1

Gateway Control Theory

The non-painful signals from TENS “close the gate” and prevent the pain signals from going to the brain. Imagine that these signals are two trains on separate tracks. Each of these two tracks converges into one single track that goes to the brain. The train on the right is the pain signal, and it’s headed for that single track to the brain. But, when the non-painful signal is stimulated-the train on the left-it heads for that same track to the brain, taking over the tracks and preventing the pain signal from getting through.