In 1988, he joined the Adaptive Systems Research Department at AT&T Bell Laboratories in Holmdel, New Jersey, United States, headed by Lawrence D. Jackel, where he developed a number of new machine learning methods, such as a biologically inspired model of image recognition called convolutional neural networks, the "Optimal Brain Damage" regularisation methods, and the Graph Transformer Networks method (similar to conditional random field), which he applied to handwriting recognition and OCR.