Antidromic action potentials fail to demonstrate known interactions between neurons.

An identified motor neuron in the stomatogastric ganglion of Panulirus interruptus inhibits four other motor neurons when it fires spontaneously or in response to depolarization of its soma. It does not inhibit these neurons when it is fired antidromically, although the attenuated antidromic spike is visible at its soma. These findings point out the difficulty of interpreting negative results from antidromic stimulation experiments and the importance of neuronal structure to the integrative activities of nervous systems.