A REEXAMINATION OF THE SYNAPTIC CONNECTION BETWEEN NEURON L7 OF THE ABDOMINAL-GANGLION AND NEURONS OF THE BRANCHIAL GANGLION IN APLYSIA-CALIFORNICA, A-KURODAI AND A-JULIANA

The presence of a synaptic connection between neuron L7 of the abdomin al ganglion and branchial ganglionic neurons (BGNs) was reexamined by means of electrophysiology and fluorescent microscopy using three Aply sia species. We succeeded in recording excitatory postsynaptic potenti als produced in a BGN, which followed impulses of L7 one-to-one with a constant latency, even in A. californica as well as in A. kurodai and A. juliana. Dye-injection revealed that fine collaterals extended fro m a major branch of L7 to the branchial ganglion and arborized in neur opil of the ganglion. The results show that L7 in the three species ha s a dual function as a motor neuron and as an interneuron for the gill . (C) 1998 Elsevier Science Ireland Ltd.