Development of Infant Sitting Postural Control in Three Groups of Infants at Various Risk Levels for Autism Spectrum Disorder.

The purpose of this study was to examine the development of sitting postural control among two groups of infants at elevated risk for autism spectrum disorders (ASD) and a group of infants at typical risk for ASD and its association with cognitive, language and communication skills at a later age. We visited infants in their home environment from the onset of sitting until sitting independence and at 12 and 18 months of age. We collected data on sitting posture (center of pressure), through a portable force platform, as well as communication, cognitive and social behavior assessments at various time points. Our results showed that postural control differences at the onset of sitting, were present among the groups of infants but there were no statistically significant differences among the groups in the development of sitting posture. In addition, there were statistically significant communication differences among the groups and mostly the change in sample entropy in the anterior/posterior direction (posture measure) was significantly correlated with other skills at a later age. This study highlights the importance of investigating multiple at-risk groups to identify unique developmental pathways that may lead to an ASD diagnosis.

Center of pressure characteristics differ during single leg stance throughout pregnancy and compared to nulligravida individuals.

BACKGROUND: Falls are common during pregnancy and present potential for injury to the pregnant individual and the baby. RESEARCH QUESTION: Do center of pressure characteristics during single leg stance differ between participants during and after pregnancy and nulligravida participants in the presence and absence of visual input? METHODS: Nineteen pregnant participants completed testing during the second trimester, the third trimester, and 4-6 months post-partum. Matched, nulligravida females completed testing once. All participants performed single leg stance on a force platform on each limb for up to 20 s with eyes open and with eyes closed. Center of pressure characteristics were compared between pregnant and nulligravida females using three separate 2 × 2 mixed way ANOVAs, one for each pregnancy time point (second trimester, third trimester, and post-partum) with Bonferroni correction. RESULTS: Pregnant females demonstrated smaller single leg stance time with eyes closed during the third trimester. During the second and third trimester, pregnant participants demonstrated smaller sway and sway velocity across eyes open and eyes closed conditions. During the third trimester and post-partum, pregnant participants demonstrated greater median frequency of the center of pressure data. Pregnant participants also demonstrated smaller sample entropy in the anteroposterior direction during the second and third trimesters and in the mediolateral direction during the second trimester. SIGNIFICANCE: The decreased total sway and sway velocity observed during pregnancy may reflect rigidity or a protective strategy during single limb stance. Additionally, center of pressure data were less smooth and more repetitive during pregnancy indicating robust differences in postural control strategies and potentially increased fall risk. Because single limb stance is a component of many activities of daily living, the single limb stance task may have clinical utility for testing or training balance in this population with a goal of decreasing falls.

The Effects of Virtual Reality Based Rehabilitation on Upper Extremity Function in a Child with Cerebral Palsy: A Case Report.

AIM: This case report was designed to assess the efficacy of virtual reality (VR) rehabilitation on improving upper extremity function for a child with spastic hemiplegic cerebral palsy. METHODS: In addition to conventional therapies completed three times per week, the participant engaged in virtual reality rehabilitation with the Neofect Smart Kids five to seven days per week for six weeks totaling just over twelve hours of intervention time. Outcome measures were administered pre-intervention, post-intervention, and 6-weeks post-intervention. RESULTS: Varying levels of improvement in motor function, quality of movement, and functional use were observed during intervention evidenced by improved scores on the following standardized assessments: Peabody Developmental Motor Scales, Second Edition; the Quality of Upper Extremity Skills Test; and the Pediatric Evaluation and Disability Inventory-Computer Adaptive Test. The participant maintained improvements in motor skills at 6-weeks post intervention, however, the quality of his movements and overall frequency of use with his affected upper extremity decreased in the 6-weeks following termination of intervention. CONCLUSIONS: Even though the results are not generalizable, the VR intervention for this child allowed for greater movement repetition and improved functional upper extremity use.

Postural control may drive the development of other domains in infancy.

BACKGROUND: To examine differences in sitting posture in infants at low- and high-risk for autism spectrum disorder and to establish the relationship between sitting postural control and other developmental domains. METHODS: A total of 19 infants participated in the study. Eight infants at high-risk and 11 infants at low-risk for autism spectrum disorder. Sitting posture at 6 months was evaluated using a force platform while center of pressure data were acquired. We utilized traditional tools of center of pressure analysis, such as range, median frequency and frequency dispersion, as well as non-linear tools such as Sample Entropy for both the medial-lateral and anterior-posterior directions. At 12 months we used the Mullen Scales of Early Learning, the Communication and Symbolic Behavior Scales Developmental Profile™ and the Ages and Stages Questionnaire, the personal-social subscale. FINDINGS: At 6 months none of the postural control measures showed statistically significant differences between groups. Infants at high-risk presented significantly lower scores in all behavioral domains than infants at low-risk at 12 months with fair effect sizes. Certain measures of postural control at 6 months could predict language and visual reception behavior at 12 months. INTERPRETATION: Infants at high-risk for autism spectrum disorder present with delays in social, communication and language behavior as well as altered postural control in the first year of life. The present data support the possibility that motor skills and specifically postural control may drive the development in other domains.

A home-based longitudinal study of vocalization behaviors across infants at low and elevated risk of autism.

Background and Aims: The purpose of this exploratory study was to expand existing literature on prelinguistic vocalizations by reporting results of the first home-based longitudinal study examining a wide variety of behaviors and characteristics, including early vocalizations, across infants at low and elevated risk of autism spectrum disorder (ASD). The study of vocalizations and vocalization changes across early developmental periods shows promise in reflecting early clinically significant differences across infants at low and elevated risk of ASD. Observations of early vocalizations and their differences during infancy could provide a reliable and essential component of an early developmental profile that would lower the average diagnostic age for ASD. However, studies employing observation of vocalization behaviors have been limited and often conducted in laboratory settings, reducing the external generalization of the findings. Methods: The present study was conducted to determine the consistency of previous findings with longitudinal data collected in home environments. Infants in the present study represented elevated risk from two etiological backgrounds, (a) infants born prematurely and with low birth weight and (b) infants who had an older sibling diagnosed with ASD. All data were collected in the infants' homes and compared with data collected from infants with low likelihood of ASD. The study included 44 participants (31 in the low-risk sample, 13 in the high-risk sample) with vocalization behaviors observed at 6- and 12-months through 20-min semi-structured play interactions with caregivers. Observations were video-recorded and later coded for speech and non-speech vocalizations. Results: Differences in the 6-month vocalization behaviors were not statistically significant across risk levels of ASD. By 12 months; however, risk group differences were evident in the total number of vocalizations overall with specific differences across groups representing moderate to large, clinically relevant effects. Infants at low risk of ASD demonstrated significantly greater developmental change between 6- and 12-months than did the infants at high risk. Data were also reviewed for differences across high-risk group etiologies. Conclusions: The present study was unique and innovative in a number of ways as the first home-based longitudinal study examining infant vocal behaviors across low and high risk of ASD. Many of the present study findings were consistent with previous cross-sectional investigations of infants at elevated risk for ASD, indicating support for further home-based longitudinal study in this area. Findings also indicated some preliminary subgroup differences between high-risk etiologies of ASD. Vocalization differences across high risk groups had not been previously addressed in the literature. Implications: Vocalization differences are notable by 12-months of age between infants at low and elevated risk of ASD and infants at high risk demonstrated reduced developmental changes between 6- and 12-months compared to the infants at low risk. Observation of early infant vocalization behaviors may reasonably occur in the home, providing early childhood professionals and researchers with empirical support for data collection of child-caregiver interactions in this setting. Potential differences across high-risk etiologies warrant further investigation.

Water Immersion Affects Episodic Memory and Postural Control in Healthy Older Adults.

BACKGROUND AND PURPOSE: Previous research has reported that younger adults make fewer cognitive errors on an auditory vigilance task while in chest-deep water compared with on land. The purpose of this study was to extend this previous work to include older adults and to examine the effect of environment (water vs land) on linear and nonlinear measures of postural control under single- and dual-task conditions. METHODS: Twenty-one older adult participants (age = 71.6 ± 8.34 years) performed a cognitive (auditory vigilance) and motor (standing balance) task separately and simultaneously on land and in chest-deep water. Listening errors (n = count) from the auditory vigilance test and sample entropy (SampEn), center of pressure area, and velocity for the balance test served as dependent measures. Environment (land vs water) and task (single vs dual) comparisons were made with a Wilcoxon matched-pair test. RESULTS: Listening errors were 111% greater during land than during water environments (single-task = 4.0 ± 3.5 vs 1.9 ± 1.7; P = .03). Conversely, SampEn values were 100% greater during water than during land environments (single-task = 0.04 ± 0.01 vs 0.02 ± 0.01; P < .001). Center of pressure area and velocity followed a similar trend to SampEn with respect to environment differences, and none of the measures were different between single- and dual-task conditions (P > .05). CONCLUSIONS: The findings of this study expand current support for the potential use of partial aquatic immersion as a viable method for challenging both cognitive and motor abilities in older adults.

Visual and somatosensory contributions to infant sitting postural control.

There are a limited number of studies that have investigated sitting posture during infancy and the contribution of the sensory systems. The goal of this study was to examine the effects of altered visual and somatosensory signals on infant sitting postural control. Thirteen infants (mean age ± SD, 259.69 ± 16.88 days) participated in the study. Initially, a single physical therapist performed the Peabody Developmental Motor Scale to determine typical motor development. Then the child was placed onto a force platform under four randomized conditions: (a) Control (C) - sat independently on the force plate, (b) Somatosensory (SS) - Sat independently on a foam pad (low density), (c) Visual (VS) - sat independently on the force plate while the lights were turned off creating dim lighting, and (d) Combination of b and c (NVSS). Center of pressure (COP) data from both the anterior-posterior (AP) and the medial-lateral (ML) directions were acquired through the Vicon software at 240 Hz. The lights off conditions, both VS and NVSS, lead to increased Root Mean Square (RMS) and Range values in the AP direction, as well as increased Lyapunov Exponent (LyE) values in the ML direction. Altered visual information lead to greater disturbances of sitting postural control in typically developing infants than altered somatosensory information. The lights off conditions (VS and NVSS), unveiled different control mechanisms for AP and ML direction during sitting. Thus, the present findings confirm the dominance of vision during the early acquisition of a new postural accomplishment.

An overview of assessment methodology for obesity-related variables in infants at risk.

BACKGROUND: The first 2 years of a child's life are a particularly critical time period for obesity prevention. AIM: An increasing amount of research across the world is aimed at understanding factors that impact early childhood obesity and developing interventions that target these factors effectively. With this growing interest, new and interdisciplinary research teams are developing to meet this research need. Due to rapid growth velocity during this phase of the lifespan, typical assessments used in older populations may not be valid or applicable in infants, and investigators need to be aware of the pros and cons of specific methodological strategies. METHODS: This paper provides an overview of methodology available to assess obesity-related factors in the areas of anthropometry and body composition, nutrient intake, and energy expenditure in infants aged 0-2 years. RESULTS: Gold standard measures for body composition, such as dual-energy X-ray absorptiometry (DXA) or other imaging techniques, are costly, require highly trained personnel, and are limited for research application. Nutrient intake methodology primarily includes surveys and questionnaires completed via parent proxy report. In terms of energy expenditure, methods of calorimetry are expensive and may not differentiate between different activities. Questionnaires or physical activity sensors offer another way of energy expenditure assessment. However, questionnaires have a certain recall bias, while the sensors require further validation. CONCLUSIONS: Overall, in addition to understanding the pros and cons of each assessment tool, researchers should take into consideration the experience of the interdisciplinary team of investigators, as well as the cost and availability of measures at their institution.

Children with moderate to severe cerebral palsy may not benefit from stochastic vibration when developing independent sitting.

PURPOSE: Determine sitting postural control changes for children with cerebral palsy (CP), using a perceptual-motor intervention and the same intervention plus stochastic vibration through the sitting surface. METHODS: Two groups of children with moderate or severe CP participated in the 12 week interventions. The primary outcome measure was center of pressure data from which linear and nonlinear variables were extracted and the gross motor function measure (GMFM). RESULTS: There were no significant main effects of intervention or time or an interaction. Both treatment groups increased the Lyapunov exponent values in the medial-lateral direction three months after the start of treatment as well as their GMFM scores in comparison with baseline. CONCLUSIONS: The stochastic vibration did not seem to advance the development of sitting postural control in children between the ages of 2 and 6 years. However, perceptual-motor intervention was found beneficial in advancing sitting behavior.

Sample Entropy Identifies Differences in Spontaneous Leg Movement Behavior between Infants with Typical Development and Infants at Risk of Developmental Delay.

We are interested in using wearable sensor data to analyze detailed characteristics of movement, such as repeatability and variability of movement patterns, over days and months to accurately capture real-world infant behavior. The purpose of this study was to explore Sample Entropy (SampEn) from wearable sensor data as a measure of variability of spontaneous infant leg movement and as a potential marker of the development of neuromotor control. We hypothesized that infants at risk (AR) of developmental delay would present significantly lower SampEn values than infants with typical development (TD). Participants were 11 infants with TD and 20 infants AR. We calculated SampEn from 1-4 periods of data of 7200 samples in length when the infants were actively playing across the day. The infants AR demonstrated smaller SampEn values (median 0.21) than the infants with TD (median 1.20). Lower values of SampEn indicate more similarity in patterns across time, and may indicate more repetitive, less exploratory behavior in infants AR compared to infants with TD. In future studies, we would like to expand to analyze longer periods of wearable sensor data and/or determine how to optimally sample representative periods across days and months.

He's just content to sit: a qualitative study of mothers' perceptions of infant obesity and physical activity.

BACKGROUND: Rates of obesity among children ages zero to five are rapidly increasing. Greater efforts are needed to promote healthy behaviors of young children. Mothers are especially important targets for promoting health as mothers' views play a vital role in helping their children foster healthy habits from an early age. Research has found parents' views of infants' weight may influence their feeding practices; however, limited research has explored mothers' view of infants' weight in relation to the promotion of physical activity. Therefore, the purpose of this study was to explore the perceptions of mothers of normal weight infants and overweight infants about their infant's weight and physical activity. METHODS: Semi-structured interviews were conducted with mothers of normal weight (n = 18) and of overweight (n = 11) infants (6.5 ± 0.5 month) in a Midwestern city in the United States. A thematic analysis was used to analyze the data. RESULTS: A majority of mothers thought infants could be overweight. However, no mothers referenced their own infant as overweight. Mothers most commonly noted infants could be overweight only if they were formula fed and/or were overfed, not if they were breastfed. Mothers views were not negatively influenced by others who mentioned that their child was either "big" or "small" and only one mother had been told her infant was overweight. A majority of mothers thought an infant could be physically active. When discussing infant activity, mothers primarily referred to it in terms of general mobility and a few thought activity level was related to a personality characteristic. Mothers intended to promote physical activity in the future either through outdoor play or specific organized activities such as sports. Despite a majority of mothers stating they were currently physically active themselves, only a few talked about interacting with their infant to promote their infant's physical activity. CONCLUSIONS: Efforts are needed by healthcare professionals and other public health professionals to inform mothers about the dangers of increased weight during infancy as well as the importance of interacting with infants to promote physical activity.

Postural control strategies differ in normal weight and overweight infants.

BACKGROUND: Evidence suggests obesity can have a negative influence on a child's motor development and postural control behavior. Little research has examined the impact of infant weight on gross motor behavior, particularly postural control at the onset of sitting. OBJECTIVE: The purpose of this study was to determine whether normal weight and overweight infants differed in their postural control strategies at the onset of sitting and one-month post onset of sitting. METHODS: 29 infants (n=19 normal weight, n=10 overweight) were recruited to participate in this study. Infant's length and weight were measured at 3 months of age (visit 1). Infant's center of pressure (COP) was measured on an AMTI force platform at the onset of sitting (visit 2) and one-month post onset (visit 3). Data were analyzed using linear measures (range and RMS for the anterior/posterior (AP) and medial/lateral (ML) directions, sway path) and nonlinear measures (Sample Entropy in AP and ML directions). RESULTS: Overweight infants had significantly greater RMS values in the ML direction at visit 2 and reduced Sway Path values in comparison to normal weight infants at visits 2 and 3. Further, there was a significant difference in Sample Entropy as overweight infants increased Sample Entropy from visit 2 to 3 while normal weight infants decreased Sample Entropy values during this time period. CONCLUSIONS: These findings suggest that overweight infants adopt a different postural control strategy. This altered strategy may limit exploration early in development. More research is needed to determine if longitudinal differences continue to emerge.

Reliability of center of pressure measures for assessing the development of sitting postural control through the stages of sitting.

Cerebral palsy (CP) impairs an individual's ability to move and control one's posture. Unfortunately, the signs and symptoms of CP may not be apparent before age two. Evaluating sitting posture is a potential way to assess the developing mechanisms that contribute to CP. The purpose of this project was to determine the reliability of linear and nonlinear measures, including inter- and intrastage reliability, when used to analyze the center of pressure (COP) time series during the stages of sitting development in children with typical development (TD) and with/at-risk for cerebral palsy (CP). We hypothesized that nonlinear tools would be more reliable than linear tools in assessing childrens' sitting development, and reliability would increase with development. COP data was recorded for three trials at eight sessions. Linear parameters used were root mean square, range of sway for the anterior-posterior (AP) and medial-lateral (ML) directions, and sway path. Nonlinear parameters used were Approximate Entropy, the largest Lyapunov Exponent, and Correlation Dimension for the AP and ML direction. Participants consisted of 33 children with TD and 26 children with/at-risk for CP. Our results determined that COP is a moderately reliable method for assessing the development of sitting postural control in stages in both groups. Thus, clinicians may be able to use measures from COP data across stages to assess the efficacy of therapeutic interventions that are intended to improve sitting postural abilities in children with/at-risk for CP.

Infant sitting postural control appears robust across changes in surface context.

AIM OF THE STUDY: Independent sitting requires the control of the involved body segments over the base of support using information obtained from the three sensory systems (visual, vestibular, and somatosensory). The contribution of somatosensory information in infant sitting has not been explored. To address this gap, we altered the context of the sitting support surface and examined the infants' immediate postural responses. MATERIALS AND METHODS: Ten 7-month-old typically developing infants sat on compliant and firm surfaces in one session. Spatial, frequency, and temporal measures of postural control were obtained using center of pressure data. Results Our results suggest that infants' postural sway is not immediately affected by the different types of foam surface while sitting. CONCLUSIONS: It seems that mature sitter infants are able to adapt to different environmental constraints by disregarding the distorted somatosensory information from the support surface and relying more on their remaining senses (visual and vestibular) to control their sitting posture.

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.

Indifference to Chaotic Motion May Be Related to Social Disinterest in Children With Autism.

Children with autism spectrum disorder tend to have little interest in the presence, actions, and motives of other persons. In addition, these children tend to present with a limited and overly redundant movement repertoire, often expressing hyperfixation and aversion to novelty. We explore whether this is related to a more fundamental lack of appreciation for various temporal dynamics, including periodic, chaotic, and aperiodic motion structures. Seven children with ASD (age, gender, and height matched with children without ASD) were asked to stand and watch the motion of a visual stimulus displayed on a large (55″) video monitor. Gaze and posture movements were recorded and assessed using cross recurrence quantification analysis for qualities of coordination, including rate and duration of bouts of coordination. Results showed that children with ASD do not express an affinity to chaotic motion of the stimulus in the same way as children without ASD. We contend that this indifference to chaotic motion is foundational to their general disinterest in biological motion.

Temporal Structure of Support Surface Translations Drive the Temporal Structure of Postural Control During Standing.

A healthy biological system is characterized by a temporal structure that exhibits fractal properties and is highly complex. Unhealthy systems demonstrate lowered complexity and either greater or less predictability in the temporal structure of a time series. The purpose of this research was to determine if support surface translations with different temporal structures would affect the temporal structure of the center of pressure (COP) signal. Eight healthy young participants stood on a force platform that was translated in the anteroposterior direction for input conditions of varying complexity: white noise, pink noise, brown noise, and sine wave. Detrended fluctuation analysis was used to characterize the long-range correlations of the COP time series in the AP direction. Repeated measures ANOVA revealed differences among conditions (p < 0.001). The less complex support surface translations resulted in a less complex COP compared to normal standing. A quadratic trend analysis demonstrated an inverted-u shape across an increasing order of predictability of the conditions (p < 0.001). The ability to influence the complexity of postural control through support surface translations can have important implications for rehabilitation.

Children's looking preference for biological motion may be related to an affinity for mathematical chaos.

Recognition of biological motion is pervasive in early child development. Further, viewing the movement behavior of others is a primary component of a child's acquisition of complex, robust movement repertoires, through imitation and real-time coordinated action. We theorize that inherent to biological movements are particular qualities of mathematical chaos and complexity. We further posit that this character affords the rich and complex inter-dynamics throughout early motor development. Specifically, we explored whether children's preference for biological motion may be related to an affinity for mathematical chaos. Cross recurrence quantification analysis (cRQA) was used to investigate the coordination of gaze and posture with various temporal structures (periodic, chaotic, and aperiodic) of the motion of an oscillating visual stimulus. Children appear to competently perceive and respond to chaotic motion, both in rate (cRQA-percent determinism) and duration (cRQA-maxline) of coordination. We interpret this to indicate that children not only recognize chaotic motion structures, but also have a preference for coordination with them. Further, stratification of our sample (by age) uncovers the suggestion that this preference may become refined with age.

Postural sway and gaze can track the complex motion of a visual target.

Variability is an inherent and important feature of human movement. This variability has form exhibiting a chaotic structure. Visual feedback training using regular predictive visual target motions does not take into account this essential characteristic of the human movement, and may result in task specific learning and loss of visuo-motor adaptability. In this study, we asked how well healthy young adults can track visual target cues of varying degree of complexity during whole-body swaying in the Anterior-Posterior (AP) and Medio-Lateral (ML) direction. Participants were asked to track three visual target motions: a complex (Lorenz attractor), a noise (brown) and a periodic (sine) moving target while receiving online visual feedback about their performance. Postural sway, gaze and target motion were synchronously recorded and the degree of force-target and gaze-target coupling was quantified using spectral coherence and Cross-Approximate entropy. Analysis revealed that both force-target and gaze-target coupling was sensitive to the complexity of the visual stimuli motions. Postural sway showed a higher degree of coherence with the Lorenz attractor than the brown noise or sinusoidal stimulus motion. Similarly, gaze was more synchronous with the Lorenz attractor than the brown noise and sinusoidal stimulus motion. These results were similar regardless of whether tracking was performed in the AP or ML direction. Based on the theoretical model of optimal movement variability tracking of a complex signal may provide a better stimulus to improve visuo-motor adaptation and learning in postural control.

Sitting postural control in infants with typical development, motor delay, or cerebral palsy.

PURPOSE: To determine whether infants born full-term, infants born preterm with motor delays, and infants born preterm who have a diagnosis of cerebral palsy (CP) differed in postural control at the emergence of early sitting. METHODS: Thirty infants born at term who were developing typically, 6 infants born preterm who were later diagnosed with CP, and 5 infants born preterm who were delayed in motor development participated in this study. Center-of-pressure data from unsupported sitting were recorded and analyzed using measures of both amount and temporal organization of center-of-pressure variability. RESULTS: Infants born full-term, infants born preterm with motor delays, and infants born preterm who have a diagnosis of CP exhibited dissimilar movement-control strategies at the onset of sitting. CONCLUSIONS: The present findings may be helpful in directing and testing intervention protocols for infants born preterm.