Spiral Ganglion Cell Type-2 Model (Hossain et al., 2005)
Author: Srdjan Antic, University Connecticut Health Center, 22-DEC-2004
Instructions for those who had no previous experience
with NEURON!
To run the model described in Hossain et al., 2005:
- Install
NEURON from http://www.neuron.yale.edu/neuron/
- Make a
new folder and copy all “Hossain et al., 2005” files to it.
- Run “mknrndll” to compile “mod” files
in that new folder.
- Once
the compiler is finished, go to the folder and double click “mosinit.hoc”.
- From
the Neuron Main Menu use File --> Load Session.
- Pick
any session from the list. The names of the sessions correspond with the
figure panels in Hossain et al., 2005.
- For
instance take session “Fig7A”.
- Once the session is loaded you will see
the following windows:
a)
Neuron Main Menu
b)
4 Voltage-Axis graphs (Graph[1] to Graph[4])
c)
RunControl
d)
PointProcessManager
e)
Temperature
f)
Global Ra, and
g)
Cell Builder (CellBuild[0]
- In the
“RunControl” window click “Init & Run” button.
- Graph[3]
shows the membrane potential transients obtained in the receptor-neural
segment (Receptor[5].v(0.5)) and in the cell body (soma). We are now at
“the lower limit of the sensitive range”. Both initial segments (ISP and
ISC) are supplied with sodium channels, just enough to pass an action potential
from the peripheral to the central axon via the cell body. To check the
actual density of hh sodium channels, go to CellBuild[0] window à
Biophysics à
Init_Seg_Per.
- In the
Cell Builder Change gNabar_hh from 929 to 928 in both, Init_Seg_Per (initial segment of
the peripheral axon) and Init_Seg_Cen
(initial segment of the central axon).
- Run
the simulation again (in “RunControl” window click “Init & Run” button).
- Action
potential (AP) now fails to invade the cell body. The only difference
between this and previous trial is the removal of 1 pS/um2 from both
initial segments.
- To
create the graph in Figure 7, panel C you need to find the “lower limits
of the sensitive range” using four different channel mechanisms. Each bar
in the histogram is represented by a session file starting with “Fig7C-“. If you load any of the
session files starting with “Fig7C-“
and then decrease the sodium conductance by only 1 pS/um2 from any initial
segment, the AP would fail to invade the cell body. Note that the session
“Fig7C-hh-black_bar.ses” is missing. This session file is identical to
“Fig7A.ses”, and therefore is omitted from the download.
>>the end<<
