(written from a Production point of view)
According to the script for Star Trek IV: The Voyage Home, toroidal space-time distortion was a type of disturbance in space-time. This disturbance had the shape of a toroid, a doughnut-shaped object.
In 2286, on his memory test, Spock was asked by the computer to identify where and whom made the first conclusive advances on this disturbance. The answer was, that in 2052, the Human scientist Ralph Seron was responsible for these advances in his workshop in Cambridge, Massachusetts.