Days-long modification of activity pattern induced by NMDA-R dependent synaptic enhancement in a semi-artificial network of living neurons

摘要

It is suitable for constitutive study for brain function that neuronal network in dissociated culture system, which is easy to be manipulate cells and to be measured electrical activity. The cultured neurons autonomously form a complex network on a culture dish and spontaneous electrical activity is often observed without any input from outer environment. We induced long-lasting synaptic enhancement in cultured neuronal networks by exposing to Mg~(2+)-free condition for 20 min. Spontaneous electrical activity was transiently enhanced in Mg~(2+)-free solution. Activity pattern of spontaneous activity was analyzed by crosscorrelogram-based method. In the method, the centralization of distribution of crosscorrelogram around the peak was estimated as an index of the degree of synchronization. After the transient exposure to Mg~(2+)-free solution, the centralization increased to 123.1±19.3%, suggesting that the accuracy of the periodicity and synchrony increased. This remarkable change was sustained in second day after the induction of the synaptic enhancement. In addition, specific blocker of NMDA type glutamate receptors (NMDA-Rs) abolished this increase in synchrony. These results suggest that the cultured neuronal network possess a regulation system for network dynamics based on the NMDA-Rs dependent synaptic plasticity.