Integral multiple interspike intervals of spontaneous activity in isolated medulla oblongata of frog

Periodic spontaneous activity of units was observed in the isolated medulla oblongata of a frog. The dynamic patterns of periodic activity of the neurons could be classified into 3 classes. In neurons belonging to the class of shortest periodicity, the interspike intervals were shown as integral multiples of those in each spike sequence. This observation suggests that the unit modules are organized in the medulla oblongata.