抄録
When electrical activities of nerve cells are investigated with microelectrodes, it is always useful to have a device to apply currents through the microelectrode, which provides the way of analysing the membrane properties of the impaled cell and injecting ions or ionized susbstances into the cell or juxtacellular space. In connexion with this technique, problems how to neutralize the input capacitance, how to reduce the shunting effect of the resistance, which carries the current to the microelectrode, upon the input impedance, and how to monitor the current intensity and the high frequency characteristics of the input circuit are discussed, and a transistorized version of an input circuit suitable for both recording with and passing currents through a single microelectrode is described. The limitation of the use of a single microelectrode is the electrode polarization which occurs by passage of the current of more than 3×10-9 A. Therefore, for relatively large currents, a double-barrelled microelectrode has been used, recording through one barrel and passing current through the other. With them, there occurs interference between the two barrels through the capacitance across the glass wall and the common resistance at the tip. Principles are described for different methods of compensation for the artifacts which arise from inter-barrel coupling. In addition, the methods of pulling and filling microelectrodes and of microminipulation are described as suitable for experiments on the mammalian central nervous system.
