Modulation Of Oscillations Research Articles

Seismic attenuation estimation using multivariate variational mode decomposition

A seismic attenuation estimation approach is proposed based on multivariate variational mode decomposition (MVMD). MVMD, as a multivariable or multichannel signal processing tool, can extract several predefined multivariable modulation oscillations from the seismic data. Intrinsic mode functions (IMFs) obtained by MVMD may highlight some seismic attenuation information in certain frequency bands with lateral continuity. For improving the accuracy of absorption gradient estimation, we define an absorption gradient by using the low-frequency and high-frequency segments of the amplitude spectrum extracted from the time-frequency map, which is generated by applying the Teager energy separation algorithm to each IMF. A weighted factor is used for highlighting the different attenuation contributions of each IMF. Model test and field data examples show that the proposed method can give more accurate absorption gradient estimation results and yield better hydrocarbon-prone interpretations than the traditional methods.

Multi-fault diagnosis of rotating machinery via iterative multivariate variational mode decomposition

Multivariate variational mode decomposition (MVMD) is a novel extension of variational mode decomposition (VMD) for multi-channel data sets. It decomposes multi-component and multi-channel signals into multivariate modulated oscillations crossing different center frequencies and limited bandwidths with sparse characteristics. MVMD inherits all the limitations of VMD and faces challenges in processing mechanical failure signals. The pre-selected values of the mode number K and balance parameters α still have the most significant impact on the decomposition results. Although the parameter-optimization method solves the problem of parameter selection to a certain extent, the result is often not optimal, and it is difficult to deal with multi-fault signals. A new multi-fault diagnosis method is proposed in this paper to solve these problems. Firstly, a new index, called the weighted combined fault index, is proposed to evaluate the fault information contained in each mode decomposed by MVMD, which is the criterion for selecting the optimal mode. Secondly, an iterative decomposition algorithm based on MVMD is proposed to iteratively decompose different fault components into the optimal modes to extract all potential fault information. Benefiting from these algorithms, this method applies MVMD to multi-fault diagnosis with adaptive parameter selection. Through simulations and experiments, the effectiveness and superiority of the proposed method are verified.

Abstract 022: Impaired Parasympathetic Cardiac Modulation In Long-COVID Postural Tachycardia Syndrome

About 1 out of 10 patients infected with Sars-CoV2 have persistent symptoms beyond 4 weeks and some of them meet diagnostic criteria for postural tachycardia syndrome (Long-COVID POTS). The pathophysiology of Long-COVID POTS is unknown, but autonomic dysfunction may play a role. We hypothesize Long-COVID POTS patients have impaired cardiovascular autonomic reflexes and cardiac sympathovagal balance. We conducted a case-control study with patients recruited from the Vanderbilt Autonomic Dysfunction Center and an historical population of healthy controls. Hemodynamic parameters were measured before and during 75° head up tilt. Supine ECG and finger blood pressure were continuously measured for spontaneous heart rate variability analysis. The Low Frequency (0.04-0.15Hz, LF RR ) and High Frequency (0.15-0.4 Hz, HF RR ) oscillatory modulations of sino-atrial node discharge were computed. We included 14 Long-COVID POTS patients and 15 controls matched by age (34 ± 11 vs 28 ± 7; p=0.09) and BMI (26.1 ± 5.3 vs 23.0 ± 2.6; p=0.06). As expected, the orthostatic HR increase was higher in Long-COVID POTS compared to controls (40 ± 18 vs 21 ± 1, p<0.05). Spectral analysis of heart rate variability in 9 patients and 15 controls (Figure) showed that Long-COVID POTS had reduced HF RR (363 ± 420 vs 933 ± 1000 ms 2 ; p<0.05) and similar LF RR (798 ± 596 vs 962 ± 1075 ms 2 ; p=0.68), resulting in a greater LF/HF ratio (3.7 ± 2.9 vs 1.4 ± 1.3; p<0.05). Patients with Long-COVID POTS have reduced markers of cardiovagal modulation, but normal cardiac sympathetic activation. Our results suggest that parasympathetic dysfunction contributes to the pathophysiology of Long-COVID POTS.

Possible reasons for the migration of tropical cyclone track over the western north pacific: Interdecadal pacific oscillation modulation

Recent studies have proposed a relatively reliable metric, i.e., the annual-mean latitude of tropical cyclone (TC) lifetime maximum intensity, to evaluate the observed trend of poleward migration of TC. The documented trend in the existing records of the metric suggests that anthropogenic factors might make considerable contributions to the poleward migration of TC. However, here we show that there is no significant TC migration trend in the western North Pacific (WNP). Instead, large interdecadal variation is found in the WNP TC track over the past 35 years. Rather than the anthropogenic factors, it is the natural variability, especially the Interdecadal Pacific Oscillation (IPO), that plays a key role in modulating the migration of WNP TC track. The IPO-related TC migration is assumed to cause systematic changes (i.e., increases and decreases) in regional hazard exposure and risk. The impact of IPO on the WNP TC migration is attributed to its influences on the large-scale circulation, TC genesis potential index, and the potential intensity in the TC prevailing region of the WNP.

Improvement on Faraday rotation measurement affected by the stray lights on the HL-2A tokamak

Formic-acid (HCOOH, λ = 432.5 μm) laser P olarimeter- I nterferomet er ( PIer ) has been developed on the HL-2A tokamak, which provides 4 channels of line-integrated electron densities and 4 channels of Faraday rotation angles, respectively. Affected by the stray lights arising from the reflection of the probe waves in the optical system, the measurement of Faraday rotation angles was drastically contaminated during the HL-2A experiments, showing an obvious oscillation modulation during the electron density ramp-up/down. This paper introduces an effective correction approach used to improve the accuracy of Faraday rotation measurement on the HL-2A tokamak. Based on the method, the deviation term originating from the stray lights can be effectively subtracted from the contaminated Faraday rotation measurement. The preliminary result indicates that the interference amplitude on Faraday rotation angle is reduced by about 80%, and the corrected data is consistent with the experimental measurement by using the optical isolator that consists of a λ/4 wave-plate and polarizer under the similar discharges.

State-dependent modulation of thalamocortical oscillations by gamma light flicker with different frequencies, intensities, and duty cycles.

Rhythmic light flickers have emerged as useful tools to modulate cognition and rescue pathological oscillations related to neurological disorders by entrainment. However, a mechanistic understanding of the entrainment for different brain oscillatory states and light flicker parameters is lacking. To address this issue, we proposed a biophysical neural network model for thalamocortical oscillations (TCOs) and explored the stimulation effects depending on the thalamocortical oscillatory states and stimulation parameters (frequency, intensity, and duty cycle) using the proposed model and electrophysiology experiments. The proposed model generated alpha, beta, and gamma oscillatory states (with main oscillation frequences at 9, 25, and 35 Hz, respectively), which were successfully transmitted from the thalamus to the cortex. By applying light flicker stimulation, we found that the entrainment was state-dependent and it was more prone to induce entrainment if the flicker perturbation frequency was closer to the endogenous oscillatory frequency. In addition, endogenous oscillation would be accelerated, whereas low-frequency oscillatory power would be suppressed by gamma (30–50 Hz) flickers. Notably, the effects of intensity and duty cycle on entrainment were complex; a high intensity of light flicker did not mean high entrainment possibility, and duty cycles below 50% could induce entrainment easier than those above 50%. Further, we observed entrainment discontinuity during gamma flicker stimulations with different frequencies, attributable to the non-linear characteristics of the network oscillations. These results provide support for the experimental design and clinical applications of the modulation of TCOs by gamma (30–50 Hz) light flicker.

Spatiotemporal pattern of periodic rhythms in delayed Van der Pol oscillators for the CPG-based locomotion of snake-like robot

This is the further research on the delayed half-center oscillator (DHCO) neural system presented in our previous paper (Song and Xu in Nonlinear Dyn 108:2595–2609, 2022. https://doi.org/10.1007/s11071-022-07222-y). The DHCO is used to construct a CPG (central pattern generator) neural system to control locomotion of a snake-like robot with pitch-yaw connecting configuration. To this end, we firstly give an improved model of the VDP (Van der Pol) oscillator. Employing mutually coupled delay, a pair of VDP oscillator is connected to produce an half-center oscillator (HCO) module with time delay that is called as a DHCO (delayed HCO) model. Based on the analysis of the Hopf bifurcation, periodic rhythm and their spatiotemporal patterns of the DHCO are illustrated in the different regions of parameters. The DHCO presents periodic rhythms with synchronous and anti-synchronous patterns, which is to control joint actuators combined in snake-like robot with pitch-yaw connecting configuration. To realize a backward propulsive wave to promote snake-like robotic locomotion, based on the DHCOs, we construct a chain type of the CPG neural system combined with a new unidirectional delay in which phase difference can be regulated. Numerical simulations are illustrated that the CPG neural system can control snake-like robot to move with serpentine, rectilinear, and side-winding patterns in the forward and backward directions. The results show that the snake-like robot can be controlled in expected locomotion patterns for a region but not a fixed value of the controlling parameters. Further, the corresponding regions of the parameters are obtained by using theoretical dynamical analysis but not a trial-and-error method. The snake-like robot gets smooth and stable gait transition with parameter changing.

Non-zero mean alpha oscillations revealed with computational model and empirical data.

Ongoing oscillations and evoked responses are two main types of neuronal activity obtained with diverse electrophysiological recordings (EEG/MEG/iEEG/LFP). Although typically studied separately, they might in fact be closely related. One possibility to unite them is to demonstrate that neuronal oscillations have non-zero mean which predicts that stimulus- or task-triggered amplitude modulation of oscillations can contribute to the generation of evoked responses. We validated this mechanism using computational modelling and analysis of a large EEG data set. With a biophysical model, we indeed demonstrated that intracellular currents in the neuron are asymmetric and, consequently, the mean of alpha oscillations is non-zero. To understand the effect that neuronal currents exert on oscillatory mean, we varied several biophysical and morphological properties of neurons in the network, such as voltage-gated channel densities, length of dendrites, and intensity of incoming stimuli. For a very large range of model parameters, we observed evidence for non-zero mean of oscillations. Complimentary, we analysed empirical rest EEG recordings of 90 participants (50 young, 40 elderly) and, with spatio-spectral decomposition, detected at least one spatially-filtred oscillatory component of non-zero mean alpha oscillations in 93% of participants. In order to explain a complex relationship between the dynamics of amplitude-envelope and corresponding baseline shifts, we performed additional simulations with simple oscillators coupled with different time delays. We demonstrated that the extent of spatial synchronisation may obscure macroscopic estimation of alpha rhythm modulation while leaving baseline shifts unchanged. Overall, our results predict that amplitude modulation of neural oscillations should at least partially explain the generation of evoked responses. Therefore, inference about changes in evoked responses with respect to cognitive conditions, age or neuropathologies should be constructed while taking into account oscillatory neuronal dynamics.

Frequency-Specific Modulation of Slow-Wave Neural Oscillations via Weak Exogeneous Extracellular Fields Reveals a Resonance Pattern.

Single neurons often exhibit endogenous oscillatory activity centered around a specific frequency band. Transcranial alternating current stimulation (tACS) can generate a weak oscillating extracellular field in the brain that causes subthreshold membrane potential shifts that can affect spike timing at the single neuron level. Many studies have now shown that the endogenous oscillation can be entrained when the tACS frequency matches that of the exogenous extracellular field. However, the effect of tACS on the amplitude of the endogenous oscillation has been less well studied. We investigated this by using exogenous extracellular fields to modulate slow-wave neural oscillations in the ketamine anesthetized male Wistar rat. We applied spatially broad extracellular fields of different frequencies while recording spiking activity from single neurons. The effect of the exogenous extracellular field on the slow-wave neural oscillation amplitude (NOA) followed a resonance pattern: large modulations were observed when the extracellular frequency matched the endogenous frequency of the neuron, while extracellular fields with frequencies far away from the endogenous frequency had little effect. No changes in spike-rate were observed for any of the extracellular fields applied. Our results demonstrate that in addition to the previously reported entrainment and Arnold tongue patterns, weak oscillating extracellular fields modulate the amplitude of the endogenous neural oscillation without any changes in spike-rate, and that this modulation follows a frequency-specific resonance pattern.SIGNIFICANCE STATEMENT Neural activity often oscillates around specific endogenous frequencies. Transcranial alternating current stimulation (tACS) is a neuromodulation method which biases spike-times and alter endogenous activity. Most tACS studies focus on entrainment effects which occur when tACS and endogenous neural frequencies are matched. In this study we varied the frequency of the applied tACS and investigated its effect on amplitude of the neural oscillation. Our results revealed a resonance pattern where tACS frequencies close to the endogenous frequency caused an increase in neural oscillation amplitude (NOA) specifically at the applied tACS frequency, while applying tACS frequencies farther away caused little or no change in NOA. Furthermore, applying tACS at differing frequencies caused the amplitude of the neural oscillation at the prestimulation endogenous frequency to decrease.

HIGH-FREQUENCY OSCILLATORS OF SWINGING FREQUENCY IN THE OUTPUT CIRCUITS OF MAGNETOELASTIC TORQUE SENSORS

To automate the operation of power units of vehicles and machining centers, it is necessary to develop reliable methods and means of measuring the main parameters characterizing their operation: torque, shaft power, axial shaft force, etc. Contactless magnetoelastic torque sensors are distinguished by high operational suitability, the measuring circuits of which, however, are obsolete and do not meet the increased requirements for measurement accuracy. The paper presents the design and describes the principle of operation of a contactless magnetoelastic torque sensor, a comparison of existing measuring circuits is given. The authors proposed a new technical solution for measuring torque, implemented on the basis of a phase shift meter with broadband frequency modulation of oscillators of swinging frequency. The test results of the prototype of the new measuring circuit demonstrated high accuracy and sensitivity compared to traditional measuring circuits. The new measuring circuit is not susceptible to errors in the electrical parameters of electronic components.

Closed-loop modulation of model parkinsonian beta oscillations based on CAR-fuzzy control algorithm.

Closed-loop deep brain stimulation (DBS) can apply on-demand stimulation based on the feedback signal (e.g. beta band oscillation), which is deemed to lower side effects of clinically used open-loop DBS. To facilitate the application of model-based closed-loop DBS in clinical, studies must consider state variations, e.g., variation of desired signal with different movement conditions and variation of model parameters with time. This paper proposes to use the controlled autoregressive (CAR)-fuzzy control algorithm to modulate the pathological beta band (13-35Hz) oscillation of a basal ganglia-cortex-thalamus model. The CAR model is used to identify the relationship between DBS frequency parameter and beta oscillation power. Then the error between the one-step-ahead predicted beta power of CAR model and the desired value is innovatively used as the input of fuzzy controller to calculate the next step stimulation frequency. Compared with 130Hz open-loop DBS, the proposed closed-loop DBS method could lower the mean stimulation frequency to 74.04Hz with similar beta oscillation suppression performance. The Mamdani fuzzy controller is selected because which could establish fuzzy controller rules according to human operation experience. Adding prediction module to closed-loop control improves the accuracy of fuzzy control, compared with proportional-integral control and fuzzy control, the proposed CAR-fuzzy control algorithm has higher tracking reliability, response speed and robustness.

Modulation of boreal summer intraseasonal oscillation on tropical cyclone genesis over the South China Sea

Modulation of boreal summer intraseasonal oscillation on tropical cyclone genesis over the South China Sea

The Impact of Emotional Arousal on Amygdala Activity, Memory Consolidation, and Long-Term Potentiation in the Hippocampus

The amygdala is important for the perception and expression of emotion. Research on the amygdala has shown that its activation through emotional arousal leads to enhanced memory of certain events. Emotional experience is known to induce the release of hormones epinephrine and cortisol, which are essential for responding to stressful events. These hormones initiate pathways between the amygdala, locus coeruleus and vagus nerve as well as aid in the activation of the hippocampus, a brain region involved in forming solid memories that can endure the tests of time. Through these hormones, the amygdala can instigate long-term potentiation (LTP) and spike-timing dependent plasticity (STPD) through hormone binding and modulation of gamma and theta frequency neuronal oscillations in the brain. Oftentimes, memories which are remembered best are emotionally saturated, but the biochemistry responsible for this effect is not yet fully understood. This review will analyze and summarize the research of many decades on this perplexing topic to hopefully help untangle a small component of the complex and intricate design of the human creation.

SIGNAL FORMATION AND PROCESSING FEATURES FROM AUTODYNE RADAR WITH A WIDE FREQUENCY MODULATION BAND. (РART 1)

Subject and Purpose. In Part 1 of the paper, a mathematical model of an autodyne self-oscillator with frequency tuning by varactor capacitance varying is built and thoroughly analyzed for the features of signal formation in autodyne radar with a wide frequency-modulation bandwidth and a nonlinearity in the modulation characteristic. The aim of the study is to appreciate the action that the nonlinearity of the oscillator modulation characteristic exerts on the spectral characteristics of signals from frequency-modulation autodyne radar. Methods and Methodology. The research method is a mathematical analysis of the operation of an autodyne oscillator with electronic frequency tuning. To examine formation processes of emitted autodyne signals, the spectral, frequency and amplitude characteristics of signals from frequency-modulation autodyne radar are constructed with the use of numerical modeling techniques. Results. Numerical modeling of autodyne response signal spectra has been performed for various distances to the reflecting object and different modulating voltages across the varactor. It has been shown that a nonlinear dependence of the generator frequency on the varactor voltage makes for the broadening of the autodyne response signal spectrum. It has been found that as the object distance increases, the frequency of the autodyne response signal moves towards the higher frequencies, while the nonlinearity makes the spectrum broaden. The obtained calculation results refer to an 8-mm Gunn diode autodyne. Conclusion. The performed research of the spectral characteristics and into the features of signal formation in autodyne transceiver devices with a wide frequency tuning has shown that in order to achieve high resolution figures from autodyne radar, certain methods are needed to be developed for adjusting the laws of frequency modulation and for the processing of response signals from reflecting objects. Such a method and ways to solve these problems will be presented in Part 2 of the work.

Alpha rhythm modulations in the intraparietal sulcus reflect decision signals during item recognition

Theoretical work and empirical observations suggest a contribution of regions along the intraparietal sulcus to the process of evidence accumulation during episodic memory retrieval. In the present study, we recorded magnetoencephalographic signals in a group of healthy human participants to test whether the pattern of oscillatory modulations in the lateral parietal lobe is consistent with the mnemonic accumulator hypothesis. To this aim, the dynamic properties and the spatial distribution of MEG oscillatory power modulations were investigated during an item recognition task in which the amount of evidence for old vs. new memory decisions was manipulated across three levels. A data-driven approach was employed to identify brain nodes where oscillatory activity was sensitive to both retrieval success and the amount of evidence for old decisions. The analysis identified three nodes in the left lateral parietal lobe where the event-related desynchronization (ERD) in the alpha frequency band showed both effects. Further analyses revealed that the alpha ERD in the intraparietal sulcus, but not in other parietal nodes: i. showed modulation of duration in response to the amount of evidence for both old and new decisions, ii. was behaviorally significant, and iii. more accurately tracked the subjective memory judgment rather than the objective memory status. The present findings provide support for a recent anatomical-functional model of the parietal involvement in episodic memory retrieval and suggest that the alpha ERD in the intraparietal sulcus might represent a neural signature of the evidence accumulation process during simple memory-based decisions.

Inhibitory and stimulatory micropeptides preferentially bind to different conformations of the cardiac calcium pump

The ATP-dependent ion pump sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) sequesters Ca2+ in the endoplasmic reticulum to establish a reservoir for cell signaling. Because of its central importance in physiology, the activity of this transporter is tightly controlled via direct interactions with tissue-specific regulatory micropeptides that tune SERCA function to match changing physiological conditions. In the heart, the micropeptide phospholamban (PLB) inhibits SERCA, while dwarf open reading frame (DWORF) stimulates SERCA. These competing interactions determine cardiac performance by modulating the amplitude of Ca2+ signals that drive the contraction/relaxation cycle. We hypothesized that the functions of these peptides may relate to their reciprocal preferences for SERCA binding; SERCA binds PLB more avidly at low cytoplasmic [Ca2+] but binds DWORF better when [Ca2+] is high. In the present study, we demonstrated this opposing Ca2+ sensitivity is due to preferential binding of DWORF and PLB to different intermediate states that SERCA samples during the Ca2+ transport cycle. We show PLB binds best to the SERCA E1-ATP state, which prevails at low [Ca2+]. In contrast, DWORF binds most avidly to E1P and E2P states that are more populated when Ca2+ is elevated. Moreover, FRET microscopy revealed dynamic shifts in SERCA–micropeptide binding equilibria during cellular Ca2+ elevations. A computational model showed that DWORF exaggerates changes in PLB–SERCA binding during the cardiac cycle. These results suggest a mechanistic basis for inhibitory versus stimulatory micropeptide function, as well as a new role for DWORF as a modulator of dynamic oscillations of PLB–SERCA regulatory interactions.

Mitotic kinase oscillation governs the latching of cell cycle switches

In 1996, Kim Nasmyth1 proposed that the eukaryotic cell cycle is an alternating sequence of transitions from G1 to S-G2-M and back again. These two phases correlate to high activity of cyclin-dependent kinases (CDKs) that trigger S-G2-M events and CDK antagonists that stabilize G1 phase. We associated these "alternative phases" with the coexistence of two stable steady states of the biochemical reactions among CDKs and their antagonists.2,3 Transitions between these steady states (G1-to-S and M-to-G1) are driven by "helper" proteins. The fact that the transitions are irreversible is guaranteed by a "latching" property of the molecular switches, as we have argued in previous publications.4,5 Here, we show that if the latch is broken, then the biochemical reactions can swing back-and-forth across the transitions; either G1-S-G1-S … (periodic DNA replication without mitosis or cell division) or M-(G1)-M-(G1) … (periodic Cdc14 release, without fully exiting mitosis). Using mathematical modeling of the molecular control circuit in budding yeast, we provide a fresh account of aberrant cell cycles in mutant strains: endoreplication in the clb1-5Δ strain6 and periodic release and resequestration of Cdc14 (an "exit" phosphatase) in the CLB2kdΔ strain.7,8 In our opinion, these "endocycles" are not autonomous oscillatory modules that must be entrained by the CDK oscillator6,7 but rather inadvertent and deleterious oscillations that are normally suppressed by the CDK latching-gate mechanism.8.

Sleep Deficits, Repetitive Behaviors, and Increased Slow Gamma Power in an Ank3 Mouse Model of Epilepsy‐Mood Disorder Comorbidity

The ANK3 gene is a leading bipolar disorder candidate gene in humans. Previous studies showed that a bipolar disorder (BD)‐associated variant of ANK3 (ANK3‐1b) leads to increased firing threshold and diminished action potential dynamic range of parvalbumin (PV) interneurons and absence epilepsy in mice, thus providing a potential mechanistic link between epilepsy and BD. To better understand the impact of PV interneurons on network activity and behavior in these mice, we examined spectral correlates of behaviors seen in Ank3‐1b knockout (KO) mice during overnight home‐cage activity using paired video‐EEG recordings. PV interneuron dysfunction and aberrant gamma rhythms have been implicated in BD. Also, the fast‐spiking properties of PV interneurons make them important for generating and modulating high frequency gamma oscillations. Thus, we anticipated changes in the power of EEG signals in the gamma frequency range (> 25 Hz) during behaviors related to BD symptoms seen in human patients such as changes in sleep and activity levels. Ank3‐1b KO mice exhibited an overall increase in slow gamma (~25‐45 Hz) power compared to controls, and slow gamma power correlated with seizure phenotype severity across behaviors. Notably, during sleep, increased slow gamma power co‐occurred with decreases in time spent in the rapid eye movement (REM) phase. We also identified a repetitive behaviors phenotype in Ank3‐1b KO mice that co‐occurred with increased slow gamma power. These results further support the association of Ank3‐1b with BD and suggest modulation of gamma oscillations as a potential therapeutic target.

A reconfigurable wireless superheterodyne receiver for multi-standard communication systems

ABSTRACT The rapid growth of the communication frequency band leads to the diversity of receiving frequency bands of smart devices. This paper proposes a reconfigurable wireless superheterodyne receiver for multi-standard communication systems. The receiver is designed through architecture design, chip selection, layout drawing, and physical measurement. The designed receiver consists of receiving module, local oscillator module, and control module. Unlike previous receivers, the proposed receiver selects the frequency channel, local oscillator frequency, and link gain through the control module in the current scene. The control module consists of a single-chip microcomputer and computer. The receiver can work in application scenarios including 2.4–2.5 GHz, 3.3–3.6 GHz, and 4.8–6.0 GHz. This paper discusses the design process of the proposed reconfigurable receiver in detail. Compared with the traditional receiver, the proposed receiver can change its working mode by software and has the characteristics of flexible reconfiguration. In addition, it has the advantages of a large link gain range and good demodulation performance. Moreover, the receiver is low in design cost and easy to manufacture. Therefore, it can be widely used in receiving modules of WLAN and 5G communication systems.

Altered alpha and theta oscillations correlate with sequential working memory in Parkinson's disease.

Daily activities such as preparing a meal rely on the ability to arrange thoughts and actions in the right order. Patients with Parkinson’s disease have difficulties in sequencing tasks. Their deficits in sequential working memory have been associated with basal ganglia dysfunction. Here we demonstrate that altered parietal alpha and theta oscillations correlate with sequential working memory in Parkinson’s disease. We included 15 patients with Parkinson’s disease (6 women, mean age: 66.0 years), 24 healthy young (14 women, mean age: 24.1 years), and 16 older participants (7 women, mean age: 68.6 years). All participants completed a picture ordering task with scalp electroencephalogram (EEG) recording, where they arranged five pictures in a specific order and memorized them over a delay. When encoding and maintaining picture sequences, patients with Parkinson’s disease showed a lower baseline alpha peak frequency with higher alpha power than healthy young and older participants. Patients with a higher baseline alpha power responded more slowly for ordered trials. When manipulating picture sequences, patients with Parkinson’s disease showed a lower frequency of maximal power change for random versus ordered trials than healthy young and older participants. Healthy older participants showed a higher frequency of maximal power change than healthy young participants. Compared with patients with frequency of maximal power change in the alpha band (8–15 Hz), patients with frequency of maximal power change in the theta band (4–7 Hz) showed a higher ordering-related accuracy cost (random versus ordered) in the main task and tended to respond more slowly and less accurately in an independent working memory test. In conclusion, altered baseline alpha oscillations and task-dependent modulation of alpha and theta oscillations may be neural markers of poor sequential working memory in Parkinson’s disease.