Graph Class Library

FHN model on a 1D ring

This applet simulates the propagation of action potentials on a ring (the edge at the right is the same as the edge at the left). An action potential is initiated by applying a stimulus.

To use the applet, press the Start button. This generates a single action potential that is initially blocked on the right so it only propagates to the left. The simulation can be paused with the Stop button and resumed using the simulation and the simulation will resume by using the Cont. button. Click inside the plot to initiate more activations. The location of each activation corresponds to the location on the x-axis and the magnitude of the activation corresponds to the value on the y-axis. To make the simulation run faster or slower, click on the corresponding buttons. To return the membrane potential of all cells to the rest value, click Reset. To initiate the original single pulse, click Restart.

Things to try:

  • Stimulate at the back of the original wave (by clicking with the mouse) and generate two new action potentials that propagate in opposite directions.
  • Adjust the timing of a stimulus during the back of a wave to be in the "vulnerable window," when only one action potential propagating in the opposite direction as the original wave is produced. The second wave is not produced in this case because the tissue is refractory closer to the original wave and cannot be excited.
  • Terminate the wave by applying a negative stimulus (below the red line) when the front is passing.

    For more information about the FitzHugh-Nagumo model, see the FitzHugh-Nagumo applet for one cell.