Fig. 1.

Presynaptic stimulation with realistic waveforms. The membrane potential oscillations of an LP neuron were recorded in normal saline. A unitary waveform was created by dividing the trace into single cycles and by averaging the cycles and low-pass filtering to eliminate the action potentials. The waveform was stored in the computer. This procedure was repeated for different LP neurons to capture different duty cycles (the ratio of time that the waveform was above its mean value). The resulting unitary waveforms, scaled to various amplitudes and frequencies, were used to voltage clamp LP neurons periodically (in TTX) in subsequent experiments.