Development of voluntary control of saccadic eye movements. I. Age-related changes in normal children.

To investigate the development of the voluntary control of saccadic eye movement, we examined eye movements in 99 normal children (4-13 years of age). Subjects were asked to fixate a central light for 3-5 s. A target was then presented, either to its right or left. In visually guided saccades, the mean latencies of the child group were longer than those of the adults, and decreased with age until the age of 12 where they reached adult levels. On the other hand, their peak saccadic velocities were not different from those of the adults. In the antisaccade task, they showed a higher rate of directional errors, indicating an inability to suppress reflexive saccades to the target. Mean latencies of correct antisaccades were significantly longer in the children than in the adults. Error rates and antisaccadic latency tended to decrease with age. We also examined the effects of an auditory warning signal during the fixation period and compared the results with those without. The warning stimulus was less effective in children than in adults in both tasks. Similar peak saccadic velocities between children and adults suggest the earlier development of the saccadic burst generator in the brainstem. In contrast, the delayed development of latency of saccades and antisaccades and the error rates of antisaccades suggest delayed maturation of the cerebral cortex, particularly the frontal association areas that are involved in both eye movement control and attentional processes.