Video 12.2 Ganglion recording. Start zoomed out and slowly drive the electrode into the saline. When the electrode enters the saline, you may hear a pop as the voltage goes to approximately zero. (If the voltage is not zero, adjust the baseline on your amplifier.) Use the amplifier to inject 1 nA of current; the resulting deflection in mV gives the electrode resistance in MΩ. With the amplifier injecting 1 nA of current, turn the bridge-balance knob to bring the voltage back to zero. This compensates for electrode resistance. Now turn off the current injection. Advance the electrode further toward the ganglia, zooming in and refocusing to follow the tip.