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Neuronal geometry and excitability
Most theoretical studies on neural excitability have dealt with either
isopotential membranes, for example the space-clamped squid axon, or
homogeneous axons. However, in most vertebrate neurons, action
potentials are initiated in a small region of the axon, the axonal
initial segment (AIS), packed with sodium channels and placed very
close to the soma. Thus there is a spatial discontinuity in channel
properties and geometry (large soma, thin axon). In addition, both the
length and position of the AIS can vary with activity. In this
presentation, I will show how neuron and AIS geometry impact the
initiation of action potentials and their backpropagation to the soma.