Roles of Non-REM and REM sleep in facilitating visual perceptual learning

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Summary This is a resubmission of the R01 grant proposal entitled “Roles of Non-REM and REM sleep in facilitating visual perceptual learning”. Visual perceptual learning (VPL) refers to long-term performance enhancement on a visual task as a result of visual experience. VPL not only provides substantial insight into visual and brain plasticity but can also help in the development of an effective clinical tool to improve vision that is damaged or declining due to disease or other causes. Thus, it is crucial to examine what factors facilitate VPL. Although a number of studies have developed effective methods to facilitate VPL during training, much less is known about the role that sleep plays in facilitating VPL (sleep facilitation). A better understanding of the roles and mechanisms of sleep facilitation may be of enormous potential in improving visual training methods. Our pilot study identified 3 types of facilitatory effects of sleep in VPL: offline performance gains, stabilization, and post-sleep learning promotion. Aim 1 will investigate the underlying mechanism of these 3 sleep facilitation effects by testing: H(ypothesis)1-1: The dorsolateral prefrontal cortex (dlPFC) and early visual areas (EVAs) play a role in inducing offline performance gains during NREM sleep, H1-2: The ventromedial PFC (vmPFC) and EVAs play a role in inducing stabilization during REM sleep, and H1-3: The vmPFC and EVAs play a role in inducing postsleep learning promotion during REM sleep. This will be done by measuring the E/I ratio changes in the retinotopically-defined EVAs, dlPFC, and vmPFC during NREM and REM sleep monitored by polysomnography (PSG) and the correlation between the E/I ratio changes and each sleep facilitation effect. If the results support these hypotheses, we will test whether the dlPFC and/or vmPFC plays a similar or different role from EVAs in inducing sleep facilitation. To do so, we will compare the E/I ratio changes and the correlation between each sleep facilitation effect and the E/I ratio changes in the dlPFC or vmPFC with those in EVAs. Our other pilot study indicates that reward provided during training and posttraining sleep interact with each other to enhance offline performance gains. This suggests that reward process is fundamentally involved in sleep facilitation. Aim 2 will examine whether and how reward interacts with sleep to enhance sleep facilitation effects. First, we will examine the other two sleep facilitation effects by testing H2-1: Reward and sleep interact with each other and enhance stabilization, and H2-2: Reward and sleep interact with each other and enhance postsleep learning promotion. Next, we will examine the mechanism underlying the interaction effect by testing H2-3: Sleep facilitation effects, which may involve the dlPFC, vmPFC and EVAs during NREM and REM sleep, interact with and are enhanced by reward. To test H2-1 to H-2-3, we will measure psychophysical performance for each sleep facilitation effect as well as the E/I ratio changes in EVAs, vmPFC and dlPFC during NREM and REM sleep monitored by PSG.