SELF-ORGANIZING MAPS. “The maps consist of thousands of units (or “neurons”) that are arranged in a two dimensional grid. In order to avoid boundary effects, the maps are often laid on the surface of a toroid that can be unwrapped for visualization. Each unit of the map has an associated vector that is originally initialized randomly.”
https://bmcsystbiol.biomedcentral.com/articles/10.1186/1752-0509-8-S2-S1