Electroencephalographic correlates of working memory deficits in children with Fetal Alcohol Spectrum Disorder using a single-electrode pair recording device

ObjectiveChildren with Fetal Alcohol Spectrum Disorder (FASD) exhibit cognitive deficits that can be probed using eye movement tasks. We employed a recently developed, single-sensor electroencephalographic (EEG) recording device in measuring EEG activity during the performance of an eye movement task probing working memory in this population.MethodsChildren with FASD (n = 18) and typically developing children (n = 19) performed a memory-guided saccade task requiring the participant to remember the spatial location of one, two or three stimuli. We hypothesized that children with FASD would (i) exhibit performance deficits, particularly at greater mnemonic loads; and (ii) display differences in theta (4–8 Hz) and alpha (8–12 Hz) frequency band power compared with controls.ResultsChildren with FASD failed to perform the task correctly more often than controls when presented with two or three stimuli, and demonstrated related reductions in alpha and theta power.ConclusionThese data suggest that the memory-guided task is sensitive to working memory deficits in children with FASD.SignificanceSimultaneous recording of EEG activity suggest differing patterns of underlying neural recruitment in the clinical group, consistent with previous literature indicating more cognitive resources are required by children with FASD in order to complete complex tasks correctly.     

Motor functioning,exploration, visuospatial cognition and language development in preschool children with autism

In order to understand typical and atypical developmental trajectories it is important to assess how strengths or weaknesses in one domain may be affecting performance in other domains. This study examined longitudinal relations between early fine motor functioning, visuospatial cognition, exploration, and language development in preschool children with ASD and children with other developmental delays/disorders. The ASD group included 63 children at T1 (Mage = 27.10 months, SD = 8.71) and 46 children at T2 (Mage = 45.85 months, SD = 7.16). The DD group consisted of 269 children at T1 (Mage = 17.99 months, SD = 5.59), and 121 children at T2 (Mage = 43.51 months, SD = 3.81). A subgroup nested within the total sample was randomly selected and studied in-depth on exploratory behavior. This group consisted of 50 children, 21 children with ASD (Mage = 27.57, SD = 7.09) and 29 children with DD (Mage = 24.03 months, SD = 6.42). Fine motor functioning predicted language in both groups. Fine motor functioning was related to visuospatial cognition in both groups and related to object exploration, spatial exploration, and social orientation during exploration only in the ASD group. Visuospatial cognition and all exploration measures were related to both receptive and expressive language in both groups. The findings are in line with the embodied cognition theory, which suggests that cognition emerges from and is grounded in the bodily interactions of an agent with the environment. This study emphasizes the need for researchers and clinicians to consider cognition as emergent from multiple interacting systems.     

Severity of depressive symptomatology and functional impairment in children and adolescents with temporal lobe epilepsy

ObjectiveDepression is a frequent psychiatric disorder in children with temporal lobe epilepsy (TLE). However, severity of depressive symptoms (DS) is frequently neglected in these patients. This study aimed to determine severity of DS and global functioning by using quantitative measures and to establish their correlation with patients’ demographics and clinical variables.Methods31 children (mean age of 11.8 ± 2.3 years) with TLE were assessed with K-SADS-PL for axis I DSM-IV diagnosis. Severity of DS was measured by Children Depression Rating Scale-Revised – CDRS-R. Global functional impairment was evaluated with Child Global Assessment Scale-CGAS.Results25 patients (56% boys; 12 ± 2.3 years) had current DS, moderate or severe in 84% according to CDRS-R T-Score. Severity of DS was not correlated with age (p = 0.377), gender (p = 0.132), seizure control (p = 0.936), age of onset (p = 0.731), duration of epilepsy (p = 0.602) and the presence of hippocampal sclerosis (p = 0.614). Patients had moderate to major functional impairment measured by CGAS (48.7 ± 8.8), being adolescents more impaired than children (p = 0.03). Impairment of global functioning was not associated with epilepsy variables (p > 0.05).ConclusionChildren with TLE had moderate to severe DS early in the course of their disease with a relevant impact on their global functional activities, especially considering adolescents. Epilepsy severity seems not to be correlated to the severity of DS, contradicting the idea of a cause–consequence relationship. More systematic research is needed to better understand the association of depressive disorders in children and adolescents with TLE.     

Does somatosensory discrimination activate different brain areas in children with unilateral cerebral palsy compared to typically developing children? An fMRI study

Aside from motor impairment, many children with unilateral cerebral palsy (CP) experience altered tactile, proprioceptive, and kinesthetic awareness. Sensory deficits are addressed in rehabilitation programs, which include somatosensory discrimination exercises. In contrast to adult stroke patients, data on brain activation, occurring during somatosensory discrimination exercises, are lacking in CP children. Therefore, this study investigated brain activation with functional magnetic resonance imaging (fMRI) during passively guided somatosensory discrimination exercises in 18 typically developing children (TD) (age, M = 14 ± 1.92 years; 11 girls) and 16 CP children (age, M = 15 ± 2.54 years; 8 girls). The demographic variables between both groups were not statistically different. An fMRI compatible robot guided the right index finger and performed pairs of unfamiliar geometric shapes in the air, which were judged on their equality. The control condition comprised discrimination of music fragments. Both groups exhibited significant activation (FDR, p < .05) in frontoparietal, temporal, cerebellar areas, and insula, similar to studies in adults. The frontal areas encompassed ventral premotor areas, left postcentral gyrus, and precentral gyrus; additional supplementary motor area (SMA_proper) activation in TD; as well as dorsal premotor, and parietal operculum recruitment in CP. On uncorrected level, p < .001, TD children revealed more left frontal lobe, and right cerebellum activation, compared to CP children. Conversely, CP children activated the left dorsal cingulate gyrus to a greater extent than TD children. These data provide incentives to investigate the effect of somatosensory discrimination during rehabilitation in CP, on clinical outcome and brain plasticity.     

Motor and cognitive assessment of infants and young boys with Duchenne Muscular Dystrophy: results from the Muscular Dystrophy Association DMD Clinical Research Network

Therapeutic trials in Duchenne Muscular Dystrophy (DMD) exclude young boys because traditional outcome measures rely on cooperation. The Bayley III Scales of Infant and Toddler Development (Bayley III) have been validated in developing children and those with developmental disorders but have not been studied in DMD. Expanded Hammersmith Functional Motor Scale (HFMSE) and North Star Ambulatory Assessment (NSAA) may also be useful in this young DMD population. Clinical evaluators from the MDA-DMD Clinical Research Network were trained in these assessment tools. Infants and boys with DMD (n = 24; 1.9 ± 0.7 years) were assessed. The mean Bayley III motor composite score was low (82.8 ± 8; p ? .0001) (normal = 100 ± 15). Mean gross motor and fine motor function scaled scores were low (both p ? .0001). The mean cognitive comprehensive (p = .0002), receptive language (p ? .0001), and expressive language (p = .0001) were also low compared to normal children. Age was negatively associated with Bayley III gross motor (r = ?0.44; p = .02) but not with fine motor, cognitive, or language scores. HFMSE (n = 23) showed a mean score of 31 ± 13. NSAA (n = 18 boys; 2.2 ± 0.4 years) showed a mean score of 12 ± 5. Outcome assessments of young boys with DMD are feasible and in this multicenter study were best demonstrated using the Bayley III.     

Requirements for and impact of a serious game for neuro-pediatric robot-assisted gait training

We investigated whether children with neurological gait disorders who walked in a driven gait orthosis could adjust their participation level according to the demands of a newly developed rehabilitation game. We further investigated if cognitive capacity and motor impairment influenced game performance. Nineteen children with neurological gait disorders (mean age: 13.4y, 42% girls) participated. To quantify game participation, electromyographic muscle activity (M. rectus femoris) and heart rate were compared in a demanding part and a less demanding part of the game. Cognitive capacity was assessed with the Test of Nonverbal Intelligence (TONI-4). Furthermore, the Functional Independence Measure for Children (WeeFIM), Manual Muscle Tests and a therapist-derived score of how well the child was able to train were assessed. Results showed that muscle activity and heart rate were higher during the demanding part of the game (30.7 ± 22.6 μV; 129.4 ± 15.7 bpm) compared to the less demanding part (16.0 ± 13.4 μV; 124.1 ± 15.9 bpm; p < 0.01 for both measures). Game performance correlated moderately with the TONI-4 (r = 0.50, p = 0.04) and the cognition subscale of the WeeFIM (ρ = 0.59, p = 0.01). The therapist-derived score correlated significantly with game performance (p = 0.75, p < 0.01) and the ability to modify muscle activity to the demands of the game (p = ?0.72, p < 0.01). Receiver operating characteristic analyses revealed that the latter factor differentiated well between those children suitable for the game and those not. We conclude that children with neurological gait disorders are able to modify their activity to the demands of the VR-scenario. However, cognitive function and motor impairment determine to which extent. These results are important for clinical decision-making.     

Relationship between brain lesion characteristics and communication in preschool children with cerebral palsy

BackgroundMRI shows promise as a prognostic tool for clinical findings such as gross motor function in children with cerebral palsy(CP), however the relationship with communication skills requires exploration.AimsTo examine the relationship between the type and severity of brain lesion on MRI and communication skills in children with CP.Methods and procedures131 children with CP (73 males(56%)), mean corrected age(SD) 28(5) months, Gross Motor Functional Classification System distribution: I = 57(44%), II = 14(11%), III = 19(14%), IV = 17(13%), V = 24(18%). Children were assessed on the Communication and Symbolic Behavioral Scales Developmental Profile (CSBS-DP) Infant-Toddler Checklist. Structural MRI was analysed with reference to type and semi-quantitative assessment of the severity of brain lesion. Children were classified for motor type, distribution and GMFCS. The relationships between type/severity of brain lesion and communication ability were analysed using multivariable tobit regression.Outcomes and resultsChildren with periventricular white matter lesions had better speech than children with cortical/deep grey matter lesions (β = −2.6, 95%CI = −5.0, −0.2, p = 0.04). Brain lesion severity on the semi-quantitative scale was related to overall communication skills (β = −0.9, 95%CI = −1.4, −0.5, p < 0.001). Motor impairment better accounted for impairment in overall communication skills than brain lesion severity.ImplicationsStructural MRI has potential prognostic value for communication impairment in children with CP.What this paper adds?This is the first paper to explore important aspects of communication in relation to the type and severity of brain lesion on MRI in a representative cohort of preschool-aged children with CP. We found a relationship between the type of brain lesion and communication skills, children who had cortical and deep grey matter lesions had overall communication skills > 1 SD below children with periventricular white matter lesions. Children with more severe brain lesions on MRI had poorer overall communication skills. Children with CP born at term had poorer communication than those born prematurely and were more likely to have cortical and deep grey matter lesions. Gross motor function better accounted for overall communication skills than the type of brain lesion or brain lesion severity.     

Role of serum levels of neurotensin in children with autism spectrum disorder

AimNeuroinflammation may play a role in the pathogenesis of autism in some patients. The aim of this study was to measure serum levels of neurotensin (NTS) in relation to the degree of the severity of autism.MethodsSerum NTS was measured in autistic children (n = 38; mean age 7.02 ± 2.03 years) and healthy, unrelated sex matched controls (n = 39); mean age 7.25 ± 1.64 years). The severity of autism symptoms was assessed using Childhood Autism Rating Scale (CARS) scores.ResultsThe serum level of NTS was significantly (P < 0.001) lower in autistic children (mean ± S.D. = 54.71 ± 12.4 pg/ml) than control group (mean ± S.D. = 77.58 ± 10.29 pg/ml). Children with severe autism had significantly lower serum NTS levels than patients with mild to moderate autism (P < 0.002). There was significant negative correlation between serum levels of NTS and CARS SCORES (r² = 0.79, P = 0.001).ConclusionsSerum NTS levels were elevated in some autistic children and they were significantly correlated with the severity of autism. However, this is an initial report that warrants further research to determine the pathogenic role of NTS and its possible link to neuroinflammation in autism.     

Oropharyngeal dysphagia in preschool children with cerebral palsy: Oral phase impairments

PurposeThis study aimed to document the prevalence and patterns of oral phase oropharyngeal dysphagia (OPD) in preschool children with cerebral palsy (CP), and its association with mealtime duration, frequency and efficiency.MethodsCross-sectional population-based cohort study of 130 children diagnosed with CP at 18–36 months ca (mean = 27.4 months, 81 males) and 40 children with typical development (mean = 26.2, 18 males). Functional abilities of children with CP were representative of a population sample (GMFCS I = 57, II = 15, III = 23, IV = 12, V = 23). Oral phase impairment was rated from video using the Dyspahgia Disorders Survey, Schedule for Oral Motor Impairment, and Pre-Speech Assessment Scale. Parent-report was collected on a feeding questionnaire. Mealtime frequency, duration and efficiency were calculated from a three day weighed food record completed by parents. Gross motor function was classified using the Gross Motor Function Classification System (GMFCS).ResultsOverall, 93.8% of children had directly assessed oral phase impairments during eating or drinking, or in controlling saliva (78.5% with modified cut-points). Directly assessed oral phase impairments were associated with declining gross motor function, with children from GMFCS I having a 2-fold increased likelihood of oral phase impairment compared to the children with TD (OR = 2.0, p = 0.18), and all children from GMFCS II–V having oral phase impairments. Difficulty biting (70%), cleaning behaviours (70%) and chewing (65%) were the most common impairments on solids, and difficulty sipping from a cup (60%) for fluids. OPD severity and GMFCS were not related to mealtime frequency, duration or efficiency, although children on partial tube feeds had significantly reduced mealtime efficiency.ConclusionsOral phase impairments were common in preschool children with CP, with severity increasing stepwise with declining gross motor function. The prevalence and severity of oral phase impairments were significantly greater for most tasks when compared to children with typical development, even for those with mild CP. Children who were partially tube fed had significantly lower feeding efficiency, so this could be a useful early indicator of children needing supplementation to their nutrition (through increasing energy density of foods/fluids, or tube feeds).     

Uric acid excretion in North American and Southeast European children with obstructive sleep apnea

Background and objectivesResponses to nocturnal hypoxemia accompanying sleep-disordered breathing (SDB) may vary in different populations. Aims of this study were to (1) assess whether severity of SDB is related to uric acid excretion in North American and Southeast European children and (2) evaluate the interaction between nocturnal hypoxemia and country of children’s origin in uric acid excretion.MethodsConsecutive US and Greek children with snoring who were referred for polysomnography were recruited. Uric acid excretion expressed as uric acid-to-creatinine concentrations ratio in a morning urine specimen was the primary outcome measure.ResultsOne hundred and twenty-six US children (6.8 ± 0.7 years old) and 123 Greek children (6.4 ± 2.5 years old) were recruited. Forty-three US and 53 Greek participants had moderate-to-severe nocturnal hypoxemia (SpO₂ nadir <90%). Obstructive apnea-hypopnea index and SpO₂ nadir were related to uric acid excretion in Greek (but not US) children after adjustment by age, gender and body mass index z-score (p < 0.05). There was a significant interaction between severity of hypoxemia and country of children’s origin in uric acid excretion after adjustment by age, gender and body mass index z-score (p = 0.036). Greek children with moderate-to-severe hypoxemia had higher uric acid excretion (0.85 ± 0.35) than those with mild/no hypoxemia (0.69 ± 0.25) (p = 0.005). US children with moderate-to-severe hypoxemia (0.41 ± 0.20) did not differ in uric acid excretion from those with mild/no hypoxemia (0.42 ± 0.22) (p = 0.823).ConclusionsUric acid excretion differs in children with SDB and different ethnic backgrounds or environmental exposures.     

Dynamic posturography in evaluation of balance in patients of Parkinson’s disease with normal pull test: Concept of a diagonal pull test

ObjectivesTo assess subclinical balance impairment in patients of Parkinson’s disease (PD) with normal “pull test”, using dynamic posturography.MethodsTwenty PD patients (H&Y stage 2) and 20 matched healthy controls were studied. The patients were evaluated in best ‘ON’ state using UPDRS and Dynamic Posturography. The latter measured dynamic balance indices and limits of stability (LOS) in 8 directions: forward (FW), backward (BW), right (RT), left (LT), forward-right (FW-RT), forward-left (FW-LT), backward-right (BW-RT) and backward-left (BW-LT).ResultsThe dynamic balance indices and total LOS scores did not differ significantly between PD and controls. Direction-wise analysis of LOS showed significantly lower scores (suggesting impaired balance) in PD compared to controls only in FW-RT (21.2 ± 13.8 vs 34.5 ± 17.5, p = 0.005) and BW-LT (20.8 ± 9.8 vs 31.8 ± 15.1, p = 0.018) directions. In LOS test, controls had better stability in FW than BW (p = 0.002) and on RT than LT directions (p = 0.0005). Analysis in diagonal directions showed greater stability in FW-RT than FW-LT, in BW-LT than BW-RT, in FW-RT than BW-RT, and BW-LT than FW-LT directions. Though PD patients maintained greater stability in FW direction like controls, they lost the advantage in other directions.ConclusionsDespite normal “pull test”, PD patients had subclinical direction-specific balance impairment, more apparent in forward-right and backward-left directions. This information may be useful in modifying the standard “pull test” with addition of pull in diagonal directions for detection of early balance impairment.     

Evaluation of serum Neuron-specific enolase,S100B,myelin basic protein and glial fibrilliary acidic protein as brain specific proteins in children with autism spectrum disorder

ObjectiveBrain specific-proteins are not found in other tissues and measurement non-invasively in the blood may identify structurally and functionally damaged brain regions and identify the severity and prognosis of neuropsychiatric diseases. For this reason, we aimed to evaluate serum brain-specific protein values as brain damage markers in children with autism spectrum disorder (ASD).Method35 children with ASD and 31 healthy subjects were included in the study. Sociodemographic form and Childhood Autism Rating Scale (CARS) were applied to each subject. Serum neuron specific enolase (NSE), S100B, Myelin basic protein (MBP) and Glial fibrillary acidic protein (GFAP) values ​​were measured with ELISA.ResultsThere was no significant difference between the two groups for NSE, MBP and S100 B values (p = 0.242; p = 0.768; p = 0.672, respectively). However, GFAP values ​​in the patient group were statistically significantly higher (mean ± SD: 0.463 ± 0.392 ng/ml) than in the healthy control group (mean ± SD: 0.256 ± 0.111 ng/ml) (p < 0.001). In addition, there was a significant positive correlation between serum GFAP values ​​and CARS score in all subjects and in the patient group (r = 0.599; p < 0.001 and r = 0.380; p = 0.024, respectively).ConclusionsWhile serum NSE, MBP, and S100 B values cannot be considered as biomarkers for ASD, GFAP may be a biomarker and is suggested as a possible indicator of autism severity.     

Perturbation-evoked electrodermal activity responds to instability,not just motor or sensory drives

ObjectiveTo determine whether electrodermal responses (EDRs) evoked by postural perturbations were sensitive to the context of compensatory balance control, or simply reflected sensory or motor components of the reaction.MethodsThirteen participants were perturbed backwards in an upright chair and (1) performed compensatory reach-to-grasp movements to a handhold to recover balance (COMP); (2) received the perturbation only and the chair stopped via mechanical support (SENS); and (3) performed rapid self-initiated reach-to-grasp movements without perturbation (MOT).ResultsEDRs were most frequent and largest in the COMP task, observed in 100% of trials (1.42 ± 0.16 μS), compared to 39% of SENS trials (0.31 ± 0.12 μS, p < 0.0001) and 85% of MOT trials (0.98 ± 0.25 μS, p = 0.073). EDRs in the MOT task followed two patterns across individuals, leading to post-hoc division of subjects into groups (smaller EDRs than COMP task, n = 7, versus equivalent EDRs to COMP task, n = 6). Motor patterns were equivalent in both groups, indicating that EDRs did not co vary with efferent drive.ConclusionsPerturbation-evoked EDRs are not a direct reflection of sensory input or motor drive.SignificanceThese findings suggest that evoked autonomic activity may play a functional role in compensatory postural control.     

Auditory event-related potentials at preschool age in children born very preterm

ObjectiveTo assess auditory event-related potentials at preschool age in children born very preterm (VP, 27.4 ± 1.9 gestational weeks, n = 70) with a high risk of cognitive dysfunction.MethodsWe used an oddball paradigm consisting of a standard tone randomly replaced by one of three infrequent deviants (differing in frequency, sound direction or duration).ResultsThe P1 and N2 latencies were inversely correlated to age (50–63 months) both in VP (r = −0.451, p < 0.001, and r = −0.305, p = 0.01, respectively) and term born controls (TC; n = 15). VP children had smaller P1 than near-term (n = 12) or TC (1.70 ± 0.17 μV vs 2.68 ± 0.41 and 2.92 ± 0.43, respectively; p < 0.05). Mismatch negativity response did not differ between groups.ConclusionsOur data suggest a fast maturation of P1 and N2 responses with fast decrease in P1 and N2 latencies around the age of 5 years. Mismatch negativity response does not seem to be a robust measure for defining abnormalities in VP children.SignificanceIn ERP studies in preschool children, even small, non-significant group differences in age at recording should be corrected for. Very preterm born children at preschool age have aERP patterns as earlier described in full-term born children with cognitive deficits.     

Toward a motor signature in autism: Studies from human-machine interaction

BackgroundAutism spectrum disorder (ASD) is a heterogeneous group of neurodevelopmental disorders which core symptoms are impairments in socio-communication and repetitive symptoms and stereotypies. Although not cardinal symptoms per se, motor impairments are fundamental aspects of ASD. These impairments are associated with postural and motor control disabilities that we investigated using computational modeling and developmental robotics through human-machine interaction paradigms.MethodFirst, in a set of studies involving a human–robot posture imitation, we explored the impact of 3 different groups of partners (including a group of children with ASD) on robot learning by imitation. Second, using an ecological task, i.e. a real-time motor imitation with a tightrope walker (TW) avatar, we investigated interpersonal synchronization, motor coordination and motor control during the task in children with ASD (n = 29), TD children (n = 39) and children with developmental coordination disorder (n = 17, DCD).ResultsFrom the human–robot experiments, we evidenced that motor signature at both groups’ and individuals’ levels had a key influence on imitation learning, posture recognition and identity recognition. From the more dynamic motor imitation paradigm with a TW avatar, we found that interpersonal synchronization, motor coordination and motor control were more impaired in children with ASD compared to both TD children and children with DCD. Taken together these results confirm the motor peculiarities of children with ASD despite imitation tasks were adequately performed.DiscussionStudies from human-machine interaction support the idea of a behavioral signature in children with ASD. However, several issues need to be addressed. Is this behavioral signature motoric in essence? Is it possible to ascertain that these peculiarities occur during all motor tasks (e.g. posture, voluntary movement)? Could this motor signature be considered as specific to autism, notably in comparison to DCD that also display poor motor coordination skills? We suggest that more work comparing the two conditions should be implemented, including analysis of kinematics and movement smoothness with sufficient measurement quality to allow spectral analysis.     

Psychometric properties of the DCD-Q-07 in children ages to 4–6

It is important to identify Developmental Coordination Disorder (DCD) early in a child's life to allow for proper and timely intervention and support, and to reduce the negative secondary consequences associated with this condition. In this study we assessed the psychometric properties (construct validity, concurrent validity, reliability and test accuracy) of the Developmental Coordination Disorder Questionnaire (DCD-Q-07) in preschool children. A community-based sample of children ages 4–6 (n = 181) were screened for motor difficulties using the Movement Assessment Battery for Children (M-ABC-2). Use of the M-ABC-2 resulted in the identification of 29 children below the 15th percentile, which we classified as probable DCD. Parents of these children concurrently completed the DCD-Q-07 to report their child's motor performance. The DCD-Q-07 demonstrated high internal consistency for both the full scale (alpha = 0.881) and each subscale: control during movement (alpha = 0.813), fine motor and handwriting (alpha = 0.869) and general coordination (alpha = 0.728). Moderate correlations (r = 0.47–0.63) were also seen between the subscales on the DCD-Q-07, the strongest correlation being between control during movement and general coordination (r = 0.63). Based on published age and sex cut points, the DCD-Q-07 showed poor sensitivity (20.7%) but high specificity (92.1%) against the M-ABC-2. Overall agreement with the M-ABC-2 was low using ROC analysis (area under the curve = 0.654). Although it is important to screen for DCD in young children, the DCD-Q-07 may not be the best choice as a screening tool for DCD in preschool children ages 4–6 due to its low test accuracy.     

Motor skill assessment in children with Down Syndrome: Relationship between performance-based and teacher-report measures

Resultsof previous studies show a large interindividual variability with regard to motor skills and motor abilities in children with Down Syndrome (DS). In order to provide detailed information for intervention, adequate assessment methods seem to be necessary to address the child's unique motor profile. Typically, children are either examined using a bottom-up (performance-based assessment of motor skills) or a top-down approach (e.g. client-report measure), but rarely both approaches. The aim of this study was to examine the relationship between standardized performance-based, and teacher-report measures of children's motor performance. The performance- and process-based assessment Test of Gross Motor Development (TGMD-2), and the teacher-based Movement Assessment Battery – Checklist (MABC-C) for young children were used to assess the motor performance of 18 children with DS (11 boys, 7 girls) aged 7–11 years (M = 9.06, SD = 0.96) and an age- and sex-matched sample of typically developing (TD) 18 children (11 boys, 7 girls; M = 8.99, SD = 0.93). TD children achieve consistently better results compared to children with DS, both in the TGMD-2 and MABC-C, which differ significantly in most cases. When gender differences were examined for the TGMD-2 scores, boys with DS were better performers of the run, gallop, leap, and catch, as well as the locomotor and object-control skill sum scores, whereas girls of the TD group were more proficient in these areas. TD children achieve significantly better results in 21 out of 28 items of Section A + B of the MABC-C, compared to the children with DS; whereas there are no significant differences for Section C (non-motor factors). Our results show more significant relationships between TGMD-2 and MABC-C sub- and overall scores for the TD sample compared to the children with DS. The correlations range between r = −.21 and −.65 for TD children and between r = −.15 and −.65 for the children with DS. The correlations between both approaches show that the combination of both methods could be useful in getting a more detailed picture of the child's individual motor profile in order to create tailor-made therapies and interventions, both for children with DS and TD children.     

Occlusion of bidirectional plasticity by preceding low-frequency stimulation in the human motor cortex

ObjectiveLow-frequency stimulation, which does not induce long-term potentiation (LTP) or long-term potentiation (LTD) by itself, suppresses consecutive LTP or LTD induction in vitro. We tested whether a similar interaction occurs in the human motor cortex.MethodsLTP- or LTD-like plasticity was induced using paired associative stimulation (PAS) with 25 and 10 ms interstimulus interval and conditioned by suprathreshold repetitive transcranial magnetic stimulation (rTMS) at a frequency of 0.1 Hz.ResultsRTMS completely abolished the significant increase of motor-evoked potential (MEP) amplitudes after PAS_25ms (PAS_25ms only: 1.05 ± 0.14 to 1.76 ± 0.66 mV, p = 0.001; rTMS + PAS_25ms: 1.08 ± 0.18 to 1.02 ± 0.44 mV, n.s.) and also abolished the significant decrease of MEP amplitudes after PAS_10ms (PAS_10ms only: 1.00 ± 0.14 to 0.73 ± 0.32 mV; rTMS + PAS_10ms: 1.15 ± 0.35 to 1.25 ± 0.43 mV, p = 0.006). RTMS alone did not significantly alter MEP amplitudes but increased SICI and LICI.ConclusionsLow frequency stimulation increases intracortical inhibition and occludes LTP- and LTD-like plasticity in the human motor cortex.SignificanceThis finding supports the concept that metaplasticity in the human motor cortex follows similar rules as metaplasticity in in vitro experiments.     

Implicit and explicit motor learning: Application to children with Autism Spectrum Disorder (ASD)

Aims and objectivesThis study aims to determine whether children with Autism Spectrum Disorder (ASD) are capable of learning a motor skill both implicitly and explicitly.MethodsIn the present study, 30 boys with ASD, aged 7–11 with IQ average of 81.2, were compared with 32 typical IQ- and age-matched boys on their performance on a serial reaction time task (SRTT). Children were grouped by ASD and typical children and by implicit and explicit learning groups for the SRTT.ResultsImplicit motor learning occurred in both children with ASD (p = .02) and typical children (p = .01). There were no significant differences between groups (p = .39). However, explicit motor learning was only observed in typical children (p = .01) not children with ASD (p = .40). There was a significant difference between groups for explicit learning (p = .01).DiscussionThe results of our study showed that implicit motor learning is not affected in children with ASD. Implications for implicit and explicit learning are applied to the CO-OP approach of motor learning with children with ASD.     

Motoneurone afterhyperpolarisation time-course following stroke

ObjectiveOur aim was to investigate any changes in the estimated time-course of the afterhyperpolarisation (AHP) in motoneurones innervating the tibialis anterior following stroke, with a secondary objective to compare the results from two different AHP estimation techniques.MethodsMotor units from tibialis anterior on the paretic and non-paretic sides of 15 subjects with chronic stroke were recorded using intramuscular electrodes during voluntary isometric contraction. Participants varied the motor unit firing rate from its lowest rate to approximately 10 Hz. The AHP duration was estimated using the interval death rate (IDR) and transition point methods.ResultsThe AHP decay time-constant was significantly different between sides (paretic: 41.7 ± 8.5 ms, non-paretic: 36.2 ± 6.4 ms). Additionally, the paretic AHP time-constant was significantly longer in participants with low motor recovery (45.9 ± 9.1 ms) than with high motor recovery (39.3 ± 10.0 ms) as measured by CMSA score. The AHP estimates from the two techniques were correlated (r = 0.78).ConclusionsThe AHP time-course prolongation on the paretic side of people with chronic stroke is more pronounced in people with low motor recovery.SignificanceChanges in the motoneurone AHP time course post-stroke were related to muscle function and may play a role in the commonly-observed reduction of motor unit discharge rate during voluntary contractions following stroke.