共查询到20条相似文献,搜索用时 15 毫秒
1.
Komolitdin Akhmedov Valerio Rizzo Beena M. Kadakkuzha Christopher J. Carter Neil S. Magoski Thomas R. Capo Sathyanarayanan V. Puthanveettil 《PloS one》2013,8(12)
How aging affects the communication between neurons is poorly understood. To address this question, we have studied the electrophysiological properties of identified neuron R15 of the marine mollusk Aplysia californica. R15 is a bursting neuron in the abdominal ganglia of the central nervous system and is implicated in reproduction, water balance, and heart function. Exposure to acetylcholine (ACh) causes an increase in R15 burst firing. Whole-cell recordings of R15 in the intact ganglia dissected from mature and old Aplysia showed specific changes in burst firing and properties of action potentials induced by ACh. We found that while there were no significant changes in resting membrane potential and latency in response to ACh, the burst number and burst duration is altered during aging. The action potential waveform analysis showed that unlike mature neurons, the duration of depolarization and the repolarization amplitude and duration did not change in old neurons in response to ACh. Furthermore, single neuron quantitative analysis of acetylcholine receptors (AChRs) suggested alteration of expression of specific AChRs in R15 neurons during aging. These results suggest a defect in cholinergic transmission during aging of the R15 neuron. 相似文献
2.
Zbinden C 《Journal of computational neuroscience》2011,31(2):285-304
In this paper, we highlight the topological properties of leader neurons whose existence is an experimental fact. Several
experimental studies show the existence of leader neurons in population bursts of activity in 2D living neural networks (Eytan
and Marom, J Neurosci 26(33):8465–8476, 2006; Eckmann et al., New J Phys 10(015011), 2008). A leader neuron is defined as a neuron which fires at the beginning of a burst (respectively network spike) more often
than we expect by chance considering its mean firing rate. This means that leader neurons have some burst triggering power
beyond a chance-level statistical effect. In this study, we characterize these leader neuron properties. This naturally leads
us to simulate neural 2D networks. To build our simulations, we choose the leaky integrate and fire (lIF) neuron model (Gerstner
and Kistler 2002; Cessac, J Math Biol 56(3):311–345, 2008), which allows fast simulations (Izhikevich, IEEE Trans Neural Netw 15(5):1063–1070, 2004; Gerstner and Naud, Science 326:379–380, 2009). The dynamics of our lIF model has got stable leader neurons in the burst population that we simulate. These leader neurons
are excitatory neurons and have a low membrane potential firing threshold. Except for these two first properties, the conditions
required for a neuron to be a leader neuron are difficult to identify and seem to depend on several parameters involved in
the simulations themselves. However, a detailed linear analysis shows a trend of the properties required for a neuron to be
a leader neuron. Our main finding is: A leader neuron sends signals to many excitatory neurons as well as to few inhibitory
neurons and a leader neuron receives only signals from few other excitatory neurons. Our linear analysis exhibits five essential
properties of leader neurons each with different relative importance. This means that considering a given neural network with
a fixed mean number of connections per neuron, our analysis gives us a way of predicting which neuron is a good leader neuron
and which is not. Our prediction formula correctly assesses leadership for at least ninety percent of neurons. 相似文献
3.
Francesco Moccia Carlo Di Cristo William Winlow Anna Di Cosmo 《Invertebrate neuroscience : IN》2009,9(1):29-41
To examine the neurochemistry underlying the firing of the RPeD1 neuron in the respiratory central pattern generator of the
pond snail, Lymnaea stagnalis, we examined electrophysiologically and pharmacologically either “active” or “silent” preparations by intracellular recording
and pharmacology. GABA inhibited electrical firing by hyperpolarizing RPeD1, while picrotoxin, an antagonist of GABAA receptors, excited silent cells and reversed GABA-induced inhibition. Action potential activity was terminated by 1 mM glutamate
(Glu) while silent cells were depolarized by the GluR agonists, AMPA, and NMDA. Kainate exerted a complex triphasic effect
on membrane potential. However, only bath application of AMPA desensitized the firing. These data indicate that GABA inhibits
RPeD1 via activation of GABAA receptors, while Glu stimulates the neuron by activating AMPA-sensitive GluRs. 相似文献
4.
To explore non-synaptic mechanisms in paroxysmal discharges, we used a computer model of a simplified hippocampal pyramidal
cell, surrounded by interstitial space and a “glial-endothelial” buffer system. Ion channels for Na+, K+, Ca2+ and Cl−
, ion antiport 3Na/Ca, and “active” ion pumps were represented in the neuron membrane. The glia had “leak” conductances and
an ion pump. Fluxes, concentration changes and cell swelling were computed. The neuron was stimulated by injecting current.
Afterdischarge (AD) followed stimulation if depolarization due to rising interstitial K+ concentration ([K+]o) activated persistent Na+ current (I
Na,P). AD was either simple or self-regenerating; either regular (tonic) or burst-type (clonic); and always self-limiting. Self-regenerating
AD required sufficient I
Na,P to ensure re-excitation. Burst firing depended on activation of dendritic Ca2+ currents and Ca-dependent K+ current. Varying glial buffer function influenced [K+]o accumulation and afterdischarge duration. Variations in Na+ and K+ currents influenced the threshold and the duration of AD. The data show that high [K+]o and intrinsic membrane currents can produce the feedback of self-regenerating afterdischarges without synaptic input. The
simulated discharge resembles neuron behavior during paroxysmal firing in living brain tissue.
Action Editor: David Terman 相似文献
5.
Excitability in neurons is associated with firing of action potentials and requires the opening of voltage-gated sodium channels
with membrane depolarization. Sustained membrane depolarization, as seen in pathophysiological conditions like epilepsy, can
have profound implications on the biophysical properties of voltage-gated ion channels. Therefore, we sought to characterize
the effect of sustained membrane depolarization on single voltage-gated Na+ channels. Single-channel activity was recorded in the cell-attached patch-clamp mode from the rNav1.2α channels expressed in CHO cells. Classical statistical analysis revealed complex nonlinear changes in channel dwell times
and unitary conductance of single Na+ channels as a function of conditioning membrane depolarization. Signal processing tools like weighted wavelet Z (WWZ) and
discrete Fourier transform analyses attributed a “pseudo-oscillatory” nature to the observed nonlinear variation in the kinetic
parameters. Modeling studies using the hidden Markov model (HMM) illustrated significant changes in kinetic states and underlying
state transition rate constants upon conditioning depolarization. Our results suggest that sustained membrane depolarization
induces novel nonlinear properties in voltage-gated Na+ channels. Prolonged membrane depolarization also induced a “molecular memory” phenomenon, characterized by clusters of dwell
time events and strong autocorrelation in the dwell time series similar to that reported recently for single enzyme molecules.
The persistence of such molecular memory was found to be dependent on the duration of depolarization. Voltage-gated Na+ channel with the observed time-dependent nonlinear properties and the molecular memory phenomenon may determine the functional
state of the channel and, in turn, the excitability of a neuron. 相似文献
6.
During pregnancy, emergence of endogenous opioid inhibition of oxytocin neurons is revealed by increased oxytocin secretion
after administration of the opioid receptor antagonist, naloxone. Here we show that prolonged estradiol-17β and progesterone
treatment (mimicking pregnancy levels) potentiates naloxone-induced oxytocin secretion in urethane-anesthetized virgin female
rats. We further show that estradiol-17β alone rapidly modifies opioid interactions with oxytocin neurons, by recording their
firing rate in anesthetized rats sensitized to naloxone by morphine dependence. Naloxone-induced morphine withdrawal strongly
increased the firing rate of oxytocin neurons in morphine dependent rats. Estradiol-17β did not alter basal oxytocin neuron
firing rate over 30 min, but amplified naloxone-induced increases in firing rate. Firing pattern analysis indicated that acute
estradiol-17β increased oxytocin secretion in dependent rats by increasing action potential clustering without an overall
increase in firing rate. Hence, rapid estradiol-17β actions might underpin enhanced oxytocin neuron responses to naloxone
in pregnancy.
Special issue article in honor of George Fink. 相似文献
7.
Recent evidence suggests that the cyclic nucleotides play a central role in the intracellular processing of neural signals.
The dynamics of this system may be seen as a realization of the enzymatic neuron model. Enzymatic neurons are formal neurons
which map binary afferent signals into patterns of excitation across an abstract membrane. The distribution of enzyme-like
elements called excitases enables a set of local threshold functions to determine the firing activity of the neuron. This
paper analyzes the basic properties of enzymatic neurons in a simple continuous-time framework, and shows how they may be
presented as reaction-diffusion networks which model the cyclic nucleotide system. We present the results of computer simulations
of this neuron and discuss its implications for selectional learning and its relation to conventional two-factor systems.
One fundamental property of the reaction-diffusion neuron is its so-called “double-dynamics” property; examination of this
property and its contribution to the computing power of the neuron provides some insight into the obscure relation between
microscopic and macroscopic models of computation. 相似文献
8.
The biophysical and morphological characteristics of acutelyisolated neurons from the rostral nucleus of the solitary tract(rNST) were investigated under current clamp conditions andcompared with the results obtained from neurons recorded inbrain slices. The passive membrane properties of the isolatedneurons were similar to rNST neurons in brain slices and theneurons maintained their morphological characteristics althoughtheir dendritic tree was truncated. The isolated neurons alsoretained their characteristic repetitive firing properties.In addition we also noted developmental changes in the intrinsicmembrane properties of the isolated neurons, such as a shorteningin action potential duration, decrease in membrane time constantand input resistance, that occurred when these parameters werecompared in neurons isolated from young (510 days) andolder animals. These enzymatically dispersed neurons thereforeretained both the membrane properties and morphology observedin the intact brainstem and in vitro brain slice preparation.The use of this isolated neuron preparation provides a basisfor further study of rNST neurobiology. Chem. Senses 21: 729737,1996 相似文献
9.
The effects of amphetamine on potential changes in both vertebrate and invertebrate central neurons and factors affecting the potential changes were tested. The animals studied included mice, newborn rat and African snail. Seizure was elicited after lethal doses of d-amphetamine (75 mg/kg, i.p.) administration in mice. Repetitive firing of the action potentials were elicited after d-amphetamine (1-30 microM) administration in thin thalamic brain slices of newborn rat. Bursting firing of action potentials in the giant African central RP4 neuron were also elicited after d-amphetamine or l-amphetamine (0.27 mM) administration. The amphetamine elicited bursting firing of action potentials was not blocked even after high concentrations of d-tubocurarine, atropine, haloperidol, hexamethonium administration. Therefore, the amphetamine elicited potential changes may not be directly related to the activation of the receptors of the neuron. The bursting firing of action potentials elicited by amphetamine occurred 20-30 min after amphetamine administration extracellularly, even after high concentrations of d-amphetamine administration (0.27, 1 mM). However, the bursting firing of potentials occurred immediately if amphetamine was administrated intracellularly at lower concentration. Extracellular application of ruthenium red, the calcium antagonist, abolished the amphetamine elicited bursting firing of action potentials. If intracellular injection of EGTA, a calcium ion chelator, or injection with high concentrations of magnesium, the bursting firing of potentials were immediately abolished. These results suggested that the active site of amphetamine may be inside of the neuron and the calcium ion in the neuron played an important role on the bursting of potentials. In two-electrode voltage clamped RP4 neuron, amphetamine, at 0.27 mM, decreased the total inward and steady outward currents of the RP4 neuron. d-Amphetamine also decreased the calcium, Ia and the steady-state outward currents of the RP4 neuron. Besides, amphetamine elicited a negative slope resistance (NSR) if membrane potential was in the range of -50 to -10 mV. The NSR was decreased in cobalt substituted calcium free and sodium free solution. The effects of secondary messengers on the amphetamine elicited potential changes were tested. The bursting firing of action potentials elicited by amphetamine in central snail neurons decreased following extracellular application of H8 (N-(2-methyl-amino) ethyl-3-isoquinoline sulphonamide dihydrochloride), a specific protein kinase A inhibitor and anisomycin, a protein synthesis inhibitor. However, the bursting firing of action potentials were not affected after extracellular application of H7 (1,(5-isoquinolinesulphonyl)-2-methylpiperasine dihydrochloride), a specific protein kinase C (PKC) inhibitor, or intracellular application of GDPbetaS, a G protein inhibitor. The oscillation of membrane potential of the bursting activity was blocked after intracellular injection of 3'-deoxyadenosine, an adenylyl-cyclase inhibitor. These results suggested that the bursting firing of action potentials elicited by d-amphetamine in snail neuron may be associated with the cyclic AMP second messenger system; on the other hand, it may not be associated with the G protein and protein kinase C activity. It is concluded that amphetamine elicited potential changes in both vertebrate and invertebrate central neurons. The changes are closely related to the ionic currents and second messengers of the neurons. 相似文献
10.
We studied the combined influence of noise and constant current stimulations on the Hodgkin–Huxley neuron model through time
and frequency analysis of the membrane-potential dynamics. We observed that, in agreement with experimental data (Guttman
et al. 1974), at low noise and low constant current stimulation the behavior of the model is well approximated by that of
the linearized Hodgkin–Huxley system. Conversely, nonlinearities due to firing dominate at large noise or current stimulations.
The transition between the two regimes is abrupt, and takes place in the same range of noise and current intensities as the
noise-induced transition characterized by the qualitative change in the stationary distribution of the membrane potential
(Tanabe and Pakdaman 2001a). The implications of these results are discussed.
Received: 27 July 2001 / Accepted in revised form: 18 December 2001 相似文献
11.
Cortical neurons receive signals from thousands of other neurons. The statistical properties of the input spike trains substantially
shape the output response properties of each neuron. Experimental and theoretical investigations have mostly focused on the
second order statistical features of the input spike trains (mean firing rates and pairwise correlations). Little is known
of how higher order correlations affect the integration and firing behavior of a cell independently of the second order statistics.
To address this issue, we simulated the dynamics of a population of 5000 neurons, controlling both their second order and
higher-order correlation properties to reflect physiological data. We then used these ensemble dynamics as the input stage
to morphologically reconstructed cortical cells (layer 5 pyramidal, layer 4 spiny stellate cell), and to an integrate and
fire neuron. Our results show that changes done solely to the higher-order correlation properties of the network’s dynamics
significantly affect the response properties of a target neuron, both in terms of output rate and spike timing. Moreover,
the neuronal morphology and voltage dependent mechanisms of the target neuron considerably modulate the quantitative aspects
of these effects. Finally, we show how these results affect sparseness of neuronal representations, tuning properties, and
feature selectivity of cortical cells.
An erratum to this article can be found at 相似文献
12.
V. L. Ézrokhi 《Neurophysiology》1974,6(2):156-162
The postinhibitory response of a slowly adapting neuron was investigated in experiments on an isolated preparation of crustacean stretch receptor and abdominal nerve chain. The structural features of this preparation are such that this response can be regarded as the response of the postsynaptic membrane to synaptic inhibition and not the action of synaptic excitation. IPSPs arise in the slowly adapting neuron in response to stimulation of the abdominal nerve chain (direct inhibition) or to excitation of the neuron itself (recurrent inhibition). The postinhibitory response consists of the development of action potentials or an increase in their amplitude and frequency. The magnitude of the response is determined by the duration of the inhibition and the state of the neuron membrane. The postinhibitory response was strongest when IPSPs were superposed on cathodal depression. IPSPs and an intracellular hyperpolarizing current evoke similar postinhibitory responses. Repetitive excitation of an inhibitory neuron may result in the appearance of a regular spike discharge from a previously inactive neuron through the mechanism of the postinhibitory response. Activation of a chain of recurrent inhibition increases the duration of the postinhibitory response evoked by direct inhibition or by a hyperpolarizing current. The existence of a chain of recurrent inhibition prevents the cessation of firing by a neuron during increasing cathodal depression. A mechanism of postinhibitory rebound lies at the basis of this phenomenon. 相似文献
13.
Stochastic leaky integrate-and-fire models are popular due to their simplicity and statistical tractability. They have been
widely applied to gain understanding of the underlying mechanisms for spike timing in neurons, and have served as building
blocks for more elaborate models. Especially the Ornstein–Uhlenbeck process is popular to describe the stochastic fluctuations
in the membrane potential of a neuron, but also other models like the square-root model or models with a non-linear drift
are sometimes applied. Data that can be described by such models have to be stationary and thus, the simple models can only
be applied over short time windows. However, experimental data show varying time constants, state dependent noise, a graded
firing threshold and time-inhomogeneous input. In the present study we build a jump diffusion model that incorporates these
features, and introduce a firing mechanism with a state dependent intensity. In addition, we suggest statistical methods to
estimate all unknown quantities and apply these to analyze turtle motoneuron membrane potentials. Finally, simulated and real
data are compared and discussed. We find that a square-root diffusion describes the data much better than an Ornstein–Uhlenbeck
process with constant diffusion coefficient. Further, the membrane time constant decreases with increasing depolarization,
as expected from the increase in synaptic conductance. The network activity, which the neuron is exposed to, can be reasonably
estimated to be a threshold version of the nerve output from the network. Moreover, the spiking characteristics are well described
by a Poisson spike train with an intensity depending exponentially on the membrane potential. 相似文献
14.
David C. Tam 《Biological cybernetics》1998,78(2):95-106
A stochastic spike train analysis technique is introduced to reveal the correlation between the firing of the next spike
and the temporal integration period of two consecutive spikes (i.e., a doublet). Statistics of spike firing times between
neurons are established to obtain the conditional probability of spike firing in relation to the integration period. The existence
of a temporal integration period is deduced from the time interval between two consecutive spikes fired in a reference neuron
as a precondition to the generation of the next spike in a compared neuron. This analysis can show whether the coupled spike
firing in the compared neuron is correlated with the last or the second-to-last spike in the reference neuron. Analysis of
simulated and experimentally recorded biological spike trains shows that the effects of excitatory and inhibitory temporal
integration are extracted by this method without relying on any subthreshold potential recordings. The analysis also shows
that, with temporal integration, a neuron driven by random firing patterns can produce fairly regular firing patterns under
appropriate conditions. This regularity in firing can be enhanced by temporal integration of spikes in a chain of polysynaptically
connected neurons. The bandpass filtering of spike firings by temporal integration is discussed. The results also reveal that
signal transmission delays may be attributed not just to conduction and synaptic delays, but also to the delay time needed
for temporal integration.
Received: 3 March 1997 / Accepted in revised form: 6 November 1997 相似文献
15.
The glucose-excited neurons in brain can sense blood glucose levels and reflect different firing states, which are mainly associated with regulation of blood glucose and energy demand in the brain. In this paper, a new model of glucose-excited neuron in hypothalamus is proposed. The firing properties and energy consumption of this type of neuron under conditions of different glucose levels are simulated and analyzed. The results show that the firing rate and firing duration of the neuron both increase with increasing extracellular glucose levels, but the maximum energy power for an AP is reduced. Further study suggests that the neuron firstly absorbs energy substrates (e.g. glucose) from the blood to prepare for the high energy demand of high-frequency spikes. 相似文献
16.
Marco A. Herrera-Valdez Erin C. McKiernan Sandra D. Berger Stefanie Ryglewski Carsten Duch Sharon Crook 《Journal of computational neuroscience》2013,34(2):211-229
Neurons show diverse firing patterns. Even neurons belonging to a single chemical or morphological class, or the same identified neuron, can display different types of electrical activity. For example, motor neuron MN5, which innervates a flight muscle of adult Drosophila, can show distinct firing patterns under the same recording conditions. We developed a two-dimensional biophysical model and show that a core complement of just two voltage-gated channels is sufficient to generate firing pattern diversity. We propose Shab and DmNa v to be two candidate genes that could encode these core currents, and find that changes in Shab channel expression in the model can reproduce activity resembling the main firing patterns observed in MN5 recordings. We use bifurcation analysis to describe the different transitions between rest and spiking states that result from variations in Shab channel expression, exposing a connection between ion channel expression, bifurcation structure, and firing patterns in models of membrane potential dynamics. 相似文献
17.
Yi Sun Douglas Zhou Aaditya V. Rangan David Cai 《Journal of computational neuroscience》2009,27(3):369-390
We present an efficient library-based numerical method for simulating the Hodgkin–Huxley (HH) neuronal networks. The key components
in our numerical method involve (i) a pre-computed high resolution data library which contains typical neuronal trajectories
(i.e., the time-courses of membrane potential and gating variables) during the interval of an action potential (spike), thus
allowing us to avoid resolving the spikes in detail and to use large numerical time steps for evolving the HH neuron equations;
(ii) an algorithm of spike-spike corrections within the groups of strongly coupled neurons to account for spike-spike interactions
in a single large time step. By using the library method, we can evolve the HH networks using time steps one order of magnitude
larger than the typical time steps used for resolving the trajectories without the library, while achieving comparable resolution
in statistical quantifications of the network activity, such as average firing rate, interspike interval distribution, power
spectra of voltage traces. Moreover, our large time steps using the library method can break the stability requirement of
standard methods (such as Runge–Kutta (RK) methods) for the original dynamics. We compare our library-based method with RK
methods, and find that our method can capture very well phase-locked, synchronous, and chaotic dynamics of HH neuronal networks.
It is important to point out that, in essence, our library-based HH neuron solver can be viewed as a numerical reduction of
the HH neuron to an integrate-and-fire (I&F) neuronal representation that does not sacrifice the gating dynamics (as normally
done in the analytical reduction to an I&F neuron). 相似文献
18.
Mid-brain dopaminergic (DA) neurons display two functionally distinct modes of electrical activity: low- and high-frequency
firing. The high-frequency firing is linked to important behavioral events in vivo. However, it cannot be elicited by standard manipulations in vitro. We had suggested a two-compartmental model of the DA cell that united data on firing frequencies under different experimental
conditions. We now analyze dynamics of this model. The analysis was possible due to introduction of timescale separation among
variables. We formulate the requirements for low and high frequencies. We found that the modulation of the SK current gating
controls the frequency rise under applied depolarization. This provides a new mechanism that limits the frequency in the control
conditions and allows high-frequency responses to depolarization if the SK current gating is downregulated. The mechanism
is based on changing Ca2 + balance and can also be achieved by direct modulation of the balance. Interestingly, such changes do not affect the high-frequency
oscillations under NMDA. Therefore, altering Ca2 + balance allows combining the high-frequency response to NMDA activation with the inability of other treatments to effectively
elevate the frequency. We conclude that manipulations affecting Ca2 + balance are most effective in controlling the frequency range. This modeling prediction gives a clue to the mechanism of
the high-frequency firing in the DA neuron in vivo and in vitro. 相似文献
19.
The Hodgkin–Huxley (HH) neuron is a nonlinear system with two stable states: A fixed point and a limit cycle. Both of them
co-exist. The behavior of this neuron can be switched between these two equilibria, namely spiking and resting respectively, by using a perturbation method. The change from spiking to resting is named Spike Annihilation, and the transition from resting to spiking is named Spike Generation. Our intention is to determine if the HH neuron in 2D is controllable (i.e., if it can be driven from a quiescent state to
a spiking state and vice versa). It turns out that the general system is unsolvable.1 In this paper, first of all,2 we analytically prove the existence of a brief current pulse, which, when delivered to the HH neuron during its repetitively
firing state, annihilates its spikes. We also formally derive the characteristics of this brief current pulse. We then proceed
to explore experimentally, by using numerical simulations, the properties of this pulse, namely the range of time when it
can be inserted (the minimum phase and the maximum phase), its magnitude, and its duration. In addition, we study the solution
of annihilating the spikes by using two successive stimuli, when the first is, of its own, unable to annihilate the neuron.
Finally, we investigate the inverse problem of annihilation, namely the spike generation problem, when the neuron switches
from resting to firing.
1 This conclusion is a consequence of three well-known fundamental results, namely Hilbert 16th Problem, the Poincare–Bendixon
Theorem
and the Hopf Bifurcation Theorem.
2 We are extremely grateful to the feedback we received from the anonymous Referees to the initial version of the paper. Their
comments significantly improved the quality of the current version. Thanks a lot! 相似文献
20.
This study sought to investigate the role of the Renshaw cell with respect to transient motoneuron firing. By studying the
cat motoneuron and Renshaw cell, several low-order lumped parameter models were developed that simulate the known characteristics
of the injected input current vs. firing rate. The neuron models in the Renshaw cell inhibition configuration were tuned to
fit experimental data from cat motoneurons. Models included both linear versions and those with sigmoidal nonlinearities.
Results of the simulation indicate that the motoneuron itself provides the adaptation seen in its firing rate and that the
Renshaw cell’s role is primarily to fine-tune the motoneuron’s adaptation process.
Received: 23 July 1993/Accepted in revised form: 9 February 1994 相似文献