Implicit and explicit motor sequence learning in children born very preterm

Background: Motor skills can be learned explicitly (dependent on working memory (WM)) or implicitly (relatively independent of WM). Children born very preterm (VPT) often have working memory deficits. Explicit learning may be compromised in these children. Aims: This study investigated implicit and explicit motor learning and the role of working memory in VPT children and controls. Methods: Three groups (6–9 years) participated: 20 VPT children with motor problems, 20 VPT children without motor problems, and 20 controls. A nine button sequence was learned implicitly (pressing the lighted button as quickly as possible) and explicitly (discovering the sequence via trial-and-error). Results: Children learned implicitly and explicitly, evidenced by decreased movement duration of the sequence over time. In the explicit condition, children also reduced the number of errors over time. Controls made more errors than VPT children without motor problems. Visual WM had positive effects on both explicit and implicit performance. Conclusion: VPT birth and low motor proficiency did not negatively affect implicit or explicit learning. Visual WM was positively related to both implicit and explicit performance, but did not influence learning curves. These findings question the theoretical difference between implicit and explicit learning and the proposed role of visual WM therein

QUANTITATIVE MUSCLE ULTRASONOGRAPHY IN THE FOLLOW-UP OF JUVENILE DERMATOMYOSITIS

Introduction: We explored the use of quantitative muscle ultrasonography (QMUS) for follow-up of juvenile dermatomyositis (JDM). Methods: Seven JDM patients were evaluated at diagnosis and 1, 3, 6, 12, and 24 months using the Childhood Myositis Assessment Scale (CMAS) and QMUS. Muscle thickness (MT) and quantitative muscle echo intensity (EI) were assessed with QMUS in 4 muscles. Results: Six patients experienced a monocyclic course. At diagnosis EI was slightly increased, and MT was relatively normal. After start of treatment MT first decreased and EI increased, with normalization of EI within 6-12 months (n = 4). One patient had higher EIs at diagnosis and slower normalization, indicating fibrosis, despite early normalization of CMAS. One patient experienced a chronic course, with high EIs and atrophy during follow-up. Conclusions: QMUS can provide additional information for follow-up of JDM regarding disease severity and residual muscle damage, particularly after normalization of CMAS