Synchronous firing patterns of a set of insect neurosecretory cells

The number of active cells in each synchronous firing event in a set of 10 neurosecretory cells in the silkmoth Bombyx meal was estimated from the amplitude and waveform of compound action potentials. One to 10 cells discharged an action potential within a period of 30 ms and one to two or nine to 10 units became active more frequently in a synchronous firing event. Numbers of active cells fluctuated like a sequence of pseudo random numbers, though the same number of cells tended to fire in two successive firing events of a short interval. These patterns suggest that electrical coupling may mediate synchronous firings in the insect neurosecretory cell system.