Global processing is achieved through iterative message passing in space and time . Spatio - temporal processing is factorized , into a space processing stage and a time processing stage , which are alternated within each iteration . We aim to decouple , conceptually , the data from the computational machine that processes the data . Thus , our nodes are processing units that receive inputs from several sources : local regions in space at the present time , their neighbor spatial nodes as well as their past memory states ( Fig . 1 ) .