Microtunnel-electrode device for elucidating axon features: Toward pharmacological manipulation of individual axons

Neural networks in the central nervous system are composed of neurons which interconnect through their axons. Although computational capacity of axons is of great interest, their small structure makes exact evaluation difficult. Culture device capable of obtaining features of individual axons and stimulating with pharmacological reagent is needed. In this study, we aimed to develop a novel culture device for evaluating and stimulating axons. First, the culture device was fabricated and neuronal cells were cultured. Their axons were maintained more than 30 days and axonal conductions were detected with substrate-embedded electrodes. Second, developmental changes in conduction delay and activity-dependent changes in conduction velocity were evaluated. As a result, it is suggested that axons of younger neurons have lower conduction velocity and easily change their conduction velocity by their firing frequency. These results show that our culture device is feasible to record conduction through individual axons and evaluate their feature.