Introduction
FTT, Der Werf, motor impairments
The observation of actions activates neural structures involved in the execution of observed tasks through a mirror mechanismManual dexterity is the ability to generate voluntary, fine and coordinated movements for grasping and manipulating objectsWhen considering strategies for enhancing motor learning, a key role of sleep has been documented on motor memory formation and consolidation after a motor trainingBased on the current evidence on AO/AO + MI effects on motor performance and sleep advantages in enhancing the acquisition of motor skills, Van Der Werf and co-workers investigated sleep effects on motor learning induced by observation in healthy subjects. These results demonstrated that the execution of a finger tapping sequence was more accurate when subjects underwent a sleep session within 12 h after the observationAgainst this background, it is reasonable to speculate that sleep might increase learning of trained motor skills such as manual dexterity, when occurring immediately after AO + MI-training. Therefore, the study was aimed at investigating the behavioral effects and neurodynamic correlates of AO + MI-training followed by immediate sleep on manual dexterity in healthy subjects. To this end, healthy participants were randomized into three groups receiving a 3-week intervention consisting of AO + MI-training immediately before sleeping (AOMI-sleep) or AO + MI-training at least 12 h before sleeping (AOMI-control) or a control stimulation (Control). Manual dexterity was assessed using functional tests (Purdue Pegboard Test—PPT and Finger Tapping Test—FTT), kinematic (kinematic indexes during Nine Hole Peg Test—NHPT) and neurophysiological outcomes (electroencephalographic signals recording during NHPT) before (T0) and after the training (T1) and at 1-month follow-up (T2). In the case of positive findings, the use of AO + MIfollowed by an early sleep-window may be considered to further enhance the acquisition of new motor skills in healthy subjects or facilitate functional recovery in patients with motor impairments.