The LTP Program is a stimulation, acquisition and on-line analysis program for studying long-term potentiation (LTP), long-term depression (LTD), and stimulus-evoked synaptic responses in general. The program is freely available from the website: www.ltp-program.com. It is a 32-bit DOS program that runs on Windows 3/95/98 computers having a Pico Technologies ADC-42, Axon Instruments' Digidata 1200, or Scientific Solution's Labmaster acquisition board. The program records two channels of activity in extracellular, current- or voltage clamp modes. It acquires < or =1,000,000 samples per sweep, and has extracellular dual pathway stimulation and epoch-like intracellular stimulation. Basic protocols include slow alternating dual pathway stimulation. LTP is induced by single train, theta burst, or primed burst stimulation. LTD is induced using fast repetitive 1 pulse sweeps (< or =2 Hz). The program analyzes all stimulus-evoked synaptic responses in both acquisition channels. Analyzes include: slope, peak amplitude/latency, population spike amplitude/latency, average amplitude, duration, area, rise time, decay time, coastline, cell resistance and patch electrode series resistance. Sweeps can be averaged and digitally filtered. Trains can be analyzed by measuring the responses of all pulses relative to the baseline of the first pulse. Stimulus artifacts can be automatically removed for accurate determination of synaptic areas and peaks during a train.