Figure 5.9

Simulation of the effect of A-type current on neuronal firing

The effect of the A-type current on neuronal firing in simulations. (a) The time course of the membrane potential in the model described in Box 5.2 in response to current injection of 8.21 µA cm2 that is just superthreshold. The delay from the start of the current injection to the neuron firing is over 300 ms. (b) The response of the model to a just suprathreshold input (7.83 µA cm2) when the A-type current is removed. The spiking rate is much faster. In order to maintain a resting potential similar to the neuron with the A-type current, the leak equilibrium potential EL is set to -72.8 mV in this simulation. (c) A plot of firing rate f versus input current I in the model with the A-type conductance shown in (a).  Note the gradual increase of the firing rate just above the threshold, the defining characteristic of Type I neurons. (d) The f-I plot of the neuron with no A-type conductance shown in (b). Note the abrupt increase in firing rate, the defining characteristic of Type II neurons.

Simulation environment:
NEURON How do I run a simulation using NEURON?
Notes

Once the simulation file is open, these are the steps to reproduce each figure:

Panel (a)

  1. In the top Parameters window, click on the checkbox next to Type I parameters
  2. Click on Set Type I threshold current
  3. Click on Init & Run in the Run Control window

Panel (b)

  1. In the top Parameters window, click on the checkbox next to Type II parameters
  2. Click on Set Type II threshold current
  3. Click on Init & Run in the Run Control window

Panel (c)

  1. In the top Parameters window, click on the checkbox next to Type I parameters
  2. Click on Plot in the Grapher window
  3. Simulations for a number of levels of current injection will be run and the firing frequency will be plotted against current in the Grapher window.
  4. Once the simulations have run, to make sure you can see these results, right-click in this graph area and select View... -> View = Plot

Panel (d)

As for panel (c), except in step 1, click on the checkbox next to Type II parameters.

Download:
Binary Data fig-5-9.nrnzip