scholarly journals The Morphology and Passive Electrical Properties of Claw Closer Neurones in Snapping Shrimp

1982 ◽  
Vol 101 (1) ◽  
pp. 307-319
Author(s):  
JOHN A. WILSON ◽  
DEFOREST MELLON
Keyword(s):  
Body Size ◽  
Electrical Properties ◽  
Cell Body ◽  
Input Resistance ◽  
Proximal Portion ◽  
Snapping Shrimp ◽  
Length Constant ◽  
The Difference ◽  
Passive Electrical Properties ◽  
Cell Body Size

The morphology and passive electrical properties of the dimorphic pincer and snapper claw closer neurones were examined in the snapping shrimp, Alpheus heterochelis. No differences were found between homologous pincer and snapper neurones for input resistance and length constant in the proximal portion of the axons, or for the proximal axonal and dendritic anatomies using intracellular cobalt staining. To determine the effect of cell body size upon the passive electrical properties of the neurones, we modelled the neurones by computer. The difference in cell body size causes less than a 3% change in the electrical properties of the neurone at the axon root. Thus, despite the striking behavioural dissimilarities between the pincer and snapper claws, there is no electrical or morphological basis in the claw closer neurones for this difference.

Thermal dependence of passive electrical properties of lizard muscle fibres

1987 ◽  
Vol 133 (1) ◽  
pp. 169-182 ◽  
Author(s):  
B. A. Adams
Keyword(s):  
Electrical Properties ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Effect Of Temperature ◽  
Muscle Fibres ◽  
Thermal Dependence ◽  
Thermophilic Species ◽  
Length Constant ◽  
Increasing Temperature ◽  
Passive Electrical Properties

1. The thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (IF) muscle of Anolis cristatellus (15–35 degrees C) and Sceloporus occidentalis (15–40 degrees C), and for twitch fibres from the white (15–45 degrees C) and red (15–40 degrees C) regions of the IF of Dipsosaurus dorsalis. These species differ in thermal ecology, with Anolis being the least thermophilic and Dipsosaurus the most thermophilic. 2. Iliofibularis fibres from the three species reacted similarly to changing temperature. As temperature was increased, input resistance (Rin) decreased (average R10 = 0.7), length constant (L) decreased (average R10 = 0.9), time constant (tau) decreased (average R10 = 0.8), sarcoplasmic resistivity (Rs) decreased (average R10 = 0.8) and apparent membrane resistance (Rm) decreased (average R10 = 0.7). In contrast, apparent membrane capacitance (Cm) increased with increasing temperature (average R10 = 1.3). 3. Rin, L, tau and apparent Rm were lowest in fibres from Anolis (the least thermophilic species) and highest in fibres from Dipsosaurus (the most thermophilic species). Anolis had the largest and Dipsosaurus the smallest diameter fibres (126 and 57 micron, respectively). Apparent Cm was highest in fibres from Sceloporus, which had fibres of intermediate diameter (101 micron). Rs did not differ significantly among species. 4. The effect of temperature on the passive electrical properties of these lizard fibres was similar to that reported for muscle fibres from other ectothermic animals (crustaceans, insects, fish and amphibians) but qualitatively different from that reported for some mammalian (cat tenuissimus, goat intercostal) fibres. The changes that occur in the passive electrical properties render the fibres less excitable as temperature increases.

scholarly journals Capacitance of the Surface and Transverse Tubular Membrane of Frog Sartorius Muscle Fibers

1969 ◽  
Vol 53 (3) ◽  
pp. 265-278 ◽  
Author(s):  
Peter W. Gage ◽  
Robert S. Eisenberg
Keyword(s):  
Electrical Properties ◽  
Time Course ◽  
Muscle Fibers ◽  
Membrane Resistance ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Tubular Membrane ◽  
Essentially Normal ◽  
The Difference ◽  
Passive Electrical Properties

The passive electrical properties of glycerol-treated muscle fibers, which have virtually no transverse tubules, were determined. Current was passed through one intracellular microelectrode and the time course and spatial distribution of the resulting potential displacement measured with another. The results were analyzed by using conventional cable equations. The membrane resistance of fibers without tubules was 3759 ± 331 ohm-cm2 and the internal resistivity 192 ohm-cm. Both these figures are essentially the same as those found in normal muscle fibers. The capacitance of the fibers without tubules is strikingly smaller than normal, being 2.24 ± 0.14 µF/cm2. Measurements were also made of the passive electrical properties of fibers in a Ringer solution containing 400 mM glycerol (which is used in the preparation of glycerol-treated fibers). The membrane resistance and capacitance are essentially normal, but the internal resistivity is somewhat reduced. These results show that glycerol in this concentration does not directly affect the membrane capacitance. Thus, the figure for the capacitance of glycerol-treated fibers, which agrees well with previous estimates made by different techniques, represents the capacitance of the outer membrane of the fiber. Estimates of the capacitance per unit area of the tubular membrane are made and the significance of the difference between the figures for the capacitance of the surface and tubular membrane is discussed.

White noise approach for estimating the passive electrical properties of neurons

1996 ◽  
Vol 76 (5) ◽  
pp. 3442-3450 ◽  
Author(s):  
W. N. Wright ◽  
B. L. Bardakjian ◽  
T. A. Valiante ◽  
J. L. Perez-Velazquez ◽  
P. L. Carlen
Keyword(s):  
Electrical Properties ◽  
White Noise ◽  
Input Impedance ◽  
Granule Cells ◽  
Short Pulse ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Somatic Membrane ◽  
Dendritic Membrane ◽  
Passive Electrical Properties

1. The passive electrical properties of whole cell patched dentate granule cells were studied with the use of zero-mean Gaussian white noise current stimuli. Transmembrane voltage responses were used to compute the first-order Wiener kernels describing the current-voltage relationship at the soma for six cells. Frequency domain optimization techniques using a gradient method for function minimization were then employed to identify the optimal electrical parameter values. Low-power white noise stimuli are presented as a favorable alternative to the use of short-pulse current inputs for investigating neuronal passive electrical properties. 2. The optimization results demonstrated that the lumped resistive and capacitive properties of the recording electrode must be included in the analytic input impedance expression to optimally fit the measured cellular responses. The addition of the electrode resistance (Re) and capacitance (Ce) to the original parameters (somatic conductance, somatic capacitance, axial resistance, dendritic conductance, and dendritic capacitance) results in a seven-parameter model. The mean Ce value from the six cells was 5.4 +/- 0.3 (SE) pF, whereas Re following formation of the patch was found to be 20 +/- 2 M omega. 3. The six dentate granule cells were found to have an input resistance of 600 +/- 20 M omega and a dendritic to somatic conductance ratio of 6.3 +/- 1.1. The electronic length of the equivalent dendritic cylinder was found to be 0.42 +/- 0.03. The membrane time constant in the soma was found to be 13 +/- 3 ms, whereas the membrane time constant of the dendrites was 58 +/- 5 ms. Incorporation of morphological estimations led to the following distributed electrical parameters: somatic membrane resistance = 25 +/- 4 k omega cm2, somatic membrane capacitance = 0.48 +/- 0.05 microF/cm2, Ri (input resistance) = 72 +/- 5 omega cm, dendritic membrane resistance = 59 +/- 4 k omega cm2, and dendritic membrane capacitance = 0.97 +/- 0.06 microF/cm2. On the basis of capacitive measurements, the ratio of dendritic surface area to somatic surface area was found to be 34 +/- 2. 4. For comparative purposes, hyperpolarizing short pulses were also injected into each cell. The short-pulse input impedance measurements were found to underestimate the input resistance of the cell and to overestimate both the somatic conductance and the membrane time constants relative to the white noise input impedance measurements.

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