Typically Developing Group Research Articles

Grandparenting children with typical development and special educational needs and disabilities

ABSTRACT The study compares the experiences of two groups of grandparents, one with a typically developing (TD) grandchild and one with a grandchild with special educational needs and disabilities (SEND). The extent and the kind of grandparents’ involvement, the quality of their relationship and the factors that could contribute to the quality were assessed. The study took place in Greece, a country with strong familial ties. 104 grandparents with a TD and 53 with a grandchild with SEND completed a structured questionnaire. The results revealed that grandparents are an important source of support in both groups. They are actively involved in the care and daily life of their grandchild. They are mentors and provide financial support especially to their grandchild with SEND. They enjoy a close relationship with their grandchild but the quality of the relationship was higher in the TD group. The knowledge of the grandchild and a close relationship with the parents were predictors of an emotionally close relationship with the grandchild in both groups. The findings of the study suggest that grandparents are actively involved in the upbringing of their grandchildren. Professionals and community services should recognize their contribution and provide them with skills, support and encouragement.

Oculomotor randomness is higher in autistic children and increases with the severity of symptoms.

A variety of studies have suggested that at least some children with autism spectrum disorder (ASD) view the world differently. Differences in gaze patterns as measured by eye tracking have been demonstrated during visual exploration of images and natural viewing of movies with social content. Here we analyzed the temporal randomness of saccades and blinks during natural viewing of movies, inspired by a recent measure of "randomness" applied to micro-movements of the hand and head in ASD (Torres et al., 2013; Torres & Denisova, 2016). We analyzed a large eye-tracking dataset of 189 ASD and 41 typically developing (TD) children (1-11 years old) who watched three movie clips with social content, each repeated twice. We found that oculomotor measures of randomness, obtained from gamma parameters of inter-saccade intervals (ISI) and blink duration distributions, were significantly higher in the ASD group compared with the TD group and were correlated with the ADOS comparison score, reflecting increased "randomness" in more severe cases. Moreover, these measures of randomness decreased with age, as well as with higher cognitive scores in both groups and were consistent across repeated viewing of each movie clip. Highly "random" eye movements in ASD children could be associated with high "neural variability" or noise, poor sensory-motor control, or weak engagement with the movies. These findings could contribute to the future development of oculomotor biomarkers as part of an integrative diagnostic tool for ASD.

Relationship between sensory processing patterns and gross motor function of children and adolescents with Down syndrome and typical development: a cross-sectional study.

Children and adolescents with Down syndrome (DS) may experience impairments in sensory and motor skills that can be interrelated. The purposes of this study were (i) to compare the sensory processing patterns and gross motor function between children and adolescents with DS and with typical development (TD) and (ii) to explore associations between these areas in both DS and TD groups. This cross-sectional study involved a sample size of 25 participants with DS (mean age 10.24±2.04years) and 25 participants with TD (mean age 10.04±2.82years). The sensory processing patterns were assessed using the Sensory Profile Second Version questionnaire, and the gross motor function was measured with the Gross Motor Function Measure (GMFM-88) dimensions (D) standing, and (E) walking, running, and jumping. Differences between groups were tested using the Mann-Whitney test, and the relationship between the variables was examined using Spearman's correlation tests, with a significance level set at 5%. Children with DS showed greater difficulties with sensory processing than TD children in Seeker (P<0.001), Avoider (P<0.001), Sensitivity (P<0.001), Registration (P<0.001), Auditory (P<0.001), Touch (P=0.001), Movements (P=0.001), Oral (P=0.028), Conduct (P=0.005), Socioemotional (P<0.001), and Attentional (P<0.001) domains. Additionally, children with DS presented lower gross motor function than TD in GMFM-88, standing (P<0.001) and walking, running, and jumping (P<0.001). Correlations were found between greater difficulties with sensory processing in Touch and lower gross motor function in walking, running, and jumping for the DS group. Our results suggest there are more difficulties in sensory processing patterns and gross motor function in children with DS than in TD. Also, there is a single association between more difficulties in sensory processing and less well-developed motor function in the DS group. Therefore, a comprehensive assessment of all these aspects should be performed in children and adolescents with DS, along with the provision of relevant interventions addressing specific needs.

Cognitive correlates of math abilities in autism spectrum disorder.

The purpose of the current study was to investigate the contribution of different cognitive processes to specific math abilities in students with autism spectrum disorder (ASD) and typically developing (TD) students. The study involved a group of students with ASD without intellectual disabilities (n = 26) and a group with TD students (n = 52). The two groups aged from six to 20 years old and were matched for age, sex ratio and visuospatial reasoning. To assess math abilities, four math tasks were administered: arithmetic facts, mental calculation, mathematical inferences and math problem solving. Concerning cognitive processes, participants were tested on vocabulary, verbal working memory, visuospatial working memory, response inhibition and interference control. The group with ASD showed lower scores on all specific math measures than the TD group; cognitive processes differently contributed to diverse math abilities, and vocabulary and verbal working memory were stronger associated to specific math abilities in the group with ASD than in the TD group. The current results suggest that students with ASD had lower math abilities that are generalized to different math tasks. Implications for research and clinical assessment and intervention were discussed.

Impaired effective functional connectivity in the social preference of children with autism spectrum disorder.

The medial prefrontal cortex (mPFC), amygdala (Amyg), and nucleus accumbens (NAc) have been identified as critical players in the social preference of individuals with ASD. However, the specific pathophysiological mechanisms underlying this role requires further clarification. In the current study, we applied Granger Causality Analysis (GCA) to investigate the neural connectivity of these three brain regions of interest (ROIs) in patients with ASD, aiming to elucidate their associations with clinical features of the disorder. Resting-state functional magnetic resonance imaging (rs-fMRI) data were acquired from the ABIDE II database, which included 37 patients with ASD and 50 typically developing (TD) controls. The mPFC, Amyg, and NAc were defined as ROIs, and the differences in fractional amplitude of low-frequency fluctuations (fALFF) within the ROIs between the ASD and TD groups were computed. Subsequently, we employed GCA to investigate the bidirectional effective connectivity between the ROIs and the rest of the brain. Finally, we explored whether this effective connectivity was associated with the social responsiveness scale (SRS) scores of children with ASD. The fALFF values in the ROIs were reduced in children with ASD when compared to the TD group. In terms of the efferent connectivity from the ROIs to the whole brain, the ASD group exhibited increased connectivity in the right cingulate gyrus and decreased connectivity in the right superior temporal gyrus. Regarding the afferent connectivity from the whole brain to the ROIs, the ASD group displayed increased connectivity in the right globus pallidus and decreased connectivity in the right cerebellar Crus 1 area and left cingulate gyrus. Additionally, we demonstrated a positive correlation between effective connectivity derived from GCA and SRS scores. Impairments in social preference ASD children is linked to impaired effective connectivity in brain regions associated with social cognition, emotional responses, social rewards, and social decision-making. This finding further reveals the potential neuropathological mechanisms underlying ASD.

The Latency of Auditory Event-Related Potential P300 Prolonged in School-Age Students with Unilateral Hearing Loss in a Mandarin Learning Environment.

Our study investigated the differences in speech performance and neurophysiological response in groups of school-age children with unilateral hearing loss (UHL) who were otherwise typically developing (TD). We recruited a total of 16 primary school-age children for our study (UHL = 9/TD = 7), who were screened by doctors at Shin Kong Wu-Ho-Su Memorial Hospital. We used the Peabody Picture Vocabulary Test-Revised (PPVT-R) to test word comprehension, and the PPVT-R percentile rank (PR) value was proportional to the auditory memory score (by The Children's Oral Comprehension Test) in both groups. Later, we assessed the latency and amplitude of auditory ERP P300 and found that the latency of auditory ERP P300 in the UHL group was prolonged compared with that in the TD group. Although students with UHL have typical hearing in one ear, based on our results, long-term UHL might be the cause of atypical organization of brain areas responsible for auditory processing or even visual perceptions attributed to speech delay and learning difficulties.

Developmental Changes in Stroop Task Performance among Individuals with High-Functioning Pervasive Developmental Disorders.

This study aimed to assess age-related changes in Stroop Color and Word test indices in individuals with high-functioning pervasive developmental disorder (HF-PDD) and compare their performance with typically developing (TD) individuals. There were a total of 125 participants (57 TD, 68 HF-PDD), aged 6-24. Stimuli were displayed on computer screens, and participants verbally responded with response times recorded via voice key function. Single regression analysis revealed age-associated trends in Stroop test indices for both groups, indicating shorter response times and reduced Stroop interference with age. The age at which the best Stroop test results were obtained ranged from 220 to 260 months for TD and from 195 to 201 months for HF-PDD. While color naming and word reading tasks showed no significant group differences, color word naming task response times were significantly longer for the HF-PDD group. Around 30% of HF-PDD participants scored over two standard deviations above the TD mean. Both TD and HF-PDD groups exhibited age-related changes in Stroop task performance, which were fitted by a quadratic regression curve. Prolongation of the color word naming task in the HF-PDD group suggests that approximately 30% of individuals with HF-PDD have difficulty with stereotype suppression. J. Med. Invest. 71 : 254-259, August, 2024.

A new methodological approach to characterize selective motor control in children with cerebral palsy.

Despite being a primary impairment in individuals with cerebral palsy (CP), selective motor control (SMC) is not routinely measured. Personalized treatment approaches in CP will be unattainable without the ability to precisely characterize the types and degrees of impairments in motor control. The objective of this study is to report the development and feasibility of a new methodological approach measuring muscle activation patterns during single-joint tasks to characterize obligatory muscle co-activation patterns that may underly impaired SMC. Muscle activation patterns were recorded during sub-maximal voluntary isometric contraction (sub-MVIC) tasks at the hip, knee, and ankle with an interactive feedback game to standardize effort across participants. We calculated indices of co-activation, synergistic movement, mirror movement, and overflow (indices range 0-2, greater scores equal to greater impairment in SMC) for each isolated joint task in 15 children - 8 with typical development (TD) (mean age 4.7 ± 1.0 SD years) and 7 with CP (mean age 5.8 ± 0.7 SD years). Indices were compared with Mann-Whitney tests. The relationships between the indices and gross motor function (GMFM-66) were examined with Pearson's r. Mean indices were higher in the CP vs. the TD group for each of the six tasks, with mean differences ranging from 0.05 (abduction and plantarflexion) to 0.44 (dorsiflexion). There was great inter-subject variability in the CP group such that significant group differences were detected for knee flexion mirroring (p = 0.029), dorsiflexion coactivation (p = 0.021), and dorsiflexion overflow (p = 0.014). Significant negative linear relations to gross motor function were found in all four indices for knee extension (r = -0.56 to -0.75), three of the indices for ankle dorsiflexion (r = -0.68 to -0.78) and in two of the indices for knee flexion (r = -0.66 to -0.67), and ankle plantarflexion (r = -0.53 to -0.60). Indices of coactivation, mirror movement, synergy, and overflow during single-joint lower limb tasks may quantify the type and degree of impairment in SMC. Preliminary concurrent validity between several of the indices of SMC and gross motor function was observed. Our findings established the feasibility of a new methodological approach that quantifies muscle activation patterns using electromyography paired with biofeedback during single-joint movement.

The Influence of Language and Cognitive Skills on Narrative Retelling for Preschoolers with and without Specific Language Impairment

Objectives: This study aimed to confirm relationships between language skills (vocabulary, sentence comprehension), cognitive skills (episodic buffer) and narrative retelling in typically developing (TD) children and children with specific language impairment (SLI).Methods: A total of 24 children aged 5 to 6 years participated in this study, including SLI (n= 8) and TD (n= 16). Participants completed a vocabulary test, sentence comprehension test, episodic buffer task, and narrative retelling task. Narratives were analyzed for macrostructure (story grammar). An independent sample &lt;i&gt;t&lt;/i&gt;-test was used to examine the difference between groups. And correlation and simple regression analysis was conducted to confirm relationships between narrative retelling and other variables in each group.Results: The SLI group showed significantly lower expressive vocabulary, sentence comprehension, episodic buffer, and narrative retelling skills. In the TD group, there was no significant correlation between narrative retelling skills and other variables. However, a significant correlation was revealed between narrative retelling skills and episodic buffer in the SLI group. Also, the episodic buffer significantly predicted the SLI group’s narrative retelling skills.Conclusion: These results confirmed that narrative retelling requires not just language skills but cognitive skills. Therefore, it is important to consider the role of cognitive skills when planning and implementing intervention for children with SLI. Further studies are required to investigate the likelihood that other language or cognitive skills have an impact on narrative skills.

Differences in Development of Activities, Participation during School Age (1st to 4th grade) According to Speech Sound Ability in Pre-school Age

Objectives: This study divided groups according to speech sound ability in the pre-school age and longitudinally examined the differences in the development patterns of activities from 1st grade to 4th grade.Methods: Longitudinal research data collected from the 7th to 11th year included in the Panel Study on Korean Child (PSKC) were used. The subjects of study were classified into three groups; Typically developing (TD), mild Speech Sound Disorder (SSD), and moderate SSD according to the results of the ‘Three Sentence Screening Test’ in the 7th year. Activities, participation are comprised of learning and applying knowledge, interaction and relationship, major life. A rating score based on the evaluation of each question by the teacher in charge of the child was used.Results: The average score of the TD group was high in all areas. The SSD group was found to show significant differences from the TD in learning and applying knowledge, major life.Conclusion: Children with speech sound disorders show difficulties not only learning skills such as literacy, mathematics, and attention, but also activities required for school education. In a clinical setting, areas that may present problems should be identified and included in the intervention plan in order to minimize not only speech problems but also related problems.

Sleep problems in children with autism spectrum disorder and attention-deficit/hyperactivity disorder: A comparative study and effects on communication skills.

Sleep disturbances are highly prevalent among children with neurodevelopmental disorders, like Autism Spectrum Disorder (ASD) and Attention-Deficit/Hiperactivity Disorder (ADHD). The first objective of this study is to examine the differences in sleep problems between a group of children with ASD without intellectual disabilities, a group with ADHD and a typically developing (TD) group. A second objective is aimed at analyzing the effects of sleep problems and symptom severity on their communication skills. Participants were 122 children between 7 and 12 years old distributed in three groups: 32 TD children, 47 children with ASD and 43 children with ADHD, matched on age and intelligence. Parents completed different questionnaires that measured sleep disturbances and communication skills. Findings show significant differences between the clinical groups and the TD group in most types of sleep disorders. Moreover, the group with ADHD showed significantly more sleep breathing disorders and hyperhidrosis in comparison with ASD and TD, as well as more total sleep problems. In contrast to ASD, the predictive power of sleep problems on communication difficulties was greater in the group with ADHD. The results of the mediation analysis indicate that in both groups, sleep problems partially mediate the relationship between symptoms and communication. This investigation highlights the need of considering sleep disorders when assessing communication skills in ASD and ADHD, given its indirect influence in this domain. Understanding the sleep dysfunctions of both conditions and their repercussions is crucial to develop adjusted interventions.

Objective assessment of autism spectrum disorder based on performance in structured interpersonal acting-out tasks with prosodic stability and variability.

In this study, we sought to objectively and quantitatively characterize the prosodic features of autism spectrum disorder (ASD) via the characteristics of prosody in a newly developed structured speech experiment. Male adults with high-functioning ASD and age/intelligence-matched men with typical development (TD) were asked to read 29 brief scripts aloud in response to preceding auditory stimuli. To investigate whether (1) highly structured acting-out tasks can uncover the prosodic of difference between those with ASD and TD, and (2) the prosodic stableness and flexibleness can be used for objective automatic assessment of ASD, we compared prosodic features such as fundamental frequency, intensity, and mora duration. The results indicate that individuals with ASD exhibit stable pitch registers or volume levels in some affective vocal-expression scenarios, such as those involving anger or sadness, compared with TD and those with TD. However, unstable prosody was observed in some timing control or emphasis tasks in the participants with ASD. Automatic classification of the ASD and TD groups using a support vector machine (SVM) with speech features exhibited an accuracy of 90.4%. A machine learning-based assessment of the degree of ASD core symptoms using support vector regression (SVR) also had good performance. These results may inform the development of a new easy-to-use assessment tool for ASD core symptoms using recorded audio signals.

Performance during object retrieval tasks in young children with and without Down syndrome: A pilot study

AbstractObject retrieval skills requiring means‐end exploration are an area of relative weakness in young children with Down syndrome (DS). The current pilot study examined the object retrieval skills of a small sample of young children with DS for tasks with varying level of complexity. Thirteen children with DS (31.55 ± 4.14 months) and 13 mental age‐matched typically developing (TD) children (17.31 ± 1.64 months) completed three tasks involving retrieving a toy from a transparent box (Task 1), an opaque box (Task 2) and a transparent box hidden inside an opaque box (Task 3). Both DS and TD group performed similarly for the simpler Task 1, but for Tasks 2 and 3, the DS group had a lower success rate, less frequent use of complex asymmetric hand actions and/or longer execution times compared to the TD group. Future studies should examine the developmental trends and specificity of means‐end exploratory behaviours in children with DS.

Dual task impact on functional mobility and interaction of functional level and balance in patients with Duchenne muscular dystrophy

BackgroundDystrophin, a protein crucial for various brain regions governing higher-order functions like learning and memory is notably absent in individuals with Duchenne muscular dystrophy (DMD). This absence of dystrophin in the brain is believed to underlie cognitive challenges in DMD. Cognitive and motor challenges observed in DMD could potentially hinder the execution of dual tasks. Research questionIs there a significant correlation between dual-task performance, functional mobility, and balance in children with DMD? MethodThe study included 28 participants (14 DMD, 14 typical development). Timed Up and Go (TUG) test results were recorded for single and dual-task conditions (motor-motor, cognitive-motor). Functional level was assessed using Motor Function Measurement-32 (MFM-32), Brooke Upper Extremity Scale, and Vignos Scale. Balance was evaluated using Balance Master System and Pediatric Functional Reach Test (PFRT). ResultsSignificant differences in TUG test scores across conditions were observed in both DMD and typical development groups (p < 0.05). Children with DMD exhibited longer completion times compared to typical development children (p < 0.05). Among children with DMD, there was a significant correlation between TUG scores in different task conditions and balance assessment (p < 0.05, r = 0.571 to −0.819). Lower MFM-32 scores in DMD children were correlated with worse TUG performance across conditions (p < 0.05, r = 0.586 to −0.868). SignifianceThis study sheds light on the multifaceted nature of dual-tasking challenges in individuals with DMD, thereby contributing to a deeper understanding of the implications for rehabilitation strategies.

Development of Deep Ensembles to Screen for Autism and Symptom Severity Using Retinal Photographs

Screening for autism spectrum disorder (ASD) is constrained by limited resources, particularly trained professionals to conduct evaluations. Individuals with ASD have structural retinal changes that potentially reflect brain alterations, including visual pathway abnormalities through embryonic and anatomic connections. Whether deep learning algorithms can aid in objective screening for ASD and symptom severity using retinal photographs is unknown. To develop deep ensemble models to differentiate between retinal photographs of individuals with ASD vs typical development (TD) and between individuals with severe ASD vs mild to moderate ASD. This diagnostic study was conducted at a single tertiary-care hospital (Severance Hospital, Yonsei University College of Medicine) in Seoul, Republic of Korea. Retinal photographs of individuals with ASD were prospectively collected between April and October 2022, and those of age- and sex-matched individuals with TD were retrospectively collected between December 2007 and February 2023. Deep ensembles of 5 models were built with 10-fold cross-validation using the pretrained ResNeXt-50 (32×4d) network. Score-weighted visual explanations for convolutional neural networks, with a progressive erasing technique, were used for model visualization and quantitative validation. Data analysis was performed between December 2022 and October 2023. Autism Diagnostic Observation Schedule-Second Edition calibrated severity scores (cutoff of 8) and Social Responsiveness Scale-Second Edition T scores (cutoff of 76) were used to assess symptom severity. The main outcomes were participant-level area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity. The 95% CI was estimated through the bootstrapping method with 1000 resamples. This study included 1890 eyes of 958 participants. The ASD and TD groups each included 479 participants (945 eyes), had a mean (SD) age of 7.8 (3.2) years, and comprised mostly boys (392 [81.8%]). For ASD screening, the models had a mean AUROC, sensitivity, and specificity of 1.00 (95% CI, 1.00-1.00) on the test set. These models retained a mean AUROC of 1.00 using only 10% of the image containing the optic disc. For symptom severity screening, the models had a mean AUROC of 0.74 (95% CI, 0.67-0.80), sensitivity of 0.58 (95% CI, 0.49-0.66), and specificity of 0.74 (95% CI, 0.67-0.82) on the test set. These findings suggest that retinal photographs may be a viable objective screening tool for ASD and possibly for symptom severity. Retinal photograph use may speed the ASD screening process, which may help improve accessibility to specialized child psychiatry assessments currently strained by limited resources.

Computer-aided autism diagnosis using visual attention models and eye-tracking: replication and improvement proposal

BackgroundAutism Spectrum Disorder (ASD) diagnosis can be aided by approaches based on eye-tracking signals. Recently, the feasibility of building Visual Attention Models (VAMs) from features extracted from visual stimuli and their use for classifying cases and controls has been demonstrated using Neural Networks and Support Vector Machines. The present work has three aims: 1) to evaluate whether the trained classifier from the previous study was generalist enough to classify new samples with a new stimulus; 2) to replicate the previously approach to train a new classifier with a new dataset; 3) to evaluate the performance of classifiers obtained by a new classification algorithm (Random Forest) using the previous and the current datasets.MethodsThe previously approach was replicated with a new stimulus and new sample, 44 from the Typical Development group and 33 from the ASD group. After the replication, Random Forest classifier was tested to substitute Neural Networks algorithm.ResultsThe test with the trained classifier reached an AUC of 0.56, suggesting that the trained classifier requires retraining of the VAMs when changing the stimulus. The replication results reached an AUC of 0.71, indicating the potential of generalization of the approach for aiding ASD diagnosis, as long as the stimulus is similar to the originally proposed. The results achieved with Random Forest were superior to those achieved with the original approach, with an average AUC of 0.95 for the previous dataset and 0.74 for the new dataset.ConclusionIn summary, the results of the replication experiment were satisfactory, which suggests the robustness of the approach and the VAM-based approaches feasibility to aid in ASD diagnosis. The proposed method change improved the classification performance. Some limitations are discussed and additional studies are encouraged to test other conditions and scenarios.

Caregiver-child interaction as an effective tool for identifying autism spectrum disorder: evidence from EEG analysis

BackgroundAutism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder that affects individuals across their lifespan. Early diagnosis and intervention are crucial for improving outcomes. However, current diagnostic methods are often time-consuming, and costly, making them inaccessible to many families. In the current study, we aim to test caregiver-child interaction as a potential tool for screening children with ASD in clinic.MethodsWe enrolled 85 preschool children (Mean age: 4.90 ± 0.65 years, 70.6% male), including ASD children with or without developmental delay (DD), and typical development (TD) children, along with their caregivers. ASD core symptoms were evaluated by Childhood Autism Rating Scale (CARS) and Autism Diagnostic Observation Schedule-Calibrated Severity Scores (ADOS-CSS). Behavioral indicators were derived from video encoding of caregiver-child interaction, including social involvement of children (SIC), interaction time (IT), response of children to social cues (RSC), time for caregiver initiated social interactions (GIS) and time for children initiated social interactions (CIS)). Power spectral density (PSD) values were calculated by EEG signals simultaneously recorded. Partial Pearson correlation analysis was used in both ASD groups to investigate the correlation among behavioral indicators scores and ASD symptom severity and PSD values. Receiver operating characteristic (ROC) analysis was used to describe the discrimination accuracy of behavioral indicators.ResultsCompared to TD group, both ASD groups demonstrated significant lower scores of SIC, IT, RSC, CIS (all p values < 0.05), and significant higher time for GIS (all p values < 0.01). SIC scores negatively correlated with CARS (p = 0.006) and ADOS-CSS (p = 0.023) in the ASD with DD group. Compared to TD group, PSD values elevated in ASD groups (all p values < 0.05), and was associated with SIC (theta band: p = 0.005; alpha band: p = 0.003) but not IQ levels. SIC was effective in identifying both ASD groups (sensitivity/specificity: ASD children with DD, 76.5%/66.7%; ASD children without DD, 82.6%/82.2%).ConclusionOur results verified the behavioral paradigm of caregiver-child interaction as an efficient tool for early ASD screening.

Children with developmental coordination disorder have less variable motor unit firing rate characteristics across contractions compared to typically developing children.

Understanding the nuances of neuromuscular control is crucial in unravelling the complexities of developmental coordination disorder (DCD), which has been associated with differences in skeletal muscle activity, implying that children with DCD employ distinct strategies for muscle control. However, force generation and control are dependent on both recruitment of motor units and their firing rates and these fine details of motor function have yet to be studied in DCD. The purpose of this study was therefore to compare motor unit characteristics in a small muscle of the hand during low level, handgrip contractions in typically developing (TD) children and children with DCD. Eighteen children (9 TD vs. 9 DCD) completed a series of manual handgrip contractions at 10 ± 5% of their maximum voluntary contraction. High density surface electromyography was used to record excitation of the first dorsal interosseus muscle. Recorded signals were subsequently decomposed into individual motor unit action potential trains. Motor unit characteristics (firing rate, inter-pulse interval, and action potential amplitude) were analysed for contractions that had a coefficient variation of <10%. This study found few differences in average motor unit characteristics (number of motor units: TD 20.24 ± 9.73, DCD 27.32 ± 14.00; firing rate: TD 7.74 ± 2.16 p.p.s., DCD 7.86 ± 2.39 p.p.s.; inter-pulse interval: TD 199.72 ± 84.24 ms, DCD 207.12 ± 103 ms) when force steadiness was controlled for, despite the DCD group being significantly older (10.89 ± 0.78 years) than the TD group (9.44 ± 1.67 years). However, differences were found in the variability of motor unit firing statistics, with the children with DCD surprisingly showing less variability across contractions (standard deviation of coefficient of variation of inter-pulse interval: TD 0.38 ± 0.12, DCD 0.28 ± 0.11). This may suggest a more fixed strategy to stabilise force between contractions used by children with DCD. However, as variability of motor unit firing has not been considered in previous studies of children further work is required to better understand the role of variability in motor unit firing during manual grasping tasks, in all children.

Differences in augmented reality games performance between individuals with Down syndrome and individuals with typical development

Introduction: Down syndrome is the most common genetic cause of intellectual disability, and the use of augmented reality can be improving the cognitive, motor, and literacy skills of this population. Objective: to compare statistical differences in learning between individuals with Down syndrome and individuals with typical development using augmented reality games. Methods: we compared the reaction time before and after the virtual reality tasks, in addition to the performance in these tasks, which consisted of correctly identifying numbers and letters in 46 people with Down syndrome and 46 controls with typical development. Results: our results indicate that the total points for the typical development group were higher (M = 13.0 and 11.9) when compared to the Down syndrome group (M = 6.6 and 4.6) for letters of the alphabet and numbers, respectively. Furthermore, the results indicated that participants in both groups were more accurate in identifying alphabetic symbols when compared to numerical symbols, and both groups were sensitive to the number of symbols presented in each phase. The down syndrome group had a lower performance when compared to the typical development group. Conclusion: despite the need for further studies, our results support the outcome that there is clinical utility of an intervention based on virtual reality tasks for people with Down syndrome. In conclusion, the use of this technology to improve the reaction time of this population is considered useful.

Knee Flexion While Walking Exceeds Knee Flexion Contracture in Children with Spastic Cerebral Palsy.

Flexed knee gait is commonly related to contractures in children with cerebral palsy (CP). Therefore, knee position while walking was compared with passive knee extension and explored with respect to functional mobility. Gait was assessed with 3D motion analysis in 30 children with bilateral spastic CP, Gross Motor Function Classification System (GMFCS) levels I-III, and in 22 typically developing (TD) children. Knee angle at initial contact (KneeAngleIC) was greater than knee flexion in stance (MinKneeFlexSt) in all groups. MinKneeFlexSt exceeded knee contractures at GMFCS levels II and III. Both KneeAngleIC and MinKneeFlexSt were greater at GMFCS II and III than at GMFCS I and the TD group. The excessive knee flexion while walking at GMFCS II and III could not be explained by knee joint contractures. Functional mobility measured with the timed-up-and-go test took longer in children at GMFCS level III compared to the other groups, assumed to be explained by the energy-requiring flexed knee gait and spatial insecurity. Discriminating between passive knee extension at the physical assessment and maximum knee extension while weight bearing may contribute to further understanding of flexed knee gait and its causes in ambulating children with spastic bilateral CP.