Authors
1 Motor Behavior, Faculty of Sport Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
2 Professor of Motor Behavior Department, Ferdowsi University of Mashhad
3 PhD Student, Motor Behavior, Faculty of Sport Sciences, Ferdowsi University of Mashhad
Abstract
Background and Aim:
Motor skill learning occurs both during practice and in the period of no practice between training sessions. In contrast to learning that happens during practice and acquisition, known as online learning, another type of learning that takes place between practice sessions is referred to as offline learning. Offline learning, also known as memory consolidation, can lead to increased resistance to interference, stabilization, or even improvement of performance. It appears that memory consolidation can occur in different states of consciousness, such as wakefulness or sleep.An important question regarding motor memory consolidation is whether sleep facilitates motor memory consolidation or not. Despite numerous studies and various hypotheses about the role of sleep in memory consolidation, it is still debated whether sleep is necessary for the process of motor memory consolidation. Therefore, answering this question may only be possible by considering an appropriate classification. Since motor memory encoding can occur both implicitly and explicitly, the encoding conditions may serve as a general classification suitable to answer this question; however, other aspects, particularly specific task conditions, should also be taken into account.
This review article examines the role of sleep in the consolidation of motor memory for explicit and implicit tasks. The main question of this review is whether classifying tasks based on encoding conditions into explicit and implicit types can help determine the role of sleep in motor memory consolidation.
Research Method:
In this narrative review, scientific articles were searched using the databases "Google Scholar," "PubMed," "Science Direct," and "Web of Science." The keywords used were "consolidation," "explicit task," "implicit task," "explicit learning," "implicit learning," and "sleep." The specific search strategy in the databases was as follows:
(((Consolidation) OR (memory consolidation) OR (motor memory consolidation)) AND ((implicit learning) OR (explicit learning) OR (implicit task) OR (explicit task)) AND (sleep))
The inclusion and selection criteria for this review article were based on methodological and clinical factors such as the population studied and the type of intervention used in the articles. Using this method, a total of 120 articles were extracted by reviewing the titles. After screening the abstracts and applying exclusion criteria, which included topics outside the scope of the review, 42 articles were selected. Finally, after examining the full texts, 25 relevant articles were chosen and used in this review article.
Findings:
In this review article, by classifying tasks based on the type of memory encoding into explicit and implicit, the role of sleep in motor memory consolidation was examined using 25 selected studies. Overall, the results indicate that the role of sleep in consolidating explicit tasks depends on various factors. These include task complexity, whether the task is discrete or continuous, whether fine or gross motor muscles are involved, and the type of memory representation of the tasks. These factors must be considered when investigating the role of sleep in motor memory consolidation. Therefore, explicit encoding conditions alone cannot determine the role of sleep in motor memory consolidation.
Regarding implicit tasks, most evidence suggests that implicit encoding conditions make motor memory consolidation in implicit tasks dependent on the passage of time. Although some studies reported conflicting results, it should be noted that these studies had doubts about the implicit nature of the task encoding. Subsequent investigations contradicted those findings and showed that the encoding in the mentioned studies was actually explicit. Therefore, it can be generally accepted that consolidation of implicit motor tasks occurs without the necessity of sleep.
In conclusion, both explicit and implicit encoding conditions (awareness of the task) play a key role in determining the role of sleep in motor memory consolidation.
Discussion and Conclusion:
This review aimed to answer the question of whether sleep plays a role in motor memory consolidation or not. To do so, tasks were classified based on encoding conditions into implicit and explicit types. The findings indicated that classifying tasks into explicit and implicit categories is suitable for examining the role of sleep in motor memory consolidation for implicit tasks but not appropriate for explicit tasks.
This article can serve as a useful reference for future research in the field of motor memory consolidation and the effects of sleep, providing a foundation for further studies and helping to clarify post-practice needs of explicit and implicit tasks.
The review did not address the role of different sleep stages, emotional components, or individual differences. Given the extensive data in each of these areas, each represents an opportunity for future research
Keywords
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