J Physiol. 1983 Mar;336:301-11.
On the site of impulse initiation in a neurone.
Moore JW, Stockbridge N, Westerfield M.

In the preceding paper (Moore & Westerfield, 1983) the 
effects of changes in membrane properties and non-uniform 
geometry on impulse propagation and threshold parameters 
were investigated. In this paper the contributions of these 
and other parameters to the site of initiation of an 
impulse were determined by computer simulations using the 
Hodgkin-Huxley membrane description, the cable equations, 
and geometry appropriate for a simplified motoneurone with 
a non-myelinated axon. Antidromic invasion of action 
potentials into the soma was found to depend upon (a) the 
ionic channel rate constants (determined by the 
temperature), (b) the abruptness of the transition from the 
small-diameter axon to the larger diameter (and increased 
load) of the soma-dendrite, (c) extensions of active 
properties into the dendrite, and (d) density of ion 
channels. The location of the apparent site of initiation 
of impulses was not necessarily at the site of synaptic 
input nor the nearest active membrane. Its position 
depended upon (a) the fraction of the dendritic tree with 
excitable membrane, and secondarily on (b) the stimulus 
strength. Even with uniform excitability in the active 
membrane, the apparent site of initiation could be moved a 
considerable distance from the soma and the site of 
stimulation by appropriate choice of the various parameters 
noted above.
