scholarly journals A phase-shifting anterior-posterior network organizes global phase relations

2021 ◽  
Author(s):  
Melisa Menceloglu ◽  
Marcia Grabowecky ◽  
Satoru Suzuki
Keyword(s):  
Phase Locking ◽  
Temporal Distribution ◽  
Detection Algorithm ◽  
Phase Relations ◽  
Oscillatory Activity ◽  
Long Distance ◽  
Eyes Closed ◽  
General Rules ◽  
Anterior Posterior ◽  
Behavioral Conditions

Prior research has identified a variety of task-dependent networks that form through inter-regional phase-locking of oscillatory activity as neural correlates of specific behaviors. Despite ample knowledge of task-specific functional networks, general rules governing global phase relations have not been investigated. In order to discover such general rules, we focused on phase modularity, measured as the degree to which global phase relations in EEG comprised distinct synchronized clusters interacting with one another at large phase lags. Synchronized clusters were detected with a standard community-detection algorithm, and the level of phase modularity was quantified by the index q. Our findings suggest that phase modularity is functionally consequential since (1) temporal distribution of q was invariant across a broad range of frequencies (3-50 Hz examined) and behavioral conditions (resting with the eyes closed or watching a silent nature video), and (2) neural interactions (measured as power correlations) in beta-to-gamma bands consistently increased in high-modularity states. Notably, we found that the mechanism controlling phase modularity is remarkably simple. A network comprising anterior-posterior long-distance connectivity coherently shifted phase relations from low-angles (|Δθ| < π/4) in low-modularity states (bottom 5% in q) to high-angles (|Δθ| > 3π/4) in high-modularity states (top 5% in q), accounting for fluctuations in phase modularity. This anterior-posterior network likely plays a fundamental functional role as it controls phase modularity across a broad range of frequencies and behavioral conditions. These results may motivate future investigations into the functional roles of phase modularity as well as the anterior-posterior network that controls it.

scholarly journals Altering Visual Feedback Conditions Impacts Postural Sway Performance in Children After Controlling for Body Mass Index and Habitual Physical Activity

2017 ◽  
Vol 5 (2) ◽  
pp. 267-279 ◽  
Author(s):  
Michael Duncan ◽  
Elizabeth Bryant ◽  
Mike Price ◽  
Samuel Oxford ◽  
Emma Eyre ◽  
...  
Keyword(s):  
Physical Activity ◽  
Body Mass Index ◽  
Body Mass ◽  
Visual Feedback ◽  
Postural Sway ◽  
Habitual Physical Activity ◽  
Eyes Closed ◽  
Computerized Posturography ◽  
Eyes Open ◽  
Anterior Posterior

This study examined postural sway in children in eyes open (EO) and eyes closed (EC) conditions, controlling for body mass index (BMI) and physical activity (PA). Sixty two children (aged 8–11years) underwent sway assessment using computerized posturography from which 95% ellipse sway area, anterior/posterior (AP) sway, medial/lateral (ML) sway displacement and sway velocity were assessed. Six trials were performed alternatively in EO and EC. BMI (kg/m2) was determined from height and mass. PA was determined using sealed pedometry. AP amplitude (p = .038), ML amplitude (p = .001), 95% ellipse (p = .0001), and sway velocity (p = .012) were higher in EC compared with EO conditions. BMI and PA were not significant as covariates. None of the sway variables were significantly related to PA. However, sway velocity during EO (p = .0001) and EC (p = .0001) was significantly related to BMI. These results indicate that sway is poorer when vision is removed, that BMI influences sway velocity, but that pedometer-assessed PA was not associated with postural sway.

scholarly journals Syllables in Sync Form a Link: Neural Phase-locking Reflects Word Knowledge during Language Learning

2020 ◽  
Vol 32 (9) ◽  
pp. 1735-1748 ◽  
Author(s):  
Laura Batterink
Keyword(s):  
Language Learning ◽  
Phase Locking ◽  
Building Blocks ◽  
Oscillatory Activity ◽  
Word Knowledge ◽  
Subjective Perception ◽  
Rate Oscillations ◽  
Word Rate ◽  
Linguistic Units ◽  
Small Building

Language is composed of small building blocks, which combine to form larger meaningful structures. To understand language, we must process, track, and concatenate these building blocks into larger linguistic units as speech unfolds over time. An influential idea is that phase-locking of neural oscillations across different levels of linguistic structure provides a mechanism for this process. Building on this framework, the goal of the current study was to determine whether neural phase-locking occurs more robustly to novel linguistic items that are successfully learned and encoded into memory, compared to items that are not learned. Participants listened to a continuous speech stream composed of repeating nonsense words while their EEG was recorded and then performed a recognition test on the component words. Neural phase-locking to individual words during the learning period strongly predicted the strength of subsequent word knowledge, suggesting that neural phase-locking indexes the subjective perception of specific linguistic items during real-time language learning. These findings support neural oscillatory models of language, demonstrating that words that are successfully perceived as functional units are tracked by oscillatory activity at the matching word rate. In contrast, words that are not learned are processed merely as a sequence of unrelated syllables and thus not tracked by corresponding word-rate oscillations.

scholarly journals Characterization of Polar Stratospheric Clouds with spaceborne lidar: CALIPSO and the 2006 Antarctic season

2007 ◽  
Vol 7 (19) ◽  
pp. 5207-5228 ◽  
Author(s):  
M. C. Pitts ◽  
L. W. Thomason ◽  
L. R. Poole ◽  
D. M. Winker
Keyword(s):  
Time Series ◽  
Winter Season ◽  
Temporal Distribution ◽  
Detection Algorithm ◽  
Polar Stratospheric Clouds ◽  
Satellite Mission ◽  
Spatial And Temporal Scales ◽  
Solar Occultation ◽  
Occultation Data ◽  
Stratospheric Clouds

Abstract. The role of polar stratospheric clouds in polar ozone loss has been well documented. The CALIPSO satellite mission offers a new opportunity to characterize PSCs on spatial and temporal scales previously impossible. A PSC detection algorithm based on a single wavelength threshold approach has been developed for CALIPSO. The method appears to accurately detect PSCs of all opacities, including tenuous clouds, with a very low rate of false positives and few missed clouds. We applied the algorithm to CALIOP data acquired during the 2006 Antarctic winter season from 13 June through 31 October. The spatial and temporal distribution of CALIPSO PSC observations is illustrated with weekly maps of PSC occurrence. The evolution of the 2006 PSC season is depicted by time series of daily PSC frequency as a function of altitude. Comparisons with "virtual" solar occultation data indicate that CALIPSO provides a different view of the PSC season than attained with previous solar occultation satellites. Measurement-based time series of PSC areal coverage and vertically-integrated PSC volume are computed from the CALIOP data. The observed area covered with PSCs is significantly smaller than would be inferred from the commonly used temperature-based proxy TNAT but is similar in magnitude to that inferred from TSTS. The potential of CALIOP measurements for investigating PSC composition is illustrated using combinations of lidar backscatter and volume depolarization for two CALIPSO PSC scenes.

Polyline Closure Law Design and Realization in Long-Distance Water-Supply Project

2010 ◽  
Author(s):  
Jian Zhang ◽  
Xiaodong Yu ◽  
Jianfeng An ◽  
Arash Hazrati
Keyword(s):  
Water Supply ◽  
Theoretical Basis ◽  
Temporal Distribution ◽  
Break Point ◽  
Water Hammer ◽  
Long Distance ◽  
Closure Time ◽  
Water Conveyance ◽  
Flow Inertia ◽  
Application Scope

Long-distance water-supply project is an effective way to solve the uneven spatial and temporal distribution of water resources, but the safety of water conveyance system is threatened seriously by water-hammer. Based on the research of the characteristic of water-hammer with pipe friction considered, the formula of indirect water-hammer is deduced and the application scope of the formula is also discussed, which is the theoretical basis for the design of polyline closure law. To the defects that valve closure time is long and response of accident is slow in the long-distance water-supply project, polyline closure law is designed with consideration of valve overflowing property, which greatly reduces the closure time and water-hammer. At the same time, the flow inertia is large in long-distance water-supply project and break point of polyline closure law is hard to fix. In order to improve the reliability of the mechanical operating system, locking device is installed, which make the polyline closure law carry out successfully and provide a new idea for water hammer protection in long-distance water-supply project.

A NEUROBIOLOGICAL THEORY OF MEANING IN PERCEPTION PART III: MULTIPLE CORTICAL AREAS SYNCHRONIZE WITHOUT LOSS OF LOCAL AUTONOMY

2003 ◽  
Vol 13 (10) ◽  
pp. 2845-2856 ◽  
Author(s):  
WALTER J. FREEMAN ◽  
GYöNGYI GAÁL ◽  
REBECKA JORSTEN
Keyword(s):  
Information Transfer ◽  
Phase Locking ◽  
Pulse Frequency ◽  
Inhibitory Neurons ◽  
Oscillatory Activity ◽  
Electrode Arrays ◽  
Ensemble Averaging ◽  
Pulse Frequency Modulation ◽  
Cortical Areas ◽  
Gamma Range

Information transfer and integration among functionally distinct areas of cerebral cortex of oscillatory activity require some degree of phase synchrony of the trains of action potentials that carry the information prior to the integration. However, propagation delays are obligatory. Delays vary with the lengths and conduction velocities of the axons carrying the information, causing phase dispersion. In order to determine how synchrony is achieved despite dispersion, we recorded EEG signals from multiple electrode arrays on five cortical areas in cats and rabbits, that had been trained to discriminate visual or auditory conditioned stimuli. Analysis by time-lagged correlation, multiple correlation and PCA, showed that maximal correlation was at zero lag and averaged 0.7, indicating that 50% of the power in the gamma range among the five areas was at zero lag irrespective of phase or frequency. There were no stimulus-related episodes of transiently increased phase locking among the areas, nor EEG "bursts" of transiently increased amplitude above the sustained level of synchrony. Three operations were identified to account for the sustained correlation. Cortices broadcast their outputs over divergent–convergent axonal pathways that performed spatial ensemble averaging; synaptic interactions between excitatory and inhibitory neurons in cortex operated as band pass filters for gamma; and signal coarse-graining by pulse frequency modulation at trigger zones enhanced correlation. The conclusion is that these three operations enable continuous linkage of multiple cortical areas by activity in the gamma range, providing the basis for coordinated cortical output to other parts of the brain, despite varying axonal conduction delays, something like the back plane of a main frame computer.

scholarly journals Differential contributions of synaptic and intrinsic inhibitory currents to speech segmentation via flexible phase-locking in neural oscillators

2020 ◽  
Author(s):  
Benjamin R. Pittman-Polletta ◽  
Yangyang Wang ◽  
David A. Stanley ◽  
Charles E. Schroeder ◽  
Miles A. Whittington ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Speech Processing ◽  
Cortical Neurons ◽  
Phase Locking ◽  
Outward Current ◽  
Speech Segmentation ◽  
Oscillatory Activity ◽  
Acoustic Features ◽  
Neural Oscillators ◽  
Speech Stream

AbstractCurrent hypotheses suggest that speech segmentation – the initial division and grouping of the speech stream into candidate phrases, syllables, and phonemes for further linguistic processing – is executed by a hierarchy of oscillators in auditory cortex. Theta (~3-12 Hz) rhythms play a key role by phase-locking to recurring acoustic features marking syllable boundaries. Reliable synchronization to quasi-rhythmic inputs, whose variable frequency can dip below cortical theta frequencies (down to ~1 Hz), requires “flexible” theta oscillators whose underlying neuronal mechanisms remain unknown. Using biophysical computational models, we found that the flexibility of phase-locking in neural oscillators depended on the types of hyperpolarizing currents that paced them. Simulated cortical theta oscillators flexibly phase-locked to slow inputs when these inputs caused both (i) spiking and (ii) the subsequent buildup of outward current sufficient to delay further spiking until the next input. The greatest flexibility in phase-locking arose from a synergistic interaction between intrinsic currents that was not replicated by synaptic currents at similar timescales. Our results suggest that synaptic and intrinsic inhibition contribute to frequency-restricted and - flexible phase-locking in neural oscillators, respectively. Their differential deployment may enable neural oscillators to play diverse roles, from reliable internal clocking to adaptive segmentation of quasi-regular sensory inputs like speech.Author summaryOscillatory activity in auditory cortex is believed to play an important role in auditory and speech processing. One suggested function of these rhythms is to divide the speech stream into candidate phonemes, syllables, words, and phrases, to be matched with learned linguistic templates. This requires brain rhythms to flexibly phase-lock to regular acoustic features of the speech stream. How neuronal circuits implement this task remains unknown. In this study, we explored the contribution of inhibitory currents to flexible phase-locking in neuronal theta oscillators, believed to perform initial syllabic segmentation. We found that a combination of specific intrinsic inhibitory currents at multiple timescales, present in a large class of cortical neurons, enabled exceptionally flexible phase-locking, suggesting that the cells exhibiting these currents are a key component in the brain’s auditory and speech processing architecture.

scholarly journals Frequency matters: Up- and Down-Regulation of Dopamine Tone Induces Similar Frequency Shifts in Cortico-Basal Ganglia Beta Oscillations

2020 ◽  
Author(s):  
L. Iskhakova ◽  
P. Rappel ◽  
G. Fonar ◽  
O. Marmor ◽  
R. Paz ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Phase Locking ◽  
Oscillatory Activity ◽  
Dopamine Depletion ◽  
Beta Oscillations ◽  
Similar Frequency ◽  
Strongly Coupled ◽  
Beta Power ◽  
Oscillatory Power ◽  
Network Studies

AbstractBeta oscillatory activity (13-30Hz) is pervasive within the cortico-basal ganglia (CBG) network. Studies in Parkinson’s disease (PD) patients and animal models suggested that beta-power increases with dopamine depletion. However, the exact relationship between oscillatory power, frequency and dopamine-tone remains unclear. We recorded neural activity in the CBG network of non-human-primates (NHP) while acutely up- and down-modulating dopamine levels. Further, we assessed changes in beta oscillations of PD patients following acute and chronic changes in dopamine-tone. Beta oscillation frequency was strongly coupled with dopamine-tone in both NHPs and human patients. In contrast, power, coherence between single-units and LFP, and spike-LFP phase-locking were not systematically regulated by dopamine levels. These results demonstrate via causal manipulations that frequency, rather than other properties, is the key property of pathological oscillations in the CBG networks. These insights can lead to improvements in understanding of CBG physiology, PD progression tracking and patient care.

scholarly journals Use of Stabilometric Platform and Evaluation of Methods for Further Measurments – A Pilot Study

2007 ◽  
Vol 50 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Jitka Jančová ◽  
Vlasta Tošnerová
Keyword(s):  
Pilot Study ◽  
Center Of Pressure ◽  
Quiet Standing ◽  
Parallel Testing ◽  
Eyes Closed ◽  
Eyes Open ◽  
Single Force ◽  
Test Retest Reliability ◽  
Evaluation Of Methods ◽  
Anterior Posterior

Posture in a still stance has been quantified by changes in the center of pressure (COP), in both anterior-posterior (A/P) and medial-lateral (M/L) directions and measured on a single force platform (Bertec PRO VEC 5.0). The purpose of this study was to estimate the variance in error and the intrasession test-retest reliability, and to determine which measures shall be taken for further measurements, especially with adults age 65 and older. We used two types of approximation for the reliability coefficient. Firstly, we used the equation according to Blahuš (2) and secondly we used the Pearson’s correlation coefficient for test-retest measurements. The findings allow us to say, among other things, that the tests of quiet standing Double Narrow Stance Eyes Open (DNSEO) and Double Narrow Stance Eyes Closed (DNSEC) are parallel, in the sense of parallel testing.

scholarly journals Age-Related Changes in Human Posture Control: Sensory Organization Tests

1990 ◽  
Vol 1 (1) ◽  
pp. 73-85 ◽  
Author(s):  
R.J. Peterka ◽  
F.O. Black
Keyword(s):  
Visual Cues ◽  
Human Subjects ◽  
Body Sway ◽  
Support Surface ◽  
Eyes Closed ◽  
Sensory Organization ◽  
Age Related ◽  
Eyes Open ◽  
Orientation Cues ◽  
Anterior Posterior

Postural control was measured in 214 human subjects ranging in age from 7 to 81 y. Sensory organization tests measured the magnitude of anterior-posterior body sway during six 21 s trials in which visual and somatosensory orientation cues were normal, altered (by rotating the visual surround and support surface in proportion to the subject’s sway), or vision eliminated (eyes closed). No age-related increase in postoral sway was found for subjects standing on a fixed support surface with eyes open or closed. However, age-related increases in sway were found for conditions involving altered visual or somatosensory cues. Subjects older tban about 55 y showed the largest sway increases. Subjects younger than about 15 y were also sensitive to alteration of sensory cues. On average, the older subjects were more affected by altered visual cues, whereas younger subjects had more difficulty with altered somatosensory cues.

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