The Hodgkin-Huxley model - action potential

Introduction

In a classic series of papers from the early 1950's, A.L. Hodgkin and A.F. Huxley performed a painstaking series of experiments on the giant axon of the squid.  Based on their observations, Hodgkin and Huxley constructed a mathematical model to explain the electrical excitability of neurons in terms of discrete Na+ and K+ currents.

What does the model show?

The model simulates an electrical signal called an action potential that passes through the axon of a neuron. Action potentials allows neurons to communicate with one another and with muscle cells. This electrical communication makes possible all of our brain's activity and all muscle movement. After you start the model and hit the stimulate button, enough current to raise the voltage +15 mV is injected into the axon. The first time you do this, you'll observe an action potential. If you hit the stimulate button again immediately after the action potential has fired, you'll notice that another action potential does not occur. If you wait a bit longer, however, and again hit the stimulate button, an action potential will again fire. This demonstrates the "refractory period". After a neuron fires, it needs to "rest" before it can fire again. If you experiment a bit with the stimulate button, you'll notice that if you hit it quickly many times in a row you can overcome the refractory period and cause the neuron to fire.

What equations does the model use?

ą
Marcin Duchiński,
Jan 25, 2010, 10:05 AM
ċ
hh3.bmp
(1165k)
Marcin Duchiński,
Jan 25, 2010, 8:21 AM
ċ
src.zip
(30k)
Marcin Duchiński,
Jan 25, 2010, 9:25 AM
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