scholarly journals Membrane Resistivity at the Distal Dendrites of Neurons

2004 ◽  
Vol 44 (4) ◽  
pp. 166-171
Author(s):  
Masashi MIYAKAWA ◽  
Masashi INOUE ◽  
Hiroki AKIYAMA ◽  
Eriko OHMORI
Keyword(s):  
Membrane Resistivity

EFFECT OF CELLULAR MEMBRANE RESISTIVITY INHOMOGENEITY ON THE THERMAL NOISE-LIMIT

2015 ◽  
Vol 11 (3) ◽  
pp. 3171-3183
Author(s):  
Gyula Vincze
Keyword(s):  
Field Strength ◽  
Thermal Noise ◽  
Cellular Membrane ◽  
Thermal Limit ◽  
Low Frequencies ◽  
Membrane Resistivity ◽  
Noise Limit ◽  
The Asymmetry ◽  
Characteristic Field

Our objective is to generalize the Weaver-Astumian (WA) and Kaune (KA) models of thermal noise limit to the case ofcellular membrane resistivity asymmetry. The asymmetry of resistivity causes different effects in the two models. In the KAmodel, asymmetry decreases the characteristic field strength of the thermal limit over and increases it below the breakingfrequency (10  m), while asymmetry decreases the spectral field strength of the thermal noise limit at all frequencies.We show that asymmetry does not change the character of the models, showing the absence of thermal noise limit at highand low frequencies in WA and KA models, respectively.

Nonequivalent cylinder models of neurons: interpretation of voltage transients generated by somatic current injection

1988 ◽  
Vol 60 (1) ◽  
pp. 125-148 ◽  
Author(s):  
P. K. Rose ◽  
A. Dagum
Keyword(s):  
Regional Differences ◽  
Dendritic Tree ◽  
Membrane Properties ◽  
Reliable Estimate ◽  
Voltage Response ◽  
Spinal Motoneurons ◽  
Membrane Resistivity ◽  
Voltage Dependent ◽  
Voltage Transients ◽  
Specific Membrane

1. Numerical methods were used to simulate the voltage responses to an intrasomatic current step of neuronal models that incorporated tapering dendrites, dendrites of unequal electrotonic length, nonlinear membrane properties, and regional differences in specific membrane resistivity (Rm). A "peeling" technique was used to estimate the time constants (tau 0 and tau 1) and coefficients (a0 and a1) of the first two exponential terms of the series of exponential terms whose sum represented the slope of the voltage response. 2. The electrotonic structure of models with a uniform Rm was calculated using equations derived by Rall or Johnston or Brown et al. The adequacy of these methods were tested using a wide variety of models that conformed to the equivalent cylinder approximation of Rall. Johnston's method provided the most reliable estimate of electrotonic length (L) and the ratio of the dendritic conductance to the somatic conductance (rho). However, if L exceeded 2 and rho was eight or larger, the equations derived by Johnston could frequently not be solved due to small errors in the peeled values of tau 0, tau 1, a0, and a1. Although the method suggested by Brown et al. could be applied to all models, this method invariably underestimated L and rho. These errors were particularly large for model neurons with L values of 1.5 or larger and rho values of four or larger. Estimates of L using Rall's method were only reliable if rho was large and L was two or less. 3. Changing the geometry of the dendritic tree (dendritic tapering or dendrites of unequal L) or the addition of a time- and voltage-dependent conductance designed to mimic a sag process commonly seen in spinal motoneurons caused systematic changes in tau 0, tau 1, a0, and a1. The sag process always led to an underestimate of tau 0 even after applying a correction procedure. On the other hand, the ratio, tau 0/tau 1, was not affected by the sag process or dendritic tapering.(ABSTRACT TRUNCATED AT 400 WORDS)

Relation Between Electrotonic Potential and Membrane Resistivity in Frog Nerve

1954 ◽  
Vol 177 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Gordon M. Schoepfle ◽  
John M. Grant
Keyword(s):  
Membrane Resistivity ◽  
Electrotonic Potential

Estimating the electrotonic structure of neurons with compartmental models

1992 ◽  
Vol 68 (4) ◽  
pp. 1438-1452 ◽  
Author(s):  
W. R. Holmes ◽  
W. Rall
Keyword(s):  
Input Resistance ◽  
Morphological Data ◽  
Unknown Parameters ◽  
Membrane Area ◽  
Time Constants ◽  
Fitting Procedure ◽  
Dendritic Membrane ◽  
Membrane Resistivity ◽  
Soma Membrane ◽  
Current Transients

1. A procedure based on compartmental modeling called the "constrained inverse computation" was developed for estimating the electrotonic structure of neurons. With the constrained inverse computation, a set of N electrotonic parameters are estimated iteratively with use of a Newton-Raphson algorithm given values of N parameters that can be measured or estimated from experimental data. 2. The constrained inverse computation is illustrated by several applications to the basic example of a neuron represented as one cylinder coupled to a soma. The number of unknown parameters estimated was different (ranging from 2 to 6) when different sets of constraints were chosen. The unknowns were chosen from the following: dendritic membrane resistivity Rmd, soma membrane resistivity Rms, intracellular resistivity Ri, membrane capacity Cm, dendritic membrane area AD, soma membrane area As, electrotonic length L, and resistivity-free length, rfl (rfl = 2l/d1/2 where l and d are length and diameter of the cylinder). The values of the unknown parameters were estimated from the values of an equal number of known parameters, which were chosen from the following: the time constants and coefficients of a voltage transient tau 0, tau 1, ..., C0, C1, ..., voltage-clamp time constants tau vc1, tau vc2, ..., and input resistance RN. Note that initially, morphological data were treated as unknown, rather than known. 3. When complete morphology was not known, parameters from voltage and current transients, combined with the input resistance were not sufficient to completely specify the electrotonic structure of the neuron. For a neuron represented as a cylinder coupled to a soma, there were an infinite number of combinations of Rmd, Rms, Ri, Cm, AS, AD, and L that could be fitted to the same voltage and current transients and input resistance. 4. One reason for the nonuniqueness when complete morphology was not specified is that the Ri estimate is intrinsically bound to the morphology. Ri enters the inverse computation only in the calculation of the electrotonic length of a compartment. The electrotonic length of a compartment is l[4 Ri/(dRmd)]1/2, where l and d are the length and diameter of the compartment. Without complete morphology, the inverse computation cannot distinguish between a change in d or l and a change in Ri. Even when morphology is known, the accuracy of the Ri estimate obtained by any fitting procedure is affected by systematic errors in length and diameter measurements (i.e., tissue shrinkage); the Ri estimate is inversely proportional to the length measurement and proportional to the square root of the diameter measurement.(ABSTRACT TRUNCATED AT 400 WORDS)

Electrotonic parameters of cat spinal α-motoneurons evaluated with an equivalent cylinder model that incorporates non-uniform membrane resistivity

1987 ◽  
Vol 435 (1-2) ◽  
pp. 398-402 ◽  
Author(s):  
Loyd L. Glenn ◽  
Brad G. Samojla ◽  
Jeffrey F. Whitney
Keyword(s):  
Membrane Resistivity ◽  
Cylinder Model ◽  
Uniform Membrane

scholarly journals Electrophysiological properties of the membrane and acetylcholine receptor in developing rat and chick myotubes.

1975 ◽  
Vol 66 (3) ◽  
pp. 327-355 ◽  
Author(s):  
A K Ritchie ◽  
D M Fambrough
Keyword(s):  
Progressive Increase ◽  
Membrane Properties ◽  
Ion Distribution ◽  
Ionic Selectivity ◽  
Passive Permeability ◽  
Electrophysiological Properties ◽  
Membrane Resistivity ◽  
Na Ions ◽  
Developing Rat ◽  
Specific Membrane

Membrane properties of rat and chick myotubes in various stages of development were studied. Resting membrane potentials (Em) increased from -8 to -55 mV in both rat and chick as the myotubes developed from myoblasts to large multinucleated fibers. In the rat myotubes, this increase was not accompanied by significant changes in specific membrane resistivity or changes in Na+ and K+ ion distribution. Nor have we observed a significant electrogenic component to the resting Em of mature rat myotubues under normal circumstances. A progressive increase in the passive permeability of the membrane to K+ relative to Na+ ions has been observed which can account for the changes in Em with development. In contrast to the changes in the ionic selectivity of the membrane, we have found that the ionic selectivity of the ACh receptor of rat and chick myotubes remains constant during the same period of myotube development.

Simulations to Derive Membrane Resistivity in Three Phenotypes of Guinea Pig Sympathetic Postganglionic Neuron

2003 ◽  
Vol 89 (5) ◽  
pp. 2430-2440 ◽  
Author(s):  
John Jamieson ◽  
Hugh D. Boyd ◽  
Elspeth M. McLachlan
Keyword(s):  
Membrane Properties ◽  
Specific Resistivity ◽  
Small Current ◽  
Membrane Area ◽  
Cell Class ◽  
Distinct Cell ◽  
Membrane Resistivity ◽  
Surface Irregularities ◽  
Current Steps ◽  
Specific Membrane

The electrotonic behavior of three phenotypes of sympathetic postganglionic neuron has been analyzed to assess whether their distinct cell input capacitances simply reflect differences in morphology. Because the distribution of membrane properties over the soma and dendrites is unknown, compartmental models incorporating cell morphology were used to simulate hyperpolarizing responses to small current steps. Neurons were classified as phasic (Ph), tonic (T), or long-afterhyperpolarizing (LAH) by their discharge pattern to threshold depolarizing current steps and filled with biocytin to determine their morphology. Responses were simulated in models with the average morphology of each cell class using the program NEURON. Specific membrane resistivity, R m, was derived in each model. Fits were acceptable when specific membrane capacitance, C m, and specific resistivity of the axoplasm, R i, were varied within realistic limits and when underestimation of membrane area due to surface irregularities was accounted for. In all models with uniform R m, solutions for R m that were the same for all classes could not be found unless C m or R i were different for each class, which seems unrealistic. Incorporation of a small somatic shunt conductance yielded values for R m for each class close to those derived assuming isopotentiality ( R m approximately 40, 27, and 15 kΩcm2 for T, Ph, and LAH neurons, respectively). It is concluded that R mis distinct between neuron classes. Because Ph and LAH neurons relay selected preganglionic inputs directly, R m generally affects function only in T neurons that integrate multiple subthreshold inputs and are modulated by peptidergic transmitters.

Specific membrane resistivity of dye-injected cat motoneurons

1971 ◽  
Vol 28 (3) ◽  
pp. 556-561 ◽  
Author(s):  
J.N. Barrett ◽  
W.E. Crill
Keyword(s):  
Membrane Resistivity ◽  
Specific Membrane
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