Low-frequency Bursts Research Articles

Prognostic Value of Burst Pacing Inducibility Post-Radiofrequency Versus Cryoablation for Paroxysmal Atrial Fibrillation.

Atrial fibrillation (AF) inducibility with burst pacing (BP) after radiofrequency ablation (RFA) has been reported to be associated with AF recurrence. In contrast, the relevance of inducibility and recurrence after cryoablation (CRA) is unclear. We investigated 367 patients undergoing initial ablation for paroxysmal AF (RFA: 174, CRA: 193). Propensity score matching was conducted, retaining 134 patients in each group. Following pulmonary vein isolation (PVI), the inducibility by BP was tested. Inductions at 250ppm were defined as low-frequency burst pacing (LFBP) positive, and those at 300ppm were classified as medium-frequency burst pacing (MFBP) positive. They were followed for 600days. Forty-eight patients (18%) had AF recurrence. There was no significant difference in the recurrence rate between RFA and CRA (17% vs. 19%, Log-rank p=0.79). In RFA, significant differences were observed for both LFBP (Log-rank p<0.001) and MFBP (Log-rank p<0.001). In contrast, in CRA, there were no significant differences for either LFBP (Log-rank p=0.39) or MFBP (Log-rank p=0.19). Multivariable analysis revealed that LFBP-positive (hazards ratio [HR]=5.75, 95% confidence interval [CI] 2.41-13.7, p<0.001) was an independent predictor for recurrence with RFA. Acute reconnection (HR=2.73, 95% CI 1.13-6.56, p=0.025) was an independent predictor for recurrence with CRA. The inducibility by BP after RFA predicted recurrence at both low and medium frequencies. LFBP-positive was an independent predictor of recurrence in multivariable analysis. In contrast, the inducibility by BP after CRA was not a predictor of recurrence. This study did not require clinical trial registration.

Relation between spatial release from informational masking and localization discrimination

Spatial release from masking (SRM) occurs when a signal of interest (target) and an interfering sound (masker) come from different locations in space. SRM and sound localization are assumed to share common mechanisms, but it is still unclear whether SRM actually depends on hearing the target and masker in different places, even in situations dominated by informational masking. The current study used a spatial rhythmic release from masking (RMR) task [J. Middlebrooks and Z. Onsan, JASA, 132, 3896–3911, 2012]. The target and masker were trains of non-simultaneous noise bursts; hearing the target temporal pattern relies on segregation from the masker, which is supported by spatial separation. Using a headphone simulation of space (HRTFs), the current study replicated key aspects of Middlebrooks and Onsan’s (2012) finding that RMR spatial thresholds were poorer for high-frequency than low-frequency bursts. We investigated whether this low/high frequency difference, and others created with degraded localization cues, were associated with variations in basic localization discrimination tasks using the same RMR stimuli. Data collection is ongoing, but preliminary results suggest a covariation of spatial release in the RMR task and sensitivity to change in spatial angle. [Work supported by NIDCD R01-01625.]

Guided Acoustic Waves in Polymer Rods with Varying Immersion Depth in Liquid.

Monitoring tanks and vessels play an important part in public infrastructure and several industrial processes. The goal of this work is to propose a new kind of guided acoustic wave sensor for measuring immersion depth. Common sensor types such as pressure sensors and airborne ultrasonic sensors are often limited to non-corrosive media, and can fail to distinguish between the media they reflect on or are submerged in. Motivated by this limitation, we developed a guided acoustic wave sensor made from polyethylene using piezoceramics. In contrast to existing sensors, low-frequency Hanning-windowed sine bursts were used to excite the L(0,1) mode within a solid polyethylene rod. The acoustic velocity within these rods changes with the immersion depth in the surrounding fluid. Thus, it is possible to detect changes in the surrounding media by measuring the time shifts of zero crossings through the rod after being reflected on the opposite end. The change in time of zero crossings is monotonically related to the immersion depth. This relative measurement method can be used in different kinds of liquids, including strong acids or bases.

Enhancing the Performance of Human Motion Energy Harvesting through Optimal Smoothing Capacity in the Rectifier

Energy harvesting offers a promising solution for powering a growing variety of low-power electronics; however, harnessing energy from human motion, with its irregular and low-frequency bursts of power, presents conversion challenges. As rectification is a common part of it, this study investigates the influence of smoothing capacitor values on rectifier output for short, intermittent signals. We propose an analytical model that identifies an optimal smoothing capacity for the full-bridge rectifier, considering harvester internal resistance, frequency, and load resistance and leading to the highest average output voltage after rectification. The model was validated with detailed computer simulations; furthermore, a similar effect was revealed on a voltage multiplier circuit as well. Experimental measurements demonstrate that deviating from the optimal smoothing capacity results in up to 10% decrease in rectified RMS voltage, leading to significant drops in output power in specific energy harvesting systems. A real-world experiment with a human motion energy harvester further confirmed the findings in a naturally varying generation environment.

Blood flow effects of percutaneous peripheral nerve stimulation. A blinded, randomized clinical trial.

The vasculature function is mainly regulated by the autonomic nervous system. Importantly, the sensory-motor nervous system also innervates peripheral vessels and has the capacity to modulate vascular tone. Here we investigated the effects of electrical stimulation of a mixed nerve trunk on blood flow in deep arteries and muscle perfusion. Our hypothesis is that stimulation of a mixed nerve can modify blood flow. Twenty-nine healthy participants were included into a randomized-crossover and blinded clinical trial. Each subject received a placebo and two percutaneous peripheral nerve stimulation (pPNS) protocols on the median nerve: Pain Threshold continuous Low Frequency (PT-cLF) and Sensory Threshold burst High Frequency (ST-bHF). Blood flow was then assessed bilaterally using Power Doppler Ultrasonography at the main arteries of the arm, and blood perfusion at the forearm muscles. Afterwards, blood flow was quantified using a semi-automatized software, freely shared here. Placebo, consisting in needle insertion, produced an immediate and generalized reduction on peak systolic velocity in all arteries. Although nerve stimulation produced mainly no effects, some significant differences were found: both protocols increased the relative perfusion area of the forearm muscles, the ST-bHF protocol prevented the reduction in peak systolic velocity and TAMEAN of the radial artery produced by the control protocol and PT-cLF produced a TAMEAN reduction of the ulnar artery. Therefore, the arterial blood flow in the arm is mainly impervious to the electrical stimulation of the median nerve, composed by autonomic and sensory-motor axons, although it produces mild modifications in the forearm muscles perfusion.

1550-P: A Gain-of-Function Maturity-Onset Diabetes of the Young (MODY)–Associated TALK1 Mutation Impairs Glucose Metabolism in Mice

A Leu substitution with Pro at position 114 (L114P) of TALK1 K+ channels has recently been identified in a MODY (maturity-onset-diabetes-of-the-young) family. Previous in vitro studies have shown this gain-of-function TALK1-L114P mutant may attenuate Ca2+ homeostasis and inhibit insulin secretion; nevertheless, how this mutant induces diabetes in vivo remains elusive. In this study, we have generated a transgenic mouse line that carries a TALK1-L114P mutation. About three-quarters of TALK1L/P and TALK1P/- mice died within ten days after birth due to hyperglycemia. Interestingly, those survival mice till adulthood exhibited diverse levels of glucose intolerance with islet morphology that is commonly observed in patients with type 2 diabetes. Electrophysiological recording further indicated that only a portion of the beta cells is glucose responsive, and high glucose challenge often yielded in low-frequency action potential bursting. According to our results, we hypothesized that despite the augment of membrane K+ conductance by the TALK1-L114P channel, high glucose might still be enough to depolarize beta cells and generate action potential bursting. This dampened beta cell excitation may result in a weakened Ca2+ influx and insufficient insulin secretion to cause glucose intolerance. In conclusion, this study has revealed a vital role of the TALK1 channel in regulating glucose homeostasis and a plausible diabetogenic mechanism of TALK1-L114P mutation. Disclosure W.Tsai: None. S.Yang: None. Funding National Science and Technology Council, Taiwan (111-2320-B-001-008-MY3)

Diversity of electroencephalographic patterns during propofol-induced burst suppression.

Burst suppression is a brain state consisting of high-amplitude electrical activity alternating with periods of quieter suppression that can be brought about by disease or by certain anesthetics. Although burst suppression has been studied for decades, few studies have investigated the diverse manifestations of this state within and between human subjects. As part of a clinical trial examining the antidepressant effects of propofol, we gathered burst suppression electroencephalographic (EEG) data from 114 propofol infusions across 21 human subjects with treatment-resistant depression. This data was examined with the objective of describing and quantifying electrical signal diversity. We observed three types of EEG burst activity: canonical broadband bursts (as frequently described in the literature), spindles (narrow-band oscillations reminiscent of sleep spindles), and a new feature that we call low-frequency bursts (LFBs), which are brief deflections of mainly sub-3-Hz power. These three features were distinct in both the time and frequency domains and their occurrence differed significantly across subjects, with some subjects showing many LFBs or spindles and others showing very few. Spectral-power makeup of each feature was also significantly different across subjects. In a subset of nine participants with high-density EEG recordings, we noted that each feature had a unique spatial pattern of amplitude and polarity when measured across the scalp. Finally, we observed that the Bispectral Index Monitor, a commonly used clinical EEG monitor, does not account for the diversity of EEG features when processing the burst suppression state. Overall, this study describes and quantifies variation in the burst suppression EEG state across subjects and repeated infusions of propofol. These findings have implications for the understanding of brain activity under anesthesia and for individualized dosing of anesthetic drugs.

Electromyography of the External Anal Sphincter during Micturition and Electrophysiological Bulbocavernosus Reflex in Healthy Spayed Female Canines.

This study aimed to find methods and interferences and illustrate the pattern of external anal sphincter (EAS) electromyography (EMG) during micturition and to determine reference intervals of electrophysiological bulbocavernosus reflex (EBCR) by using robust statistical methods in healthy spayed female canines. Ten healthy spayed female canines (no breed restriction) with a body weight of 11.3-18 kg were enrolled. EAS EMG during micturition and the EBCR test were performed under light general anesthesia. Altogether 25 out of 34 EAS EMG showed a similar pattern, including low-amplitude high-frequency bursting pattern before voiding, medium- or high-amplitude low-frequency bursting pattern at the beginning of voiding, oscillate medium- and/or high-amplitude low-frequency bursting with a low-amplitude high-frequency bursting pattern during voiding, and high-amplitude high-frequency bursting pattern at the end of voiding. An average of 100 consecutive stimulations of EBCR for one cycle were performed in each dog and another cycle was repeated to ensure reproducibility. The lower and upper limits of the reference interval of EBCR onset latency values and EBCR mean amplitude values were calculated using both standard and robust methods with untransformed and transformed Box-Cox data. The EBCR onset latency was between 13.85 and 27.44 milliseconds, whereas the EBCR mean baseline to peak amplitude was not transformed with Box-Cox transformation. All EBCR compound muscle action potentials started with a negative sharp wave, which tapers from the baseline in the upward direction, showing an upturned bell-shaped curve. In conclusion, this study was possibly the first to examine the method and provide the electrographic pattern of EAS EMG during micturition and reference intervals of EBCR onset latency in spayed female dogs, which may serve as baseline information to help veterinarians differentiate healthy from diseased dogs. Further studies should compare normal dogs and dogs with lower urinary tract abnormalities at different lesion locations.

Complex Type II Solar Radio Event on 4 July 2022

Abstract On 4 July 2022, a complex low-frequency solar radio burst was observed in Metsähovi Radio Observatory of Aalto University. The radio burst was observed at a frequency range between 20 and 80 MHz. In GOES (Geostationary Operational Environmental Satellite) class, the event was classified as C5.1. However, coronal mass ejection (CME) was not associated to this event. The observed radio burst was a long-lasting (~10 minutes) event, and it could be mainly classified as type II solar radio event. Also type III solar events were observed before long-lasting type II event. The event includes common frequency drifting emission structures, both fundamental and harmonic structures, but also rarely observed continuum-like or stationary structure. It is assumed that the continuum-like radio emission structure is originated from the stationary flare (coronal) loop, which was visible over the whole event. The drifting emission structure means accelerated electrons, which are produced by the shock related phenomena. The paper provides the observations from this event on radio wavelength, and also soft-X-ray regime and optical wavelength (AIA 171). In addition, a possible, simplified scenario is presented for forming the drifting and continuum solar radio emissions in type II solar burst.

Subthalamic low beta bursts differ in Parkinson’s disease phenotypes

ObjectiveParkinson’s disease (PD) patients may be categorized into tremor-dominant (TD) and postural-instability and gait disorder (PIGD) motor phenotypes, but the dynamical aspects of subthalamic nucleus local field potentials (STN-LFP) and the neural correlates of this phenotypical classification remain unclear. Methods35 STN-LFP (20 PIGD and 15 TD) were investigated through continuous wavelet transform and machine-learning-based methods. The beta oscillation – the main band associated with motor impairment in PD – dynamics was characterized through beta burst parameters across phenotypes and burst intervals under specific proposed criteria for optimal burst threshold definition. ResultsLow-frequency (13–22 Hz) beta burst probability was the best predictor for PD phenotypes (75% accuracy). PIGD patients presented higher average burst duration (p = 0.018), while TD patients exhibited higher burst probability (p = 0.014). Categorization into shorter and longer than 400 ms bursts led to significant interaction between burst length categories and the phenotypes (p < 0.050) as revealed by mixed-effects models. Long burst durations and short bursts probability positively correlated, respectively, with rigidity-bradykinesia (p = 0.029) and tremor (p = 0.038) scores. ConclusionsSubthalamic low-frequency beta bursts differed between TD and PIGD phenotypes and correlated with motor symptoms. SignificanceThese findings improve the PD phenotypes’ electrophysiological characterization and may define new criteria for adaptive deep brain stimulation.

Alan Maxwell (1926–2021)

Maxwell, a solar radio astronomer, founded the Harvard College Observatory’s Radio Astronomy Station and was co-discoverer of a new type of low-frequency solar radio burst. He was also a founding editor of the journal Astrophysical Letters.

Auditory nerve phase-locked response recorded from normal hearing adults using electrocochleography

Objective The auditory nerve overlapped waveform response (ANOW), a new measure that can be recorded non-invasively from humans, holds promise for providing more accurate assessment of low frequency hearing thresholds than currently used objective measures. This research aims to investigate the robustness and the nature of the ANOW response in humans. Design Repeated within-session recordings of the ANOW response using low-frequency Tone Bursts (TBs) were obtained at multiple stimulus levels. ANOW’s absolute amplitude and phase locking value (PLV) measures were analysed to obtain normative data and to test the reliability of the ANOW response. Study sample Thirteen normal hearing adults within the age range of 25 to 40 years. Results ANOW response was obtained to both 250 Hz and 500 Hz TBs and was traced down to 30–40 dB nHL. ANOW response showed significantly higher amplitude and stronger phase locking using 250 Hz TB compared to 500 Hz TB. High degree of test retest reliability of the ANOW response was found using 250 Hz TB at presentation levels higher than 40 dB nHL. Conclusions ANOW response is recordable noninvasively using low-frequency TBs and shows higher robustness as the stimulus frequency decreases.

Low-Frequency vs. Theta Burst Transcranial Magnetic Stimulation for the Treatment of Chronic Non-fluent Aphasia in Stroke: A Proof-of-Concept Study.

BackgroundAlthough low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) has shown promise in the treatment of poststroke aphasia, the efficacy of high-frequency rTMS (HF-rTMS) has yet to be determined.PurposeWe investigated the efficacy of intermittent theta burst stimulation (iTBS) in ameliorating chronic non-fluent aphasia and compared it with that of LF-rTMS.MethodsWe randomly assigned patients with poststroke non-fluent aphasia to an ipsilesional iTBS (n = 29), contralesional 1-Hz rTMS (n = 27), or sham (n = 29) group. Each group received the rTMS protocol executed in 10 daily sessions over 2 weeks. We evaluated language function before and after the intervention by using the Concise Chinese Aphasia Test (CCAT).ResultsCompared with the sham group, the iTBS group exhibited significant improvements in conversation, description, and expression scores (P = 0.0004–0.031), which characterize verbal production, as well as in auditory comprehension, reading comprehension, and matching scores (P < 0.01), which characterize language perception. The 1-Hz group exhibited superior improvements in expression, reading comprehension, and imitation writing scores compared with the sham group (P < 0.05). The iTBS group had significantly superior results in CCAT total score, matching and auditory comprehension (P < 0.05) relative to the 1-Hz group.ConclusionOur study findings contribute to a growing body of evidence that ipsilesional iTBS enhances the language recovery of patients with non-fluent aphasia after a chronic stroke. Auditory comprehension was more preferentially enhanced by iTBS compared with the 1-Hz protocol. Our findings highlight the importance of ipsilesional modulation through excitatory rTMS for the recovery of non-fluent aphasia in patients with chronic stroke.Clinical Trial Registration:[www.ClinicalTrials.gov], identifier [NCT03059225].

Effects of low-frequency repetitive transcranial magnetic stimulation combined with cerebellar continuous theta burst stimulation on spasticity and limb dyskinesia in patients with stroke

BackgroundRepetitive transcranial magnetic stimulation (rTMS) has been reported to treat muscle spasticity in post-stroke patients. The purpose of this study was to explore whether combined low-frequency rTMS (LF-rTMS) and cerebellar continuous theta burst stimulation (cTBS) could provide better relief than different modalities alone for muscle spasticity and limb dyskinesia in stroke patients.MethodsThis study recruited ninety stroke patients with hemiplegia, who were divided into LF-rTMS+cTBS group (n=30), LF-rTMS group (n=30) and cTBS group (three pulse bursts at 50 Hz, n=30). The LF-rTMS group received 1 Hz rTMS stimulation of the motor cortical (M1) region on the unaffected side of the brain, the cTBS group received cTBS stimulation to the cerebellar region, and the LF-rTMS+cTBS group received 2 stimuli as described above. Each group received 4 weeks of stimulation followed by rehabilitation. Muscle spasticity, motor function of limb and activity of daily living (ADL) were evaluated by modified Ashworth Scale (MAS), Fugl-Meyer Assessment (FMA) and Modified Barthel Index (MBI) scores, respectively.ResultsThe MAS score was markedly decreased, FMA and MBI scores were markedly increased in the three groups after therapy than before therapy. In addition, after therapy, LF-rTMS+cTBS group showed lower MAS score, higher FMA and MBI scores than the LF-rTMS group and cTBS group.ConclusionMuscle spasticity and limb dyskinesia of the three groups are all significantly improved after therapy. Combined LF-rTMS and cTBS treatment is more effective in improving muscle spasticity and limb dyskinesia of patients after stroke than LF-rTMS and cTBS treatment alone.

Detection of coherent low-frequency radio bursts from weak-line T Tauri stars

In recent years, thanks to new facilities such as LOFAR that are capable of sensitive observations, much work has been done on the detection of stellar radio emission at low frequencies. Such emission has commonly been shown to be coherent emission, generally attributed to electron-cyclotron maser (ECM) emission, and has usually been detected from main-sequence M dwarfs. Here we report the first detection of coherent emission at low frequencies from T Tauri stars, which are known to be associated with high levels of stellar activity. Using LOFAR, we detect several bright radio bursts at 150 MHz from two weak-line T Tauri stars: KPNO-Tau 14 and LkCa 4. All of the bursts have high brightness temperatures (1013 − 1014 K) and high circular polarisation fractions (60–90%), indicating that they must be due to a coherent emission mechanism. This could be either plasma emission or ECM emission. Due to the exceptionally high brightness temperatures seen in at least one of the bursts (≥1014 K), as well as the high circular polarisation levels, it seems unlikely that plasma emission could be the source; as such, ECM is favoured as the most likely emission mechanism. Assuming this is the case, the required magnetic field in the emission regions would be 40–70 G. We determine that the most likely method of generating ECM emission is plasma co-rotation breakdown in the stellar magnetosphere. There remains the possibility, however, that it could be due to an interaction with an orbiting exoplanet.

Automated virtual elephant fence based on detection, alarming, and coordinated redirection of wild elephants.

Against the backdrop of the almost total failure of conventional physical fences to prevent deaths due to human-elephant conflict and elephant-train collision, management of the problem requires novel approaches. The elephant is a giant and intelligent animal, who, as has been observed through experience, cannot be effectively confined to an area by physical barriers, most of which are built without even considering long-established elephant passes. Instead, human habitats and facilities, including highways, should be pre-planned following an overall strategy to suitably assign natural resources to each party such that natural habitats are disturbed as little as possible. Hence, we envisage the need for a virtual elephant fence as part of the aforesaid strategy to warn elephants that a certain area is not appropriate for them to be present in or best for the safety of the herd. The present study involved in-depth experimentation to investigate the effects of multiple stimuli on real elephants based on the known elephant responses to such stimuli. The proposed system is an autonomous system that detects the presence of elephants, generates alarms for concerned parties, and coordinatively and tactically repels the animals back to safer areas. Experiment results indicated that the sound of a drone and the sound of tiger growls can both exert a strong deterrent effect on elephants. The sound of bees and the low-frequency burst yielded similar results in terms of encounter and withdrawal reactions. The resulting insights may lay a foundation for a novel approach toward the management of human-elephant conflict and elephant-train collisions.

Much faster heat/mass than momentum transport in rotating Couette flows

Abstract

Dynamical transitions of the coupled Class I (II) neurons regulated by an astrocyte

Based on the minimal neural network models consisting of a pyramidal (PY) neuron, an interneuron (IN), and an astrocyte (AS), we investigate the regulating effects of astrocyte on dynamical transitions in two coupled neurons of the same type of excitability, either Class I or Class II, which is characterized by saddle-node on invariant circle (SNIC) and Hopf (HB) bifurcation, respectively. It is found that without the regulation of AS, the coupled Class I PY and IN neurons show the regular $$L^s$$ mixed-mode oscillations (MMOs) composed of L large amplitude oscillations (LAOs) and s small amplitude oscillations (SAOs) in one period. Under the AS action, the calcium signals in AS can induce and regulate the mixed-mode low-frequency bursting firings. By contrast, for the coupled Class II PY and IN neurons, when AS is ignored, as the coupling strength increases, the system shows the periodic LAO oscillations, $$L^s$$ mode of oscillations, and the chaotic behaviors. Furthermore, the period-doubling bifurcation is clearly captured. However, the presence of AS makes the PY neuron exhibit the mixed-mode low-frequency chaotic bursting activities. Interestingly, we also discover a new transition route ( $$1^0\rightarrow 1^1\rightarrow 1^2\rightarrow \ldots $$ ) of calcium signals due to the period adding bifurcation of the system, which can shape the firing patterns of the PY neuron. Our results suggest that calcium signals in AS indeed involve in and even shape the coupling dynamics of PY and IN neurons. In particular, AS may exert differential roles in modulating the dynamical properties of Class I and Class II neurons.

A Flare-type IV Burst Event from Proxima Centauri and Implications for Space Weather

Abstract Studies of solar radio bursts play an important role in understanding the dynamics and acceleration processes behind solar space weather events, and the influence of solar magnetic activity on solar system planets. Similar low-frequency bursts detected from active M-dwarfs are expected to probe their space weather environments and therefore the habitability of their planetary companions. Active M-dwarfs produce frequent, powerful flares which, along with radio emission, reveal conditions within their atmospheres. However, to date, only one candidate solar-like coherent radio burst has been identified from these stars, preventing robust observational constraints on their space weather environment. During simultaneous optical and radio monitoring of the nearby dM5.5e star Proxima Centauri, we detected a bright, long-duration optical flare, accompanied by a series of intense, coherent radio bursts. These detections include the first example of an interferometrically detected coherent stellar radio burst temporally coincident with a flare, strongly indicating a causal relationship between these transient events. The polarization and temporal structure of the trailing long-duration burst enable us to identify it as a type IV burst. This represents the most compelling detection of a solar-like radio burst from another star to date. Solar type IV bursts are strongly associated with space weather events such as coronal mass ejections and solar energetic particle events, suggesting that stellar type IV bursts may be used as a tracer of stellar coronal mass ejections. We discuss the implications of this event for the occurrence of coronal mass ejections from Proxima Cen and other active M-dwarfs.

The frequency spectrum of sympathetic nerve activity and arrhythmogenicity in ambulatory dogs

Sympathetic nerve activity, heart rate (HR), and blood pressure (BP) all have very low frequency (VLF), low frequency (LF), and high frequency (HF) oscillations. The purpose of this study was to test the hypothesis that the frequency spectra of subcutaneous nerve activity (ScNA), stellate ganglion nerve activity (SGNA), HR, and BP are important to cardiac arrhythmogenesis. We used radiotransmitters to record SGNA, ScNA, HR, and BP in 6 ambulatory dogs and determined the dominant frequency and paroxysmal atrial tachyarrhythmias (PATs) episodes in 3-minute windows over a 24-hour period. The frequency spectra determined in ScNA reflected that in SGNA. HF oscillations were present in both ScNA and SGNA at all time but could be overshadowed by the much larger LF and VLF burst activities. The dominant frequency could occur in any of the 3 frequency bands. There were circadian variations with more frequent occurrences of HF oscillations at night. HF oscillations in HR and BP matched HF oscillations in SGNA and ScNA. PATs occurred only when dominant frequencies of SGNA and ScNA were in the LF and VLF bands. HF oscillations in BP and HR correlate with HF oscillations in sympathetic nerve activity and are present at all time. HF oscillations can be overshadowed by the much larger LF and VLF burst activities. PATs occur only when LF or VLF, but not when HF, is the dominant frequency. The frequency spectra determined in ScNA reflect that in SGNA.