These files reproduce the model associated with the following paper:
Aradi I, Holmes WR. Role of multiple calcium and calcium-dependent
conductances in regulation of hippocampal dentate granule cell
excitability. J Comput Neurosci. 1999 May-Jun;6(3):215-35.
We have constructed a detailed model of a hippocampal dentate granule
(DG) cell that includes nine different channel types. Channel
densities and distributions were chosen to reproduce reported
physiological responses observed in normal solution and when blockers
were applied. The model was used to explore the contribution of each
channel type to spiking behavior with particular emphasis on the
mechanisms underlying postspike events. T-type calcium current in more
distal dendrites contributed prominently to the appearance of the
depolarizing after-potential, and its effect was controlled by
activation of BK-type calcium-dependent potassium
channels. Coactivation and interaction of N-, and/or L-type calcium
and AHP currents present in somatic and proximal dendritic regions
contributed to the adaptive properties of the model DG cell in
response to long-lasting current injection. The model was used to
predict changes in channel densities that could lead to epileptogenic
burst discharges and to predict the effect of altered buffering
capacity on firing behavior. We conclude that the clustered spatial
distributions of calcium related channels, the presence of slow
delayed rectifier potassium currents in dendrites, and calcium
buffering properties, together, might explain the resistance of DG
cells to the development of epileptogenic burst discharges.
-fig4a.hoc reproduces Figure 4A of the paper:
-schematic.ses implements the schematic model described in the paper
in Cell Builder.
To start the NEURON simulation:
Under unix systems:
to compile the mod files use the command
and run the simulation hoc file with the command
Under Windows systems:
to compile the mod files use the "mknrndll" command.
A double click on the simulation file
will open the simulation window.
Under MAC OS X:
Drag and drop the plast folder onto the mknrndll icon in the NEURON
application folder. When the mod files are finished compiling drag
and drop the mosinit.hoc file onto the nrngui icon.
Some typographical errors have been corrected in this implementation:
-The Na and KDR parameters in the paper were chosen relative to a
resting potential of 0 mV; we have adjusted them to correspond to a
resting potential of -70 mV.
-In the equation for alpha_c (N-type calcium current), 19.98 has been
replaced by 19.88.
-The intracellular calcium concentration in the equations for the SK
current is given not in uM but in mM.
These model files were supplied by Hani Nakhoul.
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