(Soc. Neurosci. Abstr. 29)
D.S. Touretzky1; A. Ladsariya1; M.V. Albert1; J.W. Johnson2; N.D. Daw1
1. Computer Science Dept., Carnegie Mellon Univ, Pittsburgh, PA, USA 2. Dept. of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
HHsim is a free, open source Hodgkin-Huxley simulator for teaching introductory neurophysiology. The simulation is "transparent", meaning all parameters of the Hodgkin-Huxley equations are viewable and modifiable. It is also "real-time": variables are plotted in a scrolling strip-chart display and stimuli are applied by clicking buttons as the simulation progresses. The third design principle of HHsim is extensive use of graphics, not only to display the simulator's output, but also to help the user understand the meanings of parameters. For example, the Hodgkin-Huxley variables m, h, and n are each calculated by integrating a differential equation written in terms of associated rate constants, e.g., alpham(V) and betam(V). The rate constants' voltage dependencies, which are described by exponential equations in three parameters, are displayed graphically by HHsim so that the effect of altering a parameter can be immediately observed. Other simulator features include the ability to observe concentration-dependent effects of channel blockers TTX and TEA, removal of inactivation with pronase, plotting membrane currents in voltage clamp mode, precise measurement of plot values via a cursor control, and exporting simulation data to a file for use by other programs.

HHsim is written in Matlab. The source code is released under the GNU GPL (General Public License), which permits free use and redistribution. But HHsim is also available as a binary executable file for users without a Matlab license. We currently provide executables for Windows, Linux, and MacOS X. Sample exercises using the simulator are also provided. The web site is http://www.cs.cmu.edu/~dst/HHsim . Both undergraduate and graduate neurophysiology students have found the simulator helpful for understanding the complexities of excitable membranes.

Support Contributed By: NSF DGE-9987588 and NIMH