The effects of maturation on spontaneous eye movements in the macaque monkey

The spontaneous eye movements of infant and adult monkeys were studied both in the dark and in the laboratory light by a magnetic search-coil technique and analysed comparatively. The spatio-temporal organization of the infant monkey's eye movements is predominantly vertical; by contrast it is predominantly horizontal in adults. Moreover, the infant monkey's eye movements have smaller amplitudes and slower velocities than adult's in both visual conditions. The linear relationships between amplitude and maximum velocity suggest that rapid eye movements of the infant monkey are saccades but with a lower rate of velocity increase than the adult's. We conclude that the eye movements in the infant and in the adult monkeys differ in many aspects and that maturation acts on both the static and dynamic characteristics of ocular motility.