The primate oculomotor system. II. Premotor system. A synthesis of anatomical, physiological, and clinical data.

Rapid, slow, and vergence eye movements are controlled by neuronal subsystems, which to some extent are anatomically separate. Furthermore, there is a similar separation of the networks controlling horizontal and vertical movements. Therefore, several single systems can be selectively affected in pathology. Anatomical and physiological investigations in monkey have demarcated the paramedian pontine reticular formation and the rostral mesencephalon as areas which generate horizontal and vertical rapid eye movements respectively. The flocculus is an important link for visually mediated movements: foveal pursuit, high velocity optokinetic nystagmus, and the visual suppression of vestibular nystagmus. The function of these structures is discussed with respect to oculomotor control, and their dysfunction related to specific neurological deficits.