The spatially guided cocktail party effect shapes contralateral neural synchronization.

Metacarpal and phalangeal fractures represent common traumatic injuries in adult population, which sometimes require surgical management and a subsequent immobilization period. Immobilization after surgical fixation for metacarpal and phalangeal fractures has been reported to induce a decay in hand performance, leading to manual dexterity deficits that persist over time after splint removal. Such deficits have been described to limit upper limb integration in routinary daily activities, requiring personalized rehabilitative interventions to enhance motor and functional recovery at immobilization end. In fact, immobilization has been reported to modulate use-dependent brain plasticity and deteriorate sensorimotor abilities, leading to a decay in hand movement accuracy and tactile function. Literature data have proved that a few hours of index finger immobilization induced a decrease in corticospinal excitability in healthy subjects. Furthermore, neurophysiological investigations have demonstrated that immobilization of the ring and little fingers of the hand resulted in decrease of motor cortex excitability of the representation of immobilized hand muscles and at the level of muscles with potential overlapping motor representations. Moreover, light-to-mild limitation of use of the whole hand has been reported in these subjects. Mirror Neuron System based interventions such as Action Observation and Motor Imagery (AOMI) have been reported to mitigate motor performance decline induced by upper limb restraint in healthy subjects and individuals with hand immobilization for musculoskeletal conditions. AO implies the observation of video-clips including motor contents, while MI consists of the mental rehearsal of the observed tasks in the absence of execution. Indeed, the observation and imagination of actions have been described to activate Mirror Neuron System substrates responsible for action execution. These brain activations have been reported to promote the acquisition or improvement of motor skills through the building of a motor memory and allow for training the sensorimotor system when active movements are not possible. When considering strategies to maintain or enhance motor abilities in the absence of active movements performance, literature data also suggested that early sleep delivered after AOMI training sessions boosted improvements in manual dexterity in healthy subjects. In particular, sleep has been reported to facilitate memory consolidation of motor patterns acquired through the systematic observation and imagination of motor tasks, transforming newly acquired motor memories into more stable memory traces. Surprisingly, Temporiti and co-workers also reported additional manual dexterity gains at 1 month after an AOMI-intervention end, highlighting an optimization of motor performance promoted by early sleep after training end.