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.

Measurement of Action Planning in Children, Adolescents, and Adults: A Comparison Between 3 Tasks.

PURPOSE: To compare age-related action planning performance on 3 different tasks, focusing on differences in task complexity. METHODS: A total of 119 participants were divided across 6 age groups (4-5, 6-7, 8-9, 10-12, 14-16, and 20-22 years). Participants performed 3 action planning tasks: the overturned cup task, the bar transport task, and the sword task. Anticipatory planning was assessed via the proportion of comfortable end postures. RESULTS: The increase in proportion of comfortable end postures developed more gradually for the overturned cup task with earlier ceiling effect (6 years) than for the other 2 tasks (10 years and no ceiling). The overturned cup task correlated fairly with the other tasks; the bar transport task and sword task correlated moderately. CONCLUSIONS: All 3 tasks can be used to measure aspects of action planning but outcomes vary. Therefore, we recommend combining these tasks in assessments of individual children to obtain a good indication of action planning development.

Learning of writing letter-like sequences in children with physical and multiple disabilities.

This study compared implicit and explicit learning instructions in hand writing. Implicit learning is the ability to acquire a new skill without a corresponding increase in knowledge about the skill. In contrast, explicit learning uses declarative knowledge to build up a set of performance rules that guide motor performance or skills. Explicit learning is dependent on working memory, implicit learning is not. Therefore, implicit learning was expected to be easier than explicit learning in children in special education, given their expected compromised working memory. Two groups of children (5-12 years) participated, children in special education with physical or multiple disabilities (study group, n=22), and typically developing controls (n=32). Children learned to write letter-like patterns on a digitizer by tracking a moving target (implicitly) and verbal instruction (explicitly). We further tested visual working memory, visual-motor integration, and gross manual dexterity. Learning curves were similar for both groups in both conditions; children in the study group did learn both implicitly and explicitly. Motor performance was related to the writing task. In contrast to our hypothesis, visual working memory was not an important factor in the explicit condition. These results shed new light on the conceptual difference between implicit and explicit learning, and the role of working memory therein.

Impaired motor planning and motor imagery in children with unilateral spastic cerebral palsy: challenges for the future of pediatric rehabilitation.

Compromised action performance is one of the most characteristic features of children with unilateral spastic cerebral palsy (USCP). Current rehabilitation efforts predominantly aim to improve the capacity and performance of the affected arm. Recent evidence, however, suggests that compromised motor planning may also negatively affect performance of activities of daily living. In this paper we will first discuss the recent evidence for this motor planning deficit, followed by studies on motor imagery in this population. Motor imagery is an experimental approach in which the contents of the motor plan become overt. Converging evidence indicates a compromised motor imagery ability in USCP. As the neural structures of both motor planning and motor imagery overlap, rehabilitation by motor imagery training may alleviate motor problems in USCP. Increasing evidence for this approach exists in older adults with stroke. We conclude this review with recommendations on such a training approach for children with USCP.

Norm scores of the box and block test for children ages 3-10 years.

This study provides new norm scores for the Box and Block Test for gross manual dexterity in children ages 3-10 yr. Two hundred fifteen Dutch children performed the Box and Block Test separately with each hand. We found an age effect for the scores; older children obtained higher scores than younger children. Concurrent validity was assessed by means of comparison with the manual dexterity subtests of the Movement Assessment Battery for Children-2; correlations were significant. Intraclass correlation coefficients for test-retest and interrater reliability measures were .85 and .99, respectively. The Box and Block Test is an easy, feasible, valid, and reliable measurement for gross manual dexterity in young children. The obtained norms can be used in clinical settings to compare the gross manual dexterity of atypically developing children with that of age-related peers and to evaluate efficacy of interventions. A larger international reference population is needed to increase generalizability.

Movement variation in infants born following IVF/ICSI with and without ovarian hyperstimulation.

BACKGROUND: The effect of in vitro fertilisation (IVF) on neurodevelopment is not fully understood. Probably, IVF does not affect traditional measures of neurodevelopment in infancy. Recently, an instrument, the Infant Motor Profile (IMP), was developed that evaluates the quality of motor behaviour. It includes the evaluation of movement variation (i.e. movement repertoire size), a parameter reflecting the integrity of cortical connectivity. AIM: To evaluate the effect of ovarian hyperstimulation and the in vitro procedure on movement variation during infancy. STUDY DESIGN: Prospective cohort study. SUBJECTS: Singletons born following IVF or intracytoplasmic sperm injection (ICSI) with conventional controlled ovarian hyperstimulation (COH-IVF/ICSI, n=68), in a modified natural cycle (MNC-IVF/ICSI, n=57) and natural conception born to subfertile couples (Sub-NC, n=90). OUTCOME MEASURES: Children were assessed with the IMP at 4, 10 and 18 months, resulting in a total IMP score and five domain scores: variation, variability, symmetry, fluency and performance. Primary outcome was the domain score variation. RESULTS: A significant effect of study group was observed for the variation score up until 18 months of age (p=0.039). COH-IVF/ICSI children had a significantly lower mean variation score than MNC-IVF/ICSI children (mean difference [95% confidence interval] -1.010 [-1.766; -0.254]). Mean variation scores of COH-IVF/ICSI and Sub-NC children were similar; the same held true for the comparison between MNC-IVF/ICSI and Sub-NC. Total IMP scores and other domain scores of the three groups were similar. CONCLUSION: The present study did not demonstrate a clear effect of ovarian hyperstimulation and the in vitro procedure on movement variation throughout infancy.

Anticipatory action planning increases from 3 to 10 years of age in typically developing children.

The primary aim of this study was to assess the development of action planning in a group of typically developing children aged 3 to 10 years (N=351). The second aim was to assess reliability of the action planning task and to relate the results of the action planning task to results of validated upper limb motor performance tests. Participants performed an action planning task in which they needed to grasp an object (a wooden play sword) and place it into a tight-fitting hole. Our main dependent variable was the grip type that participants used; that is, we measured whether initial grip was adapted in such a way that children reached a comfortable posture at the end of the action (the end-state comfort effect). Older children planned their actions more often in line with the end-state comfort effect compared with younger children. Test-retest and interrater reliability of the action planning task were good, with intraclass correlation coefficients (ICCs) of .90 and .95, respectively. We compared the action planning task with manual dexterity tests in a subset of participants (n=197). We found a marginal relation with the manual dexterity tests, indicating that the action planning task measures different processes. In sum, our study showed that action planning increases from 3 to 10 years of age and that the experimental task we used is reliable in assessing anticipatory planning. Therefore, it may be used as a reliable additional test to investigate the degree to which motor behavior is affected at the cognitive level of anticipatory planning.

Motor learning and working memory in children born preterm: a systematic review.

Children born preterm have a higher risk for developing motor, cognitive, and behavioral problems. Motor problems can occur in combination with working memory problems, and working memory is important for explicit learning of motor skills. The relation between motor learning and working memory has never been reviewed. The goal of this review was to provide an overview of motor learning, visual working memory and the role of working memory on motor learning in preterm children. A systematic review conducted in four databases identified 38 relevant articles, which were evaluated for methodological quality. Only 4 of 38 articles discussed motor learning in preterm children. Thirty-four studies reported on visual working memory; preterm birth affected performance on visual working memory tests. Information regarding motor learning and the role of working memory on the different components of motor learning was not available. Future research should address this issue. Insight in the relation between motor learning and visual working memory may contribute to the development of evidence based intervention programs for children born preterm.

Mental, psychomotor, neurologic, and behavioral outcomes of 2-year-old children born after preimplantation genetic screening: follow-up of a randomized controlled trial.

OBJECTIVE: To evaluate the effect of preimplantation genetic screening (PGS) on neurodevelopmental outcomes in children. DESIGN: Prospective, assessor-blinded, follow-up study of children born to women randomly assigned to in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) with or without PGS. SETTING: University Medical Center, Groningen, and Academic Medical Center, Amsterdam, the Netherlands. PATIENT(S): Fifty-four PGS children and 77 controls. INTERVENTION(S): PGS. MAIN OUTCOME MEASURE(S): Mental, psychomotor, neurologic, and behavioral outcomes in 2-year-old children as measured with the Bayley Scales of Infant Development, the Hempel neurologic examination, and the Child Behavior Check List. RESULT(S): The mental, psychomotor, and behavioral outcomes at 2 years in children born after IVF with and without PGS were similar overall. The PGS children showed lower neurologic optimality scores than the control children. Scores on all tests were within the normal range. CONCLUSION(S): Conception with PGS does not seem to be associated with impaired mental, psychomotor, or behavioral outcomes by age 2. However, the lower neurologic optimality scores found in the PGS children may signal less favorable long-term neurologic outcomes in PGS children. Our findings stress the need for safety evaluations with new assisted reproductive techniques before large-scale implementation.

The Groningen assisted reproductive technologies cohort study: developmental status and behavior at 2 years.

OBJECTIVE: To evaluate whether children's cognitive and psychomotor development and behavior at 2 years are affected by ovarian hyperstimulation and the IVF laboratory procedures or subfertility. DESIGN: Prospective longitudinal cohort study. SETTING: University Medical Center Groningen, the Netherlands. PATIENT(S): Singletons born after controlled ovarian hyperstimulation (COH)-IVF (n=66) and modified natural cycle-IVF (n=56), singletons born to subfertile couples who conceived naturally (subfertile-naturally conceived, n=87), and a reference group of 101 2-year-old singletons born to fertile couples. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Bayley Scales of Infant Development and Achenbach Child Behavior Checklist. RESULT(S): Mental and psychomotor development and behavioral outcome in COH-IVF, modified natural cycle-IVF, and subfertile-natural cycle groups was not different. Developmental outcome and behavior of the subfertile groups were largely similar to those of the fertile reference group. Nevertheless, the subfertile groups scored higher on the scale of anxious-depressed behavior than the reference group. CONCLUSION(S): This present relatively small study found no differences in cognitive and psychomotor development and behavior at 2 years in children born after COH-IVF or modified natural cycle-IVF or naturally conceived children of subfertile parents. Replication of the study is needed before firm conclusions can be drawn. Furthermore, long-term follow-up is needed to confirm these findings in older children.

Amplitude-integrated electroencephalographic activity is suppressed in preterm infants with high scores on illness severity.

BACKGROUND: The neonatal acute physiology score, SNAP-II, reflects the severity of illness in newborns. In term newborns, amplitude integrated EEG (aEEG), is depressed following asphyxia. In preterm infants aEEG is discontinuous, and therefore more difficult to assess compared to term infants. AIMS: Our first aim was to investigate whether assessing aEEG amplitudes by calculating amplitude centiles was consistent with assessment by pattern recognition. Our second aim was to investigate whether the aEEGs of preterm infants were influenced by SNAP-II. STUDY DESIGN AND SUBJECTS: We recorded aEEGs in 38 infants with a mean gestational age of 29.7 weeks (26.0-31.8 weeks) during the first five days of life. The mean recording time was 130 min. The aEEGs were assessed by pattern recognition, by calculating Burdjalov score, and by calculating the mean values of the 5th, 50th, and 95th centiles of the aEEG amplitudes. Illness severity was determined within the first 24h. RESULTS: We assessed 151 recordings and found strong correlations between the 5th and 50th amplitude centiles and the Burdjalov scores (r=0.71, p<0.001 and r=0.47, p<0.001, respectively). The 5th and 50th amplitude centiles correlated with SNAP-II (r=-0.34, p<0.0001 and r=-0.27, p=0.001). These correlations were the strongest on the first day of life (r=-0.55, p=0.005 and r=-0.47, p=0.018, respectively). The 5th and the 50th amplitude centiles were best predicted by gestational age, SNAP-II, and low blood pressure. CONCLUSIONS: Severe illness as measured by the SNAP-II, and low blood pressure had a negative influence on the aEEGs of preterm infants.

Implicit and explicit learning: applications from basic research to sports for individuals with impaired movement dynamics.

PURPOSE: Motor skills can be learned in an explicit or an implicit manner. Explicit learning places high demands on working memory capacity, but engagement of working memory is largely circumvented when skills are learned implicitly. We propose that individuals with impaired movement dynamics may benefit from implicit learning methods when acquiring sports-related motor skills. METHOD: We discuss converging evidence that individuals with cerebral palsy and children born prematurely have compromised working memory capacity. This may in part explain the difficulties they encounter when learning motor and other skills. We also review tentative evidence that older people, whose movement dynamics deteriorate, can implicitly learn sports-related motor skills and that this results in more durable performance gains than explicit learning. RESULTS: Individuals with altered movement dynamics and compromised working memory can benefit from implicit motor learning. CONCLUSION: We conclude with an appeal for more extensive evaluation of the merits of implicit motor learning in individuals with impaired movement dynamics.