In this experiment, shown below, current was injected into a cell with an intracellular microelectrode(top traces), and the resultant change in membrane potential was recorded with a second electrode(bottom traces). The dotted lines in the voltage records indicate Vrest. Note that for this type ofexperiment (current clamp), in which current is injected and the change in Vm is recorded, the axesreflect the sign and magnitude of current being injected (depolarizing or hyperpolarizing), rather thanthe direction of current flow in the cell.