Burst activity and cellular interaction in the pacemaker ganglion of the lobster heart.

The pacemaker ganglion of the lobster heart is a functionally complete neural structure of nine cells which is capable of spontaneously producing bursts of actionpotential discharges separated by periods of relative inactivity. The burst discharge is maintained even when the ganglion is completely removed from the heart. The somata of five of the nine cells are quite large, approximately 60 /i in diameter, making them favourable for study by means of intracellular electrodes. A number of reports have been made, dealing with intracellular studies on Panulirus interruptus and P. japomcus, the California and Japanese spiny lobsters (Bullock & Terzuolo, 1957; Watanabe, 1958; Hagiwara & Bullock, 1957; Hagiwara, Watanabe & Saito, 1959; Watanabe & Bullock, i960). Studies on Homarus americanus, the New England lobster, have been carried out by Welsh & Maynard (1951), Maynard (1955), and Hartline (1967), these investigators using extracellular recording techniques. Cooke (1966) has reported on intracellular activity in this preparation.