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.

How mothers help children learn to use everyday objects.

Children must learn specific motor actions to use everyday objects as their designers intended. However, designed actions are not obvious to children and often are difficult to implement. Children must know what actions to do and how to execute them. Previous work identified a protracted developmental progression in learning designed actions-from nondesigned exploratory actions, to display of the designed action, to successful implementation. Presumably, caregivers can help children to overcome the challenges in discovering and implementing designed actions. Mothers of 12-, 18- to 24-, and 30- to 36-month-olds (N = 74) were asked to teach their children to open containers with twist-off or pull-off lids. Mothers' manual and verbal input aligned with the developmental progression and with children's actions in the moment, pointing to the role of attuned social information in helping children learn to use objects for activities of daily living. However, mothers sometimes "overhelped" by implementing designed actions for children instead of getting children to do it themselves, highlighting the challenges of teaching novices difficult motor actions.

Assessing engagement in rehabilitation: development, validity, reliability, and responsiveness to change of the Rehabilitation Observation Measure of Engagement (ROME).

Purpose: We describe the development of an observational video coding tool, the Rehabilitation Observation Measure of Engagement (ROME), to quantify engagement in rehabilitative settings at the person (internal state of an individual) and between-system (interaction between individuals) level.Methods: Forty-nine children with unilateral spastic cerebral palsy (29 males; Age: M = 9.28 yrs, SD = 3.08 yrs) and their interventionists were videotaped during different activities. Construct validity was examined by correlating the ROME with the Engagement vs. Disaffection with Learning Survey and the Pediatric Rehabilitation Intervention Measure of Engagement - Observation questionnaire. Inter- and intra-rater reliability were examined using two independent raters. The ROME's responsiveness to change was examined by comparing scores across activities.Results: For construct validity, results showed a positive correlation for person-level engagement (r = 0.444, p = 0.003). No relationship was found between-system-level engagement. High intrarater (91.8%) and interrater (96.1%) reliability was found. The ROME's responsiveness to change was supported by children exhibiting lower engagement scores during repetitive shaping activities.Conclusion: These findings provide evidence that the ROME is a reliable tool to objectively examine the construct of engagement within rehabilitation and is valid for quantifying person-level engagement. It provides information that cannot be extracted from questionnaires and can help guide intervention decisions.

Implications for rehabilitationBehavioral characteristics, including engagement, of the agents involved in rehabilitation are largely unstudied, although engagement is expected to benefit motor learning.The Rehabilitation Observation Measure of Engagement (ROME) is an observation measure that uses predefined codes and can be used universally, as it is not limited to specific language or cognitive levels.The ROME is a reliable tool for objectively measuring the role of the construct of behavioral engagement during rehabilitation and valid for examining person-level engagement.The ROME may be used as a measure of client and service provider process, of intervention quality, or as a decision guide.

Dynamic sitting in infants: Limits of stability.

BACKGROUND: Limits of stability-defined by the maximum distances a person is willing to reach without falling or changing the base of support-are measures of dynamic balance. RESEARCH QUESTION: What are infants' sitting stability limits in the forward and right directions? METHODS: Twenty-one 6- to 10-month old infants participated in this cross-sectional study. To incentivize infants to reach beyond arm's length, caregivers began by holding a toy close to their infants at shoulder height. Caregivers then moved the toy farther away as infants tried to reach for it until infants lost balance, placed their hands on the floor, or transitioned out of sitting. All sessions were conducted via Zoom™ and video-recorded for further analyses using DeepLabCut for 2D pose estimation and Datavyu to determine timings of the reach and to code infants' postural behaviors. RESULTS: Infants' trunk excursions in the anterior-posterior plane (for forward reaches) and medio-lateral plane (for rightward reaches) represented their stability limits. Most infants ended the reach by returning to their original sitting position; however, infants with higher Alberta Infant Motor Scale (AIMS) scores transitioned out of sitting and infants with lower AIMS scores sometimes fell (mostly during rightward reaching). Trunk excursions were correlated with months of sitting experience. Rightward trunk excursions were also correlated with AIMS scores and age. Overall, infants' trunk excursions were larger in the forward than in the right direction, and such discrepancy was consistent across infants. Lastly, the more often infants adopted movement strategies with their legs (e.g., bending the knees), the greater the trunk excursion they attained. SIGNIFICANCE: Sitting control entails learning to perceive the boundaries of stability limits and acquiring anticipatory postures to suit the needs of the task. Tests and interventions that target sitting stability limits could be beneficial for infants with or at risk of motor delays.

Effect of Acupuncture on Sensorimotor Function and Mobility in Patients with Multiple Sclerosis: A Pilot Study.

Introduction: Multiple sclerosis (MS) is a progressive disease of the central nervous system that can result in highly variable effects on mobility and sensorimotor function. Persons with MS (pwMS) often use complementary and alternative approaches, such as acupuncture, to address these symptoms. However, studies of acupuncture on these symptoms have been hindered by methodologic flaws, which have limited the ability to draw conclusions about its efficacy. The purpose of this study was to examine the feasibility of an acupuncture intervention on a wide range of sensorimotor and mobility measurements in pwMS. Methods: Using a randomized crossover design, subjects experienced acupuncture or a no treatment control condition twice weekly for 4 weeks, followed by a 4-week washout period, and then crossed over to the other condition for 4 weeks. Strength, sensation, spasticity, gait, and balance were measured for all subjects, both before and after each condition. Results: Seven of the 12 subjects who started the program completed all phases. No subjects experienced adverse effects. No statistically significant changes were observed in the gait or balance measures. Small statistically significant changes were observed in upper extremity strength. Sensation and spasticity were unaffected. Discussion: The variability of MS suggests that a wide array of testing procedures be utilized, however, this may have led to difficulty with completing all phases of the study. Acupuncture did not result in changes in mobility in pwMS. Some improvements in upper extremity strength were observed. It is unclear whether these changes represent the effect of acupuncture or the inherent variability of MS.

The process of learning the designed actions of toys.

Many everyday objects require "hidden" affordances to use as designed (e.g., twist open a water bottle). Previous work found a reliable developmental progression in children's learning of designed actions with adult objects such as containers and zippers-from non-designed exploratory actions, to the basics of the designed action, to successful implementation. Many objects designed for children (e.g., toys) also entail designed actions (e.g., interlocking bricks) but might not require a protracted period of discovery and implementation. We encouraged 12- to 60-month-old children (n = 91) and a comparative sample of 20 adults to play with six Duplo bricks to test whether the developmental progression identified for children's learning of adult objects with hidden affordances holds for a popular toy expressly designed for children. We also examined whether children's moment-to-moment behaviors with Duplo bricks inform on general processes involved in discovery and implementation of hidden affordances. With age, children progressed from non-designed exploratory actions, to attempts to interlock, to success, suggesting that the three-step developmental progression revealed with everyday adult objects broadly applies to learning hidden affordances regardless of object type. Detailing the process of learning (the type and timing of children's non-designed actions and attempts to interlock) revealed that the degree of lag between steps of the progression depends on the transparency of the required actions, the availability of perceptual feedback, and the difficulty of the perceptual-motor requirements. Findings provide insights into factors that help or hinder learning of hidden affordances.

Flexibility in action: Development of locomotion under overhead barriers.

Behavioral flexibility-the ability to tailor motor actions to changing body-environment relations-is critical for functional movement. Navigating the everyday environment requires the ability to generate a wide repertoire of actions, select the appropriate action for the current situation, and implement it quickly and accurately. We used a new, adjustable barrier paradigm to assess flexibility of motor actions in 20 17-month-old (eight girls, 12 boys) and 14 13-month-old (seven girls, eight boys) walking infants and a comparative sample of 14 adults (eight women, six men). Most participants were White, non-Hispanic, and middle class. Participants navigated under barriers normalized to their standing height (overhead, eye, chest, hip, and knee heights). Decreases in barrier height required lower postures for passage. Every participant altered their initial walking posture according to barrier height for every trial, and all but two 13-month-olds found solutions for passage. Compared to infants, adults displayed a wider variety of strategies (squat-walking, half-kneeling, etc.), found more appropriate solutions based on barrier height (ducked at eye height and low crawled at knee height), and implemented their solutions more quickly (within 4 s) and accurately (without bumping their heads against the barrier). Infants frequently crawled even when the barrier height did not warrant a low posture, displayed multiple postural shifts prior to passage and thus took longer to go, and often bumped their heads. Infants' improvements were related to age and walking experience. Thus, development of flexibility likely involves the contributions of multiple domains-motor, perception, and cognition-that facilitate strategy selection and implementation. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The effect of intermittent vs. continuous walking on distance to fatigue in persons with multiple sclerosis.

PURPOSE: Previous studies provided evidence that persons with Multiple Sclerosis (pwMS) who walk intermittently experience less fatigue and walk longer distances than when walking continuously. However, total distance pwMS can walk in either condition is unknown. We examined time and distance to fatigability in pwMS comparing intermittent walking (IW) to continuous walking (CW). MATERIALS AND METHODS: 18 pwMS, with Expanded Disability Status Scale median of 4.75 [range = 2-6.5, IQR = 2.5] participated in this randomized crossover study. The IW condition consisted of alternating 30 s treadmill walking and 30 s seated rests. The CW condition consisted of treadmill walking without breaks. Treadmill speed (TS) was determined by an overground 2-min walk test. Walking fatigability was determined by participants walking on the treadmill, until gait fatigue was noted by patient or examiners. Total time and distance to gait fatigue, and subjective fatigue as measured by the Visual analog scale of fatigue were recorded. RESULTS: Participants had significantly longer duration and distance to fatigue in the IW condition than the CW condition (ps ≤ 0.037). No difference in VASF scores between the two conditions were noted. CONCLUSION: In this sample, IW allowed pwMS to perform a greater volume of walking and can be an option to improve walking endurance in this population.IMPLICATIONS FOR REHABILITATIONMultiple sclerosis (MS) is a disease that progressively impacts walking, resulting in a decrease in the maximum distance that a person with MS can walk.Intermittent walking has been shown to improve 6-min walk test performance in persons with MS (pwMS) compared to continuous walking, but its effects on longer and shorter walks is not known.The use of distance to fatigue should be considered a viable option for measuring walking fatigability in pwMS as it does not exclude persons based on their ability to complete a 6-min walk, nor would it be too easy for persons with pwMS with mild disability.By using distance to fatigue as an outcome measure, this study provides evidence that intermittent walking results in less fatigability regardless of walking ability.PwMS, regardless of their walking ability, can walk longer distances intermittently than continuously, suggesting that clinical treatment of walking fatigability in pwMS should utilize intermittent rather than continuous walking training.

Children's use of everyday artifacts: Learning the hidden affordance of zipping.

The everyday world is populated with artifacts that require specific motor actions to use objects as their designers intended. But researchers know little about how children learn to use everyday artifacts. We encouraged forty-four 12- to 60-month-old children to unzip a vinyl pouch during a single 60-s trial. Although unzipping a pouch may seem simple, it is not. Unzipping requires precise role-differentiated bimanual actions-one hand must stabilize the pouch while the other hand applies a pulling force on the tab. Moreover, kinematic data from six adults showed that the tolerance limits for applying the forces are relatively narrow (pulling the tab within 63° of the zipper teeth while stabilizing the pouch within 4 cm of the slider). Children showed an age-related progression for the unzipping action. The youngest children did not display the designed pulling action; children at intermediate ages pulled the tab but applied forces outside the tolerance limits (pulled in the wrong direction, failed to stabilize the pouch in the correct location), and the oldest children successfully implemented the designed action. Findings highlight the perceptual-motor requirements in children's discovery and implementation of the hidden affordances of everyday artifacts.

The Seated Postural & Reaching Control Test in Cerebral Palsy: A Validation Study.

Aim: Children with moderate-severe cerebral palsy (CP) show postural control deficits that affect their daily activities, like reaching. The Seated Postural and Reaching Control test (SP&R-co) was developed to address the need for clinical measures that objectively identify dimensions of postural imbalance and corresponding reaching limitations in children with CP.Methods: SP&R-co documentation was designed for test validity and rater training. Rater and internal consistency were examined using Cronbach's α. Reference SP&R-co score sheets of children and rater's scores were used for absolute item-by-item, average inter-rater, and intra-rater reliability. Motor classification systems and performance tests were used for construct and concurrent validity.Results: The SP&R-co scoring showed acceptable-good consistency (α = 0.76-0.84). Interrelatedness of SP&R-co items was good-excellent (α = 0.82-0.97). The raters demonstrated fair, good, and excellent item-by-item reliability (ICC = 0.41-0.92). Inter-rater and intra-rater reliability of SP&R-co dimensions were good-excellent (ICC = 0.68-0.86 and ICC = 0.64-0.95, respectively). Construct and concurrent validity showed moderate-excellent correlations (r = 0.49-0.88).Conclusions: Results provide evidence that the SP&R-co is a reliable and valid test for therapists to objectively examine and quantify seated postural and reaching control in children with CP.

Where Infants Go: Real-Time Dynamics of Locomotor Exploration in Crawling and Walking Infants.

Where do infants go? A longstanding assumption is that infants primarily crawl or walk to reach destinations viewed while stationary. However, many bouts of spontaneous locomotion do not end at new people, places, or things. Study 1 showed that half of 10- and 13-month-old crawlers' (N = 29) bouts end at destinations-more than previously found with walkers. Study 2 confirmed that, although infants do not commonly go to destinations, 12-month-old crawlers go to proportionally more destinations than age-matched walkers (N = 16). Head-mounted eye tracking revealed that crawlers and walkers mostly take steps in place while fixating something within reach. When infants do go to a destination, they take straight, short paths to a target fixated while stationary.

Learning the designed actions of everyday objects.

How do young children learn to use everyday artifacts-doorknobs, zippers, and so on-in the ways they were designed to be used? Although the designed actions of such objects seem obvious to adults, little is known about how young children learn the "hidden affordances" of everyday objects. We encouraged 115 11- to 37-month-old children to open 2 types of containers: circular jars with twist-off lids (Experiment 1) and rectangular Tupperware-style containers with pull-off lids (Experiment 2). We varied container size to examine effects of the body-environment fit on display of the designed action and successful implementation of the designed action. Results showed a developmental progression from nondesigned actions to performance of the designed twisting or pulling actions to successful implementation of the designed action. Nondesigned actions decreased with age as performance of the designed action increased. Successful implementation lagged behind performance of the designed action. That is, even after children appeared to know what to do, they were still unsuccessful in opening the container. Why? For twist-offs, very large lids were difficult to manipulate, and younger children often twisted to the right, or in both directions, and did not persist in consecutive turns to the left. Larger pull-off containers required new strategies to stabilize the base, such as holding the container against the tabletop or the chest. Findings provide insights into the body-environment factors that facilitate children's learning and implementation of the hidden affordances inherent in everyday artifacts. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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.

Infants plan prehension while pivoting.

Skilled object retrieval requires coordination of the perceptual and motor systems. Coordination is especially challenging when body position is changing and visual search is required to locate the target. In three experiments, we used a "pivot paradigm" to induce changes in body position: Participants were passively pivoted 180° toward a target placed at varied locations to the left and right of the center of a reaching board. Experiment 1 showed that 6- to 15-month-old infants (n = 41) plan prehension so quickly that they retrieve targets mid-turn and scale their reaches to target location relative to turn direction. Experiment 2 characterized planning mid-turn reaching in 6- to 8-month-olds (n = 5) wearing a head-mounted eye tracker. Reach planning depended on when the target appeared in the field of view-not on target fixation. Experiment 3 used head-mounted eye tracking and motion tracking to assess perceptual-motor coordination in adults (n = 13). Adults displayed more mid-turn reaching than infants. But like infants, adults scaled reaching to target location relative to turn direction, and contact time depended on when the target came into view-not on target fixation. Findings show that fast, efficient perceptual-motor coordination supports flexibility in infant prehension, and constraints on coordination are similar across the lifespan.

The Impact of Segmental Trunk Support on Posture and Reaching While Sitting in Healthy Adults.

The authors investigated postural and arm control in seated reaches while providing trunk support at midribs and pelvic levels in adults. Kinematics and electromyography of the arm and ipsiliateral and contralateral paraspinal muscles were examined before and during reaching. Kinematics remained constant across conditions, but changes were observed in neuromuscular control. With midribs support, the ipsilateral cervical muscle showed either increased anticipatory activity or earlier compensatory muscle responses, suggesting its major role in head stabilization. The baseline activity of bilateral lumbar muscles was enhanced with midribs support, whereas with pelvic support, the activation frequency of paraspinal muscles increased during reaching. The results suggest that segmental trunk support in healthy adults modulates ipsilateral or contralateral paraspinal activity while overall kinematic outputs remain invariant.

Behavioral flexibility in learning to sit.

What do infants learn when they learn to sit upright? We tested behavioral flexibility in learning to sit-the ability to adapt posture to changes in the environment-in 6- to 9-month-old infants sitting on forward and backward slopes. Infants began with slant at 0°; then slant increased in 2° increments until infants lost balance. Infants kept balance on impressively steep slopes, especially in the forward direction, despite the unexpected movements of the apparatus. Between slant adjustments while the slope was stationary, infants adapted posture to the direction and degree of slant by leaning backward on forward slopes and forward on backward slopes. Postural adaptations were nearly optimal for backward slopes. Sitting experience predicted greater postural adaptations and increased ability to keep balance on steeper changes of slant, but only for forward slopes. We suggest that behavioral flexibility is integral to learning to sit and increases with sitting experience.

Effect of Segmental Trunk Support on Posture and Reaching in Children With Cerebral Palsy.

PURPOSE: To test the effects of segmental trunk support on seated postural and reaching control in children with cerebral palsy. METHODS: Seventeen children (age range 2-15 y, Gross Motor Function Classification System levels III-V) were classified with the Segmental Assessment of Trunk Control into mild (complete trunk control/lower lumbar deficits), moderate (thoracic/upper lumbar deficits), and severe (cervical/upper thoracic deficits). Postural and arm kinematics were measured while reaching with trunk support at axillae, mid-ribs, or pelvis. RESULTS: Children in the mild group did not display changes in posture or reaching across conditions. The moderately involved group showed decrements in postural and reaching performance with pelvic compared with higher supports (P < .01). Children in the severe group were unable to maintain posture with pelvic support and showed postural deficiencies with mid-ribs compared with axillae support (P < .01). CONCLUSIONS: Children with cerebral palsy and trunk dysfunction demonstrate improved motor performance when the external assistance matches their intrinsic level of trunk control.

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

[This corrects the article on p. 94 in vol. 9, PMID: 25759646.].

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.