Cross-Correlations in High-Conductance States of a Model Cortical Network

Neuronal firing correlations are studied using simulations of a simple network model for a cortical column in a high-conductance state with dynamically balanced excitation and inhibition. Although correlations between individual pairs of neurons exhibit considerable heterogeneity, population averages show systematic behavior. When the network is in a stationary state, the average correlations are generically small: correlation coefficients are of order 1/N, where N is the number of neurons in the network. However, when the input to the network varies strongly in time, much larger values are found. In this situation, the network is out of balance, and the synaptic conductance is low, at times when the strongest firing occurs. However, examination of the correlation functions of synaptic currents reveals that after these bursts, balance is restored within a few milliseconds by a rapid increase in inhibitory synaptic conductance. These findings suggest an extension of the notion of the balanced state to include balanced fluctuations of synaptic currents, with a characteristic timescale of a few milliseconds.

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Molecular basis of proton block of L-type Ca2+ channels.

The Journal of General Physiology ◽

10.1085/jgp.108.5.363 ◽

1996 ◽

Vol 108 (5) ◽

pp. 363-374 ◽

Cited By ~ 107

Author(s):

X H Chen ◽

I Bezprozvanny ◽

R W Tsien

Keyword(s):

Divalent Cations ◽

Site Directed Mutagenesis ◽

Protonation Site ◽

Voltage Gated ◽

High Conductance State ◽

Conductance States ◽

Acting In Concert ◽

Ca2 Channels ◽

Conductance State ◽

High Conductance

Hydrogen ions are important regulators of ion flux through voltage-gated Ca2+ channels but their site of action has been controversial. To identify molecular determinants of proton block of L-type Ca2+ channels, we combined site-directed mutagenesis and unitary current recordings from wild-type (WT) and mutant L-type Ca2+ channels expressed in Xenopus oocytes. WT channels in 150 mM K+ displayed two conductance states, deprotonated (140 pS) and protonated (45 pS), as found previously in native L-type Ca2+ channels. Proton block was altered in a unique fashion by mutation of each of the four P-region glutamates (EI-EIV) that form the locus of high affinity Ca2+ interaction. Glu(E)-->Gln(Q) substitution in either repeats I or III abolished the high-conductance state, as if the titration site had become permanently protonated. While the EIQ mutant displayed only an approximately 40 pS conductance, the EIIIQ mutant showed the approximately 40 pS conductance plus additional pH-sensitive transitions to an even lower conductance level. The EIVQ mutant exhibited the same deprotonated and protonated conductance states as WT, but with an accelerated rate of deprotonation. The EIIQ mutant was unusual in exhibiting three conductance states (approximately 145, 102, 50 pS, respectively). Occupancy of the low conductance state increased with external acidification, albeit much higher proton concentration was required than for WT. In contrast, the equilibrium between medium and high conductance levels was apparently pH-insensitive. We concluded that the protonation site in L-type Ca2+ channels lies within the pore and is formed by a combination of conserved P-region glutamates in repeats I, II, and III, acting in concert. EIV lies to the cytoplasmic side of the site but exerts an additional stabilizing influence on protonation, most likely via electrostatic interaction. These findings are likely to hold for all voltage-gated Ca2+ channels and provide a simple molecular explanation for the modulatory effect of H+ ions on open channel flux and the competition between H+ ions and permeant divalent cations. The characteristics of H+ interactions advanced our picture of the functional interplay between P-region glutamates, with important implications for the mechanism of Ca2+ selectivity and permeation.

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Faculty Opinions recommendation of The high-conductance state of cortical networks.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1097198.553204 ◽

2007 ◽

Author(s):

Alain Destexhe

Keyword(s):

Cortical Networks ◽

High Conductance State ◽

Conductance State ◽

High Conductance

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High-conductance states of single benzenedithiol molecules

Applied Physics Letters ◽

10.1063/1.2363995 ◽

2006 ◽

Vol 89 (16) ◽

pp. 163111 ◽

Cited By ~ 82

Author(s):

Makusu Tsutsui ◽

Yumi Teramae ◽

Shu Kurokawa ◽

Akira Sakai

Keyword(s):

Conductance States ◽

High Conductance

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Migration of Anionic Species of Radioactive Cobalt through Soil

MRS Proceedings ◽

10.1557/proc-176-615 ◽

1989 ◽

Vol 176 ◽

Author(s):

Toshihiko Ohnuki ◽

David E. Robertson

Keyword(s):

Concentration Distribution ◽

Correlation Coefficients ◽

Ionic Species ◽

Average Concentration ◽

Disposal Site ◽

Retardation Factor ◽

Laboratory Measurements ◽

Waste Disposal Site ◽

Anionic Species ◽

Cross Correlations

ABSTRACTThe migration of an anionic species of 60Co through soil has been examined utilizing data on the migration of radionuclides leached from an aqueous waste disposal site. Correlation coefficients between concentrations of the anionic species of 60Co and those of the particulate, cationic and non-ionic species of 60Co reveal that the anionic species of 60Co was not interconverted from the other species during migration. The cross correlations of changes in the concentrations of the anionic species of 60Co with time between three different down gradient positions give a calculated retardation factor of the anionic species of 60Co of approximately 19, being 1200 times lower than the results of laboratory measurements. The average concentration distribution of the anionic species of 60Co suggests that the migration of the anionic species of 60Co consists of two migration fractions which were driven by different migration mechanisms.

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Adaptive Exponential Integrate-and-Fire Model as an Effective Description of Neuronal Activity

Journal of Neurophysiology ◽

10.1152/jn.00686.2005 ◽

2005 ◽

Vol 94 (5) ◽

pp. 3637-3642 ◽

Cited By ~ 547

Author(s):

Romain Brette ◽

Wulfram Gerstner

Keyword(s):

Simple Model ◽

Expressive Power ◽

Detailed Model ◽

Fire Model ◽

Integrate And Fire ◽

Conductance States ◽

Effective Description ◽

High Conductance

We introduce a two-dimensional integrate-and-fire model that combines an exponential spike mechanism with an adaptation equation, based on recent theoretical findings. We describe a systematic method to estimate its parameters with simple electrophysiological protocols (current-clamp injection of pulses and ramps) and apply it to a detailed conductance-based model of a regular spiking neuron. Our simple model predicts correctly the timing of 96% of the spikes (±2 ms) of the detailed model in response to injection of noisy synaptic conductances. The model is especially reliable in high-conductance states, typical of cortical activity in vivo, in which intrinsic conductances were found to have a reduced role in shaping spike trains. These results are promising because this simple model has enough expressive power to reproduce qualitatively several electrophysiological classes described in vitro.

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Synaptic plasticity through activation of GluA3-containing AMPA-receptors

eLife ◽

10.7554/elife.25462 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 21

Author(s):

Maria C Renner ◽

Eva HH Albers ◽

Nicolas Gutierrez-Castellanos ◽

Niels R Reinders ◽

Aile N van Huijstee ◽

...

Keyword(s):

Ampa Receptors ◽

Adrenergic Receptors ◽

Pyramidal Neurons ◽

Synaptic Potentiation ◽

High Conductance State ◽

Hippocampal Synapses ◽

Β Adrenergic Receptors ◽

Camp Levels ◽

Conductance State ◽

High Conductance

Excitatory synaptic transmission is mediated by AMPA-type glutamate receptors (AMPARs). In CA1 pyramidal neurons of the hippocampus two types of AMPARs predominate: those that contain subunits GluA1 and GluA2 (GluA1/2), and those that contain GluA2 and GluA3 (GluA2/3). Whereas subunits GluA1 and GluA2 have been extensively studied, the contribution of GluA3 to synapse physiology has remained unclear. Here we show in mice that GluA2/3s are in a low-conductance state under basal conditions, and although present at synapses they contribute little to synaptic currents. When intracellular cyclic AMP (cAMP) levels rise, GluA2/3 channels shift to a high-conductance state, leading to synaptic potentiation. This cAMP-driven synaptic potentiation requires the activation of both protein kinase A (PKA) and the GTPase Ras, and is induced upon the activation of β-adrenergic receptors. Together, these experiments reveal a novel type of plasticity at CA1 hippocampal synapses that is expressed by the activation of GluA3-containing AMPARs.

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Phase response analysis during in vivo-like high conductance states; dendritic SK determines the mean and variance of responses to dendritic excitation

BMC Neuroscience ◽

10.1186/1471-2202-11-s1-o12 ◽

2010 ◽

Vol 11 (S1) ◽

Author(s):

Nathan W Schultheiss ◽

Jeremy R Edgerton ◽

Dieter Jaeger

Keyword(s):

Phase Response ◽

Response Analysis ◽

Mean And Variance ◽

The Mean ◽

Conductance States ◽

High Conductance

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High-conductance states and A-type K+ channels are potential regulators of the conductance-current balance triggered by HCN channels

Journal of Neurophysiology ◽

10.1152/jn.00601.2013 ◽

2015 ◽

Vol 113 (1) ◽

pp. 23-43 ◽

Cited By ~ 21

Author(s):

Poonam Mishra ◽

Rishikesh Narayanan

Keyword(s):

Dominant Role ◽

Input Resistance ◽

Resting Membrane Potential ◽

Voltage Response ◽

Hcn Channels ◽

Type K ◽

Conductance States ◽

The Impact ◽

High Conductance

An increase in the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel conductance reduces input resistance, whereas the consequent increase in the inward h current depolarizes the membrane. This results in a delicate and unique conductance-current balance triggered by the expression of HCN channels. In this study, we employ experimentally constrained, morphologically realistic, conductance-based models of hippocampal neurons to explore certain aspects of this conductance-current balance. First, we found that the inclusion of an experimentally determined gradient in A-type K+ conductance, but not in M-type K+ conductance, tilts the HCN conductance-current balance heavily in favor of conductance, thereby exerting an overall restorative influence on neural excitability. Next, motivated by the well-established modulation of neuronal excitability by synaptically driven high-conductance states observed under in vivo conditions, we inserted thousands of excitatory and inhibitory synapses with different somatodendritic distributions. We measured the efficacy of HCN channels, independently and in conjunction with other channels, in altering resting membrane potential (RMP) and input resistance ( Rin) when the neuron received randomized or rhythmic synaptic bombardments through variable numbers of synaptic inputs. We found that the impact of HCN channels on average RMP, Rin, firing frequency, and peak-to-peak voltage response was severely weakened under high-conductance states, with the impinging synaptic drive playing a dominant role in regulating these measurements. Our results suggest that the debate on the role of HCN channels in altering excitability should encompass physiological and pathophysiological neuronal states under in vivo conditions and the spatiotemporal interactions of HCN channels with other channels.

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ON THE APPLICATION OF THE CROSS-CORRELATIONS IN THE CHINESE FUND MARKET: DESCRIPTIVE PROPERTIES AND SCALING BEHAVIORS

Advances in Complex Systems ◽

10.1142/s0219525911002871 ◽

2011 ◽

Vol 14 (01) ◽

pp. 97-109

Author(s):

WEIBING DENG ◽

WEI LI ◽

XU CAI ◽

QIUPING A. WANG

Keyword(s):

Correlation Matrix ◽

Cross Correlation ◽

Matrix Theory ◽

Factorial Moment ◽

Correlation Coefficients ◽

Mean Value ◽

Distribution Of Eigenvalues ◽

Cross Correlations ◽

The Cross ◽

Simple Definition

On the basis of the relative daily logarithmic returns of 88 different funds in the Chinese fund market (CFM) from June 2005 to October 2009, we construct the cross-correlation matrix of the CFM. It is shown that the logarithmic returns follow an exponential distribution, which is commonly shared by some emerging markets. We hereby analyze the statistical properties of the cross-correlation coefficients in different time periods, such as the distribution, the mean value, the standard deviation, the skewness and the kurtosis. By using the method of the scaled factorial moment, we observe the intermittence phenomenon in the distribution of the cross-correlation coefficients. Also by employing the random matrix theory (RMT), we find a few isolated large eigenvalues of the cross-correlation matrix, and the distribution of eigenvalues exhibits the power-law tails. Furthermore, we study the features of the correlation strength with a simple definition.

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