![]() With each increment in distance along the axon, the fraction of the injected current that flows down the axon again faces two paths and the amount of current flowing down the nerve fiber will gradually decrement as will the amount of current crossing the membrane resistance. ![]() The relative amount of current that crosses the membrane versus the amount of current that flows axially depends upon the resistance of the membrane relative to the resistance of the axial current path. It can flow axially along the interior of the axon or it can flow back to ground across the membrane. If a current is injected into the center of an axon at a single point the current can do one of two things (Figure 2). ![]() As a consequence, the passive electrical properties of axons are known as its cable properties. They can be described using a similar mathematical model to that originally first used to analyze the electrical properties of transatlantic telegraph cables. The passive electrical properties of the axon membrane are more complicated than those of a simple spherical cell described previously. This self-propagating wave of depolarization travels down the axon and ends in the nerve terminal. The action potential typically initiates in the initial segment, since this is a region where there is a high concentration of Na + channels, and then propagates down the axon by depolarizing the neighboring axon membrane. Arrows indicate the normal direction of travel of electrical excitation. In general, there is a one-way flow of electrical excitation from the presynaptic neuron to the postsynaptic neuron.įigure 1 Structure of a typical neuron. Electrical information passes from the presynaptic nerve terminal to the dendrites or cell body of the postsynaptic neuron and then travels down the axon to the nerve terminal, where it is transmitted to the next neuron. Conduction of Action Potentials along AxonsĪ typical neuron is comprised of several distinct subcellular compartments (Figure 1):
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