Digital Leak Current Subtraction > Stimulus Protocols for Leak Subtraction
One of the most commonly used leak subtraction protocols is the P/N protocol, developed by Bezanilla & Armstrong (1977). For each depolarising test pulse, there are N additional subtraction pulses, evoked by hyperpolarisng pulses 1/Nth the amplitude of the test pulse.
WinWCP's stimulus generator can be configured to produce the necessary sequence of test and leak subtraction recording sweeps, by selecting the P/N Mode leak subtraction option in a stimulus protocol (See Recording Settings). This causes the stimulus generator to produce additional scaled down and inverted stimulus pulse waveforms for evoking the linear leak currents without the voltage-activated currents. The leak current recordings are averaged and stored in a record marked as a LEAK type. The test record is marked as TEST type record. The TEST record, with its associated LEAK record, are collected together in a group (i.e. they have the same group number).