Search

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with a behavioral phenotype characterized by impaired development of social-communicative skills as well as excessive repetitive and stereotyped behaviors. Despite high phenotypic heterogeneity in ASD, a meaningful subpopulation of children with ASD (~90%) show significant general motor impairment.. More focused studies on the nature of motor impairment in ASD reveal that children with ASD are particularly impaired on tasks such as ball catching and motor imitation that require efficient visual-motor integration (VMI). Motor computational approaches also provide evidence for VMI-impairment showing that children with ASD form internal sensorimotor representations that bias proprioceptive over visual-feedback. Impaired integration of visual information to form internal representations of others’ and the external world may explain observed impairments on VMI-tasks and motor imitation of others. Motor imitation is crucial for acquiring both social and motor skills and impaired imitation skill may contribute to the observed core behavioral phenotype of ASD. The current review examines evidence supporting VMI-impairment as a core feature of ASD that may contribute to both impaired motor imitation and social-communicative skill development. We propose that understanding the neurobiological mechanisms underlying VMI-impairment in ASD may be key to discovery of therapeutics to address disability in children and adults with ASD.

Impairments in visuomotor integration (VMI) may contribute to anomalous development of motor, as well as social-communicative, skills in children with autism spectrum disorder (ASD). However, it is relatively unknown whether VMI impairments are specific to children with ASD versus children with other neurodevelopmental disorders. As such, this study addressed the hypothesis that children with ASD, but not those in other clinical control groups, would show greater deficits in high-VMI dynamic grip-force tracking versus low-VMI static presentation. Seventy-nine children, aged 7-17 years, participated: 22 children with ASD, 17 children with fetal alcohol spectrum disorder (FASD), 18 children with Attention-Deficit Hyperactivity Disorder (ADHD), and 22 typically developing (TD) children. Two grip-force tracking conditions were examined: (1) a low-VMI condition (static visual target) and (2) a high-VMI condition (dynamic visual target). Low-frequency force oscillations

The exclusion of high-motion participants can reduce the impact of motion in functional Magnetic Resonance Imaging (fMRI) data. However, the exclusion of high-motion participants may change the distribution of clinically relevant variables in the study sample, and the resulting sample may not be representative of the population. Our goals are two-fold: 1) to document the biases introduced by common motion exclusion practices in functional connectivity research and 2) to introduce a framework to address these biases by treating excluded scans as a missing data problem. We use a study of autism spectrum disorder in children without an intellectual disability to illustrate the problem and the potential solution. We aggregated data from 545 children (8-13 years old) who participated in resting-state fMRI studies at Kennedy Krieger Institute (173 autistic and 372 typically developing) between 2007 and 2020. We found that autistic children were more likely to be excluded than typically developing children, with 28.5% and 16.1% of autistic and typically developing children excluded, respectively, using a lenient criterion and 81.0% and 60.1% with a stricter criterion. The resulting sample of autistic children with usable data tended to be older, have milder social deficits, better motor control, and higher intellectual ability than the original sample. These measures were also related to functional connectivity strength among children with usable data. This suggests that the generalizability of previous studies reporting naïve analyses (i.e., based only on participants with usable data) may be limited by the selection of older children with less severe clinical profiles because these children are better able to remain still during an rs-fMRI scan. We adapt doubly robust targeted minimum loss based estimation with an ensemble of machine learning algorithms to address these data losses and the resulting biases. The proposed approach selects more edges that differ in functional connectivity between autistic and typically developing children than the naïve approach, supporting this as a promising solution to improve the study of heterogeneous populations in which motion is common.

Background Pressure-measuring insoles have the potential to measure plantar contact area (PA) during walking. However, they are not widely used for this purpose because of the need for a reliable process that can convert the insole output into PA. The purposes of this study were to: (1) develop an adaptive-threshold method for pressure-measuring insoles that can improve the accuracy of the PA measurements during walking, and (2) experimentally assess the accuracy and generalizability of this method. Methods A sample of 42 healthy, ambulatory, young adults (age = 24.3 ± 3.2 years, mass = 67.2 ± 16.9 kg, height = 1.63 ± 0.08 m) completed 10 trials walking on an elevated walkway while wearing Medilogic® pressure-measuring insoles (sizes 35–45). A total of six insole sizes were considered. Insole data were converted to PA using three unique adaptive-thresholds that were based on percentages of the maximum sum of digital values (MSDV) during an analyzed step. Three values were considered: 0.1%, 0.2%, and 0.3% of the MSDV. Additionally, a fixed-threshold, which is typically used to estimate PA, was assessed. These two techniques, applied to the insole worn on the left foot, were compared with PA obtained from high-resolution reference footprints obtained from optical pedography of the right foot and processed using digital image processing algorithms. An assumption of PA symmetry between the left (insole) and right (barefoot) feet was made and comparisons were conducted over the entire stance phase of walking. The generalizability of the algorithm was assessed by comparing PA errors from insoles with respect to the optical pedography results based on insole size criteria. Results The adaptive-thresholds of 0.1%, 0.2%, and 0.3% of MSDV produced mean errors of 7.31 ± 17.44%, −8.62 ± 15.01%, and −20.45 ± 14.18%, respectively. Using the 2-digital value fixed-threshold produced a mean error of 20.88 ± 22.44%. The best performing adaptive-threshold varied among insole sizes. Conclusion It was observed that the fixed-threshold technique produced large magnitudes of errors. The proposed adaptive-thresholds of 0.1% and 0.2% of the MSDV reduced PA error to ±10% during walking. The adaptive-threshold method consistently reduced PA error vs. the fixed-threshold for each insole size.

This study examined whether disruptions in connectivity involving regions critical for learning, planning, and executing movements are relevant to core autism symptoms. Spatially constrained ICA was performed using resting-state fMRI from 419 children (autism spectrum disorder (ASD) = 105; typically developing (TD) = 314) to identify functional motor subdivisions. Comparing the spatial organization of each subdivision between groups, we found voxels that contributed significantly less to the right posterior cerebellar component in children with ASD versus TD (P

Introduction Force platforms and pressure-measuring insoles are the most common tools used for measuring center of pressure. Earlier studies to assess these instruments suffered from limited sample sizes or an inadequate range of participant foot sizes. The purpose of this study was to propose new methods to extract and calculate comparably accurate center of pressure for the Kistler® force platform and Medilogic® insoles. Methods Center of pressure data were collected from 65 participants wearing pressure-measuring insoles (six different sizes). Participants walked over consecutive force platforms for three trials while wearing pressure-measuring insoles within socks. Onset force thresholds and center of pressure segment length thresholds were used to determine accurate center of pressure path length and width. A single step for each foot and trial was extracted from both instruments. Results A strong correlation was observed between instruments in center of pressure length (4.12 ± 6.72% difference, r = 0.74). Center of pressure width varied and was weakly correlated (–7.04 ± 4.48% difference, r = 0.11). Conclusions The results indicate that both instruments can measure center of pressure path length consistently and with comparable accuracy (differences

The purpose of this investigation was to compare fascicle and tendon length of the gastrocnemius at the end of the eccentric phase during a hop utilizing a single countermovement (sCM) versus multiple countermovement (mCM1, mCM2, mCM3) strategy. Seventeen healthy males performed nine hopping trials of sCM and nine trials of mCM. Ankle and knee joint angle and lower leg length from videography and muscle ultrasound were used to calculate muscle-tendon unit (MTU), fascicle and tendon length. Sacral marker data was used to determine hopping height. Force- and displacement-time curves were utilized to calculate work. Muscle activity of the lateral and medial gastrocnemius was also measured. Fascicle length was significantly shorter (mCM3: 6.2 ± 1.5 cm, sCM: 7.3 ± 2.0 cm) and tendon length was significantly longer (mCM3: 36.5 ± 3.6 cm, sCM: 35.5 ± 3.8 cm) at the end of the eccentric phase in mCM3 in comparison to sCM. Maximal hopping height (mCM: 14.6 ± 3.1 cm, sCM: 13.1 ± 2.5 cm), eccentric phase gastrocnemius muscle activity (mCM medial gastrocnemius: 0.10 ± 0.03 mV, mCM lateral gastrocnemius: 0.08 ± 0.04 mV, sCM medial gastrocnemius: 0.07 ± 0.03 mV, sCM lateral gastrocnemius: 0.05 ± 0.04 mV), and both eccentric (mCM3: 46.6 ± 19.4 J, sCM: 38.5 ± 15.9 J) and concentric work (mCM3: 87.6 ± 26.5 J, sCM: 80.9 ± 27.6 J) were significantly higher for mCM3 compared to sCM. The results indicate that a multiple countermovement hop strategy results in shorter fascicle length and longer tendon length at the end of the eccentric phase. In addition, greater eccentric phase muscle activity during the third countermovement (mCM3) in comparison to a single countermovement hop (sCM) was observed. A multiple countermovement strategy appears to result in higher hopping height and greater work done in both the eccentric and concentric phase indicating possible contribution of stored-elastic energy from the tendon.

Background Motor imitation difficulties are pervasive in children with Autism Spectrum Disorder (ASD). Previous research demonstrated the validity and reliability of an algorithm called Computerized Assessment of Motor Imitation (CAMI) using 3D depth cameras. However, incorporating CAMI into serious games and making it accessible in clinic and home settings requires a more scalable approach that uses “off-the-shelf” 2D cameras. Method In a brief (one-minute) task, children (23 ASD, 17 typically developing [TD]) imitated a model’s dance movements while simultaneously being recorded using Kinect Xbox motion tracking technology (Kinect 3D) and a single 2D camera. Pose-estimation software (OpenPose 2D) was used on the 2D camera video to fit a skeleton to the imitating child. Motor imitation scores computed from the fully automated OpenPose 2D CAMI method were compared to scores computed from the Kinect 3D CAMI and Human Observation Coding (HOC) methods. Results Motor imitation scores obtained from the OpenPose 2D CAMI method were significantly correlated with scores obtained from the Kinect 3D CAMI method (r40 = 0.82, p Conclusions This pilot-study demonstrated that motor imitation can be automatically quantified using a single 2D camera.

BackgroundMotor deficits in children with Autism Spectrum Disorder (ASD) are highly prevalent. High variability of motor output is commonly reported in children with ASD. Visual cueing using an exergame may be an effective intervention to reduce motor variability in children with ASD.AimTo examine the effect of visual cueing on two-legged hopping variability in children with ASD.MethodsFour children with ASD and six age-matched TD controls performed three 20-s hopping trials with no visual cueing (no cue = NC) and with a 2 Hz visual cue (visual cue = VC). Three-dimensional kinematic data of the sacrum marker and ground reaction force were collected during each hopping trial. Variability was determined using the intra-trial coefficient of variation (CoV) of hopping frequency, hop height, and negative sacral displacementResultsA marginally significant interaction between GROUP (ASD/TD) and CUE type (NC/VC) was observed for hopping frequency variability (p = 0.06) indicating greater impairment in the ASD group vs. TD group with visual vs. no-cueing. The main effect of group showed a statistically significant difference in hopping frequency (p = 0.037), hopping frequency variability (p = 0.008), and negative sacrum displacement variability (p = 0.04).ConclusionThis pilot study confirmed high motor variability in the amplitude and frequency of repetitive movements in children with ASD. However, visual cueing was ineffective at reducing the variability of motor output in children with autism.

Background Manual dexterity (MD) is important for performing most activities of daily living, and children with ASD show MD deficits. However, the specificity of MD deficits in children with ASD has not previously been examined. Similar to children with ASD, extant evidence suggests children with Fetal Alcohol Spectrum Disorder (FASD) and Attention-Deficit Hyperactivity Disorder (ADHD) also show MD impairments. The purpose of this study was to examine the specificity MD deficits in children with ASD using a cross-syndrome design. We examined dominant (D) and non-dominant (ND) hand performance using a relatively large sample of children with ASD, FASD, ADHD, and typically developing (TD) children. Method Seventy-two right-handed children (7–17 years old) participated in this study. To examine MD, the 9-hole pegboard test was completed on the D and ND-hands. The fastest time of three attempts was recorded. HPA was defined as the percent difference between D and ND-hand times. Results D-hand MD was significantly worse in children with ASD vs. typically developing (TD) children (p = 0.002). ND-hand dexterity was significantly worse in children with ASD vs. FASD (p = 0.049) and TD groups (p = 0.004). Hand performance asymmetry (HPA) was significantly lower in the FASD group compared to both the ASD and ADHD groups (p Conclusions These results show that children with ASD show specific deficits in MD not observed in children with FASD or ADHD. Furthermore, HPA was found to be a sensitive measure to prenatal alcohol exposure. Neurobiological mechanisms of ASD and FASD are discussed.

Background Postural control deficits are commonly reported in children with Autism Spectrum Disorder (ASD). However, identification of specific postural sway features that differentiate ASD from other neurodevelopmental disorders has not been examined. The current study employs a cross-syndrome approach by comparing postural sway area and direction-specific features of sway magnitude, sway velocity, and sway complexity between children with ASD, Fetal Alcohol Spectrum Disorder (FASD), Attention-Deficit Hyperactivity Disorder (ADHD), and typically developing (TD) controls. Method Eighty children (7–17 years old) participated in this study. Postural sway was measured on a force plate during 30-s of bilateral quiet stance and balance was assessed using a timed unipedal stance test. Results Results showed that (1) postural sway area and mediolateral (ML) sway magnitude were significantly greater in children with ASD vs. all groups (p Conclusions ASD-specific postural sway features were identified using a cross-syndrome design. Identifying ASD-specific motor impairments can be useful to understanding the neurological underpinnings of ASD.

Background:Monitoring footprints during walking can lead to better identification of foot structure and abnormalities. Current techniques for footprint measurements are either static or dynamic, with low resolution. This work presents an approach to monitor the plantar contact area when walking using high-speed videography.Methods:Footprint images were collected by asking the participants to walk across a custom-built acrylic walkway with a high-resolution digital camera placed directly underneath the walkway. This study proposes an automated footprint identification algorithm (Automatic Identification Algorithm) to measure the footprint throughout the stance phase of walking. This algorithm used coloration of the plantar tissue that was in contact with the acrylic walkway to distinguish the plantar contact area from other regions of the foot that were not in contact.Results:The intraclass correlation coefficient (ICC) demonstrated strong agreement between the proposed automated approach and the gold standard manual method (ICC = 0.939). Strong agreement between the two methods also was found for each phase of stance (ICC > 0.78).Conclusions:The proposed automated footprint detection technique identified the plantar contact area during walking with strong agreement with a manual gold standard method. This is the first study to demonstrate the concurrent validity of an automated identification algorithm to measure the plantar contact area during walking.

Background: Foot ulcers are a serious complication associated with diabetes peripheral neuropathy (DPN). Diabetes foot complications associated with increased ulcer risk include: 1) decreases in plantar soft-tissue thickness, 2) increases in plantar tissue stiffness, and 3) increases in forefoot (FF) to rearfoot (RF) loading. Aim: The purpose of this study was to determine whether patients with DPN demonstrate higher forefoot to rearfoot pressures during barefoot walking compared to diabetes patients without peripheral neuropathy (DWPN) and prediabetes patients without peripheral neuropathy (PWPN). Methods: Eight PWPN, twenty-six DWPN and fourteen DPN patients participated in the study. Barefoot walking trials were performed while wearing Medilogic® pressure-measuring insoles. Peak plantar pressure (PPP) and peak pressure gradient (PPG) were measured on the right foot for the FF and RF regions. FF to RF PPP and PPG ratios were then calculated and normalized to body mass. Walking velocity was used as a co-variate for ANCOVAs. A priori statistical significance was set at α=0.05. Results: No significant interactions were observed for Group*Region for PPP (F(2, 89)=1.454, p=0.239) and PPG (F(2, 89)=0.579, p=0.563). Main effects of region revealed significantly higher FF to RF loading in both PPP (F(1, 89)=6.67, p=0.011) and PPG (F(1, 89)=4.02, p=0.048) measures driven by DWPN and DPN patients. No significant differences were observed between groups for FF to RF PPP (F(2, 44)=2.624, p=0.084) or PPG (F(2, 44)=1.331, p=0.275) ratios. Conclusion: Our findings suggest DWPN and DPN patients demonstrate a pattern of loading related to elevated foot ulcer risk. However, no significant difference was observed between groups for FF to RF PPP and PPG ratios. Inclusion of a more robust sample size will allow better testing of our hypothesis. Disclosure K. Izuora: None. M. Trabia: None. J. DeBerardinis: None. D.E. Lidstone: None. M. Varre: None. A.L. Trotter: None. J.S. Dufek: None.

Pressure-measuring insoles have the potential to measure plantar contact area (PA) during walking. However, they are not widely used for this purpose because of the need for a reliable process that can convert the insole output into PA. The purposes of this study were to: (1) develop an adaptive-threshold method for pressure-measuring insoles that can improve the accuracy of the PA measurements during walking, and (2) experimentally assess the accuracy and generalizability of this method.A sample of 42 healthy, ambulatory, young adults (age=24.3±3.2years, mass=67.2±16.9kg, height=1.63±0.08m) completed 10 trials walking on an elevated walkway while wearing MedilogicThe adaptive-thresholds of 0.1%, 0.2%, and 0.3% of MSDV produced mean errors of 7.31±17.44%, -8.62±15.01%, and -20.45±14.18%, respectively. Using the 2-digital value fixed-threshold produced a mean error of 20.88±22.44%. The best performing adaptive-threshold varied among insole sizes.It was observed that the fixed-threshold technique produced large magnitudes of errors. The proposed adaptive-thresholds of 0.1% and 0.2% of the MSDV reduced PA error to ±10% during walking. The adaptive-threshold method consistently reduced PA error vs. the fixed-threshold for each insole size.

Heavy load carriage has been identified as a main contributing factor to the high incidence of overuse injuries in soldiers. Peak vertical ground reaction force (VGRFMAX) and maximal vertical loading rates (VLRMAX) may increase during heavy prolonged load carriage with the development of muscular fatigue and reduced shock attenuation capabilities. The objectives of the current study were (1) to examine physiological and biomechanical changes that occur during a prolonged heavy load carriage task, and (2) to examine if this task induces neuromuscular fatigue and changes in muscle architecture. Eight inexperienced female participants walked on an instrumented treadmill carrying operational loads for 60 minutes at 5.4 km·h–1. Oxygen consumption (), heart rate, rating of perceived exertion (RPE), trunk lean angle, and ground reaction forces were recorded continuously during task. Maximal force and in-vivo muscle architecture were assessed pre- and posttask. Significant increases were observed for VGRFMAX, VLRMAX, trunk lean angle, , heart rate, and RPE during the task. Increased vastus lateralis fascicle length and decreased maximal force production were also observed posttask. Prolonged heavy load carriage, in an inexperienced population carrying operational loads, results in progressive increases in ground reaction force parameters that have been associated with overuse injury.

Background: Previous literature has shown in vivo changes in muscle-tendon interaction during exhaustive stretch-shortening cycle (SSC) exercise. It is unclear whether these changes in muscle-tendon length during exhaustive SSC exercise are associated with changes in mechanical efficiency (ME). The purpose of the study was to investigate whether changes in platarflexor contractile component (CC) length, tendon length, and changes in plantarflexor muscle activity could explain reduction in ME during exhaustive SSC exercise. Methods: Eight males participated in an exhaustive hopping task to fatigue. Mechanical work and energy expenditure were calculated at different time-points during the hopping task. Furthermore, hopping kinetics and kinematics, medial gastrocnemius (MG) muscle activity, and in vivo ultrasound of the MG were also collected at different time-points throughout the hopping task. Results: ME did not change during the hopping protocol despite shorter tendon and longer CC lengths as subjects approached exhaustion. Percent decreases in pennation angle and muscle thickness were most strongly correlated to time to exhaustion (r = 0.94, p ⩽ 0.05; r = 0.87, p ⩽ 0.05; respectively). Percent changes in CC length change and pennation angle were strongly correlated to percent decrease in maximal voluntary isometric plantarflexion (MVIP) force (r = −0.71, p ⩽ 0.04; r = 0.70, p ⩽ 0.05; respectively). Braking/push-off EMG ratio increased from initial pre-fatigue values to all other time points showing neuromuscular adaptations to altered muscle lengths. Conclusion: Findings from the current study suggest that changes in CC and tendon lengths occur during repetitive hopping to exhaustion, with the amount change strongly related to time to exhaustion. ME of hopping remained unchanged in the presence of altered CC and tendon lengths.

Introduction Pressure-measuring insoles can provide a portable alternative to existing gait analysis tools. However, there is disagreement among researchers on their accuracy and the appropriate calibration methods. The purposes of this study were to (1) determine the validity of pressure-measuring insoles for calculating stance time and support-phase impulse during walking using two calibration procedures, and (2) examine the effect of insole size on the results. Methods Data were collected from 39 participants (23.5 ± 3.24 yrs, 66.7 ± 17.5 kg, 1.64 ± 0.09 m), each wearing appropriately sized insoles as they walked over two consecutive force platforms. Two calibration methods were evaluated: (1) manufacturer’s recommendation, and (2) a participant weight-based approach. Qualitative and quantitative evaluations were conducted. Results The results indicated that the insoles measured longer stance times than the force platform (differences are less than 10%). Both calibration methods resulted in inaccurate impulse values (differences are 30 and 50% for the two calibration methods, respectively). The results showed that when using the first calibration method, impulse values depended on insole size. The second calibration consistently underestimated the impulse. Conclusions It was concluded that while the insoles provide acceptable qualitative representation of the gait, the two studied calibration methods may lead to a misleading quantitative assessment.