Abstract
To further characterize perceptual memory consolidation during wakefulness and sleep, we used a coarse orientation discrimination task during which participants had to discern the orientation of orthogonal gratings embedded in increasing levels of background noise. In a first study (N = 11), we showed that the learning effect in this task is retinotopic (position-specific) and orientation-specific. In a second experiment, we assessed the effect of nocturnal sleep, as opposed to the effect of time, on perceptual learning. A first group of healthy volunteers was trained in the morning, tested in the evening and retested the next morning (Evening-Morning-Evening; EME; N = 11); a second group was trained in the evening, tested the next morning and retested in the evening (Morning-Evening-Morning, MEM, N = 13). Between training and testing (after a full night of sleep), EME subjects improved significantly (p [[lt]]0.005) more than MEM subjects (after 12 waking hours). Similarly, between test and retest, performance of MEM subjects (after a full night of sleep) improved significantly (p [[lt]]0.00001) more than in EME subjects (after 12 further waking hours).
These results suggest a beneficial effect of sleep on coarse orientation discrimination. Further studies are needed to characterize the neural correlates of perceptual learning and the ‘offline’ consolidation of perceptual memory.
Belgian National Fund for Scientific research, the Queen Elisabeth Medical Foundation, University of Liège, IAP