Article

Natural error patterns enable transfer of motor learning to novel contexts

Johns Hopkins Medicine, Baltimore, Maryland, United States
Journal of Neurophysiology (Impact Factor: 2.89). 09/2011; 107(1):346-56. DOI: 10.1152/jn.00570.2011
Source: PubMed

ABSTRACT

Successful behavior demands motor learning to be transferable in some cases (e.g., adjusting walking patterns as we develop and age) and context specific in others (e.g., learning to walk in high heels). Here we investigated differences in motor learning transfer in people learning a new walking pattern on a split-belt treadmill, where the legs move at different speeds. We hypothesized that transfer of the newly acquired walking pattern on the treadmill to natural over ground walking might depend on the pattern of errors experienced during learning. Error patterns within a person's natural range might be experienced as endogenous (i.e., produced by the body), encouraging general adjustments that transfer across contexts. On the other hand, larger errors might be experienced as exogenous (i.e., produced by the environment), indicating unusual conditions requiring context-specific learning. To test this, we manipulated the distribution of errors experienced during learning to lie either within or outside the normal distribution of walking errors. We found that restriction of errors to the natural range produced transfer of the new walking pattern from the treadmill to natural walking off the treadmill, while larger errors prevented transfer. This result helps explain how transfer of motor learning is controlled, and it offers an important strategy for clinical rehabilitation, where transfer of motor learning to other contexts is essential.

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Available from: Gelsy Torres-Oviedo, May 20, 2015
    • "By maintaining the original learning context but increasing sensorimotor variability, we expected that changes in control needed to match previously learned task performance would strengthen skill. This is consistent with improved retention and generalization following small rather than abrupt errors during single-session learning [17, 41]. Our results might have shown a different pattern had the intervention been devised to amplify error. "
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    ABSTRACT: Newly acquired motor skills become stabilized through consolidation [1]. However, we know from daily life that consolidated skills are modified over multiple bouts of practice and in response to newfound challenges [2]. Recent evidence has shown that memories can be modified through reconsolidation, in which previously consolidated memories can re-enter a temporary state of instability through retrieval, and in order to persist, undergo re-stabilization [3-8]. Although observed in other memory domains [5, 6], it is unknown whether reconsolidation leads to strengthened motor skills over multiple episodes of practice. Using a novel intervention after the retrieval of a consolidated skill, we found that skill can be modified and enhanced through exposure to increased sensorimotor variability. This improvement was greatest in those participants who could rapidly adjust their sensorimotor output in response to the relatively large fluctuations presented during the intervention. Importantly, strengthening required the reactivation of the consolidated skill and time for changes to reconsolidate. These results provide a key demonstration that consolidated motor skills continue to change as needed through the remapping of motor command to action goal, with strong implications for rehabilitation.
    No preview · Article · Jan 2016 · Current biology: CB
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    • "The most likely reason for this discrepancy is the difference in the amount of time the full perturbation was experienced by the gradual group (5 min in current study vs. <1 min in 2012 study). Additional reasons may include the number of subjects, the method of introducing the speed differential: incrementing the fast belt speed only (current study) vs. incrementing the fast and decrementing the slow simultaneously in [28], and the number of steps included in the calculation of the aftereffect size in adults: 10 in the current study and 5 in [28]. Reanalysis of the aftereffect using 5 steps with the adults, however, did not change the results. "
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    ABSTRACT: Children can modify learned motor skills, such as walking, to adapt to new environments. Movement errors in these new situations drive the learning. We used split-belt walking to determine whether size of the error affects the degree of learning. Twenty-two children (aged 2-5 y) walked on the split-belt treadmill on two separate days spaced 1 week apart. Twenty-eight adults served as controls. On Day 1, children experienced an abrupt change in belt speeds (from 1∶1 to 2∶1 differential) resulting in large errors, or a gradual change (same change in speed over 12-15 min), resulting in small errors. Learning was measured by the size of the aftereffect upon return to a 1∶1 differential. On Day 2 (1 week later), the leg on the fast belt was reversed, as was the method of introducing the speed differential. We found that the error size did not affect learning. Unexpectedly, learning was greater on Day 2 compared to Day 1, especially for children under 4 y of age, despite the fact that the task was opposite to that of Day 1, and did not influence learning in adults. Hence, 11 additional children under 4 y of age were tested with belts running at the same speed on Day 1, and with a 2∶1 speed differential (abrupt introduction) on Day 2. Surprisingly, learning was again greater on Day 2. We conclude that size of error during split-belt walking does not affect learning, but experience on a treadmill does, especially for younger children.
    Full-text · Article · Mar 2014 · PLoS ONE
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    • "Historically it has been assumed that large movement errors and increased practice difficulty, characteristics of sudden training, facilitate motor learning (Christina & Bjork, 1991; Schmidt & Bjork, 1992; Wolpert & Ghahramani, 2000). However, gradual training has been shown to improve or preserve the adaptation to, and retention or generalization of, novel motor skills when compared to sudden training (Kagerer, Contreras-Vidal, & Stelmach, 1997; Klassen, Tong, & Flanagan, 2005; Kluzik, Diedrichsen, Shadmehr, & Bastian, 2008; Malfait & Ostry, 2004; Torres-Oviedo & Bastian, 2012). Several studies suggest that the efficacy of gradual training may be due to subthreshold increments that reduce awareness of the changes taking place and the contribution of conscious adjustments during training (Criscimagna-Hemminger et al., 2010; Hatada, Rossetti, & Miall, 2006). "
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    ABSTRACT: ABSTRACT The cognitive demand required for a range of locomotor tasks has been described for a variety of populations. However, the effect of different training strategies on the cognitive demand required while learning novel locomotor tasks is not well understood and may inform physical rehabilitation. The authors examined whether two training strategies, gradual and sudden training, influenced the cognitive demand required while practicing a novel locomotor task, asymmetric split-belt treadmill walking. Simple reaction times and whole-body kinematics were recorded throughout practice. Gradual training resulted in significantly lower reaction times during much of training, suggesting that gradual training is less cognitively demanding than sudden training, possibly due to a reduction in error feedback or movement planning demands.
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