Abstract
To elucidate higher brain function, it is essential to estimate the functional synaptic connectivity between neurons. For this purpose, it is a suitable method that analyzing responses of living neuronal network evoked by designed stimulation. In this study, we started from a dissociated culture of rat neuronal cells as an experimental material. The connection map of the cultured neuronal network was generated from spike data by using extracellular potential multisite recording system, which can record extracellular potentials in a network of neurons on a culture dish. We developed automatic analyzing system for functional connections. The system records electrical responses evoked by a current stimulation from every 64 electrodes, changing stimulation electrode. The commercial multisite-recording system was modified to record electrical activity with automatic changing of stimulation electrodes. Evoked responses were identified as a consequence of stimulation to a specific electrode. The connection matrix represents efficacy of connections between every possible combination of electrodes. Efficacy of connection was defined as firing probability of evoked neuronal activity. According to the connection matrix, neuronal functional connections between one and other electrodes were depicted into a map. A connections map represents a snapshot of information processing in a whole neuronal circuit on multi-electrode array, and it also useful for pharmacological assay for neuron modulating compounds.
