Study On The Characteristic Of Cultured Neuronal Network With Multi-Microelectrode Array System

Recent studies have focused attention on the change of the morphologic and the firing patterns displayed by groups of neurons in vivo and in vitro. However, little is known concerning the changes in the underlying spontaneous electrical activity and the role of interneuron in neuronal network in vitro, because of the difficulty of recording the activity of many neurons simultaneously and non-invasively for a long term. In order to address this object, we describe the changes of electrical activity and the underlying mechanism in cultured networks of hippocampal neurons observed with multi-electrode arrays, in normal culture medium.On the research in this field of our laboratory, the neuron culture technique has been improved on for long-term recording over 7 months. By multi-electrode recording system, the activity of neuron network was non-invasively continuously recorded. An open source database of cultured neuronal networks recorded by multi-electrode array was constructed, which serves the study on neurophysiology and mathematical modeling with experimental data.It was found there were many firing patterns of neural network, such as single spike, burst spikes and mixed pattern. Recorded data showed that the firing rate was gradually increased from 1st to 8th week in vitro and then became stable. Meanwhile, the unsynchronized random firing was observed in the 1st week and then transformed into synchronized activity in 2 to 7 week in vitro, and finally the activities transformed into the random firing pattern. These results suggested three stages in the long-term development of neuronal network in vitro: the stage for connection, the stage of synchronized activity and the mature stage. Synchronized firing shown by spontaneous activity was an important phenomenon in high density cultured neuronal network and transformed patterns during development.During development, the bicuculline-induced firing activities transformed from a pattern of synchronized bursts throughout all active sites in 3 week in vitro, to a pattern of local synchronized or random spikes appearing in the intervals of synchronized bursts after 11 week in vitro, while the firing rate hardly changed. These results show that the inhibitory connection was age-dependent degraded in vitro and the spontaneous firing pattern was dependent on the homeostatic balance of the excitatory-inhibitory connection networks.