Noise-Induced Transition to Bursting in Responses of Paddlefish Electroreceptor Afferents

2007 ◽  
Vol 98 (5) ◽  
pp. 2795-2806 ◽  
Author(s):  
Alexander B. Neiman ◽  
Tatyana A. Yakusheva ◽  
David F. Russell
Keyword(s):  
Power Spectra ◽  
Qualitative Change ◽  
Sine Wave ◽  
Spike Trains ◽  
Broadband Noise ◽  
Noise Stimulus ◽  
Similar Frequency ◽  
Best Response ◽  
Band Limited

The response properties of ampullary electroreceptors of paddlefish, Polyodon spathula, were studied in vivo, as single-unit afferent responses to external electrical stimulation with varied intensities of several types of noise waveforms, all Gaussian and zero-mean. They included broadband white noise, Ornstein–Uhlenbeck noise, low- or high-frequency band-limited noise, or natural noise recorded from swarms of Daphnia zooplankton prey, or from individual prey. Normally the afferents fire spontaneously in a tonic manner, which is actually quasiperiodic due to embedded oscillators. 1) Weak noise stimuli increased the variability of afferent firing, but it remained tonic. 2) In contrast, stimulation with less-weak broadband noise led to a qualitative change of the firing patterns, to parabolic bursting, even though the mean firing rate was scarcely affected. 3) The transition to afferent bursting was marked by the development of two well-separated timescales: the fast frequency of spiking inside bursts at ≤250 spikes/s and the slow frequency of burst occurrences at about 9 (range 5–13) bursts/s. These two timescales were manifested as two regimes in afferent power spectra, bimodal interspike interval histograms, return maps, and autocorrelation functions of afferent spike trains. 4) The stochastic approximately 9-Hz bursts were not simply driven by similar-frequency components of noise stimuli because bursts could be dissociated from stimulus waveforms using high-pass filtered noise, or a 0.1-Hz sine-wave stimulus. 5) Arrhenius plots showed that the threshold noise intensity required to elicit bursting depended on the frequency content of a noise stimulus, being lowest, about 1.2 μV/cm, for stimuli matching the 1- to 20-Hz best response band of these cathodally excited ampullary electroreceptors. This is only slightly higher than previous behavioral estimates of the electrosensory threshold as 0.5 μV/cm. 6) Comparable threshold values for bursting came from an alternate analytical approach, based on correlation times of spike trains. 7) Simultaneous recordings from pairs of afferents showed that their bursting frequencies (bursts/s) always converged as the amplitude of a noise stimulus was raised. Thus the slow timescale of bursting is similar for different electroreceptors, even though their mean spiking rates can differ. In conclusion, the ampullary electroreceptors of paddlefish have two distinct modes of operation: their spontaneous tonic firing is modulated by the weakest stimuli, but they switch to bursting output for less-weak stimuli. We propose that afferent bursting may mediate close-range tracking of planktonic prey.

Model Reduction of Piezoelectric Energy Harvesters Subject to Band-Limited, Stochastic Base Excitation

2012 ◽  
Author(s):  
Adam M. Wickenheiser
Keyword(s):  
White Noise ◽  
Design Optimization ◽  
Broadband Noise ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Energy Harvesters ◽  
White Noise Excitation ◽  
Single Degree ◽  
Piezoelectric Energy ◽  
Band Limited

In many scenarios where vibration energy harvesting can be utilized — particularly those involving bio-motions or environmental disturbances — energy sources are broadband and non-stationary. On the other hand, design procedures have been predominantly developed for harmonic or white noise excitation, specifically for single degree of freedom approximations of the transducer. In this paper, a general approach for design optimization of cantilevered, piezoelectric energy harvesters in the presence of band-limited, white-noise excitation is outlined. For this study, human and vehicular motions are considered; these complex waveforms are distilled into a small set of dominant features with regard to their impact on the power output of the device. Criteria based on modal participation factors, including pre-filtering of the disturbance, are used in guiding the reduction of the input and plant degrees of freedom in order to make the design optimization problem tractable. This process determines the error in assuming a low-order model for the transducer in the presence of broadband noise that may excite multiple modes of vibration. Furthermore, this study considers the quantitative impact of charge cancellation in higher modes and the benefits of inserting multiple electrodes along the length. To illustrate these methods, energy harvesters are designed for acceleration data collected from walking and car idling. It is shown that a simple method that is a generalization of naïve approaches that assume harmonic or white noise excitation and a single degree of freedom can determine which simplifications are appropriate and the inaccuracies that can be expected from them.

The Effect of Plantago major on Wound Healing in Preclinical Studies: A Systematic Review

2021 ◽  
Vol 67 (1) ◽  
pp. 27-34
Author(s):  
Fernanda Cardoso ◽  
Jéssica Breder ◽  
Priscila Apolinário ◽  
Henrique Oliveia ◽  
Maria Saidel ◽  
...  
Keyword(s):  
Systematic Review ◽  
Wound Healing ◽  
Meta Analysis ◽  
Experimental Studies ◽  
Risk Of Bias ◽  
Preclinical Studies ◽  
Plantago Major ◽  
Best Response ◽  
Meta Analyses

BACKGROUND: Plantago major is a medicinal plant that has been used for centuries to treat various health conditions including wounds. PURPOSE: To investigate the effectiveness of the topical use of P major in healing skin wounds in animal models. METHODS: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review was conducted. Seven (7) electronic databases (Virtual Health Library, Public/Publisher MEDLINE, Scopus, Web of Science, Embase, Cumulative Index of Nursing and Allied Health Literature, and CAB Direct) were searched for controlled studies published in English from January 2006 to March 2020. The Collaborative Approach to Meta Analysis and Review of Animal Data from Experimental Studies tools guided the evaluation of the studies and determined their quality. The Systematic Review Center for Laboratory Animal Experimentation was used to assess the risk of bias. RESULTS: Of the 176 publications identified, 4 met the inclusion criteria. Studies included 20 to 100 animals and varying concentrations of P major. There were no reports of losses during research. Wound healing was assessed between 17 and 21 days following wounding. The best response in terms of wound contraction rate occurred with 10%, 20%, and 50% concentrations when compared with control groups. One (1) study did not have an animal ethics committee review. All studies had a high risk of bias and a lack of methodological rigor. CONCLUSION: The results of this review did not find evidence about the in vivo effectiveness of P major for wound healing. More rigorous preclinical studies with adequate sample sizes are required to identify the best concentrations and formulations as well as increase understanding about the mechanisms of action of P major in wound healing.

scholarly journals Temporal Properties of Posterior Parietal Neuron Discharges During Working Memory and Passive Viewing

2007 ◽  
Vol 97 (3) ◽  
pp. 2254-2266 ◽  
Author(s):  
Frederik C. Joelving ◽  
Albert Compte ◽  
Christos Constantinidis
Keyword(s):  
Working Memory ◽  
Posterior Parietal Cortex ◽  
Memory Task ◽  
Power Spectra ◽  
Low Frequency ◽  
Spatial Location ◽  
Spike Trains ◽  
Memory Condition ◽  
Temporal Properties ◽  
Posterior Parietal

Working memory is mediated by the discharges of neurons in a distributed network of brain areas. It was recently suggested that enhanced rhythmicity in neuronal activity may be critical for sustaining remembered information. To test whether working memory is characterized by unique temporal discharge patterns, we analyzed the autocorrelograms and power spectra of spike trains recorded from the posterior parietal cortex of monkeys performing a visuospatial working-memory task. We compared the intervals of active memory maintenance and fixation and repeated the same analysis in spike trains from monkeys never trained to perform any kind of memory task. The most salient effect we observed was a decrease of power in the 5- to 10-Hz frequency range during the presentation of visual stimuli. This pattern was observed both in the working-memory condition and the control condition, although it was more prominent in the former, where it persisted after cue presentation when the monkeys actively remembered the spatial location of the stimulus. Low-frequency power suppression resulted from relative refractory periods that were significantly longer in the working-memory condition and presumably emerged from local-circuit inhibition. We also detected a spectral peak in the 15- to 20-Hz range, although this was more prominent during fixation than during the stimulus and working-memory periods. Our results are in line with previous reports in prefrontal cortex and indicate that unique temporal patterns of single-neuron firing characterize persistent delay activity, although these do not involve the appearance of enhanced oscillations.

scholarly journals GluA1 Phosphorylation Alters Evoked Firing PatternIn Vivo

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Balázs Barkóczi ◽  
Gábor Juhász ◽  
Robert G. Averkin ◽  
Imre Vörös ◽  
Petra Vertes ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Spike Trains ◽  
Temporal Coding ◽  
Relative Contribution ◽  
Ampa Receptor Subunit ◽  
Ampa And Nmda Receptors ◽  
Characteristic Features ◽  
Evoked Activity

AMPA and NMDA receptors convey fast synaptic transmission in the CNS. Their relative contribution to synaptic output and phosphorylation state regulate synaptic plasticity. The AMPA receptor subunit GluA1 is central in synaptic plasticity. Phosphorylation of GluA1 regulates channel properties and trafficking. The firing rate averaged over several hundred ms is used to monitor cellular input. However, plasticity requires the timing of spiking within a few ms; therefore, it is important to understand how phosphorylation governs these events. Here, we investigate whether the GluA1 phosphorylation (p-GluA1) alters the spiking patterns of CA1 cellsin vivo. The antidepressant Tianeptine was used for inducing p-GluA1, which resulted in enhanced AMPA-evoked spiking. By comparing the spiking patterns of AMPA-evoked activity with matched firing rates, we show that the spike-trains after Tianeptine application show characteristic features, distinguishing from spike-trains triggered by strong AMPA stimulation. The interspike-interval distributions are different between the two groups, suggesting that neuronal output may differ when new inputs are activated compared to increasing the gain of previously activated receptors. Furthermore, we also show that NMDA evokes spiking with different patterns to AMPA spike-trains. These results support the role of the modulation of NMDAR/AMPAR ratio and p-GluA1 in plasticity and temporal coding.

scholarly journals Signal-to-noise ratio in the membrane potential of the owl's auditory coincidence detectors

2012 ◽  
Vol 108 (10) ◽  
pp. 2837-2845 ◽  
Author(s):  
Go Ashida ◽  
Kazuo Funabiki ◽  
Paula T. Kuokkanen ◽  
Richard Kempter ◽  
Catherine E. Carr
Keyword(s):  
Neural Circuit ◽  
Signal To Noise Ratio ◽  
Phase Locking ◽  
Low Frequency ◽  
Membrane Potentials ◽  
Signal To Noise ◽  
Theoretical Predictions ◽  
Noise Ratio ◽  
Band Limited

Owls use interaural time differences (ITDs) to locate a sound source. They compute ITD in a specialized neural circuit that consists of axonal delay lines from the cochlear nucleus magnocellularis (NM) and coincidence detectors in the nucleus laminaris (NL). Recent physiological recordings have shown that tonal stimuli induce oscillatory membrane potentials in NL neurons (Funabiki K, Ashida G, Konishi M. J Neurosci 31: 15245–15256, 2011). The amplitude of these oscillations varies with ITD and is strongly correlated to the firing rate. The oscillation, termed the sound analog potential, has the same frequency as the stimulus tone and is presumed to originate from phase-locked synaptic inputs from NM fibers. To investigate how these oscillatory membrane potentials are generated, we applied recently developed signal-to-noise ratio (SNR) analysis techniques (Kuokkanen PT, Wagner H, Ashida G, Carr CE, Kempter R. J Neurophysiol 104: 2274–2290, 2010) to the intracellular waveforms obtained in vivo. Our theoretical prediction of the band-limited SNRs agreed with experimental data for mid- to high-frequency (>2 kHz) NL neurons. For low-frequency (≤2 kHz) NL neurons, however, measured SNRs were lower than theoretical predictions. These results suggest that the number of independent NM fibers converging onto each NL neuron and/or the population-averaged degree of phase-locking of the NM fibers could be significantly smaller in the low-frequency NL region than estimated for higher best-frequency NL.

scholarly journals Computed Poststenotic Flow Instabilities Correlate Phenotypically With Vibrations Measured Using Laser Doppler Vibrometry: Perspectives for a Promising In Vivo Device for Early Detection of Moderate and Severe Carotid Stenosis

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Viviana Mancini ◽  
Aslak W. Bergersen ◽  
Kristian Valen-Sendstad ◽  
Patrick Segers
Keyword(s):  
Early Detection ◽  
Carotid Stenosis ◽  
Pressure Fluctuations ◽  
Laser Doppler Vibrometer ◽  
Power Spectra ◽  
Laser Doppler ◽  
Flow Instabilities ◽  
Promising Tool ◽  
The Impact

Abstract Early detection of asymptomatic carotid stenosis is crucial for treatment planning in the prevention of ischemic stroke. Auscultation, the current first-line screening methodology, comes with severe limitations that create urge for novel and robust techniques. Laser Doppler vibrometer (LDV) is a promising tool for inferring carotid stenosis by measuring stenosis-induced vibrations. The goal of the current study was to evaluate the feasibility of LDV for carotid stenosis detection. LDV measurements on a carotid phantom were used to validate our previously verified high-resolution computational fluid dynamics methodology, which was used to evaluate the impact of flowrate, flow split, and stenosis severity on the poststenotic intensity of flow instabilities (IFI). We evaluated sensitivity, specificity, and accuracy of using IFI for stenoses detection. Linear regression analyses showed that computationally derived pressure fluctuations correlated (R2 = 0.98) with LDV measurements of stenosis-induced vibrations. The flowrate of stenosed vessels correlated (R2 = 0.90) with the presence of poststenotic instabilities. Receiver operating characteristic analyses of power spectra revealed that the most relevant frequency bands for the detection of moderate (56–76%) and severe (86–96%) stenoses were 80–200 Hz and 0–40 Hz, respectively. Moderate stenosis was identified with sensitivity and specificity of 90%; values decreased to 70% for severe stenosis. The use of LDV as screening tool for asymptomatic stenosis can potentially provide improved accuracy of current screening methodologies for early detection. The applicability of this promising device for mass screening is currently being evaluated clinically.

scholarly journals Spike generation estimated from stationary spike trains in a variety of neurons in vivo

2014 ◽  
Vol 8 ◽  
Author(s):  
Anton Spanne ◽  
Pontus Geborek ◽  
Fredrik Bengtsson ◽  
Henrik Jörntell
Keyword(s):  
Spike Trains ◽  
Spike Generation

Electrosensory stimulus-intensity thresholds in the weakly electric knifefish Eigenmannia: reduced sensitivity at harmonics of its own organ discharge

1995 ◽  
Vol 198 (11) ◽  
pp. 2365-2372 ◽  
Author(s):  
I Kaunzinger ◽  
B Kramer
Keyword(s):  
Stimulus Intensity ◽  
Stimulus Frequency ◽  
Sine Wave ◽  
Response Threshold ◽  
Water Conductivity ◽  
Similar Frequency ◽  
Signal Perception ◽  
Intensity Threshold ◽  
Intensity Response ◽  
Threshold Increase

The South American knifefish Eigenmannia sp. can detect the electric organ discharges (EODs; 250­600 Hz) of conspecifics when they are superimposed over its own EOD. This study investigates the minimum frequency difference necessary for such signal perception, using the application of sine-wave stimuli. Electrosensory stimulus-intensity thresholds were determined for trained fish using stimuli associated with food rewards. These sine-wave stimuli were 'clamped' to the EOD frequency of the fish. Electrosensory thresholds were also determined for the spontaneous jamming avoidance response (JAR; a change in EOD frequency evoked by a stimulus of sufficiently similar frequency), in this case using unclamped stimuli. Over the wide frequency range investigated (0.3­3.01 times EOD frequency), the lowest stimulus-intensity thresholds of 0.6 µV cm-1 (peak-to-peak) (0 dB) at a water conductivity of 100 µS cm-1 were found close to (but not exactly at) the EOD fundamental frequency. At exact frequency identity between the EOD and the stimulus, the stimulus-intensity response threshold rose abruptly by more than 10 dB compared with slightly higher or lower stimulus frequencies. A similar 'needle-like' threshold increase was found at exactly two and three times the EOD frequency, but neither at harmonic ratios between stimulus and EOD frequency that represent fractions (e.g. at 5:4=1.25, 4:3=1.33, 3:2=1.5 or 5:3=1.67 times EOD frequency) nor at subharmonics such as half or two-thirds of the EOD frequency. The steepest increase of stimulus-intensity response threshold was in the range 0.998­1.002 times EOD frequency, corresponding to a threshold change, or electrosensory filter slope, of 5000 dB per octave. For the spontaneous JAR, a similar stimulus-intensity threshold increase was observed when EOD frequency equalled stimulus frequency. Because of the longer rise time for the stimulus amplitude (400 ms rather than 35 ms) the stimulus intensity threshold was higher (up to 32 dB; mean, 20 dB) than in the other experiments (up to 15 dB; mean, 13 dB). A difference in frequency between the EOD and the applied stimulus as small as 1 Hz (that is, 0.2 % of the EOD frequency) was sufficient for good signal perception in Eigenmannia sp. The JAR appears to be useful in avoiding insensitivity at exact integer harmonics of the EOD frequency.

scholarly journals ACAT1 Benchmark of RANS-Informed Analytical Methods for Fan Broadband Noise Prediction: Part II—Influence of the Acoustic Models

Acoustics ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 617-649
Author(s):  
Sébastien Guérin ◽  
Carolin Kissner ◽  
Pascal Seeler ◽  
Ricardo Blázquez ◽  
Pedro Carrasco Laraña ◽  
...  
Keyword(s):  
Analytical Methods ◽  
Acoustic Waves ◽  
Power Spectra ◽  
Low Frequency ◽  
Broadband Noise ◽  
Experimental Results ◽  
Acoustic Analogy ◽  
Noise Sources ◽  
Acoustic Models ◽  
The Impact

A benchmark dedicated to RANS-informed analytical methods for the prediction of turbofan rotor–stator interaction broadband noise was organised within the framework of the European project TurboNoiseBB. The second part of this benchmark focuses on the impact of the acoustic models. Twelve different approaches implemented in seven different acoustic solvers are compared. Some of the methods resort to the acoustic analogy, while some use a direct approach bypassing the calculation of a source term. Due to differing application objectives, the studied methods vary in terms of complexity to represent the turbulence, to calculate the acoustic response of the stator and to model the boundary and flow conditions for the generation and propagation of the acoustic waves. This diversity of approaches constitutes the unique quality of this work. The overall agreement of the predicted sound power spectra is satisfactory. While the comparison between the models show significant deviations at low frequency, the power levels vary within an interval of ±3 dB at mid and high frequencies. The trends predicted by increasing the rotor speed are similar for almost all models. However, most predicted levels are some decibels lower than the experimental results. This comparison is not completely fair—particularly at low frequency—because of the presence of noise sources in the experimental results, which were not considered in the simulations.

Sequence specificity of docetaxel (Doc) and the proteasome inhibitor PS-341 combinations in androgen-independent (AI) prostate cancer (CaP)

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 13150-13150
Author(s):  
W. S. Holland ◽  
P. N. Lara ◽  
T. Kimura ◽  
T. Kenosi ◽  
D. R. Gandara ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Patient Outcomes ◽  
Tumor Volume ◽  
Specific Cell ◽  
Sequence Specificity ◽  
Cycle Arrest ◽  
Best Response ◽  
Altered Cell

13150 Background: AI CaP is an invariably fatal disease. While treatment with Doc, a microtubule-stabilizing taxane, improves survival, patient outcomes remain suboptimal. PS-341 inhibits degradation of cell cycle and tumor suppressor proteins resulting in cycle arrest and apoptosis. We hypothesized that the combination of Doc with PS-341 would abrogate the abnormal survival response seen in AI CaP and lead to improved tumor cell kill, but that results would be dependent on administration schedule due to interactive cell cycle kinetics. Methods: The PC3 cell line model of AI CaP was evaluated in vitro and in vivo to determine response to Doc or PS-341 alone, and in combination in sequences of PS-341→Doc, Doc→PS-341, and simultaneous (PS-341 + Doc). Cell cycle and protein analyses were performed by flow cytometry and Western blotting, respectively. For nu/nu mouse xenografts, 5 × 106 cells were injected subcutaneously into each flank. The agents were administered either together or 24hr apart, with all regimens given weekly [IP doses: Doc: 10 mg/kg; PS-341: 0.5 mg/kg]. Results: in vitro: Each combination showed an increased apoptotic sub-G1 population versus untreated cells, in addition to altered cell cycling in a sequence-specific manner. Of the combinations, PS-341 + Doc showed the largest sub-G1 while Doc→PS-341 had the lowest sub-G1 but the largest S-phase content; in vivo: PS-341 + Doc showed a cytotoxic effect (reduction in tumor volume) while the combinations of Doc→PS-341 and PS-341→Doc both showed growth inhibition (stabilization of tumor growth) as best response. Conclusions: Combinations of PS-341 and Doc have sequence specific cell cycle effects leading to increases in apoptosis (PS-341 + Doc) or cell cycle arrest (Doc→PS-341). Clinical validation of these findings is warranted. (ACS: CRTG-0019701-CCE) No significant financial relationships to disclose.

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