scholarly journals Spontaneous Neuronal Oscillations in the Human Insula are Hierarchically Organized Traveling Waves

2021 ◽  
Author(s):  
Anup Das ◽  
John Myers ◽  
Raissa Mathura ◽  
Ben Shofty ◽  
Brian A Metzger ◽  
...  
Keyword(s):  
Frequency Band ◽  
Traveling Waves ◽  
Simultaneous Recording ◽  
Hierarchical Organization ◽  
Neuronal Oscillations ◽  
Electrophysiological Properties ◽  
Wide Range ◽  
Recording Channels ◽  
Cortical Regions ◽  
Beta Frequency

The insula plays a fundamental role in a wide range of adaptive human behaviors, but its electrophysiological dynamics are poorly understood. Here we used human intracranial electroencephalographic recordings to investigate the electrophysiological properties and hierarchical organization of spontaneous neuronal oscillations within the insula. We analyzed the neuronal oscillations of the insula directly and found that rhythms in the theta and beta frequency oscillations are widespread and spontaneously present. These oscillations are largely organized along the anterior-posterior axis of the insula. Both the left and right insula showed anterior-to-posterior decreasing gradients for the power of oscillations in the beta frequency band. The left insula also showed a posterior-to-anterior decreasing frequency gradient and an anterior-to-posterior decreasing power gradient in the theta frequency band. In addition to measuring the power of these oscillations, we also examined the phase of these signals across simultaneous recording channels and found that the insula oscillations in the theta and beta bands are traveling waves. The strength of the traveling waves in each frequency was positively correlated with the amplitude of each oscillation. However, the theta and beta traveling waves were uncoupled to each other in terms of phase and amplitude, which suggested that insula traveling waves in the theta and beta bands operate independently. Our findings provide new insights into the spatiotemporal dynamics and hierarchical organization of neuronal oscillations within the insula, which, given its rich connectivity with widespread cortical regions, indicates that oscillations and traveling waves have an important role in intra- and inter-insula communication.

scholarly journals Cortical traveling waves reflect state-dependent hierarchical sequencing of local regions in the human connectome network

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Naoyuki Sato
Keyword(s):  
Traveling Waves ◽  
Large Scale ◽  
Phase Synchronization ◽  
Hierarchical Organization ◽  
Cortical Surface ◽  
Intrinsic Frequency ◽  
Cortical Networks ◽  
State Dependent ◽  
Cortical Regions ◽  
Empirical Networks

AbstractRecent human studies using electrocorticography have demonstrated that alpha and theta band oscillations form traveling waves on the cortical surface. According to neural synchronization theories, the cortical traveling waves may group local cortical regions and sequence them by phase synchronization; however these contributions have not yet been assessed. This study aimed to evaluate the functional contributions of traveling waves using connectome-based network modeling. In the simulation, we observed stable traveling waves on the entire cortical surface wherein the topographical pattern of these phases was substantially correlated with the empirically obtained resting-state networks, and local radial waves also appeared within the size of the empirical networks (< 50 mm). Importantly, individual regions in the entire network were instantaneously sequenced by their internal frequencies, and regions with higher intrinsic frequency were seen in the earlier phases of the traveling waves. Based on the communication-through-coherence theory, this phase configuration produced a hierarchical organization of each region by unidirectional communication between the arbitrarily paired regions. In conclusion, cortical traveling waves reflect the intrinsic frequency-dependent hierarchical sequencing of local regions, global traveling waves sequence the set of large-scale cortical networks, and local traveling waves sequence local regions within individual cortical networks.

scholarly journals Causal Evidence for the Role of Neuronal Oscillations in Top–Down and Bottom–Up Attention

2019 ◽  
Vol 31 (5) ◽  
pp. 768-779 ◽  
Author(s):  
Justin Riddle ◽  
Kai Hwang ◽  
Dillan Cellier ◽  
Sofia Dhanani ◽  
Mark D'Esposito
Keyword(s):  
Visual Field ◽  
Conjunction Search ◽  
Intraparietal Sulcus ◽  
Top Down ◽  
Neuronal Oscillations ◽  
Bottom Up ◽  
Search Condition ◽  
Gamma Frequency ◽  
Task Conditions ◽  
Beta Frequency

Beta and gamma frequency neuronal oscillations have been implicated in top–down and bottom–up attention. In this study, we used rhythmic TMS to modulate ongoing beta and gamma frequency neuronal oscillations in frontal and parietal cortex while human participants performed a visual search task that manipulates bottom–up and top–down attention (single feature and conjunction search). Both task conditions will engage bottom–up attention processes, although the conjunction search condition will require more top–down attention. Gamma frequency TMS to superior precentral sulcus (sPCS) slowed saccadic RTs during both task conditions and induced a response bias to the contralateral visual field. In contrary, beta frequency TMS to sPCS and intraparietal sulcus decreased search accuracy only during the conjunction search condition that engaged more top–down attention. Furthermore, beta frequency TMS increased trial errors specifically when the target was in the ipsilateral visual field for the conjunction search condition. These results indicate that beta frequency TMS to sPCS and intraparietal sulcus disrupted top–down attention, whereas gamma frequency TMS to sPCS disrupted bottom–up, stimulus-driven attention processes. These findings provide causal evidence suggesting that beta and gamma oscillations have distinct functional roles for cognition.

scholarly journals A preliminary survey of the broadband seismic wavefield at Puu Oo, the active vent of Kilauea volcano, Hawaii

1996 ◽  
Vol 39 (2) ◽  
Author(s):  
D. Seidl ◽  
M. Hellweg ◽  
P. Okubo ◽  
H. Rademacher
Keyword(s):  
Frequency Band ◽  
Power Spectra ◽  
Volcanic Tremor ◽  
Digital Data ◽  
Periodic Pattern ◽  
Data Logger ◽  
Remarkable Feature ◽  
Wide Range ◽  
Active Vent ◽  
Seismic Wavefield

The seismic wavefield near an active volcanic vent consists of superimposed signals in a wide range of frequency bands from sources inside and outside the volcano. To characterize the broadband wavefield near Puu Oo, we deployed a profile of three three-component broadband sensors in a 200 m long line about 1.5 km WSW of the active vent. During this period, Puu Oo maintained a constant, but very low level of activity. The digital data logger recorded the wavefield continuously in the frequency band between 0.01 and 40 Hz between June 25 and July 9, 1994. At the same time, local wind conditions along with air temperature and pressure were monitored by a portable digital weather station. On the basis of characteristic elements, such as waveform, spatial coherence between stations, particle motion and power spectra, the wavefield can be divided into three bands. The dominant signals in the frequency band between 0.01 and 0.1 Hz are not coherent among the stations. Their ground velocities correlate with the wind speed. The signals in the 0.1 to 0.5 Hz band are coherent across the profile and most probably represent a superposition of volcanic tremor and microseisms from the Pacific Ocean. Much of the energy above 0.5 Hz can be attributed to activity at the vent. Power spectra from recordings of the transverse components show complex peaks between 0.5 and 3 Hz which vary in amplitude due to site effects and distance. On the other hand, power spectra calculated from the radial components show a clearly periodic pattern of peaks at 1 Hz intervals for some time segments. A further remarkable feature of the power spectra is that they are highly stationary.

scholarly journals Bio-Templating: An Emerging Synthetic Technique for Catalysts. A Review

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1364
Author(s):  
M. Carmen Herrera-Beurnio ◽  
Jesús Hidalgo-Carrillo ◽  
Francisco J. López-Tenllado ◽  
Juan Martin-Gómez ◽  
Rafael C. Estévez ◽  
...  
Keyword(s):  
Active Sites ◽  
Experimental Studies ◽  
Functional Materials ◽  
Inorganic Materials ◽  
Hierarchical Organization ◽  
Materials Synthesis ◽  
Energy Capture ◽  
Wide Range ◽  
Mineralization Processes ◽  
And Storage

In the last few years, researchers have focused their attention on the synthesis of new catalyst structures based on or inspired by nature. Biotemplating involves the transfer of biological structures to inorganic materials through artificial mineralization processes. This approach offers the main advantage of allowing morphological control of the product, as a template with the desired morphology can be pre-determined, as long as it is found in nature. This way, natural evolution through millions of years can provide us with new synthetic pathways to develop some novel functional materials with advantageous properties, such as sophistication, miniaturization, hybridization, hierarchical organization, resistance, and adaptability to the required need. The field of application of these materials is very wide, covering nanomedicine, energy capture and storage, sensors, biocompatible materials, adsorbents, and catalysis. In the latter case, bio-inspired materials can be applied as catalysts requiring different types of active sites (i.e., redox, acidic, basic sites, or a combination of them) to a wide range of processes, including conventional thermal catalysis, photocatalysis, or electrocatalysis, among others. This review aims to cover current experimental studies in the field of biotemplating materials synthesis and their characterization, focusing on their application in heterogeneous catalysis.

scholarly journals Synaptic Signals from Glutamate-Treated Neurons Induce Aberrant Post-Synaptic Signals in Untreated Neuronal Networks

2020 ◽  
Vol 14 (1) ◽  
pp. 59-62
Author(s):  
Mary Guaraldi ◽  
Sangmook Lee ◽  
Thomas B. Shea
Keyword(s):  
Cortical Neurons ◽  
Neuronal Networks ◽  
Synaptic Function ◽  
Glutamate Excitotoxicity ◽  
Synaptic Connectivity ◽  
Extracellular Glutamate ◽  
Glutamate Neurotoxicity ◽  
Wide Range ◽  
Cortical Regions

Background and Objective: Glutamate neurotoxicity is associated with a wide range of disorders and can impair synaptic function. Failure to clear extracellular glutamate fosters additional cycles and spread of regional hyperexcitation. Methods and Results: Using cultured murine cortical neurons, herein it is demonstrated that synaptic signals generated by cultures undergoing glutamate-induced hyperactivity can invoke similar effects in other cultures not exposed to elevated glutamate. Conclusion: Since sequential synaptic connectivity can encompass extensive cortical regions, this study presents a potential additional contributor to the spread of damage resulting from glutamate excitotoxicity and should be considered in attempts to mitigate neurodegeneration.

scholarly journals The Human Intraparietal Sulcus Modulates Task-Evoked Functional Connectivity

2019 ◽  
Vol 30 (3) ◽  
pp. 875-887
Author(s):  
Kai Hwang ◽  
James M Shine ◽  
Dillan Cellier ◽  
Mark D’Esposito
Keyword(s):  
Functional Connectivity ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Intraparietal Sulcus ◽  
Top Down ◽  
Adaptive Communication ◽  
Wide Range ◽  
Functional Connectivity Strength ◽  
Ventral Temporal Cortex ◽  
Cortical Regions

Abstract Past studies have demonstrated that flexible interactions between brain regions support a wide range of goal-directed behaviors. However, the neural mechanisms that underlie adaptive communication between brain regions are not well understood. In this study, we combined theta-burst transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging to investigate the sources of top-down biasing signals that influence task-evoked functional connectivity. Subjects viewed sequences of images of faces and buildings and were required to detect repetitions (2-back vs. 1-back) of the attended stimuli category (faces or buildings). We found that functional connectivity between ventral temporal cortex and the primary visual cortex (VC) increased during processing of task-relevant stimuli, especially during higher memory loads. Furthermore, the strength of functional connectivity was greater for correct trials. Increases in task-evoked functional connectivity strength were correlated with increases in activity in multiple frontal, parietal, and subcortical (caudate and thalamus) regions. Finally, we found that TMS to superior intraparietal sulcus (IPS), but not to primary somatosensory cortex, decreased task-specific modulation in connectivity patterns between the primary VC and the parahippocampal place area. These findings demonstrate that the human IPS is a source of top-down biasing signals that modulate task-evoked functional connectivity among task-relevant cortical regions.

scholarly journals Transcranial random noise stimulation (tRNS): a wide range of frequencies is needed for increasing cortical excitability

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Beatrice Moret ◽  
Rita Donato ◽  
Massimo Nucci ◽  
Giorgia Cona ◽  
Gianluca Campana
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Random Noise ◽  
High Frequency Band ◽  
Neural Excitability ◽  
Transcranial Random Noise Stimulation ◽  
Wide Range

Abstract Transcranial random noise stimulation (tRNS) is a recent neuromodulation protocol. The high-frequency band (hf-tRNS) has shown to be the most effective in enhancing neural excitability. The frequency band of hf-tRNS typically spans from 100 to 640 Hz. Here we asked whether both the lower and the higher half of the high-frequency band are needed for increasing neural excitability. Three frequency ranges (100–400 Hz, 400–700 Hz, 100–700 Hz) and Sham conditions were delivered for 10 minutes at an intensity of 1.5 mA over the primary motor cortex (M1). Single-pulse transcranial magnetic stimulation (TMS) was delivered over the same area at baseline, 0, 10, 20, 30, 45 and 60 minutes after stimulation, while motor evoked potentials (MEPs) were recorded to evaluate changes in cortical excitability. Only the full-band condition (100–700 Hz) was able to modulate excitability by enhancing MEPs at 10 and 20 minutes after stimulation: neither the higher nor the lower sub-range of the high-frequency band significantly modulated cortical excitability. These results show that the efficacy of tRNS is strictly related to the width of the selected frequency range.

Radar Absorbing Materials Based on Metamaterials

2010 ◽  
Vol 75 ◽  
pp. 215-223
Author(s):  
Andrey Nikolayevich Lagarkov ◽  
Vladimir Nikolayevich Kisel ◽  
Vladimir Nikolayevich Semenenko
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Coefficient ◽  
Frequency Band ◽  
Radar Absorbing Material ◽  
Wide Range ◽  
Absorbing Materials ◽  
Different Types ◽  
Absorbing Material ◽  
Wave Incidence

The use of metamaterial for design of radar absorbing material (RAM) is discussed. The typical features of the frequency dependencies of , , ,  of composites manufactured of different types of resonant inclusions are given as an example. The RAM characteristics obtained by the use of the composites are given. It is shown that it is possible to use for RAM design the metamaterials with both the positive values of ,  and negative ones. Making use of the frequency band with negative  and  it is possible to create a RAM with low reflection coefficient in a wide range of the angles of electromagnetic wave incidence.

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