ABSTRACT
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 properties, one initiating and the other (the DAP) maintaining the burst.
The relationship between the electrical and the neurosecretory properties of the cells is discussed.
