Repetitive activity alters spike initiation locus and conduction velocity in Aplysia axons.

During a burst of spikes in the axon of neuron R2 of Aplysia, the spike initiation zone moves down the axon. The orthodromic latency of propagated spikes decreases as the trigger zone moves distally. At the same time, the conduction velocity of the spikes slows down, which leads to lengthening of interspike intervals, especially in remote regions of the axon. Similar timing changes are seen in the chemical and electrotonic postsynaptic potentials in some follower neurons of L10.