He's credited with first introducing the CNN architecture (Neocognitron) and a way to train it with unsupervised learning, inspired by the neurological research of Hubel and Wiesel and his earlier work in training neural networks with unsupervised learning (backprop is now used instead). Probably one of the most famous neural network papers. https://www.rctn.org/bruno/public/papers/Fukushima1980.pdf