Fabrication of Microelectrodes, Suction Electrodes, and Focal Electrodes for Electrophysiological Recording in Drosophila.

Electrophysiological recording is a group of techniques used to record electrical field potentials generated by cells. These techniques rely on several types of electrodes, which can be manufactured in the laboratory. In intracellular recording, glass microelectrodes are used to pierce the cell membrane, and then to measure the electrical potential difference between the inside and the outside of the cell. Another technique, called loose patch or focal recording, is similar to intracellular recording but the electrode tip does not pierce into the cell membrane. Rather, the electrode tip is placed near a nerve or the postsynaptic side of the neuromuscular junction (NMJ) to record extracellular changes in local potentials. A third technique involves a suction electrode, which is used to draw part of the motor nerve into the electrode so that electrical pulses can be applied to elicit action potentials of the nerve. Suction electrodes are specifically used to evoke synaptic potentials at the Drosophila larval NMJ. This protocol details some basic methods for manufacturing microelectrodes used for intracellular recording and two-electrode voltage-clamp and loose patch electrodes used for focal recording. In addition, a method is provided for manufacturing homemade suction electrodes used for nerve stimulation.