Abstract
Cultured neurons reconstruct a neuronal network on a culture dish. The network structure is modified by input from outer world in activity dependent manner. Cultured rat hippocampal neurons on a multielectrodes array (MEA) dish are suitable for analyzing such complex network dynamics and developmental processes of network formation. To elucidate network dynamics, we applied shots of electrical stimuli in several types of inter-stimulus intervals. The electrical activity pattern of the living neuronal network evoked by paired stimulation is quite different from one evoked by a single stimulation. In this report, the feature of this type of network hysteresis was investigated and the hysteresis was kept for at least 1 s and not kept for 10 s. In addition, this hysteresis was remarkable only in long cultures with matured complex networks.