Postural sway changes during static standing with concurrent task in children with traumatic brain injury

Objectives:To investigate the effects of concurrent tasks (motor and cognitive) on postural control performance in children with traumatic brain injury (TBI) compared to typically developing (TD) control subjects.Methods:Sixteen children with TBI (aged 11.63±1.89 years) and 22 TD controls (aged 11.41±2.24 years) participated in this case-control study. This study was conducted between May 2016 and March 2017. Each child performed static standing under 3 different conditions: single, concurrent motor, and concurrent cognitive task. Postural control performance measure includes sway area, anterior-posterior (AP) sway velocity, medio-lateral (ML) sway velocity, AP sway distance and ML sway distance as measured using the APDM® Mobility Lab (Oregon, Portland). A repeated-measure analysis of variance was used to analyse the data.Results:We found that children with TBI showed significantly more deterioration in postural control performance than TD children (p<0.05). Both concurrent tasks (motor and cognitive) significantly decreased postural control performance in both groups with more pronounced changes in children with TBI than that of the TD controls.Conclusion:The results demonstrated that, performing concurrent tasks (motor and cognitive) during upright standing resulted in deterioration of postural control performance. The existence of cognitive and balance impairment in children with TBI will possibly cause concurrent tasks to be more complex and demands greater attention compared to single task.

Traumatic brain injury is frequently referred to as a ‘silent epidemic’, with the majority of society being unaware on the magnitude a TBI can cause on an individual’s function.1 It remains a leading cause of death and long-term disability in children worldwide with approximately 3 million children experiencing TBI annually.2 Consequently, TBI may lead to neurological impairment which contributes to long-term disability among this group of children.With the cognitive and behavioral deficit, individuals with TBI are faced with a long-term functional disability including postural control instability.3,4 Postural control refers to the act of maintaining, achieving or restoring the line of gravity or centre of mass (COM) within the base of support (BOS).5 It is a complex collaboration of sensory, motor, and central nervous system. Disruption of any components such as visual, vestibular sensory inputs, muscle weakness and loss of proprioception will result in postural control instability. This impairment could seriously interfere with the child’s level of independence and lead to increased risk of falls.5The maintenance and control of posture and balance, whether in static or dynamic conditions, are essential requirements for daily activity. Postural control requires a lot of cognitive resources.6 The more challenging postural task required more cognitive processing in order to sustain the position. Children with TBI have both cognitive and information processing deficits that impact attention and functional abilities.7,8 In daily life, children encounter situations in which they must perform cognitive and motor tasks simultaneously, such as responding to verbal instructions or manipulating objects while sitting or standing. These situations may be complex and challenging for children with TBI as they present with both attention and information processing deficit. Using dual-task methodology, it can examine the effect of adding a concurrent task during a motor task. Trials using dual-task paradigm are commonly used in a clinical setting to measure automatic control of movement indirectly. It is crucial to understand the effects of a concurrent task on postural control performance while designing a dual-task paradigm intervention program in this population. The dual-task intervention during postural control could be more challenging and may improve the postural stability better as compared to single task intervention.Since attention is a limited resource, it may become overloaded by competing for attention demands and subsequently might lead to reduced performance in one or all tasks.9 Children with TBI may need more attention during postural control and as a result might be more vulnerable to falls while doing concurrent task. A recent study among healthy children and youth 5-18 years old showed concurrent cognitive task resulted in decreased postural stability.10 Comparing the effects of different surface (firm vs. foam surface) on postural stability during concurrent cognitive task reveals that the foam surface caused greater interference in postural stability.10 A normative database was created as a result of this study, which may benefit future investigations of post-concussion performances with potential to assess post-concussion severity. In addition, it also focuses on assessing both motor and cognitive domains simultaneously. This study also reports information regarding the effect of cognitive task on postural stability in healthy children & youth. The examined effect of concurrent cognitive and motor task conditions on postural control in children with TBI is limited. Therefore, the objective of the present study was to investigate the postural control performance under concurrent tasks in children with TBI and TD controls. We hypothesized that both concurrent motor and cognitive tasks would cause significant postural control deterioration compared to single task condition.     

Mild impairments of motor imagery skills in children with DCD

It has been hypothesized that the underlying mechanism of clumsy motor behaviour in children with Developmental Coordination Disorder (DCD) is caused by a deficit in the internal modelling for motor control. An internal modelling deficit can be shown on a behavioural level by a task that requires motor imagery. Motor imagery skills are suggested to be related to anticipatory action planning, but motor imagery and action planning have not been tested within the same child. In the present study, action planning and motor imagery skills were assessed in 82 children between 7 and 12 years of age. Twenty-one of these children met the criteria for DCD, which was assessed by the McCarron Assessment of Neuromuscular Development and 56 of these children were used in the control group. Motor imagery was tested by a mental rotation task of hands that were shown from a back and palm point of view. The results show that motor imagery is affected in children with DCD but only in conditions with complex task constraints (i.e., rotation of hand stimuli presented in palm view). These results provide partial support for the internal modelling deficit hypothesis. We were not able to elicit motor planning deficits in this group, however, and argue that more complex planning tasks may be needed to identify such deficits.     

Dual-task clinical and functional MRI correlates in Parkinson's disease with postural instability and gait disorders

BackgroundDual-task is a challenge for Parkinson's disease patients with postural instability and gait disorders (PD-PIGD).ObjectiveThis study investigated clinical, cognitive and functional brain correlates of dual-task deficits in PD-PIGD patients using quantitative gait analysis, neuropsychological evaluations and functional MRI (fMRI).MethodsTwenty-three PD-PIGD patients performed a clinical assessment of gait/balance abilities. Single and dual-task Timed-Up-and-Go tests were monitored using an optoelectronic system to study turning velocity. Patients underwent executive-attentive function evaluation and two fMRI tasks: motor-task (foot anti-phase movements), and dual-task (foot anti-phase movements while counting backwards by threes starting from 100). Twenty-three healthy subjects underwent neuropsychological and fMRI assessments.ResultsDual-task in PD-PIGD patients resulted in worse gait performance, particularly during turning. Performing the dual-task relative to the motor-fMRI task, healthy subjects showed widespread increased recruitment of sensorimotor, cognitive and cerebellar areas and reduced activity of inferior frontal and supramarginal gyri, while PD-PIGD patients showed increased recruitment of inferior frontal gyrus and supplementary motor area and reduced activity of primary motor, supramarginal and caudate areas. Dual-task gait alterations in patients correlated with balance and executive deficits and with altered dual-task fMRI brain activity of frontal areas.ConclusionsThis study suggested the correlation between dual-task gait difficulties, postural instability and executive dysfunction in PD-PIGD patients. FMRI results suggest that an optimized recruitment of motor and cognitive networks is associated with a better dual-task performance in PD-PIGD. Future studies should evaluate the effect of specific gait/balance and dual-task trainings to improve gait parameters and optimize brain functional activity during dual-tasks.     

The effectiveness of exercise intervention on inhibitory control in children with developmental coordination disorder: Using a visuospatial attention paradigm as a model

Children with developmental coordination disorder (DCD) have been demonstrated to show a deficit of inhibitory control in volitional shifts of attention. The aim of this study was to use ecological intervention to investigate the efficacy of table-tennis training on treating both problems with attentional networks and motor disorder in children with DCD. Forty-three children aged 9–10 years old were screened using the Movement Assessment Battery for Children and divided into DCD (n = 27) and typically developing (TD, n = 16) groups. Children with DCD were then quasi-randomly assigned to either a DCD-training group who underwent a ten-week table-tennis training program with a frequency of 3 times a week or a DCD non-training group. Before and after training, the capacity of inhibitory control was examined with the endogenous Posner paradigm task for DCD and TD groups. Table-tennis training resulted in significant improvement of cognitive and motor functions for the children with DCD. The study demonstrated that exercise intervention employed within the school setting can benefit the inhibitory control and motor performance in children with DCD. However, future research efforts should continue to clarify whether the performance gains could be maintained over time.     

Mobile Brain/Body Imaging of cognitive-motor impairment in multiple sclerosis: Deriving EEG-based neuro-markers during a dual-task walking study

ObjectiveIndividuals with a diagnosis of multiple sclerosis (MS) often present with cognitive and motor deficits, and thus the ability to perform tasks that rely on both domains may be particularly impaired. Yet, dual-task walking studies yield mixed results. Individual variance in the ability to cope with brain insult and mobilize additional brain resources may contribute to mixed findings.MethodsTo test this hypothesis, we acquired event-related potentials (ERP) in individuals with MS and healthy controls (HCs) performing a Go/NoGo task while sitting (i.e., single task) or walking (i.e., dual-task) and looked at the relationship between task related modulation of the brain response and performance.ResultsOn the Go/NoGo task the MS group showed dual-task costs when walking, whereas HCs showed a dual-task benefit. Further, whereas the HC group showed modulation of the brain response as a function of task load, this was not the case in the MS group. Analysis for the pooled sample revealed a positive correlation between load-related ERP effects and dual-task performance.ConclusionsThese data suggest a neurophysiological marker of cognitive-motor dysfunction in MS.SignificanceUnderstanding neural processes underlying dual-task walking will help identify objective brain measurements of real-world issues and may improve assessment of MS.     

Association between visual perceptual deficits and motor deficits in children with developmental coordination disorder

This study explored the relation between a motor-free visual perceptual deficit, different visual-motor integration deficits, and different motor skills in children with developmental coordination disorder (DCD). Thirty-six children (22 males), aged 9 or 10 years, with DCD and a control group (n=36), matched for age and sex, were assessed with the Movement Assessment Battery for Children (MABC), a ball-catching test, a jumping test, a timed response task to a visual moving stimulus, and the Beery-Buktenica Developmental Test of Visual-Motor Integration, incorporating copying, visual discrimination, and tracing tasks. Children with DCD performed significantly worse than the control group on all measures. The visual discrimination task did not correlate significantly with any of the motor tasks. The visual timing task correlated significantly with the ball-catching test in the DCD group. The copying test was significantly correlated with the MABC in the DCD group. The association between visual-perceptual deficits and motor tasks was shown to be task specific.     

Dual-task repetition alters event-related brain potentials and task performance

ObjectiveWe examined the modulation of event-related brain potentials (ERPs) and the accuracy of sensori-motor coordination on short-term repetition of the concurrent performance of a somatosensory discrimination (oddball) task and a visuo-motor tracking task.MethodsThe subjects concurrently performed visuomotor tracking and somatosensory oddball tasks. In the dual-task condition, the subjects performed the visuomotor tracking and somatosensory oddball tasks concurrently for about an hour. In the oddball-only condition, they performed just the oddball task for the same period.ResultsTracking performance improved with task repetition. The amplitude of the P300 elicited by somatosensory stimulation in the oddball-only condition decreased significantly with task repetition, whereas in the dual-task condition, it showed a complex pattern of change. The earlier responses were decreased in amplitude in the dual-task condition compared to the oddball-only condition, and gradually decreased with task repetition in both conditions.ConclusionsDynamic changes in ERPs and task performance with dual-task repetition support the idea that dual-task repetition produces changes in resource allocation following the automation of stimulus processing in addition to so-called habituation.SignificanceThis study also provides evidence for use of ERP amplitudes as physiological indices of functionally different types of resources.     

Mathematical difficulties in developmental coordination disorder: Symbolic and nonsymbolic number processing

At school, children with Developmental Coordination Disorder (DCD) struggle with mathematics. However, little attention has been paid to their numerical cognition abilities. The goal of this study was to better understand the cognitive basis for mathematical difficulties in children with DCD.Twenty 7-to-10 years-old children with DCD were compared to twenty age—matched typically developing children using dot and digit comparison tasks to assess symbolic and nonsymbolic number processing and in a task of single digits additions.Results showed that children with DCD had lower performance in nonsymbolic and symbolic number comparison tasks than typically developing children. They were also slower to solve simple addition problems. Moreover, correlational analyses showed that children with DCD who experienced greater impairments in the nonsymbolic task also performed more poorly in the symbolic tasks.These findings suggest that DCD impairs both nonsymbolic and symbolic number processing. A systematic assessment of numerical cognition in children with DCD could provide a more comprehensive picture of their deficits and help in proposing specific remediation.     

Short-term motor learning of dynamic balance control in children with probable Developmental Coordination Disorder

PurposeTo explore the differences in learning a dynamic balance task between children with and without probable Developmental Coordination Disorder (p-DCD) from different cultural backgrounds.ParticipantsTwenty-eight Dutch children with DCD (p-DCD-NL), a similar group of 17 South African children (p-DCD-SA) and 21 Dutch typically developing children (TD-NL) participated in the study.MethodsAll children performed the Wii Fit protocol. The slope of the learning curve was used to estimate motor learning for each group. The protocol was repeated after six weeks. Level of motor skill was assessed with the Movement ABC-2.ResultsNo significant difference in motor learning rate was found between p-DCD-NL and p-DCD-SA, but the learning rate of children with p-DCD was slower than the learning rate of TD children. Speed–accuracy trade off, as a way to improve performance by slowing down in the beginning was only seen in the TD children, indicating that TD children and p-DCD children used different strategies. Retention of the level of learned control of the game after six weeks was found in all three groups after six weeks. The learning slope was associated with the level of balance skill for all children. This study provides evidence that children with p-DCD have limitations in motor learning on a complex balance task. In addition, the data do not support the contention that learning in DCD differs depending on cultural background.     

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.     

Visuo-spatial processing in Parkinson's disease: evidence for diminished visuo-spatial sketch pad and central executive resources

A dual-task study compared the visuo-spatial sketch pad and central executive components of working memory as potential cognitive mechanisms of visuo-spatial dysfunction in Parkinson's disease. Mildly to moderately affected Parkinsonian patients (n = 15) and controls (n = 15) performed the Corsi blocks task concurrently with tasks designed to load on the visuo-spatial sketch pad (spatial tapping) or the central executive (random interval repetition). Patients performed more poorly in both concurrent task conditions, implicating a reduction in both visuo-spatial sketch pad and central executive resources. The impact of the concurrent tasks varied with disease severity, with the central executive deficit prominent at disease onset, but the visuo-spatial sketch pad deficit becoming apparent only in the moderate stages of the illness.     

Patterns of Structural Reorganization of the Corticospinal Tract in Children With Sturge-Weber Syndrome

BackgroundReorganization of the corticospinal tract after early damage can limit motor deficit. In this study, we explored patterns of structural corticospinal tract reorganization in children with Sturge-Weber syndrome.MethodsFive children (age 1.5-7 years) with motor deficit resulting from unilateral Sturge-Weber syndrome were studied prospectively and longitudinally (1-2 years follow-up). Corticospinal tract segments belonging to hand and leg movements were separated and their volume was measured by diffusion tensor imaging tractography using a recently validated method. Corticospinal tract segmental volumes were normalized and compared between the Sturge-Weber syndrome children and age-matched healthy controls. Volume changes during follow-up were also compared with clinical motor symptoms.ResultsIn the Sturge-Weber syndrome children, hand-related (but not leg-related) corticospinal tract volumes were consistently decreased in the affected cerebral hemisphere at baseline. At follow-up, two distinct patterns of hand corticospinal tract volume changes emerged. (1) Two children with extensive frontal lobe damage showed a corticospinal tract volume decrease in the lesional hemisphere and a concomitant increase in the nonlesional (contralateral) hemisphere. These children developed good hand grasp but no fine motor skills. (2) The three other children, with relative sparing of the frontal lobe, showed an interval increase of the normalized hand corticospinal tract volume in the affected hemisphere; these children showed no gross motor deficit at follow-up.ConclusionsDiffusion tensor imaging tractography can detect differential abnormalities in the hand corticospinal tract segment both ipsi- and contralateral to the lesion. Interval increase in the corticospinal tract hand segment suggests structural reorganization, whose pattern may determine clinical motor outcome and could guide strategies for early motor intervention.     

Working memory, processing speed, and set-shifting in children with developmental coordination disorder and attention-deficit-hyperactivity disorder

It has been suggested that the high levels of comorbidity between attention-deficit-hyperactivity disorder (ADHD) and developmental coordination disorder (DCD) may be attributed to a common underlying neurocognitive mechanism. This study assessed whether children with DCD and ADHD share deficits on tasks measuring working memory, set-shifting, and processing speed. A total of 195 children aged between 6 years 6 months and 14 years 1 month (mean 10y 4mo [SD 2y 2mo]) were included in this study. A control group (59 males, 79 females), a DCD group (12 males, six females), an ADHD-predominantly inattentive group (16 males, four females), and an ADHD-combined group (15 males, four females), were tested on three executive functioning tasks. Children with DCD were significantly slower on all tasks, supporting past evidence of a timing deficit in these children. With few exceptions, children with ADHD did not perform more poorly than control children. These findings demonstrate the importance of identifying children with motor deficits when examining tasks involving a timing component.     

Motor imagery training enhances motor skill in children with DCD: A replication study

BackgroundChildren with impaired motor coordination (or DCD) have difficulty using motor imagery. We have suggested that this difficulty is explained by the internal modeling deficit (IMD) hypothesis of DCD. Our previous training study lent support for this hypothesis by showing that a computerized imagery training protocol (involving action observation, and mental- and overt-rehearsal) was equally effective to perceptual-motor therapy (PMT) in promoting motor skill acquisition.AimsThe study presented here was designed to replicate and extend this finding, targeting a select group of children with moderate-to-severe DCD.Methods and ProceduresAll 36 children with DCD who participated were referred to the study and scored below the 10th percentile for their age on the Movement Assessment Battery for Children (MABC). Using a randomized control trial, the referred children were assigned randomly to one of three groups using a blocked procedure: imagery training, perceptual-motor training (PMT), and wait-list control. Motor proficiency was measured using the MABC, pre and post-training. Individual training consisted of 60-min sessions, conducted once a week for 5 weeks.ResultsResults showed that the imagery protocol was equally effective as PMT in promoting motor skill acquisition, with moderate-to-large effect sizes. Individual differences showed that the majority of children in the two intervention groups improved their motor performance significantly.ConclusionsOverall, these results further support the use of motor imagery protocols in the treatment of DCD, and tentative support for the IMD hypothesis. Developmental and dose issues in the implementation of imagery-based intervention are discussed.     

A staged approach for identifying children with developmental coordination disorder from the population

The purpose of this study was to describe the motor, attention and intellectual characteristics of a population-based sample of children first screened for motor impairment and to discuss the recruitment and identification methods employed. A two stage cross-sectional, school-based survey was conducted to screen for children with motor coordination difficulties and to identify children with an existing diagnosis of attention deficit hyperactivity disorder/attention deficit disorder (ADHD/ADD). The identified children, and a random sample of typically developing children, were assessed to confirm or rule out the presence of developmental coordination disorder (DCD).Six thousand four hundred and seventy five children were invited to participate; 2943 children, with parental consent, completed the initial screening process. Two hundred eighty four children with possible motor impairment were identified. The parents of 113 children consented to a full assessment. Sixty eight children of the 113 children met diagnostic criteria for DCD, and 26 also had ADHD. Twenty eight of the 55 children who screened in with a diagnosis of ADHD were subsequently found to have DCD. The total number of children with confirmed characteristics of DCD was reduced after application of DCD diagnostic criteria. This study differs from others with regard to the additional screening for children with ADHD/ADD. The second stage assessment notably increased the number of children identified with both ADHD and DCD.     

Health-related quality of life of children with Developmental Coordination Disorder

BackgroundAlthough Developmental Coordination Disorder (DCD) is primarily a motor disorder, it can also impact emotional and psychosocial functioning of children with this condition. Evidence suggests that children with DCD experience lower quality of life than their peers, but few studies have explicitly examined the health-related quality of life (HRQOL) of these children.AimsTo: (1) describe HRQOL of children with DCD compared to typically-developing children; (2) compare HRQOL from the perspectives of children with DCD and their parents; and (3) explore predictors of HRQOL for children with DCD.MethodsData from the KidScreen-52 and Strength and Difficulties Questionnaire were collected from 50 children with DCD [Mean(SD) age: 9.8 (1.2) years] and their parents and compared to normative data.ResultsChildren with DCD and their parents report significantly lower HRQOL compared to published norms. Caregivers have a significantly lower perception of their child’s HRQOL than their child’s self-report in many domains. Parents of children with DCD report that their children experience significantly more emotional and behavioral disturbances compared to norms. Poor motor function and attentional difficulties predict HRQOL.Conclusion and implicationsDCD appears to contribute to lower perceived HRQOL. Findings inform therapeutic targets for children with DCD, beyond motor skill intervention.     

Intrusive images and voluntary memory for affective pictures: Contextualization and dual-task interference

Background and objectivesThe present study addressed the role of context information and dual-task interference during the encoding of negative pictures on intrusion development and voluntary recall.MethodsHealthy participants were shown negative pictures with or without context information. Pictures were either viewed alone or concurrently with a visuospatial or verbal task. Participants reported their intrusive images of the pictures in a diary. At follow-up, perceptual and contextual memory was tested.ResultsParticipants in the context group reported more intrusive images and perceptual voluntary memory than participants in the no context group. No effects of the concurrent tasks were found on intrusive image frequency, but perceptual and contextual memory was affected according to the cognitive load of the task.LimitationsThe analogue method cannot be generalized to real-life trauma and the secondary tasks may differ in cognitive load.ConclusionsThe findings challenge a dual memory model of PTSD but support an account in which retrieval strategy, rather than encoding processes, accounts for the experience of involuntary versus voluntary recall.     

Motor Impairment Three Months Post Stroke Implies A Corresponding Cognitive Deficit

BackgroundWhile both motor and cognitive impairment are common after stroke, the focus of (early) treatment has always been on motor deficit.AimsThe objective of the current study was to explore the link between motor and cognitive performance in stroke patients and to examine whether motor performance is associated with cognitive functioning at three months post stroke.MethodsIn both stroke patients (n = 142) and controls (n = 135), with the groups matched on age, gender and premorbid IQ, motor functioning was evaluated using both objective (Purdue Pegboard Test) and subjective measures (specific items from the Frenchay Activities Index and Barthel Index). Cognition, specifically information processing speed, working memory and cognitive flexibility, was assessed using objective tasks. The data were analyzed using Pearson product-moment correlation coefficients and logistic regression.ResultsSignificant correlations between motor and cognitive functioning were found in stroke patients. The objective motor task was stronger than subjective measures in statistically explaining and predicting cognitive deficit, irrespective of stroke severity.ConclusionsWe conclude that motor impairment at three months post-stroke should serve as a ‘red flag’ for professionals: cognitive impairment is likely and should also be evaluated.     

Abstracts of platform and poster presentations

Abstract

Two experiments were conducted to study the interference effects of different concurrent verbal tasks on unimanual single-finger tapping and unimanual sequential finger tapping. Experiment 1 involved 24 right-handed university students. In the dual-task conditions, right-handers showed a greater right-hand than left-hand performance reduction for single-finger tapping, and an equal right-hand and left-hand reduction for sequential tapping. Experiment 2 involved 60 left-handed university students, divided into four groups according to familial sinistrality and writing hand posture. In the dual-task conditions, left-handers showed a greater left-hand than right-hand performance reduction for single-finger tapping, and an equal left-hand and right-hand reduction for sequential finger tapping. A dichotic listening task revealed a left hemispheric dominance for auditory linguistic functioning in most of the left-handers. Familial sinistrality and hand posture, on the whole, did not influence tapping performances. However, these factors influenced the ear asymmetries on the dichotic listening task. It is speculated that, with single-finger tapping, interference only takes place beyond the point of language motor programming, that is to say, at the motor areas and the supplementary motor areas of the cortex.     

Deficits of visuospatial attention with reflexive orienting induced by eye-gazed cues in children with developmental coordination disorder in the lower extremities: An event-related potential study

The present study aims to investigate and compare the behavioral performance and event-related potentials (ERPs) measures in children with developmental coordination disorder (DCD) and typically developing (TD) children when performing the visuospatial attention task with reflexive orienting. Thirty children with DCD and 30 TD children were recruited and presented with central eye-gazed cues. The children needed to detect and respond to laterally presented reaction signals preceded by centrally presented non-predictive directional and non-directional eye-gazed cues, which directed them to attend covertly to the right or left field location, or straight ahead, via stepping on pedals with their bilateral lower limbs, while brain ERPs were concurrently recorded. The behavioral data showed that children with DCD responded slowly and exhibited a deficit in inhibitory control capacity as compared to TD children. In terms of electrophysiological characteristics, children with DCD showed distinct modulatory effects upon longer N2 and P3 latencies, smaller P3 amplitude, an elongated interval between N2 and the motor response (N2 latency-RT), and small areas on Contingent Negative Variation (CNV). The behavioral and ERP data suggest that children with DCD could have deficits in the ventral attention network and the mechanisms on the inhibitory control difficulty, when performing such a task, could be a slower response inhibitory process and stimulus classification speed, less ability in interhemispheric and cognitive-to-motor transfer speed, and less mature abilities with regard to anticipatorily executive and motor preparatory processes.