His research is focused on understanding the cellular bases of motor behaviour; in particular, he has shown how neuronal circuits in the spine help control rhythmic movements, such as those needed for locomotion.

For his work, in 2008 he was awarded the $1 million Kavli Prize for deciphering the basic mechanisms which govern the development and functioning of the networks of cells in the brain and spinal cord.

Early on he demonstrated that networks within the mammalian spinal cord can produce the detailed motor pattern of locomotion involving the coordination of hundreds of different muscles.

In a paper published in 1987, he and James Buchanan provided a putative network scheme of interacting interneurons in the lamprey spinal cord, a model vertebrate system.

His later work is directed towards understanding the forebrain mechanisms underlying selection of behavior, and has shown that the organization of the basal ganglia, dopamine system, habenulae and pallium is evolutionary conserved in considerable detail over more than 500 million years.