Creating a channel from an HH-style specification

Our goal is to implement a new voltage-gated macroscopic current whose properties are described by HH-style equations.

For this example, we will borrow the equations for the HH sodium current because they are familiar and because we can easily check our new current against NEURON's built-in HH mechanism.

The HH sodium current is given by: i_Na = g_Na (V - E_Na)
where: g_Na = gbar_Na m³ h
gbar_Na = 0.12 S/cm²
and the gating variables m and h are governed by first order differential equations of the form: x' = a_x (1 - x) - b_x x
Specifically: a_m = 0.1 (V + 40) / [1 - e^{- (V + 40) / 10}]
b_m = 4 e^{- (V + 65) / 18}
a_h = 0.07 e^{- (V + 65) / 20}
b_h = 1 / [e^{- (V + 35) / 10} + 1]
with time in ms and all voltages in mV.

Here's the outline of how we'll proceed :

Step 1. Bring up a Channel Builder

Step 2. Specify the channel's basic properties

Step 3. Specify "channel gating," i.e. :
     specify the states that control channel gating
     specify transitions between kinetic scheme states
     specify how voltage and ligands affect states and transitions

Step 4. Test the channel

Go back to the main page ("Using the Channel Builder") to work on a different tutorial.