Sleep deprivation delays saccadic learning

Depending on the memory system tested, sleep has been shown to have different effects on memory consolidation. Up to now, only one task has been described in which any improvement after learning is postponed until after a sleep period. Here, we investigated the influence of sleep on performance changes related to training of saccadic eye movements. Subjects were trained in a prosaccade task (saccade to a visual target). Performance was tested in the prosaccade and the antisaccade task (saccade to opposite direction of the target) before training, after a night of sleep or sleep deprivation, after a night of recovery sleep, and finally in a follow-up test four weeks later. We found no immediate improvement in saccadic reaction time (SRT) during training, but a delayed reduction in SRT, indicating a slow learning process. This reduction occurred only, after the first night of sleep after training, i.e. after the first night in the sleep condition and after recovery sleep in the sleep deprivation condition. This improvement was stable during the 4-week follow-up. Furthermore, SRT reduction was transferred from the trained to the untrained side and from the trained prosaccade to the untrained antisaccade task. Our data suggest that the mechanisms responsible for the slow learning process operate either on top of the saccade network or control the „final common pathway“ of saccades.