Providing distinct vergence and version dynamics in a bilateral oculomotor network.

Given reported interactions between vergence and version dynamics, ocular reflexes cannot be properly modelled as separate independent subsystems. Using a model structure compatible with known anatomy, we show that a single bilateral system can produce results consistent with observed data both at the central and ocular levels. This model provides for both vergence and conjugate integrators in a single controller, and explains the observed modulation on abducens interneurons and mesencephalic vergence cells during vergence responses. Reported interactions between version and vergence would then be a natural consequence of a shared premotor network. Major implications include: the need to record both eyes in a protocol, since cross-talk is always possible; and adaptation to monocular changes could be distributed in all motor projections to both eyes.