (FLOW) were recorded for 5 min in steady state. Autoregressive spectral and cross-spectral analyses and digital filtering were performed. The variation coefficient (VC%), calculated from the overall variance of each signal, was 5–7%, with the exception of perfusion pressure (VC% = 1%). The frequency-related percentage of total variance was distributed among three frequency bands: two were < 0.20 Hz [lower (F1) and higher (F2; low-frequency range = F1 + F2)], and one was > 0.20 Hz (respiratory, F3). F3 was not always present in RR, which, however, oscillated also in F1 and F2, although with limited amplitude; ABP showed large respiratory and low-frequency oscillations; the FLOW oscillations were in the low-frequency range. Cross-spectral analysis showed high squared coherence in the relevant frequency bands between variables in the three couples: RR-ABP, RR-FLOW, and ABP-FLOW. Changes in RR preceded changes in ABP and in FLOW by > or = 3 s, whereas FLOW was approximately in phase opposition to ABP. It was concluded that, in the chloralose-anesthetized dog, 1) arterial pressure and heart rate oscillate with frequencies corresponding to those described in conscious humans, 2) low-frequency arterial pressure oscillations are due to changes in peripheral vascular resistance, and 3) peripheral vascular resistance does not display respiratory oscillations. Furthermore it was suggested that oscillations of vasomotor tone are generated by a rhythm of central origin and that F1 and F2 oscillations may recognize a common mechanism.

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