Two identified interneurons modulate the firing pattern of pacemaker bursting cells in Helix

Two interneurons modulating the firing pattern of two endogeneous bursting neurons have been identified in the visceral ganglion. They are characterized by large depolarizing afterpotentials and doublets due to the delayed firing of a dense layer of terminal processes converging onto the axon branches from the two bursters. Firing of the terminal processes upon soma or axon stimulation needs either subthreshold depolarization of the cell or conditioning nerve stimulation acting as a gating mechanism.