The Study Of Development Of Neuronal Networks By Planar Multi-electrod Array

Recent studies have focused attention on the change of the morphologic and the firing patterns displayed by groups of neurons during development. However, little is known concerning the developmental changes of the underlying synchronous electrical activity, because of the difficulty of recording the activity of many neurons simultaneously and non-invasively. In order to address this, we used electrode arrays appropriate for the study of network activity. Here, we describe the developmental changes of electrical activity in networks of hippocampal neurons observed with multi-electrode arrays, in normal culture medium.On the base of this research of our laboratory, we improved on the hippocampal neuron culture technique, and observed the morphological changes of neuronal networks with the microscope. Long-term recording of spontaneous activity in cultured neuronal networks was carried out using substrates containing multi-electrode arrays. Spontaneous firing appeared within the first 4 days in vitro (DIV) and rapid changed in the firing rate,amplitude and inter spike interval (ISI) from the 4 to 15 DIV. The changes become smaller from 16 to 28 DIV, and the electrical activity becomes lower and lower from 30 DIV. In the research of learning, we found the networks in the mature stage had functional plasticity. With the thermo controller, we observed that the networks had the thermosensity, which was depressed with the development of the networks.These findings indicate that at the end stage, the electrical activity of cultured hippocampal neuron networks becomes more and more weak, and the thermosensity decreases; the mature networks have abundant synapses and the plasticity of its function.