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Robin L. Davis - One of the best experts on this subject based on the ideXlab platform.
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I _h and HCN Channels in Murine Spiral Ganglion Neurons: Tonotopic Variation, Local Heterogeneity, and Kinetic Model
Journal of the Association for Research in Otolaryngology, 2014Co-Authors: Qing Liu, Paul B. Manis, Robin L. DavisAbstract:One of the major contributors to the response profile of neurons in the auditory pathways is the I _h current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420–1432, 1993 ; Fu et al., J Neurophysiol 78:2235–2245, 1997 ; Bal and Oertel, J Neurophysiol 84:806–817, 2000 ; Cao and Oertel, J Neurophysiol 94:821–832, 2005 ; Rodrigues and Oertel, J Neurophysiol 95:76–87, 2006 ; Yi et al., J Neurophysiol 103:2532–2543, 2010 ), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019–3027, 1997 ), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because I _h in the apical neurons have more positive Half-Activation Voltage levels than basal neurons. Even within a single cochlear region, however, I _h current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates I _h current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the I _h current and generated a mathematical model to better understand varied I _h on spiral ganglion function. Regardless of whether I _h currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010 ) or at the somata of spiral ganglion neurons, they have comparable mean Half-Activation Voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of I _h on synaptic physiology.
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Erratum to: Ih and HCN channels in murine spiral ganglion neurons: Tonotopic variation, local heterogeneity, and kinetic model (JARO - Journal of the Association for Research in Otolaryngology DOI: 10.1007/s10162-014-0446-z)
Journal of the Association for Research in Otolaryngology : JARO, 2014Co-Authors: Qing Liu, Paul B. Manis, Robin L. DavisAbstract:One of the major contributors to the response profile of neurons in the auditory pathways is the Ih current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420–1432, 1993; Fu et al., J Neurophysiol 78:2235–2245, 1997; Bal and Oertel, J Neurophysiol 84:806–817, 2000; Cao and Oertel, J Neurophysiol 94:821–832, 2005; Rodrigues and Oertel, J Neurophysiol 95:76–87, 2006; Yi et al., J Neurophysiol 103:2532–2543, 2010), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019–3027, 1997), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because Ih in the apical neurons have more positive Half-Activation Voltage levels than basal neurons. Even within a single cochlear region, however, Ih current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates Ih current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the Ih current and generated a mathematical model to better understand varied Ih on spiral ganglion function. Regardless of whether Ih currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010) or at the somata of spiral ganglion neurons, they have comparable mean Half-Activation Voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of Ih on synaptic physiology.
Qing Liu - One of the best experts on this subject based on the ideXlab platform.
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I _h and HCN Channels in Murine Spiral Ganglion Neurons: Tonotopic Variation, Local Heterogeneity, and Kinetic Model
Journal of the Association for Research in Otolaryngology, 2014Co-Authors: Qing Liu, Paul B. Manis, Robin L. DavisAbstract:One of the major contributors to the response profile of neurons in the auditory pathways is the I _h current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420–1432, 1993 ; Fu et al., J Neurophysiol 78:2235–2245, 1997 ; Bal and Oertel, J Neurophysiol 84:806–817, 2000 ; Cao and Oertel, J Neurophysiol 94:821–832, 2005 ; Rodrigues and Oertel, J Neurophysiol 95:76–87, 2006 ; Yi et al., J Neurophysiol 103:2532–2543, 2010 ), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019–3027, 1997 ), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because I _h in the apical neurons have more positive Half-Activation Voltage levels than basal neurons. Even within a single cochlear region, however, I _h current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates I _h current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the I _h current and generated a mathematical model to better understand varied I _h on spiral ganglion function. Regardless of whether I _h currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010 ) or at the somata of spiral ganglion neurons, they have comparable mean Half-Activation Voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of I _h on synaptic physiology.
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Erratum to: Ih and HCN channels in murine spiral ganglion neurons: Tonotopic variation, local heterogeneity, and kinetic model (JARO - Journal of the Association for Research in Otolaryngology DOI: 10.1007/s10162-014-0446-z)
Journal of the Association for Research in Otolaryngology : JARO, 2014Co-Authors: Qing Liu, Paul B. Manis, Robin L. DavisAbstract:One of the major contributors to the response profile of neurons in the auditory pathways is the Ih current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420–1432, 1993; Fu et al., J Neurophysiol 78:2235–2245, 1997; Bal and Oertel, J Neurophysiol 84:806–817, 2000; Cao and Oertel, J Neurophysiol 94:821–832, 2005; Rodrigues and Oertel, J Neurophysiol 95:76–87, 2006; Yi et al., J Neurophysiol 103:2532–2543, 2010), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019–3027, 1997), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because Ih in the apical neurons have more positive Half-Activation Voltage levels than basal neurons. Even within a single cochlear region, however, Ih current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates Ih current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the Ih current and generated a mathematical model to better understand varied Ih on spiral ganglion function. Regardless of whether Ih currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010) or at the somata of spiral ganglion neurons, they have comparable mean Half-Activation Voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of Ih on synaptic physiology.
Paul B. Manis - One of the best experts on this subject based on the ideXlab platform.
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I _h and HCN Channels in Murine Spiral Ganglion Neurons: Tonotopic Variation, Local Heterogeneity, and Kinetic Model
Journal of the Association for Research in Otolaryngology, 2014Co-Authors: Qing Liu, Paul B. Manis, Robin L. DavisAbstract:One of the major contributors to the response profile of neurons in the auditory pathways is the I _h current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420–1432, 1993 ; Fu et al., J Neurophysiol 78:2235–2245, 1997 ; Bal and Oertel, J Neurophysiol 84:806–817, 2000 ; Cao and Oertel, J Neurophysiol 94:821–832, 2005 ; Rodrigues and Oertel, J Neurophysiol 95:76–87, 2006 ; Yi et al., J Neurophysiol 103:2532–2543, 2010 ), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019–3027, 1997 ), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because I _h in the apical neurons have more positive Half-Activation Voltage levels than basal neurons. Even within a single cochlear region, however, I _h current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates I _h current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the I _h current and generated a mathematical model to better understand varied I _h on spiral ganglion function. Regardless of whether I _h currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010 ) or at the somata of spiral ganglion neurons, they have comparable mean Half-Activation Voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of I _h on synaptic physiology.
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Erratum to: Ih and HCN channels in murine spiral ganglion neurons: Tonotopic variation, local heterogeneity, and kinetic model (JARO - Journal of the Association for Research in Otolaryngology DOI: 10.1007/s10162-014-0446-z)
Journal of the Association for Research in Otolaryngology : JARO, 2014Co-Authors: Qing Liu, Paul B. Manis, Robin L. DavisAbstract:One of the major contributors to the response profile of neurons in the auditory pathways is the Ih current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420–1432, 1993; Fu et al., J Neurophysiol 78:2235–2245, 1997; Bal and Oertel, J Neurophysiol 84:806–817, 2000; Cao and Oertel, J Neurophysiol 94:821–832, 2005; Rodrigues and Oertel, J Neurophysiol 95:76–87, 2006; Yi et al., J Neurophysiol 103:2532–2543, 2010), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019–3027, 1997), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because Ih in the apical neurons have more positive Half-Activation Voltage levels than basal neurons. Even within a single cochlear region, however, Ih current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates Ih current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the Ih current and generated a mathematical model to better understand varied Ih on spiral ganglion function. Regardless of whether Ih currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010) or at the somata of spiral ganglion neurons, they have comparable mean Half-Activation Voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of Ih on synaptic physiology.
Alain Vinet - One of the best experts on this subject based on the ideXlab platform.
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From Squid to Mammals with the HH Model through the Nav Channels' Half-Activation-Voltage Parameter
PloS one, 2015Co-Authors: Nedialko I. Krouchev, Frank Rattay, Mohamad Sawan, Alain VinetAbstract:The model family analyzed in this work stems from the classical Hodgkin-Huxley model (HHM). for a single-compartment (space-clamp) and continuous variation of the Voltage-gated sodium channels (Nav) Half-Activation-Voltage parameter ΔV1/2, which controls the window of sodium-influx currents. Unlike the baseline HHM, its parametric extension exhibits a richer multitude of dynamic regimes, such as multiple fixed points (FP's), bi- and multi-stability (coexistence of FP's and/or periodic orbits). Such diversity correlates with a number of functional properties of excitable neural tissue, such as the capacity or not to evoke an action potential (AP) from the resting state, by applying a minimal absolute rheobase current amplitude. The utility of the HHM rooted in the giant squid for the descriptions of the mammalian nervous system is of topical interest. We conclude that the model's fundamental principles are still valid (up to using appropriate parameter values) for warmer-blooded species, without a pressing need for a substantial revision of the mathematical formulation. We demonstrate clearly that the continuous variation of the ΔV1/2 parameter comes close to being equivalent with recent HHM 'optimizations'. The neural dynamics phenomena described here are nontrivial. The model family analyzed in this work contains the classical HHM as a special case. The validity and applicability of the HHM to mammalian neurons can be achieved by picking the appropriate ΔV1/2 parameter in a significantly broad range of values. For such large variations, in contrast to the classical HHM, the h and n gates' dynamics may be uncoupled--i.e. the n gates may no longer be considered in mere linear correspondence to the h gates. ΔV1/2 variation leads to a multitude of dynamic regimes--e.g. models with either 1 fixed point (FP) or with 3 FP's. These may also coexist with stable and/or unstable periodic orbits. Hence, depending on the initial conditions, the system may behave as either purely excitable or as an oscillator. ΔV1/2 variation leads to significant changes in the metabolic efficiency of an action potential (AP). Lower ΔV1/2 values yield a larger range of AP response frequencies, and hence provide for more flexible neural coding. Such lower values also contribute to faster AP conduction velocities along neural fibers of otherwise comparable-diameter. The 3 FP case brings about an absolute rheobase current. In comparison in the classical HHM the rheobase current is only relative--i.e. excitability is lost after a finite amount of elapsed stimulation time. Lower ΔV1/2 values translate in lower threshold currents from the resting state.
Paul Albert Fuchs - One of the best experts on this subject based on the ideXlab platform.
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Voltage-dependent potassium currents in cochlear hair cells of the embryonic chick
Journal of neurophysiology, 1996Co-Authors: Corinne E. Griguer, Paul Albert FuchsAbstract:1. Hair cells were isolated from apical and basal regions of the embryonic chick9s cochlea. Outward potassium currents were recorded using whole cell tight-seal Voltage clamp. 2. Outward currents in basal hair cells activated and inactivated rapidly. The average time to half-maximum at 0 mV was 2.9 ms. The time constant of inactivation at 0 mV was 71 ms. Boltzmann fits to conductance-Voltage curves gave an average Half-Activation Voltage of -36 mV, and steady-state inactivation was half-maximal at -62 mV. 3. Potassium currents in apical hair cells had slower kinetics, with a time to half-maximum of 6.7 ms and an inactivation time constant of 242 ms at + 10 mV. The Half-Activation Voltage derived from Boltzmann fits was -16 mV and that for inactivation was -43 mV. 4. With respect to kinetic and Voltage-dependent properties, the rapidly and slowly activating potassium currents of embryonic cells were similar to the rapidly inactivating "A" current of mature short hair cells and to the delayed rectifier of mature tall hair cells. However, unlike the adult currents, the embryonic currents did not show differential sensitivities to tetraethylammonium chloride and 4-aminopyridine. As early as the tenth day of embryogenesis, hair cells at the apical and basal extremes of the cochlea produced functionally distinct Voltage-gated potassium currents.
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Kinetic analysis of barium currents in chick cochlear hair cells
Biophysical journal, 1995Co-Authors: M. Zidanic, Paul Albert FuchsAbstract:Inward barium current (IBa) through Voltage-gated calcium channels was recorded from chick cochlear hair cells using the whole-cell clamp technique. IBa was sensitive to dihydropyridines and insensitive to the peptide toxins omega-agatoxin IVa, omega-conotoxin GVIa, and omega-conotoxin MVIIC. Changing the holding potential over a -40 to -80 mV range had no effect on the time course or magnitude of IBa nor did it reveal any inactivating inward currents. The activation of IBa was modeled with Hodgkin-Huxley m2 kinetics. The time constant of activation, tau m, was 550 microseconds at -30 mV and gradually decreased to 100 microseconds at +50 mV. A Boltzmann fit to the activation curve, m infinity, yielded a half activation Voltage of -15 mV and a steepness factor of 7.8 mV. Opening and closing rate constants, alpha m and beta m, were calculated from tau m and m infinity, then fit with modified exponential functions. The H-H model derived by evaluating the exponential functions for alpha m and beta m not only provided an excellent fit to the time course of IBa activation, but was predictive of the time course and magnitude of the IBa tail current. No differences in kinetics or Voltage dependence of activation of IBa were found between tall and short hair cells. We conclude that both tall and short hair cells of the chick cochlea predominantly, if not exclusively, express noninactivating L-type calcium channels. These channels are therefore responsible for processes requiring Voltage-dependent calcium entry through the basolateral cell membrane, such as transmitter release and activation of Ca(2+)-dependent K+ channels.
