Coping with asymmetry: how infants and adults walk with one elongated leg

Multidimensional Biomechanics-Based Score to Assess Disease Progression in Duchenne Muscular Dystrophy

(1) Background: Duchenne (DMD) is a rare neuromuscular disease that progressively weakens muscles, which severely impairs gait capacity. The Six Minute-Walk Test (6MWT), which is commonly used to evaluate and monitor the disease's evolution, presents significant variability due to extrinsic factors such as patient motivation, fatigue, and learning effects. Therefore, there is a clear need for the establishment of precise clinical endpoints to measure patient mobility. (2) Methods: A novel score (6M+ and 2M+) is proposed, which is derived from the use of a new portable monitoring system capable of carrying out a complete gait analysis. The system includes several biomechanical sensors: a heart rate band, inertial measurement units, electromyography shorts, and plantar pressure insoles. The scores were obtained by processing the sensor signals and via gaussian-mixture clustering. (3) Results: The 6M+ and 2M+ scores were evaluated against the North Star Ambulatory Assessment (NSAA), the gold-standard for measuring DMD, and six- and two-minute distances. The 6M+ and 2M+ tests led to superior distances when tested against the NSAA. The 6M+ test and the 2M+ test in particular were the most correlated with age, suggesting that these scores better characterize the gait regressions in DMD. Additionally, the 2M+ test demonstrated an accuracy and stability similar to the 6M+ test. (4) Conclusions: The novel monitoring system described herein exhibited good usability with respect to functional testing in a clinical environment and demonstrated an improvement in the objectivity and reliability of monitoring the evolution of neuromuscular diseases.

Neuroimaging Techniques as Descriptive and Diagnostic Tools for Infants at Risk for Autism Spectrum Disorder: A Systematic Review

Autism Spectrum Disorder (ASD) has traditionally been evaluated and diagnosed via behavioral assessments. However, increasing research suggests that neuroimaging as early as infancy can reliably identify structural and functional differences between autistic and non-autistic brains. The current review provides a systematic overview of imaging approaches used to identify differences between infants at familial risk and without risk and predictive biomarkers. Two primary themes emerged after reviewing the literature: (1) neuroimaging methods can be used to describe structural and functional differences between infants at risk and infants not at risk for ASD (descriptive), and (2) neuroimaging approaches can be used to predict ASD diagnosis among high-risk infants and developmental outcomes beyond infancy (predicting later diagnosis). Combined, the articles highlighted that several neuroimaging studies have identified a variety of neuroanatomical and neurological differences between infants at high and low risk for ASD, and among those who later receive an ASD diagnosis. Incorporating neuroimaging into ASD evaluations alongside traditional behavioral assessments can provide individuals with earlier diagnosis and earlier access to supportive resources.

Motor Development: Embodied, Embedded, Enculturated, and Enabling

Motor development and psychological development are fundamentally related, but researchers typically consider them separately. In this review, we present four key features of infant motor development and show that motor skill acquisition both requires and reflects basic psychological functions. ( a) Motor development is embodied: Opportunities for action depend on the current status of the body. ( b) Motor development is embedded: Variations in the environment create and constrain possibilities for action. ( c) Motor development is enculturated: Social and cultural influences shape motor behaviors. ( d) Motor development is enabling: New motor skills create new opportunities for exploration and learning that instigate cascades of development across diverse psychological domains. For each of these key features, we show that changes in infants' bodies, environments, and experiences entail behavioral flexibility and are thus essential to psychology. Moreover, we suggest that motor development is an ideal model system for the study of psychological development.

The effects of practice schedules on the process of motor adaptation

OBJECTIVES

Walking is a well-practiced skill but requires adapting steps online to meet external constraints. The objective of this study was to examine the effects of types of practice schedules (i.e., blocked versus random practice) on the process of adapting and generalizing motor actions.

METHODS

To examine how practice schedules influence the process of adaptation and generalization during walking, 60 young, healthy adults walked to normal, slow, and fast metronome paces: 30 with blocked practice and 30 with random practice. Paces were interspersed with 2 carryover trials with no beat. Subsequent paces were a test of generalizing adaptation from the old to the new metronome pace.

RESULTS

The results showed that participants who received blocked practice acclimated more quickly to the metronome beat. Specifically, the blocked practice group altered their walking more quickly during the fast metronome pace. In contrast, the random practice group matched the metronome beat more quickly during the slow pace. Participants who received blocked practice demonstrated carryover effects during carryover trials after walking to the metronome.

CONCLUSIONS

These findings extend an understanding of how the process of adaptation unfolds over time with the imposition of timing constraints.

Development (of Walking): 15 Suggestions

Although a fundamental goal of developmental science is to identify general processes of change, developmental scientists rarely generalize beyond their specific content domains. As a first step toward a more unified approach to development, we offer 15 suggestions gleaned from a century of research on infant walking. These suggestions collectively address the multi-leveled nature of change processes, cascades of real-time and developmental events, the diversity of developmental trajectories, inter- and intraindividual variability, starting and ending points of development, the natural input for learning, and the roles of body, environment, and sociocultural context. We argue that these 15 suggestions are not limited to motor development, and we encourage researchers to consider them within their own areas of research.

Places and postures: A cross-cultural comparison of sitting in 5-month-olds

Motor development-traditionally described in terms of age-related stages-is typically studied in the laboratory with participants of Western European descent. Cross-cultural studies typically focus on group differences in age-related stages relative to Western norms. We adopted a less traditional approach: We observed 5-month-olds and their mothers from six cultural groups around the world during one hour at home while they engaged in natural daily activities. We examined group differences in infants' sitting proficiency, everyday opportunities to practice sitting, the surfaces on which sitting took place, and mothers' proximity to sitting infants. Infants had opportunities to practice sitting in varied contexts-including ground, infant chairs, and raised surfaces. Proficiency varied considerably within and between cultural groups: 64% of the sample sat only with support from mother or furniture and 36% sat independently. Some infants sat unsupported for 20+ minutes, in some cases so securely that mothers moved beyond arms' reach of their infants even while infants sat on raised surfaces. Our observations of infant sitting across cultures provide new insights into the striking range of ability, varied opportunities for practice, and contextual factors that influence the proficiency of infant motor skills.

Walking to the beat of their own drum: how children and adults meet timing constraints

Walking requires adapting to meet task constraints. Between 5- and 7-years old, children's walking approximates adult walking without constraints. To examine how children and adults adapt to meet timing constraints, 57 5- to 7-year olds and 20 adults walked to slow and fast audio metronome paces. Both children and adults modified their walking. However, at the slow pace, children had more trouble matching the metronome compared to adults. The youngest children's walking patterns deviated most from the slow metronome pace, and practice improved their performance. Five-year olds were the only group that did not display carryover effects to the metronome paces. Findings are discussed in relation to what contributes to the development of adaptation in children.