SLEEP-DEPENDENT MOTOR MEMORY CONSOLIDATION: ROLE OF CONSCIOUS AWARENESS OF ACTIONS

Repetitive training is fundamental for motor learning and efficient motor execution. However, subjective awareness of one’s actions (SAA) – as a subjective evaluation of motor efficiency – can also modulate these outcomes. In addition, post-learning sleep contributes to the consolidation of motor memory by reactivating the neural networks mobilized during acquisition. These processes are observed at the cortical level during non-rapid eye movement stage 2 (NREM2) sleep, through rhythmic brain oscillations called sleep spindles (11-16 Hz; 0.3-2 s).

Thirty-four participants were recruited and randomly assigned to either the awareness group or the irrelevant judgment control group. Using a motor sequence learning task and recording EEG activity during a post-learning daytime nap, the present study aimed to: (i) determine the impact of SAA on performance during acquisition and delayed, post-nap retention, and (ii) explore the impact of SAA on the neurophysiological mechanisms underlying motor memory consolidation during sleep (i.e., sleep spindles characteristics). Participants were tested before (pre-test) and after (post-test) an acquisition phase, and after a 90-minute nap (retention test).

Results confirmed that SAA improved skill acquisition performance relative to controls, although the control group exhibited early post-acquisition performance gains from the end of training to the post-test. Moreover, SAA promoted sleep-dependent stabilization of motor skills. EEG measures further revealed negative correlations between sleep spindle activity and skill consolidation in the awareness group, suggesting that SAA-related explicit knowledge may have been preferentially reactivated during spindles, thereby competing with (and potentially diminishing) the consolidation of implicitly learned motor skills.