This simplified neuron model could be used to represent a fast spiking
interneuron in a cortical network. However, the model was created to
provide an example of GENESIS scripting, rather than to fit the current
clamp firing patterns of typical cortical inhibitory interneurons. Some
parameter adjustments are likely to be necessary before it is used in a
realistic cortical network model. The single-compartment RScell model with
the muscarinic current removed would also be a good starting point for a
parameter search over passive cell parameters and the conductance densities
for the Na and K currents.
The main script FScell.g uses the cell reader to create a simple
two-compartment neuron with a dendrite compartment, a soma, and an axon.
The dendrite contains synaptically activated excitatory and inhibitory
channels and the soma contains "squid-like" voltage-activated
Hodgkin-Huxley sodium and potassium channels, plus a spikegen element that
acts like the intial part of an axon. This may be used to provide synaptic
input to another cell.
The simulation is based on an example script to create a neuron from a
specified cell parameter file, with channels taken from the prototypes
created by the file protodefs.g. It can be customized for another cell by
changing strings that are defined in the main script, providing a cell
parameter file for the new cell, and providing a modified protodefs.g file
to create the necessary prototype elements. When used with the GUI
functions defined in graphics.g, it allows a an injection current and a
variety of synaptic inputs to be applied.
The CONTROL PANEL of the GUI (defined in graphics.g) allows a steady
injection current to be applied to the cell, and/or synaptic activation to
be applied to the synchan that is specified in the string variable
'synpath'. If the value of synpath is '' (empty), then the synaptic input
form does not appear.
In the synaptic input form, 'gmax' is used to set the gmax field of the
specied synchan. Poisson-distributed background activation can be applied
to the synchan by setting the 'Frequency' (the average activation
frequency) to a non-zero value. This sets the frequency field of the
synchan to that value. The 'Spike input ON/OFF' toggle turns on and off
the application of trains of spikes at the specified 'Spike interval'.