Neuroendocrine (bag) cells of Aplysia: spike blockade and a mechanism for potentiation.

Bag cell activity in Aplysia can be recorded intracellularly and extracellularly. Electrical stimulation anywhere along the connective nerves can produce prepotentials which are not synaptic potentials but represent the passive invasion of action potentials blocked in the neurites. Potentiation of these prepotentials results from progressive movement of the site of spike blockade toward the somata. This type of propagation plasticity may occur in many networks of low conduction safety.