Adding depth to the picture

Recent studies showing that pontine burst cells carry a monocular code for rapid eye movements raise questions about the organisation of signals at mo re central levels. Evidence that the superior colliculus may also be involv ed in the coding of movements in depth is reviewed. Recent work shelving th at the global effect is a property of refixations in 3-D space is another i ndication that the oculomotor systems for direction and depth are centrally coupled.