Multichannel optical recording of neuronal network activity and synaptic potentiation in dissociated cultures from rat hippocampus

The activity of neuronal networks formed by dissociated rat hippocampal neurons was observed with a 128-channel optical recording apparatus using an absorptive voltage-sensitive dye,RH482. Two-dimensional patterns of neural electrical events along somata and neurites in the networks were visualized as the responses to pulse stimuli applied to the somata of the presynaptic neurons by patch-clamp electrodes. Synaptic delay was analyzed from propagation delay of the responses along the neurites. Synaptic potentiation was also observed in postsynaptic responses that were amplified by a factor of 1.24 after tetanization. In contrast, presynaptic components were unaffected by the procedure. In the light of the present results, multichannel optical recording promises to promote our understanding of neuronal interactions at cellular level.