Analysis of the electrical excitation of CNS neurons.

The artificial excitation process of neurons of the central nervous system depends on the applied extracellular field, on the geometry of the neuron and on the electrical properties of the neural subunits. Results of computer simulations are based on a compartment model of the neuron and its equivalent electrical network. Furthermore, a theory is presented which generalizes the activating function concept known from peripheral nerve stimulation. The theory predicts the influence of electrical and geometrical parameters on the excitation threshold. Generally, the myelinated axon is the part of a neuron which is most excitable to a given applied field. An example demonstrates that for a target neuron the quotient (anodic threshold current)/(cathodic threshold current) essentially depends on the position and orientation of the neuron relative to the electrode.