Sit happens: Does sitting development perturb reaching development, or vice versa?

Reaching While Learning to Sit: Capturing the Kinematics of Co-Developing Skills at Home

This study examined the co-development of infant reaching and postural control across the transition to arms-free sitting at home. We observed infants with typical likelihood (TL; n = 24) and elevated likelihood (EL; n = 20) for autism at four biweekly sessions spanning the transition to arms-free sitting (infant age = 4.5-8 months at first session). At each session, infants sat on a pressure-sensitive mat with external support or independently, wore magneto-inertial sensors on both wrists, and reached for toys presented at midline. Analyses focused on characterizing and comparing control of sitting during reaching actions and standard kinematic metrics of reaching during Supported versus Independent Sitting. Although EL infants achieved arms-free sitting later than TL peers, there were no group differences on any measures. Across sessions, infants' control of the sitting posture during concurrent reaching movements improved in both contexts, though they were less stable as they reached when sitting independently compared to when sitting with support. A similar effect was apparent in the kinematics of reaches, with overall improvement over time, but evidence of poorer control in Independent relative to Supported Sitting. Taken together, these findings underscore the mutually influential and dynamic relations between emerging skills and well-established behaviors.

Effects of Limbs' Spasticity on Spinopelvic Alignment in Post-Stroke Patients: A Cross-Sectional Study

Objectives: This study aimed to determine the impacts of upper and lower limb (UL and LL) spasticity and impairment on spinal alignment in chronic post-stroke patients. Methods: A total of 45 consecutive chronic post-stroke patients, 18 women and 27 men, from 18 to 70 years old who presented post-stroke hemiparesis were recruited in this cross-sectional study. The clinical assessment included the Modified Ashworth Scale (UL-MAS and LL-MAS spasticity), Upper Limb Motricity Index (UL-MI), FAST-UL, and Five Times Sit-to-Stand Test (5T-STS); the Associated Reaction Rating Scale was used to measure associated reactions in the hemiparetic UL, the plumb line distance from the spinous process of C7 on the sagittal (PL-C7s) and frontal plane (Pl-C7f), the kyphosis apex (PL-AK), and the spinous process of L3 (PL-L3). Angular measures of spinal alignment were measured by a Bunnell scoliometer™ (angle of trunk rotation-ATR) and a gravity-dependent inclinometer (inclination at C7-T1 and T12-L1). Results: In chronic post-stroke patients, there was found to be an association between the 5T-STS and PL-C7f (β = 0.41, p = 0.05) and the angle of inclination at T12-L1 (β = 0.44, p = 0.01). The FAST-UL correlated with PL-C7f (β = -0.41, p = 0.05), while the UL-MI correlated with this last parameter (β = -0.36, p = 0.04) and the ATR (β = -0.31, p = 0.05). The UL-MAS showed correlation with the ATR (β = 0.38, p = 0.01). Conclusions: The results lead to the possibility that, in chronic post-stroke patients, spinal misalignment on the frontal and sagittal plane is associated both with strength impairment and UL spasticity. The improvement or restoration of spinopelvic parameters can take advantage of therapeutic interventions targeted at motor improvement and spasticity reduction of the hemiparetic side.

An update of the development of motor behavior

This primer describes research on the development of motor behavior. We focus on infancy when basic action systems are acquired-posture, locomotion, manual actions, and facial actions-and we adopt a developmental systems perspective to understand the causes and consequences of developmental change. Experience facilitates improvements in motor behavior and infants accumulate immense amounts of varied everyday experience with all the basic action systems. At every point in development, perception guides behavior by providing feedback about the results of just prior movements and information about what to do next. Across development, new motor behaviors provide new inputs for perception. Thus, motor development opens up new opportunities for acquiring knowledge and acting on the world, instigating cascades of developmental changes in perceptual, cognitive, and social domains. This article is categorized under: Cognitive Biology > Cognitive Development Psychology > Motor Skill and Performance Neuroscience > Development.

Early development of saliency-driven attention through object manipulation

In the first years of life, infants progressively develop attention selection skills to gather information from visually clustered environments. As young as newborns, infants are sensitive to the distinguished differences in color, orientation, and luminance, which are the components of visual saliency. However, we know little about how saliency-driven attention emerges and develops socially through everyday free-viewing experiences. The present work assessed the saliency change in infants' egocentric scenes and investigated the impacts of manual engagements on infant object looking in the interactive context of object play. Thirty parent-infant dyads, including infants in two age groups (younger: 3- to 6-month-old; older: 9- to 12-month-old), completed a brief session of object play. Infants' looking behaviors were recorded by the head-mounted eye-tracking gear, and both parents' and infants' manual actions on objects were annotated separately for analyses. The present findings revealed distinct attention mechanisms that underlie the hand-eye coordination between parents and infants and within infants during object play: younger infants are predominantly biased toward the characteristics of the visual saliency accompanying the parent's handled actions on the objects; on the other hand, older infants gradually employed more attention to the object, regardless of the saliency in view, as they gained more self-generated manual actions. Taken together, the present work highlights the tight coordination between visual experiences and sensorimotor competence and proposes a novel dyadic pathway to sustained attention that social sensitivity to parents' hands emerges through saliency-driven attention, preparing infants to focus, follow, and steadily track moving targets in free-flow viewing activities.

Focused attention as a new sitter: How do infants balance it all?

This study investigated the impact of postural control on infants' Focused Attention (FA). Study 1 examined whether and how sitting independently versus with support impacted 6- to 8-month-old infants' ability to focus attention during object exploration. FA measures did not depend on support condition. However, sitting experience was significantly negatively correlated with FA measures in the supported condition, suggesting that infants with more sitting experience performed fewer exploratory movements, possibly due to faster information processing ability compared to infants with less sitting experience. These unexpected findings prompted an exploration of more subtle looking behaviors during FA in Study 2-a case study of three infants who wore a head-mounted eye-tracker during an FA task. The ability to rapidly shift visual attention was key to gathering environmental information useful for problem solving-an interpretation that is supported by prior findings of the relationship between fast looks and faster information processing.

Infant Sitting and Multi-Directional Reaching Skill

We tested twenty-one 6- to 10-month-old infants with a wide range of sitting experience in forward and rightward reaching during unsupported sitting on the floor. Sessions were video-recorded for further behavioral and machine learning-based kinematic analyses. All infants, including novice sitters, successfully touched and grasped toys in both directions. Infant falls, hand support, and base of support changes were rare. Infants with more sitting experience showed better upright posture than novice sitters. However, we found no differences in trunk displacement or reaching kinematics between directions or across sitting experience. Thus, multi-directional reaching is functional in both novice and experienced infant sitters. We suggest that trunk and arm stability in sagittal and frontal planes is integral to learning to sit.

Gahvora cradling in Tajikistan: Cultural practices and associations with motor development

In Tajikistan, infants are bound supine in a "gahvora" cradle that severely restricts movement. Does cradling affect motor development and body growth? In three studies (2013-2018), we investigated associations between time in the gahvora (within days and across age) and motor skills and flattened head dimensions in 8-24-month-old Tajik infants (N = 269, 133 girls, 136 boys)) and 4.3-5.1-year-old children (N = 91, 53 girls, 38 boys). Infants had later motor onset ages relative to World Health Organization standards and pronounced brachycephaly; cradling predicted walk onset age and the proficiency of sitting, crawling, and walking. By 4-5 years, children's motor skills were comparable with US norms. Cultural differences in early experiences offer a unique lens onto developmental processes and equifinality in development.

Bidding on the go: Links between walking, social actions, and caregiver responses in infant siblings of children with autism spectrum disorder

The development of walking is associated with a shift in how neurotypical infants initiate social interactions. Walking infants are more likely to locate objects in distant places, carry them, and then share those objects by approaching caregivers and using gestures to show or offer their discoveries (i.e., moving bids). The simultaneous organization of the behaviors necessary to generate moving bids requires the coordination of multiple skills-walking, fine motor skills, and gesturing. Infants with an elevated likelihood (EL) for autism spectrum disorder (ASD) exhibit differences and delays in each of these behaviors. This study investigated interconnections between infant walking, social actions, and caregiver responses in 18-month-old EL infants with diverse developmental outcomes (ASD, non-ASD language delay, no diagnosis). We observed 85 infant-caregiver dyads at home during everyday activities for 45 minutes and identified all times when infants walked, instances of walking paired with social action (i.e., approaching the caregiver, approaching while carrying an object, producing a moving bid), and whether caregivers responded to their infants' social actions. There were no group differences in infants' production of social actions. Caregiver responses, however, were more clearly modulated by outcome group. While all caregivers were similarly and highly likely to respond to moving bids, caregivers of EL-ASD infants were substantially more likely to respond when their infants simply approached them (with or without an object in hand). Taken together, this research underscores the complexity of EL infant-caregiver interactions and highlights the role that each partner plays in shaping how they unfold.

Developing language in a developing body, revisited: The cascading effects of motor development on the acquisition of language

In the first years of life, infants rapidly acquire a series of new motor skills. They learn to sit independently, to walk with skill, and to engage in a wide variety of interactions with objects. Over these same years, infants also begin to develop language. These are not isolated events. In a complex developing system, even small changes in one domain can have far-reaching effects on development in other domains. This is the fundamental idea behind the rich framework known as the developmental cascades perspective. Here we employ this framework to show how early motor advances can exert downstream effects on the development of language. Focusing first on the emergence of independent sitting, then on the development of walking, and finally on changes in the ways in which infants act on and combine actions on objects, we describe how the nature and quality of infant actions change dramatically over the first few years and how this brings with it new possibilities for engaging the environment, more sophisticated ways of interacting with people, and significant alterations in communications directed by caregivers to the infant and coordinated with infant action in time and in meaning. The developmental cascades framework provides an approach for understanding how advances in motor skills influence communicative and language development, and more generally, for conceptualizing the constant, dynamic, and complex interplay between developing infants and their environments as it unfolds over time. This article is categorized under: Linguistics > Language Acquisition Psychology > Motor Skill and Performance Psychology > Development and Aging.

Posture Matters: Object Manipulation During the Transition to Arms-Free Sitting in Infants at Elevated vs. Typical Likelihood for Autism Spectrum Disorder

Aims: We investigated how infants grasped and transferred toys over a four-week period as they transitioned to arms-free sitting. We compared object manipulation in infants with typical likelihood (TL) and elevated likelihood (EL) for autism spectrum disorder (ASD) as they sat with vs. without support.Methods: Eighteen infants (7 EL; 11 TL; 5-8 months of age at the start of the study) were observed during three sessions at home across the transition to arms-free sitting. At each session, toys were presented to the infants in two different postures: sitting with support from a boppy pillow and sitting independently. Mean percentage of time spent grasping and rates of transferring objects between two hands were calculated for each infant at each session.Results: Both grasping time and transfer rate increased across the transition to arms-free sitting. EL infants, but not TL infants, spent significantly less time grasping toys when sitting independently than when sitting with support.Conclusions: Sitting plays a significant role in the development of object manipulation skills. Our results reveal a need to examine object manipulation skills in multiple posture contexts, especially in infants who exhibit motor delays.

The Effectiveness of Additional Core Stability Exercises in Improving Dynamic Sitting Balance, Gait and Functional Rehabilitation for Subacute Stroke Patients (CORE-Trial): Study Protocol for a Randomized Controlled Trial

Background: Trunk impairment produces disorders of motor control, balance and gait. Core stability exercises (CSE) are a good strategy to improve local strength of trunk, balance and gait. Methods and analysis: This is a single-blind multicenter randomized controlled trial. Two parallel groups are compared, and both perform the same type of therapy. A control group (CG) (n = 110) performs conventional physiotherapy (CP) (1 h per session) focused on improving balance. An experimental group (EG) (n = 110) performs CSE (30 min) in addition to CP (30 min) (1 h/session in total). EG is divided in two subgroups, in which only half of patients (n = 55) perform CSE plus transcutaneous electrical nerve stimulation (TENS). Primary outcome measures are dynamic sitting, assessed by a Spanish version of Trunk Impairment Scale and stepping, assessed by Brunel Balance Assessment. Secondary outcomes are postural control, assessed by Postural Assessment Scale for Stroke patients; standing balance and risk of fall assessed by Berg Balance Scale; gait speed by BTS G-Walk (accelerometer); rate of falls, lower-limb spasticity by Modified Ashworth Scale; activities of daily living by Barthel Index; and quality of life by EQ-5D-5L. These are evaluated at baseline (T0), at three weeks (T1), at five weeks (end of the intervention) (T2), at 17 weeks (T3) and at 29 weeks (T4). Study duration per patient is 29 weeks (a five-week intervention, followed by a 24-week post-intervention).

Does late preterm birth impact trunk control and early reaching behavior?

The aims of the study were to 1) verify the level of trunk control longitudinally and reaching behavior while sitting in two positions in late preterm (LPT) and full-term (FT) infants, 2) determine whether the level of trunk control relates to reaching outcomes. Twenty LPT infants and 36 infants born FT were assessed via three in-lab visits: at 6, 7, and 8 months. At each visit, the Segmental Assessment of Trunk Control (SATCo) and reaching assessment were performed, where the infants were positioned sitting in the ring and at 90° of flexion of hips, knees, and ankles. Accurate manual support to the trunk was provided in each visit. LPT infants presented a lower level of trunk control over time. LPT infants presented a higher percentage of unimanual reaches and successful grasping at 7 months' visit, and a higher number of reaches at 8 months' visit compared to FT infants. The sitting positions did not influence reaching performance. The level of trunk control relates to functional reaching strategies only in FT infants. This study might provide insights for clinicians for understanding the level of trunk control, the importance of reaching behaviors for exploration, and considering these behaviors as strategies for intervention.

Design and validation of a smart garment to measure positioning practices of parents with young infants

The aim of this cross-sectional study was to evaluate the feasibility, construct validity, and reliability of a smart garment to characterize parent-child positioning practices in infants less than six months old. The smart garment (Get Around Garment, GG) was developed through feedback from seven infants and their parents. The final system was then tested with sixteen infants (M = 3.1 ± 1.1 months) assessed in their homes during one visit that consisted of a: 1) Structured Play Assessment (2.5 min): infant was placed in each of five positions (prone, supine, reclined/inclined, and upright) for 30 s, 2) Free Play Assessment (40-60 min): parents were asked to engage in typical daily activities, and 3) second Structured Play Assessment. Infants' body position was both coded from video and identified from sensor data using a custom program. Feasibility was measured by data from a Daily Wearing Log and Garment Perception Questionnaire. Validity was evaluated by comparing the coding and sensor data. Reliability was measured by comparing the sensor data between the two Structured Play Assessments. The GG was considered feasible for use. The smart wearable system showed high levels of accuracy for classifying body position secondby- second and when comparing cumulative duration across time. Reliability of the smart garment was excellent. Young infants spent more time in supine and supported upright positions relative to prone, reclined, or inclined positions. The results suggest that accelerometers can be integrated into garments in a manner that is feasible to provide accurate and consistent data about positioning practices of parents with young infants. Monitoring early positioning practices is important because these practices impact future motor and cognitive developmental trajectories.

Fetal development of the thoracolumbar fascia with special reference to the fascial connection with the transversus abdominis, latissimus dorsi, and serratus posterior inferior muscles

PURPOSE

The three-layered thoracolumbar fascia (TLF) encapsulates the erector spinae and the quadratus lumborum and has been a major concern for physical therapists. However, knowledge of its prenatal development and growth is limited.

METHODS

Histological examination of 25 embryos and fetuses at 6-37 weeks (CRLs, 15-310 mm).

RESULTS

At the posterior end, the abdominal muscles continued toward an initial posterior layer of the TLF (pTLF) at 6 weeks, but the connection became narrow and limited to the obliquus externus aponeurosis until near term. The middle layer of the TLF (mTLF) appeared as a posterior continuation of the transversalis fascia at 9 weeks and, depending on a mechanical demand for the vertebral column extension near term, it grew as a thick intermuscular septum between the iliocostalis and quadratus lumborum. Thus, the mTLF lateral end changed from the abdominal wall to the back or pTLF. The serratus posterior inferior originated from the pTLF after 9 weeks, but a connection of the latissimus dorsi with the fascia was established much later. Near term, the gluteus maximus was attached to an aponeurosis covering the multifidus behind the sacrum. Therefore, the pTLF extended to cover the gluteal muscles.

CONCLUSION

We rejected the hypothesis that the mTLF develops as a marginal tissue between the primitive epaxial and hypaxial muscles. This study seemed to be the first report showing a fact that, within prenatal life, a drastic change is likely to occur in interfascial connections and their topographical relation to muscles; the TLF might be the best sample.

Spatial, But Not Temporal, Kinematics of Spontaneous Upper Extremity Movements Are Related to Gross and Fine Motor Skill Attainment in Infancy

Background: Spontaneous upper extremity movements in infancy provide insight on neuromotor development. Spatiotemporal kinematics have been used to evaluate typical development of reaching, a foundational motor skill in infancy. This study evaluates the relationship between spontaneous upper extremity movements, not elicited by a toy, and motor skill attainment. Methods: N = 12 healthy infants (2–8 months) participated in this longitudinal study (one to four sessions). Motor skills were assessed with the Bayley Scales of Infant and Toddler Development, 3rd Edition: gross motor subtest (GM) and fine motor subtest. Spontaneous upper extremity movements were collected using 3D motion capture technology. Infants were placed in supine for three to twelve 30-s trials, and their movements were recorded. Repeated measure correlation coefficients (Rmcorr) were used to evaluate relationships between variables. Results: There were significant, moderate, positive relationships between the straight distance from start to end of a movement and (a) fine motor score (Rmcorr = .55, p = .03), (b) GM score (Rmcorr = .63, p = .01), and (c) age (Rmcorr = .56, p = .02). There was a significant, moderate, negative relationship between straightness ratio and GM score (Rmcorr = −.52, p = .047). Discussion: Fine and GM skills are related to the straight distance from start to end of a movement and the straightness ratio of underlying spontaneous upper extremity movements.

Effect of whole-body vibration on abdominal thickness and sitting ability in children with spastic diplegia

Objective

Reduced muscle and bone mass, improper muscle function, and varying degrees of mobility dysfunctions are the main complications of cerebral palsy (CP). Many children with CP also present with poor abdominal muscle activation. Whole-body vibration (WBV) is a unique approach for enhancing strength and motor abilities in several clinical conditions. This study aimed to determine the influence of a 12-week WBV intervention on the thickness of the abdominal muscles and the sitting ability of children with diplegia.

Methods

A total of 30 children with spastic diplegic CP (aged 4–6 years) were randomly divided into two groups (control and experimental). The control group received a selected physical therapy program for 1 h, and the study group received WBV training for 10 min in addition to the same selected program for the control group for 3 times/week over a period of 12 weeks. Thereafter, abdominal muscle thickness and sitting ability were measured using ultrasonography and the Gross Motor Function Measure-88 (GMFM-88, sitting domain).

Results

Post treatment values revealed significant improvement in the measured variables in favour of the experimental group (p < 0.05), as there was improvement in the thickness of the four abdominal muscles compared to the control group (external oblique: F = 38.783; internal oblique: F = 99.547; transverse abdominis: F = 111.557, and rectus abdominis: F = 129.940, p < 0.05). Additionally, the study group showed a significantly greater improvement in GMFM-88 values compared to the control group (F = 129.940, p < 0.05).

Conclusion

WBV can be a viable strategy for improving sitting ability and abdominal muscle thickness among children with spastic diplegia.

Object exploration during the transition to sitting: A study of infants at heightened risk for autism spectrum disorder

Learning to sit promotes infants' object exploration because it offers increased access to objects and an improved position for exploration (e.g., ). Infants at heightened risk (HR) for autism spectrum disorder (ASD) exhibit delays in sitting and differences in object exploration. However, little is known about the association between sitting and object exploration among HR infants. We examined changes in object exploration as HR infants (N = 19) and comparison infants with no family history of ASD (Low Risk; LR; N = 23) gained experience sitting independently. Infants were observed monthly from 2.5 months until 1 month after the onset of independent sitting. At 12, 18, 24, and 36 months, infants completed standardized developmental assessments, and HR infants were assessed for ASD symptoms at 36 months. Although HR infants began sitting later than LR infants, both groups increased time spent grasping, shaking, banging, and mouthing objects as they gained sitting experience. Groups only differed in time spent actively mouthing objects, with LR infants showing a greater increase in active mouthing than HR infants. Findings suggest that HR infants experience a similar progression of object exploration across sitting development, but on a delayed time scale.

Postural, Visual, and Manual Coordination in the Development of Prehension

We investigated the real-time cascade of postural, visual, and manual actions for object prehension in 38 6- to 12-month-old infants (all independent sitters) and eight adults. Participants' task was to retrieve a target as they spun past it at different speeds on a motorized chair. A head-mounted eye tracker recorded visual actions and video captured postural and manual actions. Prehension played out in a coordinated sequence of postural-visual-manual behaviors starting with turning the head and trunk to bring the toy into view, which in turn instigated the start of the reach. Visually fixating the toy to locate its position guided the hand for toy contact and retrieval. Prehension performance decreased at faster speeds, but quick planning and implementation of actions predicted better performance.

Sitting Matters! Differences Between Sitters and Nonsitters at 6 Months' Adjusted Age in Infants At-Risk and Born Preterm

PURPOSE

Sitting delays in infants born preterm compound cognitive and language deficits. This retrospective study examines differences in prematurity-related risk and compares developmental outcomes between sitters and nonsitters at 6 months' adjusted age.

METHODS

A total of 105 graduates of the neonatal intensive care unit met inclusion criteria. Infant demographic and medical risk profiles and 6-month Bayley Scales of Infant Development-3rd edition (BSID-III) cognitive and language scores were retrieved. Infants who sat with hands free greater than 60 seconds were classified as "sitters."

RESULTS

Sixty-nine percent of the sample were nonsitters and were born earlier, had lower birth weights, were chronologically older at follow-up, and spent more days with respiratory support. BSID-III scores were significantly higher in sitters but did not differ by gender, multiple birth, head ultrasound results, payment type, or race/ethnicity.

CONCLUSION

Sitting abilities at 6 months' adjusted age are associated with prematurity risk factors. Cognitive and language scores differ significantly between sitters and nonsitters.

Object interaction and walking: Integration of old and new skills in infant development

Manual skills such as reaching, grasping, and exploring objects appear months earlier in infancy than locomotor skills such as walking. To what extent do infants incorporate an old skill (manual actions on objects) into the development of a new skill (walking)? We video recorded 64 sessions of infants during free play in a laboratory playroom. Infants' age (12.7-19.5 months), walking experience (0.5-10.3 months), and walking proficiency (speed, step length, etc.) varied widely. We found that the earlier developing skills of holding and exploring objects are immediately incorporated into the later developing skill of walking. Although holding incurred a reliable cost to infants' gait patterns, holding and exploring objects in hand were relatively common activities, and did not change with development. Moreover, holding objects was equally common in standing and walking. However, infants did not interact with objects indiscriminately: Object exploration was more frequent while standing than walking, and infants selectively chose lighter objects to carry and explore. Findings suggest that the earlier appearance of some skills may serve to motivate and enrich later appearing skills.

Embodied Cognition in Practice: Exploring Effects of a Motor-Based Problem-Solving Intervention

BACKGROUND

Embodied cognition interests physical therapists because efforts to advance motor skills in young infants can affect learning. However, we do not know if simply advancing motor skill is enough to support advances in cognition.

OBJECTIVE

The objective was to examine the effect of 2 interventions on the developing motor skill of sitting and problem solving and to describe the feasibility of using eye-tracking technology to explore visual and motor interaction.

DESIGN

This was a longitudinal, randomized comparison of interventions.

METHODS

Twenty infants with developmental delay and/or cerebral palsy, ranging in age from 8 to 34 months (mean [SD] = 15 [6.9] months), participated in an intervention emphasizing motor-based problem solving, and an intervention focused on advancing motor skill through assistance for attaining optimal movement patterns. Outcome measures were the Gross Motor Function Measure sitting subsection and the Early Problem Solving for Infants test. Active touch and looks were measured with eye-tracking technology.

RESULTS

Participants in both groups made significant motor gains from baseline, with no difference between intervention groups on Gross Motor Function Measure change scores. Participants in the problem-solving group showed significant gains in Early Problem Solving for Infants scores over the participants in the optimal movement patterns group. Overall, participants increased active touch of toys and increased concurrent looking with active touching.

LIMITATIONS

This exploratory study was small, with variation in participants' skills. The sampled behaviors for analysis were a small portion of the overall function of the participant.

CONCLUSIONS

An intervention using motor-based problem solving could improve infants' problem-solving skill. The use of eye-tracking could help to understand embodied cognition as infants develop, but the challenges of embedding the method in natural settings require further work. Listen to the author interview at https://academic.oup.com/ptj/pages/podcasts.

Sitting Together And Reaching To Play (START-Play): Protocol for a Multisite Randomized Controlled Efficacy Trial on Intervention for Infants With Neuromotor Disorders

BACKGROUND

There is limited research examining the efficacy of early physical therapy on infants with neuromotor dysfunction. In addition, most early motor interventions have not been directly linked to learning, despite the clear association between motor activity and cognition during infancy.

OBJECTIVE

The aim of this project is to evaluate the efficacy of Sitting Together And Reaching To Play (START-Play), an intervention designed to target sitting, reaching, and motor-based problem solving to advance global development in infants with motor delays or neuromotor dysfunction.

DESIGN

This study is a longitudinal multisite randomized controlled trial. Infants in the START-Play group are compared to infants receiving usual care in early intervention (EI).

SETTING

The research takes place in homes in Pennsylvania, Delaware, Washington, and Virginia.

PARTICIPANTS

There will be 140 infants with neuromotor dysfunction participating, beginning between 7 to 16 months of age. Infants will have motor delays and emerging sitting skill.

INTERVENTION

START-Play provides individualized twice-weekly home intervention for 12 weeks with families to enhance cognition through sitting, reaching, and problem-solving activities for infants. Ten interventionists provide the intervention, with each child assigned 1 therapist.

MEASUREMENTS

The primary outcome measure is the Bayley III Scales of Infant Development. Secondary measures include change in the Early Problem Solving Indicator, change in the Gross Motor Function Measure, and change in the type and duration of toy contacts during reaching. Additional measures include sitting posture control and parent-child interaction.

LIMITATIONS

Limitations include variability in usual EI care and the lack of blinding for interventionists and families.

CONCLUSIONS

This study describes usual care in EI across 4 US regions and compares outcomes of the START-Play intervention to usual care.

Early human motor development: From variation to the ability to vary and adapt

This review summarizes early human motor development. From early fetal age motor behavior is based on spontaneous neural activity: activity of networks in the brainstem and spinal cord that is modulated by supraspinal activity. The supraspinal activity, first primarily brought about by the cortical subplate, later by the cortical plate, induces movement variation. Initially, movement variation especially serves exploration; its associated afferent information is primarily used to sculpt the developing nervous system, and less to adapt motor behavior. In the next phase, beginning at function-specific ages, movement variation starts to serve adaptation. In sucking and swallowing, this phase emerges shortly before term age. In speech, gross and fine motor development, it emerges from 3 to 4 months post-term onwards, i.e., when developmental focus in the primary sensory and motor cortices has shifted to the permanent cortical circuitries. With increasing age and increasing trial-and-error exploration, the infant improves its ability to use adaptive and efficicient forms of upright gross motor behavior, manual activities and vocalizations belonging to the native language.

Cognition-Action Trade-Offs Reflect Organization of Attention in Infancy

This chapter discusses what cognition-action trade-offs in infancy reveal about the organization and developmental trajectory of attention. We focus on internal attention because this aspect is most relevant to the immediate concerns of infancy, such as fluctuating levels of expertise, balancing multiple taxing skills simultaneously, learning how to control attention under variable conditions, and coordinating distinct psychological domains. Cognition-action trade-offs observed across the life span include perseveration during skill emergence, errors and inefficient strategies during decision making, and the allocation of resources when attention is taxed. An embodied cognitive-load account interprets these behavioral patterns as a result of limited attentional resources allocated across simultaneous, taxing task demands. For populations where motor errors could be costly, like infants and the elderly, attention is typically devoted to motor demands with errors occurring in the cognitive domain. In contrast, healthy young adults tend to preserve their cognitive performance by modifying their actions.

Influence of Sitting Positions and Level of Trunk Control During Reaching Movements in Late Preterm and Full-Term Infants

In order to acquire reaching and independent sitting, refinement of trunk control is needed by gradually and progressively incorporating the head, thoracic, lumbar, and sacral segments. Previous studies have evaluated trunk control in a segmental way, standardizing the level of manual support in the infants' trunk during reaching. The aim of this study was to identify the level of trunk control and to analyze the influence of the difference sitting positions in late preterm and full-term infants between 6 and 8 months of age during reaching. Therefore, 36 infants born full term (control group)-FTG and 20 late preterm infants at a corrected age (experimental group)-PTG were evaluated. Most of the infants started the study at 6 months and they were evaluated monthly until 8 months of age (longitudinal study) in a total of 1-3 visits. The Segmental Assessment of Trunk Control was used to identify the level of trunk control in a segmental way, as well as to verify the capacity of the infant to maintain or regain the vertical position while sitting. Kinematic analysis was used for reaching. The infants were in a ring sitting position and at 90° of flexion. To elicit reaching, an attractive object was presented at the infant's midline and at 45° to the right and left. We found that PTG infants presented lower trunk control scores, i.e., worse control. For both groups, the ring sitting position and at 90° of flexion did not influence most kinematic variables during reaching because accurate manual support was provided for the infants' trunk. The PTG group presented less trunk displacement when at 90° of flexion. Compared to the FTG, even with accurate trunk support, the PTG group presented more immature reaches. These results suggest that accurate manual trunk support favored more stability of the trunk during the reach. Thus, early intervention is suggested for PTG infants and reaching in this age group should be trained in the ring sitting position with their trunk accurately manually supported. SATCo is an effective tool for segmental trunk evaluation.

The development of motor behavior

This article reviews research on the development of motor behavior from a developmental systems perspective. We focus on infancy when basic action systems are acquired. Posture provides a stable base for locomotion, manual actions, and facial actions. Experience facilitates improvements in motor behavior and infants accumulate immense amounts of experience with all of their basic action systems. At every point in development, perception guides motor behavior by providing feedback about the results of just prior movements and information about what to do next. Reciprocally, the development of motor behavior provides fodder for perception. More generally, motor development brings about new opportunities for acquiring knowledge about the world, and burgeoning motor skills can instigate cascades of developmental changes in perceptual, cognitive, and social domains. WIREs Cogn Sci 2017, 8:e1430. doi: 10.1002/wcs.1430 For further resources related to this article, please visit the WIREs website.

A Perceptual Motor Intervention Improves Play Behavior in Children with Moderate to Severe Cerebral Palsy

For children with moderate or severe cerebral palsy (CP), a foundational early goal is independent sitting. Sitting offers additional opportunities for object exploration, play and social engagement. The achievement of sitting coincides with important milestones in other developmental areas, such as social engagement with others, understanding of spatial relationships, and the use of both hands to explore objects. These milestones are essential skills necessary for play behavior. However, little is known about how sitting and play behavior might be affected by a physical therapy intervention in children with moderate or severe CP. Therefore, our overall purpose in this study was to determine if sitting skill could be advanced in children with moderate to severe CP using a perceptual motor intervention, and if play skills would change significantly as sitting advanced. Thirty children between the ages of 18 months and 6 years who were able to hold prop sitting for at least 10 s were recruited for this study. Outcome measures were the sitting subsection of the Gross Motor Function Measure (GMFM), and the Play Assessment of Children with Motor Impairment play assessment scale, which is a modified version of the Play in Early Childhood Evaluation System. Significant improvements in GMFM sitting scores (p < 0.001) and marginally significant improvement in play assessment scores (p = 0.067) were found from pre- to post-intervention. Sitting change explained a significant portion of the variance in play change for children over the age of 3 years, who were more severely affected by CP. The results of this study indicate that advances in sitting skill may be a factor in supporting improvements in functional play, along with age and severity of physical impairment.

Sit to Talk: Relation between Motor Skills and Language Development in Infancy

Relations between walking skills and language development have been reported in 10- to 14-month-old infants. However, whether earlier emerging motor milestones also affect language skills remains unknown. The current research fills this gap by examining the relation between reaching and sitting skills and later language development, respectively. Reaching and sitting were assessed eight times, starting when infants (N = 29) were around 3 months of age. All assessments were completed and recorded remotely via videoconference using Skype or FaceTime. Subsequently, infants' language and motor skills were assessed via parent questionnaires (Communicative Development Inventories and Early Motor Questionnaire) at 10 and 14 months of age. Results revealed a significant correlation between the emergence of sitting skills and receptive vocabulary size at 10 and 14 months of age. Regression analyses further confirmed this pattern and revealed that the emergence of sitting is a significant predictor of subsequent language development above and beyond influences of concurrent motor skills. These findings suggest that the onset of independent sitting may initiate a developmental cascade that results in increased language learning opportunities. Further, this study also demonstrates how infants' early motor skills can be assessed remotely using videoconference.

Upper extremity function: What's posture got to do with it?

This perspective paper reviews the linkage between developing postural control and upper extremity function. We suggest updated principles for guiding clinical practice, based on current views from motor learning, motor development, and motor control research. Using three clinical examples, we illustrate principles focusing on the use of variability, the importance of errors in learning movement, task specific exploration and practice, and the critical timing necessary to build skill of the upper extremity in a variety of postures. These principles differ from historic approaches in therapeutic exercise, which treated posture as a separate system and a precursor for extremity skill building. We maintain that current movement science supports the tight interaction of posture and upper extremity function through developmental time and in real time, such that one system cannot be considered separate from the other. Specific suggestions for clinical practice flow from the guiding principles outlined in this paper.

A new twist on old ideas: how sitting reorients crawlers

Traditionally, crawling and sitting are considered distinct motor behaviors with different postures and functions. Ten- to 12-month-old infants were observed in the laboratory or in their homes while being coaxed to crawl continuously over long, straight walkways (Study 1; N = 20) and during spontaneous crawling during free play (Study 2; N = 20). In every context, infants stopped crawling to sit 3-6 times per minute. Transitions from crawling to sitting frequently turned infants' bodies away from the direction of heading; subsequent transitions back to crawling were offset by as much as 180° from the original direction of heading. Apparently, body reorientations result from the biomechanics of transitioning between crawling and sitting. Findings indicate that sustained, linear crawling is likely an epiphenomenon of how gait is studied in standard paradigms. Postural transitions between crawling and sitting are ubiquitous and can represent a functional unit of action. These transitions and the accompanying body reorientations likely have cascading effects for infants' exploration, visual perception, and spatial cognition.

The development of trunk control and its relation to reaching in infancy: a longitudinal study

The development of reaching is crucially dependent on the progressive control of the trunk, yet their interrelation has not been addressed in detail. Previous studies on seated reaching evaluated infants during fully supported or unsupported conditions; however, trunk control is progressively developed, starting from the cervical/thoracic followed by the lumbar/pelvic regions for the acquisition of independent sitting. Providing external trunk support at different levels to test the effects of controlling the upper and lower regions of the trunk on reaching provides insight into the mechanisms by which trunk control impacts reaching in infants. Ten healthy infants were recruited at 2.5 months of age and tested longitudinally, until 8 months. During the reaching test, infants were placed in an upright seated position and an adjustable support device provided trunk fixation at pelvic and thoracic levels. Kinematic and electromyographic data were collected. Results showed that prior to independent sitting, postural instability was higher when infants were provided with pelvic compared to thoracic support. Associated reaches were more circuitous, less smooth and less efficient. In response to the instability, there was increased postural muscle activity and arm muscle co-activation. Differences between levels of support were not observed once infants acquired independent sitting. These results suggest that trunk control is acquired in a segmental sequence across the development of upright sitting, and it is tightly correlated with reaching performance.

Relation between hand function and gross motor function in full term infants aged 4 to 8 months

Background:

In children, reaching emerges around four months of age, which is followed by rapid changes in hand function and concomitant changes in gross motor function, including the acquisition of independent sitting. Although there is a close functional relationship between these domains, to date they have been investigated separately.

Objective:

To investigate the longitudinal profile of changes and the relationship between the development of hand function (i.e. reaching for and manipulating an object) and gross motor function in 13 normally developing children born at term who were evaluated every 15 days from 4 to 8 months of age.

Method:

The number of reaches and the period (i.e. time) of manipulation to an object were extracted from video synchronized with the Qualisys^(r) movement analysis system. Gross motor function was measured using the Alberta Infant Motor Scale. ANOVA for repeated measures was used to test the effect of age on the number of reaches, the time of manipulation and gross motor function. Hierarchical regression models were used to test the associations of reaching and manipulation with gross motor function.

Results:

Results revealed a significant increase in the number of reaches (p<0.001), the time of manipulation (p<0.001) and gross motor function (p<0.001) over time, as well as associations between reaching and gross motor function (R²=0.84; p<0.001) and manipulation and gross motor function (R²=0.13; p=0.02) from 4 to 6 months of age. Associations from 6 to 8 months of age were not significant.

Conclusion:

The relationship between hand function and gross motor function was not constant, and the age span from 4 to 6 months was a critical period of interdependency of hand function and gross motor function development.

Limited fine motor and grasping skills in 6-month-old infants at high risk for autism

Atypical motor behaviors are common among children with autism spectrum disorders (ASD). However, little is known about onset and functional implications of differences in early motor development among infants later diagnosed with ASD. Two prospective experiments were conducted to investigate motor skills among 6-month-olds at increased risk (high risk) for ASD (N1  = 129; N2  = 46). Infants were assessed using the Mullen Scales of Early Learning (MSEL) and during toy play. Across both experiments, high-risk infants exhibited less mature object manipulation in a highly structured (MSEL) context and reduced grasping activity in an unstructured (free-play) context than infants with no family history of ASD. Longitudinal assessments suggest that between 6 and 10 months, grasping activity increases in high-risk infants.

Children's head movements and postural stability as a function of task

Manual dexterity and postural control develop throughout childhood, leading to changes in the synergistic relationships between head, hand and posture. But the postural developments that support complex manual task performance (i.e. beyond pointing and grasping) have not been examined in depth. We report two experiments in which we recorded head and posture data whilst participants simultaneously performed a visuomotor task. In Experiment 1, we explored the extent to which postural stability is affected by concurrently performing a visual and manual task whilst standing (a visual vs. manual-tracking task) in four age groups: 5-6 years (n = 8), 8-9 years (n = 10), 10-11 years (n = 7) and 19-21 years (n = 9). For visual tracking, the children's but not adult's postural movement increased relative to baseline with a larger effect for faster moving targets. In manual tracking, we found greater postural movement in children compared to adults. These data suggest predictive postural compensation mechanisms develop during childhood to improve stability whilst performing visuomotor tasks. Experiment 2 examined the extent to which posture is influenced by manual activity in three age groups of children [5-6 years (n = 14), 7-8 years (n = 25), and 9-10 years (n = 24)] when they were seated, given that many important tasks (e.g. handwriting) are learned and performed whilst seated. We found that postural stability varied in a principled manner as a function of task demands. Children exhibited increased stability when tracing a complex shape (which required less predictive postural adjustment) and decreased stability in an aiming task (which required movements that were more likely to perturb posture). These experiments shed light on the task-dependant relationships that exist between postural control mechanisms and the development of specific types of manual control.

Sitting infants alter the magnitude and structure of postural sway when performing a manual goal-directed task

In typical daily life, adults routinely adapt posture so that balance can be maintained while other goal-directed activities are performed. Interestingly, newly standing infants also control posture based on the demands of a task. It is unknown if the ability to properly adapt postural movements as a goal-directed task is performed emerges soon after the acquisition of independent stance or if it is present at earlier key postural milestones, such as independent sitting. In this study, the postural sway patterns of independently sitting infants were compared while either holding or not holding a toy. Infants exhibited less postural sway when holding the toy. This reduction in sway allowed infants to look at and stabilize the toy in their hand. Thus, the ability to adjust postural movements while performing a concurrent goal-directed task emerges long before the acquisition of independent stance.

Postural position constrains multimodal object exploration in infants

Recent research has revealed the important role of multimodal object exploration in infants' cognitive and social development. Yet, the real time effects of postural position on infants' object exploration have been largely ignored. In the current study, 5- to 7-month-old infants (N = 29) handled objects while placed in supported sitting, supine, and prone postures, and their spontaneous exploratory behaviors were observed. Infants produced more manual, oral, and visual exploration in sitting compared to lying supine and prone. Moreover, while sitting, infants more often coupled manual exploration with mouthing and visual examination. Infants' opportunities for learning from object exploration are embedded within a real time postural context that constrains the quantity and quality of exploratory behavior.