Walsh & Hoyt: Smooth Pursuit

Summary. Smooth pursuit eye movements serve to maintain the image of a small object on or near the fovea if the object or the head moves slowly. Areas V5 (MT) and V5a (MST) at the junction of temporal-occipital cortex are important structures in the cortical control of smooth pursuit. Lesions in this region lower the speed of ipsiversive smooth pursuit; they also lower the speed of pursuit of a slowly moving target and the accuracy of saccades in all directions in the contralateral visual field. FEF lesions also cause ipsiversive smooth pursuit defects. Projections from V5 and V5a are to nuclei in the ipsilateral basal pons that, in turn, project to the dorsal cerebellar vermis and the flocculus. Each flocculus controls pursuit by inhibiting neurons in the vestibular nucleus. Second-order vestibular neurons share smooth pursuit and vestibulo-ocular reflex signals and deliver them to motoneurons.