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  • 'Allow Mistakes': Study of Infants With CP Emphasizes Importance of Balanced Approach to Movement Learning

    Infant prone mobility, considered strongly linked to later mobility gains and psychological development, can be difficult for children with cerebral palsy (CP), putting them at a disadvantage later in childhood. Now authors of a new study believe that pairing special assistive technology with a careful combination of movement learning strategies could facilitate important gains in this population. The study was published as part of a special issue of PTJ (Physical Therapy) focused on the intersection of pediatric physical therapy and development science.

    Researchers were particularly interested in impacts of 2 separate learning "mechanisms" that have been shown to have positive effects on skill learning in adults with neurological deficits: reinforcement learning (RL) and error-based learning (EBL). RL is aimed at optimizing the reception of rewards or penalties, focusing on the outcome; in contrast, EBL focuses on the errors made in movement.

    Both EBL and RL can be useful approaches, authors write, but they each have pros and cons: EBL promotes faster learning but is easier to forget; RL tends to be a longer process with more exploration (and variability) involved but is better retained. Authors of the study hypothesized that infants with CP would achieve better prone mobility gains through a combination of the 2 mechanisms than from RL alone.

    To test their hypothesis, researchers used the Self-Initiated Prone Progression Crawler (SIPPC), a device developed by study coauthor Thubi Kolobe, PT, PhD. The SIPPC resembles a skateboard outfitted with special motors and monitors. Infants are placed on them in a prone position that allows them to move their arms and legs. The SIPPC can then be programmed to sense and respond to movement the child initiates.

    Thanks to the addition of a specially wired onesie, the SIPPC's movement response was able to work as both an RL and EBL mechanism. Calibrated one way, the SIPPC reinforced RL by rewarding a movement that is consistent with achieving a goal—for instance, moving toward a toy. Set another way, the SIPCC could add an EBL element by picking up on movements that are not consistent with the goal achievement and move the infant in unintended directions.

    For the study, researchers divided 30 infants aged 4.5–6.5 months into 3 groups: infants with CP who received SIPPC sessions with the special suit that could combine RL and EBL, infants with CP who received only an RL experience through the SIPPC, and typically developing infants who received the RL experience only through the SIPPC. The sessions involved 3 5-minute trials that included caregiver-led movement of the SIPPC and of the infants' arms and legs as well as periods during which the infant was encouraged to move independently toward either a toy or the caregiver. Sessions were conducted twice a week for up to 12 weeks.

    Researchers found that after 12 weeks, infants in the combined RL and EBL group made improvements over the RL-only group in the areas of rotational amplitude—essentially, the amount of trial-and-error used—and the length of linear paths achieved. Wrist and foot path lengths remained about the same between the groups, but the combined group registered significantly higher scores than the RL-only group in the Movement Observation Coding Scheme (MOCS), a measure of goal-directed movement.

    "Overall the findings support the differential effect of RL and EBL in skill learning in infants with CP," authors write, adding that the greater use of trial-and-error methods among the combined group reflects the ways that infant learning of new motor skills may at times require RL but at the same time involve uncoordinated movements, a cognitively demanding process "that is likely to respond better to EBL." The ultimate result: greater travel distances and more goal-directed movement among the combined group.

    In a video interview at the 2019 APTA NEXT Conference and Exposition, Kolobe boiled down the essential findings of the study. [Scroll down for video]

    "Allow mistakes," Kolobe said, "because that's part of [infants'] repertoire of learning how to do something. Allow them to go after other options, because eventually they get the right one."

    Kolobe also believes the study scratches the surface of another important consideration—the complex nature of cognitive elements during movement learning.

    "A lot of cognition enters into [learning movement]," Kolobe said. "Infants do strategize. There's a lot of executive function required to move."

    Authors believe the executive function demands may be of special note among infants with CP. In their study population, they write, "adapted behaviors were not readily repeated at the next sessions"—a finding that partly may be attributable to the ease with which EBL can be forgotten and partly attributable to the type of brain insult associated with CP. The memory decay "highlights the need to carefully balance RL and EBL approaches," they add.

    Research-related stories featured in PT in Motion News are intended to highlight a topic of interest only and do not constitute an endorsement by APTA. For synthesized research and evidence-based practice information, visit the association's PTNow website.

     

     

     

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