Model program for the paper:
Sergey M. Korogod, Irina B. Kulagina, and Suzanne Tyc-Dumont
Transfer Properties of Neuronal Dendrites with Tonically Activated Conductances
Neirofiziologiya/Neurophysiology
Vol.30, Nos.4/5, pp.259-264, July-October, 1998
(Kluwer Academic/ Plenum Publishers English version: Neurophysiology
30(4/5):203-207, 1999)
Running the mosinit.hoc program recreates Figures 2 and 3 of the paper.
To compute and display a figure click on the corresponding item, e.g.
"Fig.2. A-D" or "Fig.3. C", of the "Article Results" menu window
operating similar to "NEURON Main Menu". Then click on "Init & Run"
in "RunControl" window.
Click on "Quiet" in "RunControl" window to get the results quicker.
To see 3D shape of simulated dendrites click on "Graph" and "Shape plot"
in "NEURON Main Menu" when the corresponding Fig.2 or 3 is activated.
For details of the individual dendrite geometry see also Figure 1 of the
paper (Fig1.gif file).
This presentation was programmed by Valery I. Kukushka.
The models extend those described in
Korogod SM and Kulagina IB (1998) Biol Cybern 79: 231-242
by using geometry of digitally reconstructed dendritic arborization of
rat abducens motoneuron.
Models 1 and 2 include, respectively, a moderately complex single dendrite
and the whole arborization. They show how the membrane properties and
stochastic geometry define the somatopetal current transfer from tonic
excitatory synaptic inputs distributed over the dendrites. Introducing
uniform steady synaptic conductivity in the dendritic membrane simulates
such input. The extrasynaptic dendritic conductances were either passive or
active, Hodgkin-Huxley type Na and K conductances.
The simpler model 1 (Fig.2) shows effects of random branching and diameter
variation on the contribution from each dendritic site to the total current
reaching the soma. For that the NEURON programs compute and display the
path profiles of the membrane voltage (A, E), total and partial
conductivities (B, F), total current per unit membrane area (C, G) and the
core current increment per unit path length (D, H). The latter is the
estimate of the current transfer effectiveness.
The heterogeneous depolarization increases with path distance from the soma
with unequal rates (gradients) along different dendritic paths. The voltage
path profiles diverge according to the branching asymmetry due to greater
depolarization of longer sister paths. More depolarized dendritic sites
generate inward membrane current of smaller density. Path profiles of the
core current increment that is the product of the membrane current density
and perimeter are modulated by randomly varying diameter (cf. Fig.2. D, H
and Fig.1).
The complex model 2 (Fig.3) shows that, in the whole reconstructed
arborization receiving distributed input, whatever are membrane properties,
passive or Hodgkin-Huxley type active (B or C, respectively), the path
profiles of depolarization form bundles, which correspond to those of the
passive transfer effectiveness from single site inputs (A). The bundles
indicate the groups of dendritic paths, which although hardly
distinguishable, morphologically are functionally distinct due to
between-group difference and within-group similarity of their electrical
behavior. Random diameter variations perturb bundling of the path profiles
of the current transfer from distributed sources (D).
Membrane mechanisms:
PasD.mod - passive extrasynaptic and synaptic currents (models with passive
dendrites)
PasS.mod - passive synaptic current (models with active dendrites)
Hh1.mod - sodium, potassium and leak currents of Hodgkin-Huxley type (models
with active dendrites)
PasSA.mod: passive membrane current of the soma and axon (all models)
For further details see the above-mentioned papers or contact the authors at:
Laboratory of Biophysics and Bioelectronics,
Dniepropetrovsk National University,
49050 Dniepropetrovsk, Ukraine
Phone/FAX: +38056 776 91 24
E-mails: korogod@ff.dsu.dp.ua; kulagina@ff.dsu.dp.ua; valery@ff.dsu.dp.ua
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