Visuo-motor learning differently modulates cortical topology of sleep slow oscillations and of fast rhythms expression during NREM sleep: a high-density sleep EEG study

Memory benefits of NREM sleep and the slow/fast rhythms coordination appears to convey the consolidation of brain plasticity due to the acquisition of new information occurring during wakefulness. We studied NREM sleep modulation as a function of a visuo-motor learning task in 7 healthy volunteers (2 females). We used as control condition a similar motor task, however not requiring the learning of new motor patterns. The two tasks were performed in different days (1 week of separation) and both before and after the night we recorded sleep EEG. Also, a week before the experiment, participants spent a night in the laboratory, as adaptation to the experimental condition. The two sleep recordings were performed with high density EEG (128-electrodes HydroCel Geodesic Sensor Nets and GES300-EGI). EEG data analysis took into account two markers of the thalamo-cortical entrainment: the Sleep Slow Oscillations (SSO) and sleep spindles. For both graphoelements with estimated morphological and topological characteristics. We have identified a differential behaviour of both SSO and sleep spindles regarding wave amplitude and topology of detections. For SSO, the learning task increases wave detection in the motor/premotor areas of the dominant hemisphere and increases fast rhythms grouping in the SSO upstate in the visuo-motor integration areas. For spindles, the learning task increases frontal spindle density, and shift the peak amplitude to the central areas. Results indicate that visuo-motor learning increases the entrainment within thalamo-cortical circuits related to areas involved in the task.