Sleep is required for improving reaction times after training on a procedural visuo-motor task.

Sleep has been found to enhance consolidation of many different forms of memory. However in most procedural tasks, a sleep-independent, fast learning component interacts with slow, sleep-dependent improvements. Here, we show that in humans a visuo-motor saccade learning task shows no improvements during training, but only during a delayed recall testing after a period of sleep. 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 4 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 a period of sleep, i.e. after the first night in the sleep group and after recovery sleep in the sleep deprivation group. This improvement was stable during the 4-week follow-up. Saccadic training can thus induce covert changes in the saccade generation pathway. During the following sleep period, these changes in turn bring about overt performance improvements, presuming a learning effect based on synaptic tagging.

Long-term eye movement recordings with a scleral search coil-eyelid protection device allows new applications.

The search coil technique is regarded as the gold standard in eye movement recordings. The manufacturers of scleral search coils (SSC) do not recommend using them longer than 30 min. The temporal limitations result from potential cornea damage and from irritations of the lid margins and palpebral conjunctiva which subjects perceive as unpleasant. Here we introduce a new coil-eyelid protection device (CEPD) which allows recording intervals up to 2 h with considerably reduced discomfort. Ophthalmic examinations and saccade recordings were used for comparison with the conventional SSC recording technique. In three experiments subjects were examined using SSCs with a commercially available cornea bandage lens on top of the search coil up to 120 min recording time. Ophthalmic testing revealed no apparent harmful effects on eyes or lid surface. Saccade parameters (main sequence) remained unchanged comparing SSC and CEPD recordings. Subjects rated less discomfort by using the CEPD. For the first time we show that SSC recordings can be extended over about 120 min without hazard to the eye, when using an eyelid protection lens. This advanced method allows new applications like eye movement recordings during sleep (rapid eye movements) or perceptional or motor learning tasks, e.g. saccade adaptation paradigms.