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Mark Dimaline, Randell Beer, and Hillel Chiel (Case Western Reserve) HH is a program with which the user can graphically specify the physical and electrical characteristics of a multiple compartment model of a neuron with Hodgkin and Huxley’s voltage-gated potassium and sodium ion channels. Each compartment can be stimulated by injecting an electrical current. The voltage of each compartment can be clamped at one to six constant levels. The resulting system of equations is numerically integrated with the exponential technique and the time course of various compartment components plotted in graph windows.

A neuron in HH consists of, at least, a soma compartment and, optionally, axon/ dendrite compartments. A compartment (soma or axon/dendrite) may have an injected electrical current and it may also be voltage clamped. The Editor window (below) provides a graphical representation of the neuron: the soma compartment is represented by a circle and axon/dendrite compartments are represented by rectangles.

Double-clicking on a component in the Editor window will open the Edit Compartment dialog box. It is possible to edit the current compartment’s electrical parameters, and to activate and deactivate the potassium and sodium channels. The bottom window in the figure above shows the Potassium Channel Editor dialog box.

It is also possible to modify the current to be injected into the current compartment and to set up to six voltage clamps and stops for the current compartment. Graphs can be defined to plot voltage, injected current, potassium N gate, potassium conductance or current, and sodium M gate, sodium H gate, and sodium conductance or current.

Screen Shots

The Neuron Editor window.

The Edit Compartment dialog box (top) and the Potassium Channel Editor dialog box (bottom).

System Requirements

Macintosh or Power Macintosh

• System 7.1 or better.
• Macintosh II or higher.
• At least 4MB RAM, more recommended.