On the endogenous bursting properties of 'light yellow' neurosecretory cells in the freshwater snail Lymnaea stagnalis (L.).

Intracellular microelectrodes were used to study a cluster of neurosecretory 'Light Yellow' Cells (LYC) in the central nervous system of Lymnaea stagnalis. LYC usually have a spontaneous firing pattern of bursts, lasting 10--600 s, alternating with periods of silence. Experiments on isolated single cells showed that the bursting activity has an endogenous origin. Each action potential is followed by a depolarizing afterpotential (DAP), with an amplitude of about 10 mV, lasting several seconds. Bursts end with a subthreshold DAP. It is concluded that two pace-maker mechanisms are responsible for the bursting pr-perties, one initiating and the other (the DAP) maintaining the burst. The relationship between the electrical and the neurosecretory properties of the cells is discussed.