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Panchev, Christo, i Stefan Wermter. "Spike-timing-dependent synaptic plasticity: from single spikes to spike trains". Neurocomputing 58-60 (czerwiec 2004): 365–71. http://dx.doi.org/10.1016/j.neucom.2004.01.068.
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S B, Jadhav, Vichare S V i Katwate S M. "Evaluation of Hybrids and Cultivars of Single type Tuberose (Polianthes tuberosa)". Journal of Horticultural Sciences 15, nr 1 (30.06.2020): 67–71. http://dx.doi.org/10.24154/jhs.2020.v15i01.009.
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Hybrids and cultivars of single type tuberose was evaluated to fulfill the need to develop new hybrids as demanded by commercial growers. Evaluation of fifteen genotypes showed significant variation in growth, floral and bulb characters. Cultivar Arka Prajwal was significantly superior over all genotypes, which recorded least number of days for opening of 1st floret (78.55 days) with maximum diameter of spike (1.18 cm), length of floret (6.05 cm), weight of individual floret (3.12 g) and weight of spike (121.43 g).The hybrid genotype L1P4 (Variegated X Phule Rajani) was observed to be superior in terms of rachis length (39.78 cm), inter-nodal length (7.25 cm), length of bulb (8.09 cm), diameter of bulb (3.76 cm) and diameter of bulb-lets (1.85 cm). Among the hybrid genotypes L1P4 also recorded maximum plant height (116.39 cm), spike length (109.58 cm), weight of cut spike (105.08 g) and vase life (11.00 days). However, it was foundto be at par for number of florets per spike (57.25), length of floret (5.92 cm) and number of spikes per clump (10.14) with all other cultivars and hybrids tested. From the overall performance, it was found that the cultivar Arka Prajwal was the best. Genotype L1P4 found promising for loose as well as cut flower production because of its number of florets, inter-nodal length and spikes per clump which are important characters considering loose flower for taking maximum number of pickings. However, characters such as rachis length, spike length, vase life and weight of spike which are imperative for cut flowers are also noted superior in genotype L1P4.
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S B, Jadhav, Vichare S V i Katwate S M. "Evaluation of Hybrids and Cultivars of Single type Tuberose (Polianthes tuberosa)". Journal of Horticultural Sciences 15, nr 1 (30.06.2020): 67–71. http://dx.doi.org/10.24154/jhs.v15i1.785.
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Hybrids and cultivars of single type tuberose was evaluated to fulfill the need to develop new hybrids as demanded by commercial growers. Evaluation of fifteen genotypes showed significant variation in growth, floral and bulb characters. Cultivar Arka Prajwal was significantly superior over all genotypes, which recorded least number of days for opening of 1st floret (78.55 days) with maximum diameter of spike (1.18 cm), length of floret (6.05 cm), weight of individual floret (3.12 g) and weight of spike (121.43 g).The hybrid genotype L1P4 (Variegated X Phule Rajani) was observed to be superior in terms of rachis length (39.78 cm), inter-nodal length (7.25 cm), length of bulb (8.09 cm), diameter of bulb (3.76 cm) and diameter of bulb-lets (1.85 cm). Among the hybrid genotypes L1P4 also recorded maximum plant height (116.39 cm), spike length (109.58 cm), weight of cut spike (105.08 g) and vase life (11.00 days). However, it was foundto be at par for number of florets per spike (57.25), length of floret (5.92 cm) and number of spikes per clump (10.14) with all other cultivars and hybrids tested. From the overall performance, it was found that the cultivar Arka Prajwal was the best. Genotype L1P4 found promising for loose as well as cut flower production because of its number of florets, inter-nodal length and spikes per clump which are important characters considering loose flower for taking maximum number of pickings. However, characters such as rachis length, spike length, vase life and weight of spike which are imperative for cut flowers are also noted superior in genotype L1P4.
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Lu, Maolin. "Single-Molecule FRET Imaging of Virus Spike–Host Interactions". Viruses 13, nr 2 (21.02.2021): 332. http://dx.doi.org/10.3390/v13020332.
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As a major surface glycoprotein of enveloped viruses, the virus spike protein is a primary target for vaccines and anti-viral treatments. Current vaccines aiming at controlling the COVID-19 pandemic are mostly directed against the SARS-CoV-2 spike protein. To promote virus entry and facilitate immune evasion, spikes must be dynamic. Interactions with host receptors and coreceptors trigger a cascade of conformational changes/structural rearrangements in spikes, which bring virus and host membranes in proximity for membrane fusion required for virus entry. Spike-mediated viral membrane fusion is a dynamic, multi-step process, and understanding the structure–function-dynamics paradigm of virus spikes is essential to elucidate viral membrane fusion, with the ultimate goal of interventions. However, our understanding of this process primarily relies on individual structural snapshots of endpoints. How these endpoints are connected in a time-resolved manner, and the order and frequency of conformational events underlying virus entry, remain largely elusive. Single-molecule Förster resonance energy transfer (smFRET) has provided a powerful platform to connect structure–function in motion, revealing dynamic aspects of spikes for several viruses: SARS-CoV-2, HIV-1, influenza, and Ebola. This review focuses on how smFRET imaging has advanced our understanding of virus spikes’ dynamic nature, receptor-binding events, and mechanism of antibody neutralization, thereby informing therapeutic interventions.
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Scott, John W., i Lisa Sherrill. "Effects of Odor Stimulation on Antidromic Spikes in Olfactory Sensory Neurons". Journal of Neurophysiology 100, nr 6 (grudzień 2008): 3074–85. http://dx.doi.org/10.1152/jn.90399.2008.
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Spikes were evoked in rat olfactory sensory neuron (OSN) populations by electrical stimulation of the olfactory bulb nerve layer in pentobarbital anesthetized rats. The latencies and recording positions for these compound spikes showed that they originated in olfactory epithelium. Dual simultaneous recordings indicated conduction velocities in the C-fiber range, around 0.5 m/s. These spikes are concluded to arise from antidromically activated olfactory sensory neurons. Electrical stimulation at 5 Hz was used to track changes in the size and latency of the antidromic compound population spike during the odor response. Strong odorant stimuli suppressed the spike size and prolonged its latency. The latency was prolonged throughout long odor stimuli, indicating continued activation of olfactory receptor neuron axons. The amounts of spike suppression and latency change were strongly correlated with the electroolfactogram (EOG) peak size evoked at the same site across odorants and across stimulus intensities. We conclude that the curve of antidromic spike suppression gives a reasonable representation of spiking activity in olfactory sensory neurons driven by odorants and that the correlation of peak spike suppression with the peak EOG shows the accuracy of the EOG as an estimate of intracellular potential in the population of olfactory sensory neurons. In addition, these results have important implications about traffic in olfactory nerve bundles. We did not observe multiple peaks corresponding to stimulated and unstimulated receptor neurons. This suggests synchronization of spikes in olfactory nerve, perhaps by ephaptic interactions. The long-lasting effect on spike latency shows that action potentials continue in the nerve throughout the duration of an odor stimulus in spite of many reports of depolarization block in olfactory receptor neuron cell bodies. Finally, strong odor stimulation caused almost complete block of antidromic spikes. This indicates that a very large proportion of olfactory axons was activated by single strong odor stimuli.
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Herfst, Lucas J., i Michael Brecht. "Whisker Movements Evoked by Stimulation of Single Motor Neurons in the Facial Nucleus of the Rat". Journal of Neurophysiology 99, nr 6 (czerwiec 2008): 2821–32. http://dx.doi.org/10.1152/jn.01014.2007.
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The lateral facial nucleus is the sole output structure whose neuronal activity leads to whisker movements. To understand how single facial nucleus neurons contribute to whisker movement we combined single-cell stimulation and high-precision whisker tracking. Half of the 44 stimulated neurons gave rise to fast whisker protraction or retraction movement, whereas no stimulation-evoked movements could be detected for the remainder. Direction, speed, and amplitude of evoked movements varied across neurons. Protraction movements were more common than retraction movements ( n = 16 vs. n = 4), had larger amplitudes (1.8 vs. 0.3° for single spike events), and most protraction movements involved only a single whisker, whereas most retraction movements involved multiple whiskers. We found a large range in the amplitude of single spike-evoked whisker movements (0.06–5.6°). Onset of the movement occurred at 7.6 (SD 2.5) ms after the spike and the time to peak deflection was 18.2 (SD 4.3) ms. Each spike reliably evoked a stereotyped movement. In two of five cases peak whisker deflection resulting from consecutive spikes was larger than expected when based on linear summation of single spike-evoked movement profiles. Our data suggest the following coding scheme for whisker movements in the facial nucleus. 1) Evoked movement characteristics depend on the identity of the stimulated neuron (a labeled line code). 2) The facial nucleus neurons are heterogeneous with respect to the movement properties they encode. 3) Facial nucleus spikes are translated in a one-to-one manner into whisker movements.
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Doron, Guy, i Michael Brecht. "What single-cell stimulation has told us about neural coding". Philosophical Transactions of the Royal Society B: Biological Sciences 370, nr 1677 (19.09.2015): 20140204. http://dx.doi.org/10.1098/rstb.2014.0204.
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In recent years, single-cell stimulation experiments have resulted in substantial progress towards directly linking single-cell activity to movement and sensation. Recent advances in electrical recording and stimulation techniques have enabled control of single neuron spiking in vivo and have contributed to our understanding of neuronal coding schemes in the brain. Here, we review single neuron stimulation effects in different brain structures and how they vary with artificially inserted spike patterns. We briefly compare single neuron stimulation with other brain stimulation techniques. A key advantage of single neuron stimulation is the precise control of the evoked spiking patterns. Systematically varying spike patterns and measuring evoked movements and sensations enables ‘decoding’ of the single-cell spike patterns and provides insights into the readout mechanisms of sensory and motor cortical spikes.
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Gong, Xiajing, Wu Li i Hualou Liang. "Spike-field Granger causality for hybrid neural data analysis". Journal of Neurophysiology 122, nr 2 (1.08.2019): 809–22. http://dx.doi.org/10.1152/jn.00246.2019.
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Neurotechnological innovations allow for simultaneous recording at various scales, ranging from spiking activity of individual neurons to large neural populations’ local field potentials (LFPs). This capability necessitates developing multiscale analysis of spike-field activity. A joint analysis of the hybrid neural data is crucial for bridging the scales between single neurons and local networks. Granger causality is a fundamental measure to evaluate directional influences among neural signals. However, it is mainly limited to inferring causal influence between the same type of signals—either LFPs or spike trains—and not well developed between two different signal types. Here we propose a model-free, nonparametric spike-field Granger causality measure for hybrid data analysis. Our measure is distinct from existing methods in that we use “binless” spikes (precise spike timing) rather than “binned” spikes (spike counts within small consecutive time windows). The latter clearly distort the information in the mixed analysis of spikes and LFP. Therefore, our spectral estimate of spike trains is directly applied to the neural point process itself, i.e., sequences of spike times rather than spike counts. Our measure is validated by an extensive set of simulated data. When the measure is applied to LFPs and spiking activity simultaneously recorded from visual areas V1 and V4 of monkeys performing a contour detection task, we are able to confirm computationally the long-standing experimental finding of the input-output relationship between LFPs and spikes. Importantly, we demonstrate that spike-field Granger causality can be used to reveal the modulatory effects that are inaccessible by traditional methods, such that spike→LFP Granger causality is modulated by the behavioral task, whereas LFP→spike Granger causality is mainly related to the average synaptic input. NEW & NOTEWORTHY It is a pressing question to study the directional interactions between local field potential (LFP) and spiking activity. In this report, we propose a model-free, nonparametric spike-field Granger causality measure that can be used to reveal directional influences between spikes and LFPs. This new measure is crucial for bridging the scales between single neurons and neural networks; hence it represents an important step to explicate how the brain orchestrates information processing.
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Zhang, Rui, Dianlei Han, Guolong Yu, Haitao Wang, Haibao Liu, Haibin Yu i Jianqiao Li. "Bionic research on spikes based on the tractive characteristics of ostrich foot toenail". SIMULATION 96, nr 9 (10.06.2020): 713–23. http://dx.doi.org/10.1177/0037549720927080.
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Inspired by the superior fixed and traction characteristics of ostrich foot toenails, we devised, optimized and manufactured the single structure and group arrangement of a new-style bionic spike for sprint shoes to improve athletic performance. The tractive performance of the bionic spike was tested by finite element analysis and experimental verification. The optimized single structure of the bionic spike had a top slope angle of 13° and the radius of the medial groove of 7.3 mm. Compared with the conventional conic spike, the maximal and stable extrusion resistances of the single bionic spike decreased by about 25% and 40% respectively, while the maximal and stable horizontal thrusts increased by about 16% and 10%, respectively. In addition, the arrangement of the bionic spikes was also optimized. Compared with the conventional spike group, the maximal and stable extrusion resistances of the bionic spike group decreased by 11.0% and 6.2%, respectively, while the maximal and stable horizontal thrusts increased by 20.0% and 16.0%, respectively. The current results may provide useful mechanical information that can help develop a better design of athletic shoes with the potential for advanced performance.
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Park, In Yong, Junsik Eom, Hanbyol Jang, Sewon Kim, Sanggeon Park, Yeowool Huh i Dosik Hwang. "Deep Learning-Based Template Matching Spike Classification for Extracellular Recordings". Applied Sciences 10, nr 1 (31.12.2019): 301. http://dx.doi.org/10.3390/app10010301.
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We propose a deep learning-based spike sorting method for extracellular recordings. For analysis of extracellular single unit activity, the process of detecting and classifying action potentials called “spike sorting” has become essential. This is achieved through distinguishing the morphological differences of the spikes from each neuron, which arises from the differences of the surrounding environment and characteristics of the neurons. However, cases of high structural similarity and noise make the task difficult. And for manual spike sorting, it requires professional knowledge along with extensive time cost and suffers from human bias. We propose a deep learning-based spike sorting method on extracellular recordings from a single electrode that is efficient, robust to noise, and accurate. In circumstances where labelled data does not exist, we created pseudo-labels through principal component analysis and K-means clustering to be used for multi-layer perceptron training and built high performing spike classification model. When tested, our model outperformed conventional methods by 2.1% on simulation data of various noise levels, by 6.0% on simulation data of various clusters count, and by 1.7% on in-vivo data. As a result, we showed that the deep learning-based classification can classify spikes from extracellular recordings, even showing high classification accuracy on spikes that are difficult even for manual classification.
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Zanos, Theodoros P., Patrick J. Mineault i Christopher C. Pack. "Removal of Spurious Correlations Between Spikes and Local Field Potentials". Journal of Neurophysiology 105, nr 1 (styczeń 2011): 474–86. http://dx.doi.org/10.1152/jn.00642.2010.
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Single neurons carry out important sensory and motor functions related to the larger networks in which they are embedded. Understanding the relationships between single-neuron spiking and network activity is therefore of great importance and the latter can be readily estimated from low-frequency brain signals known as local field potentials (LFPs). In this work we examine a number of issues related to the estimation of spike and LFP signals. We show that spike trains and individual spikes contain power at the frequencies that are typically thought to be exclusively related to LFPs, such that simple frequency-domain filtering cannot be effectively used to separate the two signals. Ground-truth simulations indicate that the commonly used method of estimating the LFP signal by low-pass filtering the raw voltage signal leads to artifactual correlations between spikes and LFPs and that these correlations exert a powerful influence on popular metrics of spike–LFP synchronization. Similar artifactual results were seen in data obtained from electrophysiological recordings in macaque visual cortex, when low-pass filtering was used to estimate LFP signals. In contrast LFP tuning curves in response to sensory stimuli do not appear to be affected by spike contamination, either in simulations or in real data. To address the issue of spike contamination, we devised a novel Bayesian spike removal algorithm and confirmed its effectiveness in simulations and by applying it to the electrophysiological data. The algorithm, based on a rigorous mathematical framework, outperforms other methods of spike removal on most metrics of spike–LFP correlations. Following application of this spike removal algorithm, many of our electrophysiological recordings continued to exhibit spike–LFP correlations, confirming previous reports that such relationships are a genuine aspect of neuronal activity. Overall, these results show that careful preprocessing is necessary to remove spikes from LFP signals, but that when effective spike removal is used, spike–LFP correlations can potentially yield novel insights about brain function.
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Telenczuk, Bartosz, Stuart N. Baker, Andreas V. M. Herz i Gabriel Curio. "High-frequency EEG covaries with spike burst patterns detected in cortical neurons". Journal of Neurophysiology 105, nr 6 (czerwiec 2011): 2951–59. http://dx.doi.org/10.1152/jn.00327.2010.
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Invasive microelectrode recordings measure neuronal spikes, which are commonly considered inaccessible through standard surface electroencephalogram (EEG). Yet high-frequency EEG potentials (hf-EEG, f > 400 Hz) found in somatosensory evoked potentials of primates may reflect the mean population spike responses of coactivated cortical neurons. Since cortical responses to electrical nerve stimulation vary strongly from trial to trial, we investigated whether the hf-EEG signal can also echo single-trial variability observed at the single-unit level. We recorded extracellular single-unit activity in the primary somatosensory cortex of behaving macaque monkeys and identified variable spike burst responses following peripheral stimulation. Each of these responses was classified according to the timing of its spike constituents, conforming to one of a discrete set of spike patterns. We here show that these spike patterns are accompanied by variations in the concomitant epidural hf-EEG. These variations cannot be explained by fluctuating stimulus efficacy, suggesting that they were generated within the thalamocortical network. As high-frequency EEG signals can also be reliably recorded from the scalp of human subjects, they may provide a noninvasive window on fluctuating cortical spike activity in humans.
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Hamilton, K. A., i J. S. Kauer. "Responses of mitral/tufted cells to orthodromic and antidromic electrical stimulation in the olfactory bulb of the tiger salamander". Journal of Neurophysiology 59, nr 6 (1.06.1988): 1736–55. http://dx.doi.org/10.1152/jn.1988.59.6.1736.
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1. Responses evoked by electrical stimulation of the olfactory nerve and olfactory tracts were analyzed in 46 output cells of the salamander olfactory bulb, in vivo. Labeling of several cells with horseradish peroxidase indicated that they were mitral and/or tufted neurons. The responses contained reproducible sequences of depolarizing and hyperpolarizing potentials, which changed with increases in stimulus intensity. 2. Stimulation of the nerve with intensities subthreshold for evoking spikes in the recorded cell resulted in a small depolarization followed by a period of hyperpolarization, during which spontaneous spikes were suppressed. With suprathreshold stimulus intensities, a single spike or often a burst of spikes was evoked, followed by a complex prolonged hyperpolarization. When full spikes were blocked by injecting hyperpolarizing current through the recording electrode, an excitatory postsynaptic potential (EPSP) with two major components and sometimes a fast prepotential were observed at the beginning of the response. Amplitudes of the EPSP and hyperpolarization increased with graded increases in stimulus intensity. In tests with paired stimulus volleys, spike generation was inhibited for at least 1 s and often for several seconds during the hyperpolarization. 3. Stimulation of the tracts with intensities subthreshold for evoking spikes in the recorded cell resulted in a complex prolonged hyperpolarization. With suprathreshold stimulus intensities, a single spike was evoked, followed by a similar period of hyperpolarization. When full spikes were blocked by injecting hyperpolarizing current through the recording electrode, a small antidromic spike, presumably generated in the axon or initial segment, was often observed. Amplitude of the hyperpolarization increased with graded increases in stimulus intensity. In tests with paired volleys, generation of a full antidromic spike was inhibited for a period that usually began 20-30 ms, following the spike evoked by the conditioning stimulus and lasted 100-500 ms. Full antidromic spikes were evoked prior to the period of inhibition and small antidromic spikes were evoked during the period. 4. The mean latencies of single evoked spikes or the first spikes of bursts decreased from 22 to 17 ms with increases in the intensity of nerve stimulation and from 7 to 6 ms with increases in the intensity of tract stimulation. Only decreases in orthodromic latency were significant at P less than or equal to 0.05, as determined by one-sided t tests between the means of responses subdivided according to response pattern and relative stimulus intensity.(ABSTRACT TRUNCATED AT 400 WORDS)
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Paulin, M. G., L. F. Hoffman i C. Assad. "Dynamics and the Single Spike". IEEE Transactions on Neural Networks 15, nr 5 (wrzesień 2004): 987–94. http://dx.doi.org/10.1109/tnn.2004.832814.
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Kim, J. H., S. Ohara i F. A. Lenz. "Mental Arithmetic Leads to Multiple Discrete Changes From Baseline in the Firing Patterns of Human Thalamic Neurons". Journal of Neurophysiology 101, nr 4 (kwiecień 2009): 2107–19. http://dx.doi.org/10.1152/jn.91087.2008.
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Primate thalamic action potential bursts associated with low-threshold spikes (LTS) occur during waking sensory and motor activity. We now test the hypothesis that different firing and LTS burst characteristics occur during quiet wakefulness (spontaneous condition) versus mental arithmetic (counting condition). This hypothesis was tested by thalamic recordings during the surgical treatment of tremor. Across all neurons and epochs, preburst interspike intervals (ISIs) were bimodal at median values, consistent with the duration of type A and type B γ-aminobutyric acid inhibitory postsynaptic potentials. Neuronal spike trains (117 neurons) were categorized by joint ISI distributions into those firing as LTS bursts (G, grouped), firing as single spikes (NG, nongrouped), or firing as single spikes with sporadic LTS bursting (I, intermediate). During the spontaneous condition (46 neurons) only I spike trains changed category. Overall, burst rates (BRs) were lower and firing rates (FRs) were higher during the counting versus the spontaneous condition. Spike trains in the G category sometimes changed to I and NG categories at the transition from the spontaneous to the counting condition, whereas those in the I category often changed to NG. Among spike trains that did not change category by condition, G spike trains had lower BRs during counting, whereas NG spike trains had higher FRs. BRs were significantly greater than zero for G and I categories during wakefulness (both conditions). The changes between the spontaneous and counting conditions are most pronounced for the I category, which may be a transitional firing pattern between the bursting (G) and relay modes of thalamic firing (NG).
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Kistler, Werner M., Wulfram Gerstner i J. Leo van Hemmen. "Reduction of the Hodgkin-Huxley Equations to a Single-Variable Threshold Model". Neural Computation 9, nr 5 (1.07.1997): 1015–45. http://dx.doi.org/10.1162/neco.1997.9.5.1015.
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It is generally believed that a neuron is a threshold element that fires when some variable u reaches a threshold. Here we pursue the question of whether this picture can be justified and study the four-dimensional neuron model of Hodgkin and Huxley as a concrete example. The model is approximated by a response kernel expansion in terms of a single variable, the membrane voltage. The first-order term is linear in the input and its kernel has the typical form of an elementary postsynaptic potential. Higher-order kernels take care of nonlinear interactions between input spikes. In contrast to the standard Volterra expansion, the kernels depend on the firing time of the most recent output spike. In particular, a zero-order kernel that describes the shape of the spike and the typical after-potential is included. Our model neuron fires if the membrane voltage, given by the truncated response kernel expansion, crosses a threshold. The threshold model is tested on a spike train generated by the Hodgkin-Huxley model with a stochastic input current. We find that the threshold model predicts 90 percent of the spikes correctly. Our results show that, to good approximation, the description of a neuron as a threshold element can indeed be justified.
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Friedrich, Reut, i Uri Ashery. "From spike to graph—A complete automated single-spike analysis". Journal of Neuroscience Methods 193, nr 2 (listopad 2010): 271–80. http://dx.doi.org/10.1016/j.jneumeth.2010.09.004.
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Takahashi, Susumu, Yuichiro Anzai i Yoshio Sakurai. "Automatic Sorting for Multi-Neuronal Activity Recorded With Tetrodes in the Presence of Overlapping Spikes". Journal of Neurophysiology 89, nr 4 (1.04.2003): 2245–58. http://dx.doi.org/10.1152/jn.00827.2002.
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Multi-neuronal recording is a powerful electrophysiological technique that has revealed much of what is known about the neuronal interactions in the brain. However, it is difficult to detect precise spike timings, especially synchronized simultaneous firings, among closely neighboring neurons recorded by one common electrode because spike waveforms overlap on the electrode when two or more neurons fire simultaneously. In addition, the non-Gaussian variability (nonstationarity) of spike waveforms, typically seen in the presence of so-called complex spikes, limits the ability to sort multi-neuronal activities into their single-neuron components. Because of these problems, the ordinary spike-sorting techniques often give inaccurate results. Our previous study has shown that independent component analysis (ICA) can solve these problems and separate single-neuron components from multi-neuronal recordings. The ICA has, however, one serious limitation that the number of separated neurons must be less than the number of electrodes. The present study combines the ICA and the efficiency of the ordinary spike-sorting technique (k-means clustering) to solve the spike-overlapping and the nonstationarity problems with no limitation on the number of single neurons to be separated. First, multi-neuronal activities are sorted into an overly large number of clusters by k-means clustering. Second, the sorted clusters are decomposed by ICA. Third, the decomposed clusters are progressively aggregated into a minimal set of putative single neurons based on similarities of basis vectors estimated by ICA. We applied the present procedure to multi-neuronal waveforms recorded with tetrodes composed of four microwires in the prefrontal cortex of awake behaving monkeys. The results demonstrate that there are functional connections among neighboring pyramidal neurons, some of which fire in a precise simultaneous manner and that precisely time-locked monosynaptic connections are working between neighboring pyramidal neurons and interneurons. Detection of these phenomena suggests that the present procedure can sort multi-neuronal activities, which include overlapping spikes and realistic non-Gaussian variability of spike waveforms, into their single-neuron components. We processed several types of synthesized data sets in this procedure and confirmed that the procedure was highly reliable and stable. The present method provides insights into the local circuit bases of excitatory and inhibitory interactions among neighboring neurons.
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Parc, Yong, Chi Shim i Dong Kim. "Toward the Generation of an Isolated TW-Attosecond X-ray Pulse in XFEL". Applied Sciences 8, nr 9 (7.09.2018): 1588. http://dx.doi.org/10.3390/app8091588.
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The isolated terawatt (TW) attosecond (as) hard X-ray pulse will expand the scope of ultrafast science, including the examination of phenomena that have not been studied before, such as the dynamics of electron clouds in atoms, single-molecule imaging, and examining the dynamics of hollow atoms. Therefore, several schemes for the generation of an isolated TW-as X-ray pulse in X-ray free electron laser (XFEL) facilities have been proposed with the manipulation of electron properties such as emittance or current. In a multi-spike scheme, a series of current spikes were employed to amplify the X-ray pulse. A single-spike scheme in which a TW-as X-ray pulse can be generated by a single current spike was investigated for ideal parameters for the XFEL machine. This paper reviews the proposed schemes and assesses the feasibility of each scheme.
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He, Jufang, i Bin Hu. "Differential Distribution of Burst and Single-Spike Responses in Auditory Thalamus". Journal of Neurophysiology 88, nr 4 (1.10.2002): 2152–56. http://dx.doi.org/10.1152/jn.2002.88.4.2152.
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The medial geniculate body (MGB) of the auditory thalamus comprises lemniscal and nonlemniscal neurons that project to the primary auditory cortex and limbic structures, respectively. Here we show that in anesthetized guinea pigs, MGB responses to a noise-burst stimulus exhibit distinct and synaptic pathway-specific firing patterns. The majority of nonlemniscal MGB cells exhibited bursting responses, whereas lemniscal neurons discharged mainly single or spike doublets. The burst firing is delayed in nonlemniscal neurons and exhibited several features that are characteristics of those mediated by low-threshold Ca2+ spikes. Such a synaptic pathway-specific allocation of bursting and single-spike firing patterns is consistent with the notion of parallel processing of auditory information in thalamocortical system.
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Zając, Tadeusz, Wiesław Szafrański i Jacek Strojny. "Kernel mass of winter triticale depending on placing position in a spikelet and a spike, with regard to its productiveness". Acta Agrobotanica 57, nr 1-2 (2013): 175–86. http://dx.doi.org/10.5586/aa.2004.017.
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The investigations were carried outin 1996-1997 on degraded chernozem developed from loess. The winter triticale cv. 'Presto' cultivated after 4 forecrops (spring cereals with red clover undersown and triticale in pure stand). Studied were correlation between the number of spikeIets and kernels and their placing position in a spike and spikelet, and the grain weight from three spike size groups. The number of productive spikelets per spike and fertility of inflorescence per spikelet, measured as a number of kernels, were the biggest in big spikes group. Kernels placed in positions 1 and 2 in a kernel had the biggest mass, whereas the kernels developed from the inflorescence in positions 3 and 4 were conspicuous for their smaller mass, particularly in the small and medium-size spike groups. The analysis of correlation coefficient values revealed that grain weight per spike was strongly correlated with the number of kernels per spike in all determined size classes. Also a significant effect of single kemel weight on yield per spike was noticed, but the coefficient value was lower (r=0.30). Spikelets in positions from 3 to 7 level (on both sides of spike) had the greatest share in grain weight per spike for the smallest spike group, whereas for medium- size and big spikes respectively spikelets in positions 3 through 9 and 2 through 10.
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Guyonneau, Rudy, Rufin VanRullen i Simon J. Thorpe. "Neurons Tune to the Earliest Spikes Through STDP". Neural Computation 17, nr 4 (1.04.2005): 859–79. http://dx.doi.org/10.1162/0899766053429390.
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Spike timing-dependent plasticity (STDP) is a learning rule that modifies the strength of a neuron's synapses as a function of the precise temporal relations between input and output spikes. In many brains areas, temporal aspects of spike trains have been found to be highly reproducible. How will STDP affect a neuron's behavior when it is repeatedly presented with the same input spike pattern? We show in this theoretical study that repeated inputs systematically lead to a shaping of the neuron's selectivity, emphasizing its very first input spikes, while steadily decreasing the postsynaptic response latency. This was obtained under various conditions of background noise, and even under conditions where spiking latencies and firing rates, or synchrony, provided conflicting informations. The key role of first spikes demonstrated here provides further support for models using a single wave of spikes to implement rapid neural processing.
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Hooper, Scott L., Christoph Guschlbauer, Géraldine von Uckermann i Ansgar Büschges. "Different Motor Neuron Spike Patterns Produce Contractions With Very Similar Rises in Graded Slow Muscles". Journal of Neurophysiology 97, nr 2 (luty 2007): 1428–44. http://dx.doi.org/10.1152/jn.01014.2006.
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Graded muscles produce small twitches in response to individual motor neuron spikes. During the early part of their contractions, contraction amplitude in many such muscles depends primarily on the number of spikes the muscle has received, not the frequency or pattern with which they were delivered. Stick insect ( Carausius morosus) extensor muscles are graded and thus would likely show spike-number dependency early in their contractions. Tonic stimulations of the extensor motor nerve showed that the response of the muscles differed from the simplest form of spike-number dependency. However, these differences actually increased the spike-number range over which spike-number dependency was present. When the motor nerve was stimulated with patterns mimicking the motor neuron activity present during walking, amplitude during contraction rises also depended much more on spike number than on spike frequency. A consequence of spike-number dependency is that brief changes in spike frequency do not alter contraction slope and we show here that extensor motor neuron bursts with different spike patterns give rise to contractions with very similar contraction rises. We also examined in detail the early portions of a large number of extensor motor neuron bursts recorded during single-leg walking and show that these portions of the bursts do not appear to have any common spike pattern. Although alternative explanations are possible, the simplest interpretation of these data is that extensor motor neuron firing during leg swing is not tightly controlled.
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Zanos, Stavros, Theodoros P. Zanos, Vasilis Z. Marmarelis, George A. Ojemann i Eberhard E. Fetz. "Relationships between spike-free local field potentials and spike timing in human temporal cortex". Journal of Neurophysiology 107, nr 7 (1.04.2012): 1808–21. http://dx.doi.org/10.1152/jn.00663.2011.
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Intracortical recordings comprise both fast events, action potentials (APs), and slower events, known as local field potentials (LFPs). Although it is believed that LFPs mostly reflect local synaptic activity, it is unclear which of their signal components are most closely related to synaptic potentials and would therefore be causally related to the occurrence of individual APs. This issue is complicated by the significant contribution from AP waveforms, especially at higher LFP frequencies. In recordings of single-cell activity and LFPs from the human temporal cortex, we computed quantitative, nonlinear, causal dynamic models for the prediction of AP timing from LFPs, at millisecond resolution, before and after removing AP contributions to the LFP. In many cases, the timing of a significant number of single APs could be predicted from spike-free LFPs at different frequencies. Not surprisingly, model performance was superior when spikes were not removed. Cells whose activity was predicted by the spike-free LFP models generally fell into one of two groups: in the first group, neuronal spike activity was associated with specific phases of low LFP frequencies, lower spike activity at high LFP frequencies, and a stronger linear component in the spike-LFP model; in the second group, neuronal spike activity was associated with larger amplitude of high LFP frequencies, less frequent phase locking, and a stronger nonlinear model component. Spike timing in the first group was better predicted by the sign and level of the LFP preceding the spike, whereas spike timing in the second group was better predicted by LFP power during a certain time window before the spike.
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de Lange, Enno, i Martin Hasler. "Predicting single spikes and spike patterns with the Hindmarsh–Rose model". Biological Cybernetics 99, nr 4-5 (listopad 2008): 349–60. http://dx.doi.org/10.1007/s00422-008-0260-y.
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S A, Safeena, Thangam M i Singh N P. "Evaluation of Different Cultivars of Tuberose (Polianthes tuberosa L.) under Humid agro Climatic conditions of Goa". Journal of Horticultural Sciences 14, nr 2 (31.12.2019): 109–14. http://dx.doi.org/10.24154/jhs.2019.v14i02.004.
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Tuberose (Polianthes tuberosa L.) is one of the most important tropical bulbous-ornamental cultivated for production of long-lasting flowers spikes. Adaptation and acclimatization of different cultivars under humid agro-climatic conditions of Goa are to be confirmed for their better performance. The present investigation was conducted to evaluate the performance of tuberose cultivars under agro-climatic conditions of Goa during 2014- 2017. Five single and six double cultivars of tuberose were evaluated during the study period. All the cultivars differed in their growth and flowering behaviour. Among the single cultivars, evaluated, maximum number of florets per spike (47.00) was observed in Pune local whereas spike-length (75.59 cm) was maximum in Mexican Single. Among the double cultivars, evaluated, maximum plant height (52.21 cm) and maximum number of leaves per plant (59.63) were recorded with cultivar Arka Suvasini. Leaf length was significantly higher (52.93 cm) in Pearl double whereas leaf width (2.04 cm) was maximum in Calcutta Double. Days to appearance of flower spike were earlier in Arka Suvasini. Minimum days taken for opening of basal floret (84.88 days) were recorded with cultivar Arka Suvasini. Spike girth (0.68 cm), Spike fresh-weight (69.06 cm), floret stalk-length (3.6 cm), floret diameter (5.24 cm), weight of individual floret (3.49 g) and vase life (7.93 days) was significantly maximum in Cv. Arka Suvasini followed by Pearl Double. Based on the performance evaluation cv. Mexican Single among single types and cv. Arka Suvasini and Pearl Double among double types could be recommended for commercial cultivation under agro climatic conditions of Goa.
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S A, Safeena, Thangam M i Singh N P. "Evaluation of Different Cultivars of Tuberose (Polianthes tuberosa L.) under Humid agro Climatic conditions of Goa". Journal of Horticultural Sciences 14, nr 2 (31.12.2019): 109–14. http://dx.doi.org/10.24154/jhs.v14i2.793.
Pełny tekst źródłaStreszczenie:
Tuberose (Polianthes tuberosa L.) is one of the most important tropical bulbous-ornamental cultivated for production of long-lasting flowers spikes. Adaptation and acclimatization of different cultivars under humid agro-climatic conditions of Goa are to be confirmed for their better performance. The present investigation was conducted to evaluate the performance of tuberose cultivars under agro-climatic conditions of Goa during 2014- 2017. Five single and six double cultivars of tuberose were evaluated during the study period. All the cultivars differed in their growth and flowering behaviour. Among the single cultivars, evaluated, maximum number of florets per spike (47.00) was observed in Pune local whereas spike-length (75.59 cm) was maximum in Mexican Single. Among the double cultivars, evaluated, maximum plant height (52.21 cm) and maximum number of leaves per plant (59.63) were recorded with cultivar Arka Suvasini. Leaf length was significantly higher (52.93 cm) in Pearl double whereas leaf width (2.04 cm) was maximum in Calcutta Double. Days to appearance of flower spike were earlier in Arka Suvasini. Minimum days taken for opening of basal floret (84.88 days) were recorded with cultivar Arka Suvasini. Spike girth (0.68 cm), Spike fresh-weight (69.06 cm), floret stalk-length (3.6 cm), floret diameter (5.24 cm), weight of individual floret (3.49 g) and vase life (7.93 days) was significantly maximum in Cv. Arka Suvasini followed by Pearl Double. Based on the performance evaluation cv. Mexican Single among single types and cv. Arka Suvasini and Pearl Double among double types could be recommended for commercial cultivation under agro climatic conditions of Goa.
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Richmond, Barry J., Mike W. Oram i Matthew C. Wiener. "Response Features Determining Spike Times". Neural Plasticity 6, nr 4 (1999): 133–45. http://dx.doi.org/10.1155/np.1999.133.
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Interpreting messages encoded in single neuronal responses requires knowing which features of the responses carry information. That the number of spikes is an important part of the code has long been obvious. In recent years, it has been shown that modulation of the firing rate with about 25 ms precision carries information that is not available from the total number of spikes across the whole response. It has been proposed that patterns of exactly timed (1 ms precision) spikes, such as repeating triplets or quadruplets, might carry information that is not available from knowing about spike count and rate modulation. A model using the spike count distribution, the low pass filtered PSTH (bandwidth below 30 Hz), and, to a small degree, the interspike interval distribution predicts the numbers and types of exactly-timed triplets and quadruplets that are indistinguishable from those found in the data. From this it can be concluded that the coarse (<30 Hz) sequential correlation structure over time gives rise to the exactly timed patterns present in the recorded spike trains. Because the coarse temporal structure predicts the fine temporal structure, the information carried by the fine temporal structure must be completely redundant with that carried by the coarse structure. Thus, the existence of precisely timed spike patterns carrying stimulus-related information does not imply control of spike timing at precise time scales.
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Srivastava, Kyle H., Caroline M. Holmes, Michiel Vellema, Andrea R. Pack, Coen P. H. Elemans, Ilya Nemenman i Samuel J. Sober. "Motor control by precisely timed spike patterns". Proceedings of the National Academy of Sciences 114, nr 5 (18.01.2017): 1171–76. http://dx.doi.org/10.1073/pnas.1611734114.
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A fundamental problem in neuroscience is understanding how sequences of action potentials (“spikes”) encode information about sensory signals and motor outputs. Although traditional theories assume that this information is conveyed by the total number of spikes fired within a specified time interval (spike rate), recent studies have shown that additional information is carried by the millisecond-scale timing patterns of action potentials (spike timing). However, it is unknown whether or how subtle differences in spike timing drive differences in perception or behavior, leaving it unclear whether the information in spike timing actually plays a role in brain function. By examining the activity of individual motor units (the muscle fibers innervated by a single motor neuron) and manipulating patterns of activation of these neurons, we provide both correlative and causal evidence that the nervous system uses millisecond-scale variations in the timing of spikes within multispike patterns to control a vertebrate behavior—namely, respiration in the Bengalese finch, a songbird. These findings suggest that a fundamental assumption of current theories of motor coding requires revision.
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Stüttgen, Maik C., Lourens J. P. Nonkes, H. Rüdiger A. P. Geis, Paul H. Tiesinga i Arthur R. Houweling. "Temporally precise control of single-neuron spiking by juxtacellular nanostimulation". Journal of Neurophysiology 117, nr 3 (1.03.2017): 1363–78. http://dx.doi.org/10.1152/jn.00479.2016.
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Temporal patterns of action potentials influence a variety of activity-dependent intra- and intercellular processes and play an important role in theories of neural coding. Elucidating the mechanisms underlying these phenomena requires imposing spike trains with precisely defined patterns, but this has been challenging due to the limitations of existing stimulation techniques. Here we present a new nanostimulation method providing control over the action potential output of individual cortical neurons. Spikes are elicited through the juxtacellular application of short-duration fluctuating currents (“kurzpulses”), allowing for the sub-millisecond precise and reproducible induction of arbitrary patterns of action potentials at all physiologically relevant firing frequencies (<120 Hz), including minute-long spike trains recorded in freely moving animals. We systematically compared our method to whole cell current injection, as well as optogenetic stimulation, and show that nanostimulation performance compares favorably with these techniques. This new nanostimulation approach is easily applied, can be readily performed in awake behaving animals, and thus promises to be a powerful tool for systematic investigations into the temporal elements of neural codes, as well as the mechanisms underlying a wide variety of activity-dependent cellular processes. NEW & NOTEWORTHY Assessing the impact of temporal features of neuronal spike trains requires imposing arbitrary patterns of spiking on individual neurons during behavior, but this has been difficult to achieve due to limitations of existing stimulation methods. We present a technique that overcomes these limitations by using carefully designed short-duration fluctuating juxtacellular current injections, which allow for the precise and reliable evocation of arbitrary patterns of neuronal spikes in single neurons in vivo.
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McCollum, Jonn, John Larson, Tim Otto, Frank Schottler, Richard Granger i Gary Lynch. "Short-Latency Single Unit Processing in Olfactory Cortex". Journal of Cognitive Neuroscience 3, nr 3 (lipiec 1991): 293–99. http://dx.doi.org/10.1162/jocn.1991.3.3.293.
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Single-unit recording of layer II—III cells in olfactory (piriform) cortex was performed on awake, unrestrained rats actively engaged in learning novel odors in an olfactory discrimination task. Five of the 67 cells tested had very brief monophasic action potentials and high spontaneous firing rates (30–80 Hz); it is suggested that these units were interneurons. The remainder of the neurons had broader spikes and did not discharge for prolonged periods. Thirty-nine percent of the broad spike cells responded to at least one and usually more of the odors presented to the rats during either of the first two trials on which that odor was present, but, in most cases, these responses occurred only very infrequently over the course of subsequent trials. Six percent of the broad-spike group, how ever, continued firing robustly to a single odor but not to others. From these results it appears that most cells in piriform cortex do not respond to most odors, i.e., coding is exceedingly sparse. A subgroup of the predominant broad-spike cell type does react to several odors but this response drops out with repeated exposure, perhaps because of training. However, a few members of this class (a small fraction of the total cell population) do go on responding to a particular odor, thus exhibiting a form of odor specificity. The results are discussed with regard to predictions from recently developed models of the olfactory cortex.
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Diggelmann, Roland, Michele Fiscella, Andreas Hierlemann i Felix Franke. "Automatic spike sorting for high-density microelectrode arrays". Journal of Neurophysiology 120, nr 6 (1.12.2018): 3155–71. http://dx.doi.org/10.1152/jn.00803.2017.
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High-density microelectrode arrays can be used to record extracellular action potentials from hundreds to thousands of neurons simultaneously. Efficient spike sorters must be developed to cope with such large data volumes. Most existing spike sorting methods for single electrodes or small multielectrodes, however, suffer from the “curse of dimensionality” and cannot be directly applied to recordings with hundreds of electrodes. This holds particularly true for the standard reference spike sorting algorithm, principal component analysis-based feature extraction, followed by k-means or expectation maximization clustering, against which most spike sorters are evaluated. We present a spike sorting algorithm that circumvents the dimensionality problem by sorting local groups of electrodes independently with classical spike sorting approaches. It is scalable to any number of recording electrodes and well suited for parallel computing. The combination of data prewhitening before the principal component analysis-based extraction and a parameter-free clustering algorithm obviated the need for parameter adjustments. We evaluated its performance using surrogate data in which we systematically varied spike amplitudes and spike rates and that were generated by inserting template spikes into the voltage traces of real recordings. In a direct comparison, our algorithm could compete with existing state-of-the-art spike sorters in terms of sensitivity and precision, while parameter adjustment or manual cluster curation was not required. NEW & NOTEWORTHY We present an automatic spike sorting algorithm that combines three strategies to scale classical spike sorting techniques for high-density microelectrode arrays: 1) splitting the recording electrodes into small groups and sorting them independently; 2) clustering a subset of spikes and classifying the rest to limit computation time; and 3) prewhitening the spike waveforms to enable the use of parameter-free clustering. Finally, we combined these strategies into an automatic spike sorter that is competitive with state-of-the-art spike sorters.
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Schmidt, Helmut, Gerald Hahn, Gustavo Deco i Thomas R. Knösche. "Ephaptic coupling in white matter fibre bundles modulates axonal transmission delays". PLOS Computational Biology 17, nr 2 (8.02.2021): e1007858. http://dx.doi.org/10.1371/journal.pcbi.1007858.
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Axonal connections are widely regarded as faithful transmitters of neuronal signals with fixed delays. The reasoning behind this is that extracellular potentials caused by spikes travelling along axons are too small to have an effect on other axons. Here we devise a computational framework that allows us to study the effect of extracellular potentials generated by spike volleys in axonal fibre bundles on axonal transmission delays. We demonstrate that, although the extracellular potentials generated by single spikes are of the order of microvolts, the collective extracellular potential generated by spike volleys can reach several millivolts. As a consequence, the resulting depolarisation of the axonal membranes increases the velocity of spikes, and therefore reduces axonal delays between brain areas. Driving a neural mass model with such spike volleys, we further demonstrate that only ephaptic coupling can explain the reduction of stimulus latencies with increased stimulus intensities, as observed in many psychological experiments.
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Peterson, C. J., C. L. Peterson i D. F. Moser. "A Single Cereal Spike, Thresher-Planter". Journal of Production Agriculture 1, nr 3 (lipiec 1988): 247–48. http://dx.doi.org/10.2134/jpa1988.0247.
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Ahn, Changrim, i P. Bozhilov. "Finite-size effects for single spike". Journal of High Energy Physics 2008, nr 07 (24.07.2008): 105. http://dx.doi.org/10.1088/1126-6708/2008/07/105.
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Vilimelis Aceituno, Pau, Masud Ehsani i Jürgen Jost. "Spiking time-dependent plasticity leads to efficient coding of predictions". Biological Cybernetics 114, nr 1 (24.12.2019): 43–61. http://dx.doi.org/10.1007/s00422-019-00813-w.
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AbstractLatency reduction in postsynaptic spikes is a well-known effect of spiking time-dependent plasticity. We expand this notion for long postsynaptic spike trains on single neurons, showing that, for a fixed input spike train, STDP reduces the number of postsynaptic spikes and concentrates the remaining ones. Then, we study the consequences of this phenomena in terms of coding, finding that this mechanism improves the neural code by increasing the signal-to-noise ratio and lowering the metabolic costs of frequent stimuli. Finally, we illustrate that the reduction in postsynaptic latencies can lead to the emergence of predictions.
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Legendy, C. R., i M. Salcman. "Bursts and recurrences of bursts in the spike trains of spontaneously active striate cortex neurons". Journal of Neurophysiology 53, nr 4 (1.04.1985): 926–39. http://dx.doi.org/10.1152/jn.1985.53.4.926.
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Simultaneous recordings were made from small collections (2-7) of spontaneously active single units in the striate cortex of unanesthetized cats, by means of chronically implanted electrodes. The recorded spike trains were computer scanned for bursts of spikes, and the bursts were catalogued and studied. The firing rates of the neurons ranged from 0.16 to 32 spikes/s; the mean was 8.9 spikes/s, the standard deviation 7.0 spikes/s. Bursts of spikes were assigned a quantitative measure, termed Poisson surprise (S), defined as the negative logarithm of their probability in a random (Poisson) spike train. Only bursts having S greater than 10, corresponding to an occurrence rate of about 0.01 bursts/1,000 spikes in a random spike train, were considered to be of interest. Bursts having S greater than 10 occurred at a rate of about 5-15 bursts/1,000 spikes, or about 1-5 bursts/min. The rate slightly increased with spike rate; averaging about 2 bursts/min for neurons having 3 spikes/s and about 4.5 bursts/min for neurons having 30 spikes/s. About 21% of the recorded units emitted significantly fewer bursts than the rest (below 1 burst/1,000 spikes). The percentage of these neurons was independent of spike rate. The spike rate during bursts was found to be about 3-6 times the average spike rate; about the same for longer as for shorter bursts. Bursts typically contained 10-50 spikes and lasted 0.5-2.0 s. When the number of spikes in the successively emitted bursts was listed, it was found that in some neurons these numbers were not distributed at random but were clustered around one or more preferred values. In this sense, bursts occasionally "recurred" a few times in a few minutes. The finding suggests that neurons are highly reliable. When bursts of two or more simultaneously recorded neurons were compared, the bursts often appeared to be temporally close, especially between pairs of neurons recorded by the same electrode; but bursts seldom started and ended simultaneously on two channels. Recurring bursts emitted by one neuron were occasionally accompanied by time-locked recurring bursts by other neurons.
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Sharma, A. K., Rashmi Nigam, M. S. Rathi, Joginder Singh i Amol Godara. "Study of nitrogen and GA3 on growth, flowering and bulbs production of tuberose (Polianthes tuberosa L.) cv. Double". International Journal of Agricultural Invention 1, nr 02 (31.12.2016): 150–54. http://dx.doi.org/10.46492/ijai/2016.1.2.5.
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The present investigation was conducted at Horticultural Research Farm J. V. College, Baraut, Baghpat. The experiment carried out following Complete randomized design (CRD) with three replications of eight treatment combinations including three levels GA3 and single dose of nitrogen, In which Tuberose (Polianthes tuberosa L.) cv. Double is used to effect on growth, flowering and bulb production response of GA3 (100, 150 and 200 ppm) and single dose of nitrogen 7g along with having control, these doses were applied with check. Growth regulators results also indicated that, GA3 150 ppm and nitrogen @7g/pot decreases the days to sprouting and increases maximum number of sprout per bulb as compared to other treatment of gibberellic acid, while GA3 200 ppm and nitrogen @ 7 g observed the better effect on , number of leaves per plant, length of leaf, days taken to first flowering spike initiation, number of florets per spike, length of spike, number of spikes per plant, weight of spike and bulb production bulbs per plant of tuberose in western Uttar Pradesh condition.
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Bowman, D. M., J. J. Eggermont i G. M. Smith. "Effect of stimulation on burst firing in cat primary auditory cortex". Journal of Neurophysiology 74, nr 5 (1.11.1995): 1841–55. http://dx.doi.org/10.1152/jn.1995.74.5.1841.
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1. Neural activity was recorded extracellularly with two independent microelectrodes aligned in parallel and advanced perpendicular to isofrequency sheets in cat primary auditory cortex. Multiunit activity was separated into single-unit spike trains using a maximum variance spike sorting algorithm. Only units that demonstrated a high quality of sorting and a minimum spontaneous firing rate of 0.2 spikes/s were considered for analysis. The primary aim of this study was to describe the effect of periodic click train and broadband noise stimulation on short-time-scale (< or = 50 ms) bursts in the spike trains of single auditory cortical units and to determine whether stimulation influenced the occurrence, spike count, and/or temporal structure of burst firing relative to a spontaneous baseline. 2. Extracellular recordings were made in 20 juvenile and adult cats from 69 single auditory cortical units during click train stimulation and silence, and from 30 single units during noise stimulation and in silence. In an additional 15 single units the effect of both click train and noise stimulation was investigated. The incidence, spike count, and temporal structure of short-time-scale burst firing in the first 100 ms following stimulus presentation was compared with burst firing in the period starting 500 ms after stimulus presentation and with spontaneous burst firing. In addition, the serial dependence of interspike intervals within a burst was tested during periods of stimulation. 3. Burst firing was present in the stimulation, poststimulation, and spontaneous conditions. Longer bursts (consisting of > or = 3 spikes) were more commonly observed in the poststimulation and spontaneous conditions than in the stimulation condition. This effect was most pronounced during click stimulation. A period of elevated firing activity was present in a subset of units 0.5-1.5 s after stimulus presentation, indicating prolonged effects of stimulation on single-unit firing behavior. 4. For both stimuli, the proportion of single-unit responses composed of bursts was significantly greater in poststimulation and spontaneous periods than during stimulation. Burst rate was higher in post-click-train stimulation and spontaneous periods than during periods of click stimulation. The isolated spike rate was significantly higher during periods of noise and click stimulation than in the poststimulation and spontaneous periods. 5. An examination of the autocorrelograms and higher-order interspike interval histograms of single-unit responses during click train stimulation indicated that 25% of single-unit spike trains contained an excess of brief first-order intervals and 14% of spike trains contained a shortage of long higher-order interspike intervals relative to a spontaneous baseline. During noise stimulation, 10% of single-unit responses contained an excess of short intervals relative to baseline. Interspike intervals of short-duration bursts were not serially dependent during periods of stimulation. 6. A comparison of the autocorrelograms and higher-order interval histograms of single-unit responses in the poststimulation and spontaneous conditions indicated that 20% of single-unit spike trains contained an excess of short first-, second-, and third-order intervals following stimulation. This subgroups of single units could not be distinguished on the basis of the age of the animal or the depth at which the recording was made. 7. The low incidence of burst firing during stimulation opposes the view that bursts serve as a mechanism to emphasize or amplify particular stimulus-related responses in the presence of ongoing spontaneous activity in the primary auditory cortex. Moreover, there is little evidence to support the notion that brief bursts represent neural codes, because intraburst intervals are not serially dependent. It is suggested that pyramidal burst firing may be an effective way to evoke postsynaptic firing in inhibitory interneurons and subsequ
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Lin, Yi-Jyun, Min-Jeng Li, Hung-Chien Hsing, Tien-Kuan Chen, Ting-Ting Yang i Swee-Suak Ko. "Spike Activator 1, Encoding a bHLH, Mediates Axillary Bud Development and Spike Initiation in Phalaenopsis aphrodite". International Journal of Molecular Sciences 20, nr 21 (30.10.2019): 5406. http://dx.doi.org/10.3390/ijms20215406.
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Double-spikes Phalaenopsis orchids have greater market value than those with single-spike. In this study, a gene designated as Spike Activator 1 (SPK1), which encodes a basic helix-loop-helix (bHLH) transcription factor, was isolated and characterized from Phalaenopsis aphrodite (moth orchid). SPK1 was highly expressed in the meristematic tissues. In the axillary bud, SPK1 was highly upregulated by a moderately low temperature of 20 °C but downregulated by a spike inhibition temperature of 30 °C. SPK1 protein is localized in the nucleus. Another bHLH, bHLH35, which is also highly expressed in young tissues in the same way as SPK1 was also identified. In contrast to SPK1, bHLH35 transcripts are downregulated at 20 °C but upregulated at 30 °C. Bimolecular florescence complementation assay and yeast two-hybrid assays indicated that SPK1 interacts with bHLH35 and forms a heterodimer. Virus-induced gene silencing (VIGS) showed that 7 out of 15 vector control plants produced double spikes but that only 1 out of 15 VIGS-spk1 plants produced double spikes. RT-qPCR results indicated that VIGS-spk1 downregulated gene expression levels of SPK1, FT, CYCB, and EXPA8. Overall, we propose that SPK1 plays an essential role in early axillary bud development and spike initiation of P. aphrodite.
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Calton, Jeffrey L., Maeng-Hee Kang, Wilkie A. Wilson i Scott D. Moore. "NMDA-Receptor-Dependent Synaptic Activation of Voltage-Dependent Calcium Channels in Basolateral Amygdala". Journal of Neurophysiology 83, nr 2 (1.02.2000): 685–92. http://dx.doi.org/10.1152/jn.2000.83.2.685.
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Afferent stimulation of pyramidal cells in the basolateral amygdala produced mixed excitatory postsynaptic potentials (EPSPs) mediated by N-methyl-d-aspartate (NMDA) and non-NMDA glutamate receptors during whole cell current-clamp recordings. In the presence of GABAA receptor blockade, the mixed EPSPs recruited a large “all-or-none” depolarizing event. This recruited event was voltage dependent and had a distinct activation threshold. An analogous phenomenon elicited by exogenous glutamate in the presence of tetrodotoxin (TTX) was blocked by Cd2+, suggesting that the event was a Ca2+ spike. Selective glutamatergic blockade revealed that these Ca2+ spikes were recruited readily by single afferent stimulus pulses that elicited NMDA EPSPs. In contrast, non-NMDA EPSPs induced by single stimuli failed to elicit the Ca2+ spike even at maximal stimulus intensities although these non-NMDA EPSPs depolarized the soma more effectively than mixed EPSPs. Elongation of non-NMDA EPSPs by cyclothiazide or brief trains of stimulation were also unable to elicit the Ca2+ spike. Blockade of K+ channels with intracellular Cs+enabled single non-NMDA EPSPs to activate the Ca2+ spike. The finding that voltage-dependent calcium channels are activated preferentially by NMDA-receptor-mediated EPSPs provides a mechanism for NMDA-receptor-dependent plasticity independent of Ca2+influx through the NMDA receptor.
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S.X.Sullieva i Q.G'.Zokirov. "The structure of the yield of winter wheat when using herbicides against weeds". International Journal on Integrated Education 3, nr 11 (5.11.2020): 37–40. http://dx.doi.org/10.31149/ijie.v3i11.819.
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This article argues that when weeds in winter wheat fields are grown without eradication, the weeds will have a significant amount of shade, absorb some water and nutrients, and adversely affect the structure of the crop. Puma super (1 l / to) against cereals, Granstar (15 g / to) against biphasic weeds, and the elimination of Kroshka variety of winter wheat resulted in a long spike, a large number of grains in the spikes, spikes and spikes in a single spike. increased grain yield this condition has been reported to improve radically the efficiency of the grain structure when mixed and sprayed with Puma super (1 l / to), two-stage weed Granstar (15 g / to) herbicides against more grain weeds.
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Graham, Bruce P., Ausra Saudargiene i Stuart Cobb. "Spine Head Calcium as a Measure of Summed Postsynaptic Activity for Driving Synaptic Plasticity". Neural Computation 26, nr 10 (październik 2014): 2194–222. http://dx.doi.org/10.1162/neco_a_00640.
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We use a computational model of a hippocampal CA1 pyramidal cell to demonstrate that spine head calcium provides an instantaneous readout at each synapse of the postsynaptic weighted sum of all presynaptic activity impinging on the cell. The form of the readout is equivalent to the functions of weighted, summed inputs used in neural network learning rules. Within a dendritic layer, peak spine head calcium levels are either a linear or sigmoidal function of the number of coactive synapses, with nonlinearity depending on the ability of voltage spread in the dendrites to reach calcium spike threshold. This is strongly controlled by the potassium A-type current, with calcium spikes and the consequent sigmoidal increase in peak spine head calcium present only when the A-channel density is low. Other membrane characteristics influence the gain of the relationship between peak calcium and the number of active synapses. In particular, increasing spine neck resistance increases the gain due to increased voltage responses to synaptic input in spine heads. Colocation of stimulated synapses on a single dendritic branch also increases the gain of the response. Input pathways cooperate: CA3 inputs to the proximal apical dendrites can strongly amplify peak calcium levels due to weak EC input to the distal dendrites, but not so strongly vice versa. CA3 inputs to the basal dendrites can boost calcium levels in the proximal apical dendrites, but the relative electrical compactness of the basal dendrites results in the reverse effect being less significant. These results give pointers as to how to better describe the contributions of pre- and postsynaptic activity in the learning “rules” that apply in these cells. The calcium signal is closer in form to the activity measures used in traditional neural network learning rules than to the spike times used in spike-timing-dependent plasticity.
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Lynch, M., Ü. Sayin, G. Golarai i T. Sutula. "NMDA Receptor-Dependent Plasticity of Granule Cell Spiking in the Dentate Gyrus of Normal and Epileptic Rats". Journal of Neurophysiology 84, nr 6 (1.12.2000): 2868–79. http://dx.doi.org/10.1152/jn.2000.84.6.2868.
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Because granule cells in the dentate gyrus provide a major synaptic input to pyramidal neurons in the CA3 region of the hippocampus, spike generation by granule cells is likely to have a significant role in hippocampal information processing. Granule cells normally fire in a single-spike mode even when inhibition is blocked and provide single-spike output to CA3 when afferent activity converging into the entorhinal cortex from neocortex, brainstem, and other limbic regions increases. The effects of enhancement of N-methyl-d-aspartate (NMDA) receptor-dependent excitatory synaptic transmission and reduction in γ-aminobutyric acid-A (GABAA) receptor-dependent inhibition on spike generation were examined in granule cells of the dentate gyrus. In contrast to the single-spike mode observed in normal bathing conditions, perforant path stimulation in Mg2+-free bathing conditions evoked graded burst discharges in granule cells which increased in duration, amplitude, and number of spikes as a function of stimulus intensity. After burst discharges were evoked during transient exposure to bathing conditions that relieve the Mg2+ block of the NMDA receptor, there was a marked increase in the NMDA receptor-dependent component of the EPSP, but no significant increase in the non-NMDA receptor-dependent component of the EPSP in normal bathing medium. Supramaximal perforant path stimulation still evoked only a single spike, but granule cell spike generation was immediately converted from a single-spike firing mode to a graded burst discharge mode when inhibition was then reduced. The induction of graded burst discharges in Mg2+-free conditions and the expression of burst discharges evoked in normal bathing medium with subsequent disinhibition were both blocked bydl-2-amino-4-phosphonovaleric acid (APV) and were therefore NMDA receptor dependent, in contrast to long-term potentiation (LTP) in the perforant path, which is induced by NMDA receptors and is also expressed by α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate (AMPA) receptors. The graded burst discharge mode was also observed in granule cells when inhibition was reduced after a single epileptic afterdischarge, which enhances the NMDA receptor-dependent component of evoked synaptic response, and in the dentate gyrus reorganized by mossy fiber sprouting in kindled and kainic acid-treated rats. NMDA receptor-dependent plasticity of granule cell spike generation, which can be distinguished from LTP and induces long-term susceptibility to epileptic burst discharge under conditions of reduced inhibition, could modify information processing in the hippocampus and promote epileptic synchronization by increasing excitatory input into CA3.
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Brette, Romain. "Exact Simulation of Integrate-and-Fire Models with Exponential Currents". Neural Computation 19, nr 10 (październik 2007): 2604–9. http://dx.doi.org/10.1162/neco.2007.19.10.2604.
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Neural networks can be simulated exactly using event-driven strategies, in which the algorithm advances directly from one spike to the next spike. It applies to neuron models for which we have (1) an explicit expression for the evolution of the state variables between spikes and (2) an explicit test on the state variables that predicts whether and when a spike will be emitted. In a previous work, we proposed a method that allows exact simulation of an integrate-and-fire model with exponential conductances, with the constraint of a single synaptic time constant. In this note, we propose a method, based on polynomial root finding, that applies to integrate-and-fire models with exponential currents, with possibly many different synaptic time constants. Models can include biexponential synaptic currents and spike-triggered adaptation currents.
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Shao, Li-Rong, i F. Edward Dudek. "Repetitive Perforant-Path Stimulation Induces Epileptiform Bursts in Minislices of Dentate Gyrus From Rats With Kainate-Induced Epilepsy". Journal of Neurophysiology 105, nr 2 (luty 2011): 522–27. http://dx.doi.org/10.1152/jn.00456.2010.
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The epileptic hippocampus has an enhanced propensity for seizure generation, but how spontaneous seizures start is poorly understood. Using whole cell and field-potential recordings, this study explored whether repetitive perforant-path stimulation at physiological frequencies could induce epileptiform bursts in dentate gyrus minislices from rats with kainate-induced epilepsy. Control slices from saline-treated rats responded to single perforant-path stimulation with an excitatory postsynaptic potential (EPSP) and a single population spike in normal medium, and repetitive stimulation at different frequencies (0.1, 1, 2, 5, 10 Hz) did not cause significant increases in the responses. Most minislices (82%) from rats with kainate-induced epilepsy also responded to single perforant-path stimulation with an EPSP and a single population spike/action potential, but some slices (18%) had a more robust response with a prolonged duration and negative DC shift or responses with two to three population spikes. Repetitive perforant-path stimulation at 5–10 Hz, however, transformed the single-spike responses into epileptiform bursts with multiple spikes in half (52%) of the slices, while lower frequency (e.g., ≤1 Hz) stimulation failed to produce these changes. The emergence of epileptiform bursts was consistently associated with a negative field-potential DC shift and membrane depolarization. The results suggest that compared with the controls, the “gate” function of the dentate gyrus is compromised in rats with kainate-induced epilepsy, and epileptiform bursts (but not full-length seizure events) can be induced in minislices by repetitive synaptic stimulation at physiological frequencies in the range of hippocampal theta rhythm (i.e., 5–10 Hz).
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Wang, Yu-Feng, Xiao-Bing Gao i Anthony N. van den Pol. "Membrane Properties Underlying Patterns of GABA-Dependent Action Potentials in Developing Mouse Hypothalamic Neurons". Journal of Neurophysiology 86, nr 3 (1.09.2001): 1252–65. http://dx.doi.org/10.1152/jn.2001.86.3.1252.
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Spikes may play an important role in modulating a number of aspects of brain development. In early hypothalamic development, GABA can either evoke action potentials, or it can shunt other excitatory activity. In both slices and cultures of the mouse hypothalamus, we observed a heterogeneity of spike patterns and frequency in response to GABA. To examine the mechanisms underlying patterns and frequency of GABA-evoked spikes, we used conventional whole cell and gramicidin perforation recordings of neurons ( n = 282) in slices and cultures of developing mouse hypothalamus. Recorded with gramicidin pipettes, GABA application evoked action potentials in hypothalamic neurons in brain slices of postnatal day 2–9( P2- 9) mice. With conventional patch pipettes (containing 29 mM Cl−), action potentials were also elicited by GABA from neurons of 2–13 days in vitro (2–13 DIV) embryonic hypothalamic cultures. Depolarizing responses to GABA could be generally classified into three types: depolarization with no spike, a single spike, or complex patterns of multiple spikes. In parallel experiments in slices, electrical stimulation of GABAergic mediobasal hypothalamic neurons in the presence of glutamate receptor antagonists [10 μM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), 100 μM 2-amino-5-phosphonopentanoic acid (AP5)] resulted in the occurrence of spikes that were blocked by bicuculline (20 μM). Blocking ionotropic glutamate receptors with AP5 and CNQX did not block GABA-mediated multiple spikes. Similarly, when synaptic transmission was blocked with Cd2+ (200 μM) and Ni2+(300 μM), GABA still induced multiple spikes, suggesting that the multiple spikes can be an intrinsic membrane property of GABA excitation and were not based on local interneurons. When the pipette [Cl−] was 29 or 45 mM, GABA evoked multiple spikes. In contrast, spikes were not detected with 2 or 10 mM intracellular [Cl−]. With gramicidin pipettes, we found that the mean reversal potential of GABA-evoked current ( E GABA) was positive to the resting membrane potential, suggesting a high intracellular [Cl−] in developing mouse neurons. Varying the holding potential from −80 to 0 mV revealed an inverted U-shaped effect on spike probability. Blocking voltage-dependent Na+ channels with tetrodotoxin eliminated GABA-evoked spikes, but not the GABA-evoked depolarization. Removing Ca2+ from the extracellular solution did not block spikes, indicating GABA-evoked Na+-based spikes. Although E GABA was more positive within 2–5 days in culture, the probability of GABA-evoked spikes was greater in 6- to 9-day cells. Mechanistically, this appears to be due to a greater Na+ current found in the older cells during a period when the E GABA is still positive to the resting membrane potential. GABA evoked similar spike patterns in HEPES and bicarbonate buffers, suggesting that Cl−, not bicarbonate, was primarily responsible for generatingmultiple spikes. GABA evoked either single or multiple spikes; neurons with multiple spikes had a greater Na+ current, a lower conductance, a more negative spike threshold, and a greater difference between the peak of depolarization and the spike threshold. Taken together, the present results indicate that the patterns of multiple action potentials evoked by GABA are an inherent property of the developing hypothalamic neuron.
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Liu, Tao, Gang Quan i Wujie Wen. "FPT-spike: a flexible precise-time-dependent single-spike neuromorphic computing architecture". CCF Transactions on High Performance Computing 2, nr 3 (16.06.2020): 254–71. http://dx.doi.org/10.1007/s42514-020-00037-6.
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Soares, Daphne, Raymond A. Chitwood, Richard L. Hyson i Catherine E. Carr. "Intrinsic Neuronal Properties of the Chick Nucleus Angularis". Journal of Neurophysiology 88, nr 1 (1.07.2002): 152–62. http://dx.doi.org/10.1152/jn.2002.88.1.152.
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In vitro whole cell recording revealed intrinsic firing properties and single-cell morphology in the cochlear nucleus angularis (NA) of the chick. We classified three major classes of neurons: one-spike, damped, and tonic. A delayed inward rectifying current was observed in all classes during hyperpolarization injections. One-spike neurons responded with a single spike to depolarizing current injection and had small (stubby) radiate dendritic trees. Damped neurons responded with only a few spikes at the onset of positive current injection. More positive current inputs led to a damped response. Damped cell dendrites had a planar orientation parallel to the isofrequency axis in NA. Tonic cells produced trains of action potentials in response to a depolarizing current injection. Three variations of the tonic type had multipolar morphology, with dendrites oriented either radially (I and III) or perpendicular to the tonotopic axis (II; vertical). Tonics I and III differed in the shape of their action potential undershoot. Thus NA is both physiologically and morphologically heterogeneous.
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Arcas, Blaise Agüera y., Adrienne L. Fairhall i William Bialek. "Computation in a Single Neuron: Hodgkin and Huxley Revisited". Neural Computation 15, nr 8 (1.08.2003): 1715–49. http://dx.doi.org/10.1162/08997660360675017.
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A spiking neuron “computes” by transforming a complex dynamical input into a train of action potentials, or spikes. The computation performed by the neuron can be formulated as dimensional reduction, or feature detection, followed by a nonlinear decision function over the low-dimensional space. Generalizations of the reverse correlation technique with white noise input provide a numerical strategy for extracting the relevant low-dimensional features from experimental data, and information theory can be used to evaluate the quality of the low-dimensional approximation. We apply these methods to analyze the simplest biophysically realistic model neuron, the Hodgkin-Huxley (HH) model, using this system to illustrate the general methodological issues. We focus on the features in the stimulus that trigger a spike, explicitly eliminating the effects of interactions between spikes. One can approximate this triggering “feature space” as a two-dimensional linear subspace in the high-dimensional space of input histories, capturing in this way a substantial fraction of the mutual information between inputs and spike time. We find that an even better approximation, however, is to describe the relevant subspace as two dimensional but curved; in this way, we can capture 90% of the mutual information even at high time resolution. Our analysis provides a new understanding of the computational properties of the HH model. While it is common to approximate neural behavior as “integrate and fire,” the HH model is not an integrator nor is it well described by a single threshold.