Fast conducting electrosensory pathway in the mormyrid fish, Gnathonemus petersii.

A compound action potential of short latency was recorded from the ganglion mesencephali extrolaterale in response to both the fish's own electric organ discharge and electric stimulation of the whole fish or a branch of the posterior lateral line nerve. The time difference between the response in the nerve, 16 mm from its entry into the brain, and the mesencephalic ganglion, which is positioned 10 mm anterior in the CNS, was found to be 1.6 msec. This rapid conduction pathway involves peripheral nerve fibres of high conduction velocity (40 m/sec) and presumably two electric synapses, one at the rhombencephalic and the other at the mesencephalic level.