Uniform unbranched cable with Hodgkin-Huxley sodium and potassium channels showing a prpoagating action potential. The task specification and reference results come from Upi Bhalla's 1992 Rallpack distribution, part of which is included below. The rest in the file README.upi.

The model produces three graphs showing the reference data computed by Neuron (green) and Genesis (orange) and calculated curves in other colors according to the timestep used: magenta : 1ms, cyan : 20us, blue : 1us. The only difference between the graphs are the axis ranges: they all show the same data. The reference data was computed with 1us timesteps.

If the system performs correctly, the blue line (1us timestep) and reference green and orange should be almost coincident at the beginning and differ by less than 0.2ms after 250ms.

The magenta and cyan lines show how increasing the timestep makes very little change to the spike shape, but changes the period slightly such that by the end of the calculation the longer timestep calculation has spikes a few milliseconds behind. This is a normal feature of the implicit euler method arising from the use of forward differencing for the time derivative.