Neural Correlates of the Contextual Interference Effect in Motor Learning: A Transcranial Magnetic Stimulation Investigation

Division of Biokinesiology and Physical Therapy, School of Dentistry, University of Southern California, Los Angeles, CA, USA.
Journal of Motor Behavior (Impact Factor: 1.42). 07/2010; 42(4):223-32. DOI: 10.1080/00222895.2010.492720
Source: PubMed


The authors applied transcranial magnetic stimulation (TMS) to investigate the causal role of the primary motor cortex (M1) for the contextual-interference effect in motor learning. Previous work using a nonfocal TMS coil suggested a casual role for M1 during high-interference practice conditions, but this hypothesis has not yet been proven. In the 1st experiment, participants practiced 3 rapid elbow flexion-extension tasks in either a blocked or random order, with learning assessed by a delayed retention test. TMS was delivered immediately after feedback during practice using a circular coil, centered over the contralateral M1. Each participant practiced with 1 of 3 TMS conditions: no TMS, real TMS, or sham TMS. Although no significant differences were observed between groups during acquisition, retention of the random group was better than the blocked group. The learning benefits of random practice were attenuated in the real-TMS condition, but not in the sham-TMS or no-TMS conditions. In the second experiment, the authors studied the effects of suprathreshold TMS and subthreshold TMS over M1, lateral premotor cortex, and peripheral arm stimulation using a focal figure-8 coil on motor learning under random practice conditions. The authors found that only suprathreshold TMS on M1 produced significant disruption of retention compared to the other stimulation conditions. Results suggest that a high-threshold neuronal population within M1 is causally important for enhanced retention following random, but not block, practice. Results also support the early intertrial interval as a critical period of M1 activity during practice. Overall, these results suggest neural circuits within M1 contribute to motor learning processing that depends on learners' training experience. Results contribute to knowledge of the critical and specific role that M1 plays in generating a learning advantage following high-interference practice conditions.

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Available from: Carolee Winstein, Jul 12, 2014
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    • "encoding, consolidation and retrieval) and states that the efficiency of these processes can be reflected in performance measures at different time points. Such a framework is important because motor memory processes, for example encoding [11], [12] and consolidation [13], [14] processes, can be differentially affected by different practice structures. "
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    ABSTRACT: The contextual interference (CI) effect is a robust phenomenon in the (motor) skill learning literature. However, CI has yielded mixed results in complex task learning. The current study addressed whether the CI effect is generalizable to bimanual skill learning, with a focus on the temporal evolution of memory processes. In contrast to previous studies, an extensive training schedule, distributed across multiple days of practice, was provided. Participants practiced three frequency ratios across three practice days following either a blocked or random practice schedule. During the acquisition phase, better overall performance for the blocked practice group was observed, but this difference diminished as practice progressed. At immediate and delayed retention, the random practice group outperformed the blocked practice group, except for the most difficult frequency ratio. Our main finding is that the random practice group showed superior performance persistence over a one week time interval in all three frequency ratios compared to the blocked practice group. This study contributes to our understanding of learning, consolidation and memory of complex motor skills, which helps optimizing training protocols in future studies and rehabilitation settings.
    PLoS ONE 06/2014; 9(6):e100906. DOI:10.1371/journal.pone.0100906 · 3.23 Impact Factor
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    ABSTRACT: During the last twenty-five years, the contextual interference effect has been thoroughly studied. This review finds that the effect is relatively robust in basic research, but considerably weaker in applied settings. Motor learning scholars have urged practitioners to develop instructional strategies based upon the inferences of the contextual interference effect. The smaller effects seem to indicate that the concept may have more limited use for the physical educator. It appears that the generalization of procedures from other domains may not adequately accommodate the complexity of motor skills. Manipulating the task difficulty, both nominal and functional, and the contextual continuum may be a promising route for the practitioner.
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    ABSTRACT: Behavioral research in cognitive psychology provides evidence for an important distinction between immediate performance that accompanies practice and long-term performance that reflects the relative permanence in the capability for the practiced skill (i.e. learning). This learning-performance distinction is strikingly evident when challenging practice conditions may impair practice performance, but enhance long-term retention of motor skills. A review of motor learning studies with a specific focus on comparing differences in performance between that at the end of practice and at delayed retention suggests that the delayed retention or transfer performance is a better indicator of motor learning than the performance at (or end of) practice. This provides objective evidence for the learning-performance distinction. This behavioral evidence coupled with an understanding of the motor memory processes of encoding, consolidation and retrieval may provide insight into the putative mechanism that implements the learning-performance distinction. Here, we propose a simplistic empirically-based framework--motor behavior-memory framework--that integrates the temporal evolution of motor memory processes with the time course of practice and delayed retention frequently used in behavioral motor learning paradigms. In the context of the proposed framework, recent research has used noninvasive brain stimulation to decipher the role of each motor memory process, and specific cortical brain regions engaged in motor performance and learning. Such findings provide beginning insights into the relationship between the time course of practice-induced performance changes and motor memory processes. This in turn has promising implications for future research and practical applications.
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