Amplitude Of Positive Peak Research Articles

Modelling mouse auditory response dynamics along a continuum of consciousness using a deep recurrent neural network

Objective. Understanding neurophysiological changes that accompany transitions between anaesthetized and conscious states is a key objective of anesthesiology and consciousness science. This study aimed to characterize the dynamics of auditory-evoked potential morphology in mice along a continuum of consciousness. Approach. Epidural field potentials were recorded from above the primary auditory cortices of two groups of laboratory mice: urethane-anaesthetized (A, n = 14) and conscious (C, n = 17). Both groups received auditory stimulation in the form of a repeated pure-tone stimulus, before and after receiving 10 mg kg−1 i.p. ketamine (AK and CK). Evoked responses were then ordered by ascending sample entropy into AK, A, CK, and C, considered to reflect physiological correlates of awareness. These data were used to train a recurrent neural network (RNN) with an input parameter encoding state. Model outputs were compared with grand-average event-related potential (ERP) waveforms. Subsequently, the state parameter was varied to simulate changes in the ERP that occur during transitions between states, and relationships with dominant peak amplitudes were quantified. Main results. The RNN synthesized output waveforms that were in close agreement with grand-average ERPs for each group (r 2 > 0.9, p < 0.0001). Varying the input state parameter generated model outputs reflecting changes in ERP morphology predicted to occur between states. Positive peak amplitudes within 25–50 ms, and negative peak amplitudes within 50–75 ms post-stimulus-onset, were found to display a sigmoidal characteristic during the transition from anaesthetized to conscious states. In contrast, negative peak amplitudes within 0–25 ms displayed greater linearity. Significance. This study demonstrates a method for modelling changes in ERP morphology that accompany transitions between states of consciousness using an RNN. In future studies, this approach may be applied to human data to support the clinical use of ERPs to predict transition to consciousness.

Suppressive Modulation of the Chick Forebrain Network for Imprinting by Thyroid Hormone: An in Vitro Study.

The thyroid hormone 3,5,3′-triiodothyronine (T3) is considered to act acutely in the chick forebrain because focal infusion of T3 to the intermediate medial mesopallium (IMM) causes 4 to 6-day-old hatchlings to become imprintable approximately 30 min after the infusion. To understand the mechanism of this acute T3 action, we examined synaptic responses of IMM neurons in slice preparations in vitro. Extracellular field potential responses to local electrical stimulation were pharmacologically dissociated to synaptic components mediated by AMPA and NMDA receptors, as well as GABA-A and -B receptors. Bath-applied T3 (20–40 μM) enhanced the positive peak amplitude of the field potential, which represented the GABA-A component. Bicuculline induced spontaneous epileptic bursts by NMDA receptor activation, and subsequent application of T3 suppressed the bursting frequency. Pretreatment of slices with T3 failed to influence the synaptic potentiation caused by tetanic stimulation. Intracellular whole-cell recording using a patch electrode confirmed the T3 actions on the GABA-A and NMDA components. T3 enhanced the GABA-A response and suppressed the NMDA plateau potential without changes in the resting membrane potential or the threshold of action potentials. Contrary to our initial expectation, T3 suppressed the synaptic drives of IMM neurons, and did not influence activity-dependent synaptic potentiation. Imprinting-associated T3 influx may act as an acute suppressor of the IMM network.

Modeling pressure variations generated by short train passing in open air

The pressure variation generated when a high-speed train passes in open air affects structures on the ground and causes environmental problems. It was assumed in past studies that the effect of the train nose passage is independent of the tail passage for long trains (with 16 cars). In these studies, only the effect of the nose passage was analyzed with a point source model. However, as the superposition of the effect of the nose and tail is not negligible for short trains (consisting of less than 10 cars), the entire pressure variation should be analyzed. For this purpose, the positions of sources representing the nose and tail need to be considered. In this study, a model experiment and theoretical analysis on the pressure variation when a short train passes in an open air environment were performed. The experimental results show that the negative peak amplitude is greater than the positive peak amplitude for observation points located over 1/10 of the train length away from the train, because of superposition. The distance between the two zero-pressure points is different from the train length. The effects of nose and tail configurations are considered in the proposed line source model and point source model based on the typical potential theory; the prediction results of the models showed good agreement in the waveforms and peak values of the pressure variation compared with those in model experiments. Therefore, we herein demonstrate that the line source model is valid, and the point source model is applicable to short trains when considering the positions of the point sources.

GPR based RTM imaging technology for estimating rhizome diameters and application in the western China mining area

The rhizome functions are of great significance to the ecological protection of the western China mining area, whose ecological management can be provided with technical support via accurate calculations of the rhizome biomass. The rhizome diameter is an important index parameter of rhizome biomass. In this study, we propose an estimation of rhizome diameters based on ground penetrating radar (GPR)-based reverse time migration (RTM) imaging technology. First, the spatial distribution of shallow rhizomes is simulated using the finite difference time domain method. The simulation data are examined via RTM imaging and single-channel rhizome analysis to obtain the rhizome index parameters: Δh, the width of the maximum positive peak amplitude measured at an amplitude of zero, and ΔH, the distance between the zero-amplitude position above the largest positive peak in the shallow region and the zero-amplitude position below the largest positive peak in the deeper region. The experiments of physical models verify the effectiveness of the two parameters (Δh and ΔH). and indicate that the values of Δh and ΔH are independent of the rhizome burial depth; instead, they are only related to the diameter of the rhizome. For both the numerical simulations and the physical model experiment, the estimation errors of Δh and ΔH for the rhizome diameters can be constrained to less than 6% and 5%, respectively, which shows that the estimation of the rhizome diameters using GPR based RTM imaging technology is reasonable and effective and its high estimation accuracy meets the technical requirements.

Alternating streamer propagation in mineral oil under bipolar oscillating impulse voltage

This study aimed to clarify the basic process of streamer propagation in mineral oil at bipolar oscillating impulse voltage. Shadow images and light signals of streamers showed that under bipolar oscillating impulse, positive and negative streamers propagated in an alternating manner: after polarity reversal, new streamers with opposite polarity were initiated and propagated first through the gaseous channels left behind by former streamers and then toward the ground electrode. The velocity of positive streamers was found nearly an order of magnitude higher than that of negative ones; thus, positive streamers are primarily responsible for the insulation failure of mineral oil. Negative streamers played the role of maintaining gaseous channels and facilitating positive streamers initiation due to their strong heat effect. High oscillation frequency and large damping factor decreased the durations and amplitudes of positive peaks, which restrained positive streamer propagation and further resulted in the increase in the breakdown voltage. Experiments on dielectric behavior of mineral oil were conducted to verify above inferences.

2-3-13. Components analysis of transcranial electrical stimulation motor evoked potentials

Muscle action potentials induced by transcranial electrical stimulation (TCSMEP) are well used to know the impairment of motor function under general anesthesia. Though the components of waveforms are not known. We analyzed the origin or meaning of TCSMEP waveforms. All data were obtained from gastrocnemius with a pair of needle electrodes (belly-tendon method) during six times spinal surgeries (intramedurally tumor 5, disk herniation 1). Waveforms consisted of the initial negative spiky wave’s complex (INSWC) and the dull wave of the latter half (LHDW). The smallest negative peak amplitude (SNPA) had positive correlation with the average of other negative peak amplitudes among the initial wave complex. And SNPA is not affected by the fluctuation of positive waveforms. SNPA seemed to be suitable for the indicator of intraoperative monitoring. Furthermore, there was a positive relationship between SNPA and the positive peak amplitudes of LHDW. LHDW seemed to show the difference of electrical potentials that resulted from the shortening of gap distance while the muscle contracted. TCSMEP waveform may consist of major 2 parts at least. INSWC is electrical activity around EC junctions. LHDW is mechanical activity of muscle contractions. These findings are helpful to evaluate and assess TCSMEP precisely.

Variability of Surface Reflection Amplitudes of GPR Horn Antenna Depending on Distance between Antenna and Surface

Abstract The study focused on variability of surface reflections amplitudes of GPR horn antenna in relation to distance between an antenna and a surface is presented in the paper. The air-coupled antenna with the central frequency of 1 GHz was used in the investigation. Four types of surfaces (dry pavement, wet pavement, metal plate and composite layer from gypsum and wood) were tested. The distance of antenna above the surfaces was changed in the range from 37.5 cm to 53.5 cm. The amplitudes of negative and positive peaks and their variability were analysed in relation to the distance of antenna above the surfaces. Moreover, the influence of changes in the peaks of negative and positive amplitudes on the total amplitudes was assessed. It was found out the amplitudes of negative peaks for all investigated surfaces were relatively consistent in the range from 40.5 cm to 48.5 cm and the moderate decline was identified in the case of amplitudes of positive peaks in the range of distances from 37.5 cm to 51.5 cm. This decline influences the tendency of total amplitudes. Based on the results of analysis it can be stated the distance of air-coupled antenna above the surface can influence the value of total amplitude and the differences depend on the type of surface.

Experimental Investigation of Vibration Characteristics for Vapor Cavitation in Plain Journal Bearing

The phenomenon of lubricant cavitation in hydrodynamic bearings and its detrimental effects have been documented in many literatures. Collapse of vapor cavitation bubbles may cause erosion wear that limits the life of the bearings. The ability to detect the occurrence of vapor cavitation using a well established condition monitoring technique is essential for the equipment operator. An experiment was conducted to investigate the vibration characteristics of vapor cavitation in steadily loaded plain journal bearings. Vibration data were collected from the bearings operating under the influence of vapor cavitation. It is shown that, vapor cavitation exhibits distinct characteristics on the vibration plots. Low amplitude, forward and reverse 0.063X frequency components, and a series of harmonics with frequencies lower than 0.5X, are observed on the full spectrum. A unique waveform with the positive peak amplitude fluctuating above and below the zero axis line is also observed.

Accurate decoding of sub-TR timing differences in stimulations of sub-voxel regions from multi-voxel response patterns

We investigated the decoding of ocular dominance stimulations with millisecond-order timing difference from the blood oxygen level dependent (BOLD) signal in human functional magnetic resonance imaging (fMRI). In our experiment, ocular dominance columns were activated by monocular visual stimulation with 500- or 100- ms onset differences. We observed that the event-related hemodynamic response (HDR) in the human visual cortex was sensitive to the subtle onset difference. The HDR shapes were related to the stimulus timings in various manners: the timing difference was represented in either the amplitude of positive peak, amplitude of negative peak, delay of peak time, or response duration of HDR. These complex relationships were different across voxels and subjects. To find an informative feature of HDR for discriminating the subtle timing difference of ocular dominance stimulations, we examined various characteristics of HDR including response amplitude, time to peak, full width at half-maximum response, as inputs for decoding analysis. Using a canonical HDR function for estimating the voxel's response did not yield good decoding scores, suggesting that information may reside in the variability of HDR shapes. Using all the values from the deconvolved HDR also showed low performance, which could be due to an over-fitting problem with the large data dimensionality. When using either positive or negative peak amplitude of the deconvolved HDR, high decoding performance could be achieved for both the 500ms and the 100ms onset differences. The high accuracy even for the 100ms difference, given that the signal was sampled at a TR of 250ms and 2×2×3-mm voxels, implies a possibility of spatiotemporally hyper-resolution decoding. Furthermore, both down-sampling and smoothing did not affect the decoding accuracies very much. These results suggest a complex spatiotemporal relationship between the multi-voxel pattern of the BOLD response and the population activation of neuronal columns. The demonstrated possibility of decoding stimulations for columnar-level organization with 100-ms onset difference using lower resolution imaging data may broaden the scope of application of the BOLD fMRI.

Development of BOLD signal hemodynamic responses in the human brain

In the rodent brain the hemodynamic response to a brief external stimulus changes significantly during development. Analogous changes in human infants would complicate the determination and use of the hemodynamic response function (HRF) for functional magnetic resonance imaging (fMRI) in developing populations. We aimed to characterize HRF in human infants before and after the normal time of birth using rapid sampling of the Blood Oxygen Level Dependent (BOLD) signal. A somatosensory stimulus and an event related experimental design were used to collect data from 10 healthy adults, 15 sedated infants at term corrected post menstrual age (PMA) (median 41 + 1 weeks), and 10 preterm infants (median PMA 34 + 4 weeks). A positive amplitude HRF waveform was identified across all subject groups, with a systematic maturational trend in terms of decreasing time-to-peak and increasing positive peak amplitude associated with increasing age. Application of the age-appropriate HRF models to fMRI data significantly improved the precision of the fMRI analysis. These findings support the notion of a structured development in the brain's response to stimuli across the last trimester of gestation and beyond.

Propagation properties of PD-induced electromagnetic wave in GIS model tank with T branch structure

The authors investigated the influence of a T-branch on propagation properties of PD-induced electromagnetic (EM) wave measured with ultra high frequency (UHF) sensors in 66 kV and 154 kV gas insulated switchgears (GIS). A low pass filtering (LPF) process for the cutoff frequency of TE11 mode was used to eliminate the higher order mode above TE11 of detected signal. The authors discussed the effects of the T-branch on the positive peak amplitude of the first wave Vp of propagating EM wave after the LPF processing. As a result, TEM mode propagates according to the traveling theory based on the distributed constant circuit with considering the characteristic impedance of the T-branch. In addition, a high pass filtering (HPF) process for the cutoff frequency of TE11 mode was used to eliminate the lower frequency component below TE11 of the detected signal. The authors discussed the effects of the T-branch on the peak to peak amplitude Vpp of propagating EM wave after the HPF processing. The authors compared transmission rate THS of propagating EM wave after HPF processing through T-branch in a straight direction with that THR of propagating EM wave after HPF processing turning in a right angle direction at the T-branch. As a result, it was found that THS was larger than THR with the HPF processing.

Corrigendum

CorrigendaCorrigendumPublished Online:01 Nov 2009https://doi.org/10.1152/jn.z9k-9775-corr.2009Original articleMoreSectionsPDF (152 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Volume 102, August 2009Tolnai S, Englitz B, Scholbach J, Jost J, and Rübsamen R. Spike Transmission Delay at the Calyx of Held In Vivo: Rate Dependence, Phenomenological Modeling, and Relevance for Sound Localization. J Neurophysiol 102: , 2009. First published June 10, 2009; doi:10.1152/jn.00275.2009; http://jn.physiology.org/cgi/content/full/102/2/1206.During production, parts of Fig. 1 were shifted and gave a misleading illustration of the measurements depicted. The corrected version of Fig. 1 appears here.Fig. 1.Measuring the action potential transmission delay (ATD). A: extracellular recordings of responses to acoustic stimulations of principal cells of the medial nucleus of the trapezoid body (MNTB) and their presynaptic input, the calyces of Held in the Mongolian gerbil. Due to the size of the calyx, extracellular recordings resemble complex waveforms that consist of the discharge of the calyx (prepotential) and the action potential (AP) of the principal cell. ATD was measured as the distance between the positive peak amplitudes of prepotential and postsynaptic AP. B: ATD measured under silent condition depends on the spontaneous discharge rate of a given MNTB unit. Significantly higher ATDspont are found in units with higher spontaneous rates. C: extracellular recording (top) of a unit's response to a sequence of pure tones (bottom, duration: 100 ms, interstimulus interval: 100 ms, stimulus amplitudes in decreasing order, not to scale). D: mean complex waveforms of the same unit as in C for 5 different ATDs (380–460 μs, black to red) aligned to the prepotential (top) and to the postsynaptic AP (bottom). Individual complex waveforms of ATDs in a 10 μs bin were pooled into each mean complex waveform. E and F: changes in ATD and firing rate correlate (same unit as in C). ATD (E) changes as a function of intensity and frequency of the acoustic stimulus and the firing rate (F) show a very similar profile.Download figureDownload PowerPointThis article has no references to display. Download PDF Previous Back to Top FiguresReferencesRelatedInformationRelated ArticlesSpike Transmission Delay at the Calyx of Held In Vivo: Rate Dependence, Phenomenological Modeling, and Relevance for Sound Localization 01 Aug 2009Journal of Neurophysiology More from this issue > Volume 102Issue 5November 2009Pages 3077-3077 Copyright & PermissionsCopyright © 2009 the American Physiological Societyhttps://doi.org/10.1152/jn.z9k-9775-corr.2009History Published online 1 November 2009 Published in print 1 November 2009 Metrics

Magnetic Field Generation at Early-Stage KrF Excimer Laser Ablation Of Solid Substrates

AbstractMagnetic field generation at early-stage of KrF excimer laser ablation of solid substrates (for delay time less than 200 ns) is investigated. Based on classical electrodynamics, fast and dynamic emission of electrons and positive ions at the beginning of laser ablation induces an electromagnetic field nearby. A tiny iron probe wrapped with 50-turn coil is applied to detect this dynamic magnetic field. It is found that signal waveform is closely related to probe distance from the laser spot. For probe distance less than a threshold, the signal has a double-peak profile with a negative peak appearing first and peak durations in tens of nanoseconds. As probe distance increases, the amplitude of positive peak reduces much faster than the negative one. It disappears for probe distance up to the threshold and signal waveform becomes a negative peak with a wider duration. Mechanism on magnetic field generation at early-stage of laser ablation is analyzed to obtain more information on charged particle dynamics. Dependence of the magnetic signal on laser fluence, substrate bias and pulse number is also studied during laser ablation of solid substrates and removal of metallic oxide layer on the surface.

Motor unit size estimation: confrontation of surface EMG with macro EMG

Surface EMG (SEMG) is little used for diagnostic purposes in clinical neurophysiology, mainly because it provides little direct information on individual motor units (MUs). One of the techniques to estimate the MU size is intra-muscular Macro EMG. The present study compares SEMG with Macro EMG. Fifty-eight channel SEMG was recorded simultaneously with Macro EMG. Individual MUPs were obtained by single fiber triggered averaging. All recordings were made from the biceps brachii of healthy subjects during voluntary contraction at low force. High positive correlations were found between all Macro and Surface motor unit potential (MUP) parameters: area, peak-to-peak amplitude, negative peak amplitude and positive peak amplitude. The MUPs recorded with SEMG were dependent on the distance between the MU and the skin surface. Normalizing the SEMG parameters for MU location did not improve the correlation coefficient between the parameters of both techniques. The two measurement techniques had almost the same relative range in MUP parameters in any individual subject compared to the others, especially after normalizing the surface MUP parameters for MU location. MUPs recorded with this type of SEMG provide useful information about the MU size.

Motor unit potential contribution to surface electromyography.

The background of the bioelectric activity of muscle recorded from the surface of the skin (surface electromyography) in terms of the representation of single motor units of the underlying muscle(s) is not very well documented or understood. An insight into the composition of an electromyogram is essential for the proper interpretation of one of the most widely applied electrophysiological techniques. In the present paper, a study of the contribution of single motor unit potentials to the surface electromyogram is presented. To this end, the decline of different components of the motor unit potential with depth of the motor unit is quantified. Experimentally, the action potentials from motor units at several positions in the muscle were recorded by 30 skin surface electrodes. Simultaneous use of scanning electromyography provided information about the actual position and size of the motor unit. Observed linear log-log relationships between motor unit potential magnitudes and distance indicated the usefulness of a power function to describe the motor unit potential's dependence on recording distance. It is shown that different specific surface motor unit potential characteristics fall off differently with depth. The magnitude-distance relationship is shown to be dependent on the recording configuration (unipolar vs. bipolar recording, including the inter-electrode distance) and the chosen motor unit potential parameter (negative peak amplitude, positive peak amplitude and area).

A 4-parameter discriminator of neuronal spike activity

A discriminator for the real-time segregation of the unit activity of different neurons according to any combination of the following parameters of its waveform is described: (a) positive peak amplitude (separated into seven levels); (b) peak value of the negative spike wave (seven levels); (c) time interval (partitioned into 16 classes) between consecutive crossings of two preset levels; (d) the sequence of positive and negative parts of the spike. The discriminator, which implements several innovations, has shown good results in practical applications. The output of the discrimiminator (coded into 12 bits) can be evaluated either by a laboratory computer where it acts as a peripheral device, or by a supplementary apparatus, which is also described.