CONICAL Demo 1:

Cylinder & Injector

Introduction

This program demonstrates the use of the Cylinder and Injector classes. A single cylindrical compartment is created with dimensions similar to a neuron body, and with only passive membrane properties. Into this cell a steady current is injected. The membrane voltage over time is sent to the output stream.

This demo reproduces the behavior of the GENESIS script "tutorial2.g", as included in the distribution and described in The Book of Genesis. This allows us to check the accuracy of CONICAL's integration, as well as compare various attributes of the two modeling systems.

Code Overview

The complete code for the program is contained in main.cpp. As you can see, the code is very short, and can be summarized as follows:
  1. Create a cylindrical compartment (setting attributes from global variables)
  2. Create a current injector
  3. For each time step,
    1. print out values of interest
    2. call gStepmaster->StepAll(dt)
The last step -- "toggle gCurrent" -- is a command which must always be included in a CONICAL simulation loop. (In the future, we plan to have a Simulation object which keeps a list of Steppers, and automatically updates both them and the gCurrent variable.)

Program Output

The actual output of this program is here, and has been graphed (by importing the data to ClarisWorks) below. As a steady current is injected into the compartment, its membrane potential "charges up" with a time constant of about 5 ms.

Building the Program

If you have the full set of CONICAL source code, you should be able to simply copy main.cpp into your project and build it. Of course, this will contain quite a few files you don't need. A minimal project would contain just the following files:

Source FilesHeader Files
Cmprtmnt.cpp
Cylinder.cpp
main.cpp
Stepmaster.cpp
VSink.cpp 		Cmprtmnt.h
Current.h
Cylinder.h
Injector.h
Stepper.h
Stepmaster.h
VSink.h
VSource.h