Do 'clumsy' children have visual deficits

Motor and visuospatial processing profile in a cross-conditions study: A comparison between developmental coordination disorder and nonverbal learning disability

BACKGROUND

Neurodevelopmental conditions often exhibit overlapping symptoms, posing challenges for differential diagnosis. Developmental Coordination Disorder (DCD) manifests as fundamental motor impairments, often along with co-occurring visuospatial difficulties. Nonverbal Learning Disorder (NLD) features visuospatial core challenges, with a less consistent characterization of its motor profile. Strikingly, to date no study has directly compared DCD and NLD profiles.

AIMS

The present study aimed to analyze whether DCD and NLD share any characteristics by contrasting their motor and visuospatial performances, comparing them with non-diagnosed (ND) peers.

METHODS AND PROCEDURES

A total of 102 participants (8-16 years; DCD N = 29, NLD N = 29, ND N = 44) completed motor and visuospatial tasks. The groups' performance was compared, and the discriminatory power of the measures administered was analyzed.

OUTCOMES AND RESULTS

Our findings support the substantial motor and visuospatial impairments in DCD and NLD, respectively. Regarding diagnostic efficacy, motor and visuospatial tasks effectively differentiated DCD or NLD from ND, with specificities related to each condition. Balance, and to a lesser extent, Spatial Processing revealed significant predictive power in distinguishing between DCD and NLD.

CONCLUSIONS AND IMPLICATIONS

Our results revealed cross-disorder similarities and highlighted specific hallmarks, corroborating the need of a comprehensive motor and visuospatial assessment for distinguishing between DCD and NLD.

The Effect of a Table Tennis Exercise Program With a Task-Oriented Approach on Visual Perception and Motor Performance of Adolescents With Developmental Coordination Disorder

In this study we investigated the effects of an 8-week table tennis exercise program with a task-oriented approach on visual perception and motor performance of 31 adolescents with developmental coordination disorder (DCD). The participants were identified by their teachers as having greater difficulty than their peers (450 students from three Korean middle schools) in physical education (PE) classes. On the Bruininks-Oseretsky Test of Motor Proficiency-2, these adolescents scored below the 15th percentile and showed difficulties in performing daily life activities due to motor performance problems; they did not have physical defects, intellectual or neurological impairments, or Attention Deficit Hyperactivity Disorder. Of 98 prospective adolescents with PE difficulties, we obtained personal assent and parents' informed consent from 54, and 31 of these met screening criteria for DCD through the Developmental Coordination Disorder Questionnaire-Korean. This final group was divided in non-random fashion (based on the proximal geographic grouping of the children's schools) between an experimental group (n = 16) and a control group (n = 15). The experimental group participated in the 8-week task-oriented table tennis training program with three 90-minute sessions per week, while the control group only participated in regular PE classes twice per week. We measured participants' visual perception and motor performance in the same environment before and after the intervention program. Participants' visual perception was significantly more improved in the experimental group than the control group, with specific improved skills in visual-motor search, visual-motor speed, figure-ground, and visual closure; copying and perceptual constancy skills did not improve significantly. In addition, total motor performance and motor sub-skills, including fine manual control, manual coordination, body coordination, strength, and agility were significantly more improved in the experimental group than in the control group. Thus, our task-oriented table tennis exercise program was of greater assistance than general PE classes for improving visual perception and motor performance in adolescents at risk of DCD.

Navigation abilities and spatial anxiety in individuals with and without Developmental Coordination Disorder (DCD/Dyspraxia)

BACKGROUND

Navigation skills are essential for independent living as they allow us to explore our environment; find our way to new locations, refine pathways to familiar locations and retrace our route home. Alongside motor coordination difficulties, there is evidence that individuals with Developmental Coordination Disorder (DCD/Dyspraxia) experience spatial processing difficulties, which are known to negatively affect navigation abilities. However, although self-reports indicate that adults with DCD have difficulties with sense of direction and navigation, no known studies have measured navigation abilities and strategies in adults with DCD. Furthermore, given evidence that individuals with DCD report higher levels of anxiety, we will additionally investigate associations between anxiety and navigation in this group.

AIMS

This study compares navigation abilities, navigation strategies and spatial anxiety in adults with and without DCD.

METHODS

Participants include 226 Adults aged 18-55 years, across two groups 1) DCD (N = 138, 111 F:25 M; 2:Other) 2); Typically Developing (N = 88, 77 F: 11 M). In this cross-sectional study, participants completed a series of tasks on the online Qualtrics platform. This included the Adult Developmental Coordination Disorder Checklist, the State-Trait Anxiety Inventory, the Wayfinding Anxiety Measure, the Wayfinding Questionnaire, the Wayfinding Strategy Questionnaire, and a navigation task.

RESULTS

Our analysis shows that 1) compared to those with typical development, individuals with DCD have similar navigation performance but lower navigation and orientation scores, and distance estimation scores. 2) Movement co-ordination difficulties were only a significant predictor of landmark recognition and egocentric path route knowledge, and played no role for other aspects of navigation performance. 3) For wayfinding strategy use the DCD group used orientation strategies significantly less often than those with typical development, however there was no group difference in the use of route strategies. 4) The DCD group had significantly higher spatial anxiety scores across navigation, manipulation and imagery spatial sub-domains, even after controlling for general anxiety. 5) Spatial navigation anxiety was a significant predictor of navigational skill for all three wayfinding measures (navigation & orientation, distance estimation and spatial anxiety).

CONCLUSIONS

The findings establish benchmarks of navigational skills in DCD and highlight spatial anxiety and route strategies as factors that may inhibit navigation success and could help specify suitable intervention targets.

Possible disrupted biological movement processing in Developmental Coordination Disorder

AIM

There is emerging evidence that the Mirror Neuron System (MNS) might contribute to the motor learning difficulties characteristic of Developmental Coordination Disorder (DCD). This study aimed to identify whether MNS activity differed between children with and without DCD during action observation, action execution and during a non-action baseline.

METHODS

Electroencephalography (EEG) was used to measure mu rhythm (a proxy for MNS activation) in 8-12-year-old children either with (n = 20) or without (n = 19) a diagnosis of DCD. The mu rhythm was recorded at rest and during five experimental conditions: (1) observation of gross motor and (2) fine motor actions; (3) execution of gross motor and (4) fine motor actions; and (5) non-biological movement. To address whether potential co-occurring traits of other neurodevelopmental conditions were associated with differences in mu rhythm, parents reported their child's attention and social communication skills. Mixed and repeated measure ANOVAs were conducted to examine differences in mu desynchronization and mu power respectively.

RESULTS

The non-DCD group showed greater mu rhythm desynchronization than children with DCD (i.e., more MNS activity), with both groups demonstrating increasing desynchronization from observation of fine actions to execution of gross actions. However, we also found that the children with DCD had less mu power during the non-biological movement condition than the non-DCD children, although mu power did not differ between groups during the resting condition. Correlations between mu desynchronization and children's attention and motor skills showed that poorer attention and motor abilities were associated with reduced MNS activity.

CONCLUSION

Compared to children without DCD, the MNS in children with DCD did not distinguish between biological and non-biological movement. It is possible that the reduced specificity of the MNS in children with DCD is an underlying factor in the motor impairments observed in the disorder. The differential MNS activity could reflect broader atypical activity in perceptual networks that feed into the MNS in DCD.

Sensory Processing Impairments in Children with Developmental Coordination Disorder

The two objectives of this systematic review were to examine the following: (1) the difference in sensory processing areas (auditory, visual, vestibular, touch, proprioceptive, and multi-sensory) between children with and without developmental coordination disorder (DCD), and (2) the relationship between sensory processing and motor coordination in DCD. The following databases were comprehensively searched for relevant articles: PubMed, Science Direct, Web of Science, and Cochrane library. There were 1107 articles (published year = 2010 to 2021) found in the initial search. Full-text articles of all possibly relevant citations were obtained and inspected for suitability by two authors. The outcome measures were sensory processing impairments and their relationship with motor coordination. A total of 10 articles met the inclusion criteria. Children with DCD showed significant impairments in visual integration, tactile integration, proprioceptive integration, auditory integration, vestibular integration, and oral integration processes when compared with typically developing children. Evidence also supported that sensory processing impairments were associated with poor motor coordination in DCD. Preliminary support indicated that DCD have sensory processing impairments in visual, tactile, proprioceptive, auditory, and vestibular areas, which might contribute to participation restriction in motor activities. It is important to apply sensory integration therapy in rehabilitation programs for DCD in order to facilitate participation in daily activities.

Dorsal and Ventral Stream Function in Children With Developmental Coordination Disorder

Dorsal stream cortical networks underpin a cluster of visuomotor, visuospatial, and visual attention functions. Sensitivity to global coherence of motion and static form is considered a signature of visual cortical processing in the dorsal stream (motion) relative to the ventral stream (form). Poorer sensitivity to global motion compared to global static form has been found across a diverse range of neurodevelopmental disorders, suggesting a “dorsal stream vulnerability.” However, previous studies of global coherence sensitivity in Developmental Coordination Disorder (DCD) have shown conflicting findings. We examined two groups totalling 102 children with DCD (age 5–12 years), using the “Ball in the Grass” psychophysical test to compare sensitivity to global motion and global static form. Motor impairment was measured using the Movement-ABC (M-ABC). Global coherence sensitivity was compared with a typically developing control group (N = 69) in the same age range. Children with DCD showed impaired sensitivity to global motion (p = 0.002), but not global form (p = 0.695), compared to controls. Within the DCD group, motor impairment showed a significant linear relationship with global form sensitivity (p < 0.001). There was also a significant quadratic relationship between motor impairment and global motion sensitivity (p = 0.046), where poorer global motion sensitivity was only apparent with greater motor impairment. We suggest that two distinct visually related components, associated with global form and global motion sensitivity, contribute to DCD differentially over the range of severity of the disorder. Possible neural circuitry underlying these relationships is discussed.

Visual tracking behaviour of two-handed catching in boys with developmental coordination disorder

BACKGROUND

Developmental coordination disorder (DCD) is a motor learning disability that affects coordination resulting in an inability to perform movement skills at an age appropriate level. One area suspected to contribute to the movement difficulties experienced are deficits in visuomotor control.

AIMS

This study investigated visual tracking behaviour during catching in children with DCD.

METHODS AND PROCEDURES

Twenty-four boys completed the study: 11 with DCD (9.43 years ±0.73) and 13 controls (9.16 years ± 0.68). Participants performed 10 central catching trials, with the best five used to evaluate tracking behaviour and motor responses.

OUTCOMES AND RESULTS

Prior to ball release, the DCD group exhibited more fixations (p = 0.043) of lesser duration (p = 0.045). During flight, the DCD group took longer to initiate smooth pursuit (p = 0.003) however, once initiated, both groups were effectively able to maintain smooth pursuit. Despite initial delays, these had no impact on movement initiation time (p = 0.173), however, movement time was significantly slower in the DCD group (p = 0.031).

CONCLUSIONS AND IMPLICATIONS

The results of this study demonstrate that catching performance in children with DCD likely reflect a combination of errors in attending to visual information and movement organisation.

Relationship between Motor Coordination, Cognitive Abilities, and Academic Achievement in Japanese Children with Neurodevelopmental Disorders

Background/Objective

Motor coordination impairment is common in children with neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (AD/HD). The purpose of this study was to investigate the relationship between motor coordination, cognitive ability, and academic achievement in Japanese children with neurodevelopmental disorders.

Methods

Thirty-four school-age (6–12 years old) children with neurodevelopmental disorders and 34 age-matched typically developing (TD) children were recruited in this study. Correlations between the scores of the Movement Assessment Battery for Children-2 (M-ABC2) and the Kaufman Assessment Battery for Children — Second Edition (K-ABCII) that assesses cognitive abilities, and academic achievement were analyzed.

Results

The children with neurodevelopmental disorders obtained a lower total score and all component scores on M-ABC2 compared to the TD children. In children with neurodevelopmental disorders, M-ABC2 Manual Dexterity score was significantly correlated with K-ABCII Simultaneous Processing (r = .345, p = .046), Knowledge (r = .422, p = .013), Reading (r = .342, p = .048), Writing (r = .414, p = .017), and Arithmetic (r = .443, p = .009) scores. In addition, M-ABC2 Balance score was significantly correlated with K-ABCII Learning (r = .341, p = .048), Writing (r = .493, p = .004), and Arithmetic (r = .386, p = .024) scores.

Conclusion

These findings stress that it is essential to accurately identify motor coordination impairments and the interventions that would consider motor coordination problems related to cognitive abilities and academic achievement in Japanese children with neurodevelopmental disorders.

Using somatosensory mismatch responses as a window into somatotopic processing of tactile stimulation

Brain responses to tactile stimulation have often been studied through the examination of ERPs elicited to touch on the body surface. Here, we examined two factors potentially modulating the amplitude of the somatosensory mismatch negativity (sMMN) and P300 responses elicited by touch to pairs of body parts: (a) the distance between the representation of these body parts in somatosensory cortex, and (b) the physical distances between the stimulated points on the body surface. The sMMN and the P300 response were elicited by tactile stimulation in two oddball protocols. One protocol leveraged a discontinuity in cortical somatotopic organization, and involved stimulation of either the neck or the hand in relation to stimulation of the lip. The other protocol involved stimulation to the third or fifth finger in relation to the second finger. The neck-lip pairing resulted in significantly larger sMMN responses (with shorter latencies) than the hand-lip pairing, whereas the reverse was true for the amplitude of the P300. Mean sMMN amplitude and latency did not differ between finger pairings. However, larger P300 responses were elicited to stimulation of the fifth finger than the third finger. These results suggest that, for certain combinations of body parts, early automatic somatosensory mismatch responses may be influenced by distance between the cortical representations of these body parts, whereas the later P300 response may be more influenced by the distance between stimulated body parts on the body surface. Future investigations can shed more light on this novel suggestion.

New insights into the role of motion and form vision in neurodevelopmental disorders

A selective deficit in processing the global (overall) motion, but not form, of spatially extensive objects in the visual scene is frequently associated with several neurodevelopmental disorders, including preterm birth. Existing theories that proposed to explain the origin of this visual impairment are, however, challenged by recent research. In this review, we explore alternative hypotheses for why deficits in the processing of global motion, relative to global form, might arise. We describe recent evidence that has utilised novel tasks of global motion and global form to elucidate the underlying nature of the visual deficit reported in different neurodevelopmental disorders. We also examine the role of IQ and how the sex of an individual can influence performance on these tasks, as these are factors that are associated with performance on global motion tasks, but have not been systematically controlled for in previous studies exploring visual processing in clinical populations. Finally, we suggest that a new theoretical framework is needed for visual processing in neurodevelopmental disorders and present recommendations for future research.

A developmental and clinical perspective of rhythmic interpersonal coordination: From mimicry toward the interconnection of minds

Imitation plays a critical role in the development of intersubjectivity and serves as a prerequisite for understanding the emotions and intentions of others. In our review, we consider spontaneous motor imitation between children and their peers as a developmental process involving repetition and perspective-taking as well as flexibility and reciprocity. During childhood, this playful dynamic challenges developing visuospatial abilities and requires temporal coordination between partners. As such, we address synchrony as form of communication and social signal per se, that leads, from an experience of similarity, to the interconnection of minds. In this way, we argue that, from a developmental perspective, rhythmic interpersonal coordination through childhood imitative interactions serves as a precursor to higher- level social and cognitive abilities, such as theory of mind (TOM) and empathy. Finally, to clinically illustrate our idea, we focus on developmental coordination disorder (DCD), a condition characterized not only by learning difficulties, but also childhood deficits in motor imitation. We address the challenges faced by these children on an emotional and socio-interactional level through the perspective of their impairments in intra- and interpersonal synchrony.

Navigating through apertures: perceptual judgements and actions of children with Developmental Coordination Disorder

Passing through a narrow gap/aperture involves a perceptual judgement regarding the size of the gap and an action to pass through. Children with DCD are known to have difficulties with perceptual judgements in near space but whether this extends to far space is unknown. Furthermore, in a recent study it was found that adults with DCD do not scale movements when walking through an aperture in the same way as their peers. The current study, therefore, considered perceptual judgements and motor behaviour of children with DCD while looking at or walking through apertures. Twenty‐nine children with DCD and 29 typically developing (TD) children took part. In Experiment 1, participants completed a perceptual task, where they made passability judgements. Children with DCD showed a significantly smaller critical ratio (aperture size at which a participant first rotates the shoulders to pass through) compared to their TD peers. In Experiment 2, participants completed an action task where they walked through the same apertures. Children with DCD showed a significantly larger critical ratio than TD peers when body size alone was accounted for. Taken together these results suggest that perception within a static context is different from that within a dynamic context for children with DCD. However, despite this difference we have demonstrated a clear relationship between perception and action in children with DCD. A video abstract of this article can be viewed at: https://youtu.be/SABXFrAJtF8

Impact of tactile function on upper limb motor function in children with Developmental Coordination Disorder

This study investigated the presence of, and relationship between tactile dysfunction and upper limb motor function in children with Developmental Coordination Disorder (DCD) compared to typical developing (TD) children. Participants were 36 children aged 6-12 years. Presence of DCD (n=20) or TD (n=16) was confirmed using the Movement Assessment Battery for Children, second edition. All children participated in a comprehensive assessment of tactile registration (Semmes Weinstein Monofilaments); tactile spatial perception (Single Point Localisation (SPL) and two-point discrimination (2PD)); haptic perception (Stereognosis); speed of simple everyday manual tasks (Jebsen-Taylor Test of Hand Function (JTTHF)); and handwriting speed and accuracy (Evaluation Tool of Children's Handwriting (ETCH)). Compared to TD children, children with DCD demonstrated poorer localisation of touch in the non-dominant hand (p=0.04), slower speed of alphabet writing (p<0.05) and less legible handwriting (p<0.01), but no difference in speed of simple everyday manual tasks (JTTHF: p>0.05). Regression analysis showed that spatial tactile perception (SPL) predicted handwriting legibility (ETCH: r=0.11) and speed of functional tasks (JTTHF: r=0.33). These results suggest that tactile function, specifically single point localisation, should be a primary tactile assessment employed to determine reasons for upper limb motor difficulties experienced by children with DCD.

Quiet eye training facilitates visuomotor coordination in children with developmental coordination disorder

INTRODUCTION

Quiet eye training (QET) has been shown to be more effective than traditional training (TT) methods for teaching a throw and catch task to typically developing 8-10 yr old children. The current study aimed to apply the technique to children with developmental coordination disorder (DCD).

METHOD

30 children with DCD were randomly allocated into TT or QET intervention groups. The TT group were taught how to control their arm movements during the throw and catch phases, while the QET group were also taught to fixate a target location on the wall prior to the throw (quiet eye1; QE1), followed by tracking the ball prior to the catch (quiet eye2; QE2). Performance, gaze and motion analysis data were collected at pre/post-training and 6-week retention.

RESULTS

The QET group significantly increased QE durations from pre-training to delayed retention (QE1 = +247 ms, QE2 = +19%) whereas the TT group experienced a reduction (QE1 = -74 ms, QE2 = -4%). QET participants showed significant improvement in the quality of their catch attempts and increased elbow flexion at catch compared to the TT group (QET = -28°, TT = -1°).

CONCLUSION

QET changed DCD children's ability to focus on a target on the wall prior to the throw, followed by better anticipation and pursuit tracking on the ball, which in turn led to improved catching technique. QET may be an effective adjunct to traditional instructions, for therapists teaching visuomotor skills to children with DCD.

Motor impairments screened by the movement assessment battery for children-2 are related to the visual-perceptual deficits in children with developmental coordination disorder

This study was to examine to what extent the motor deficits of children with Developmental Coordination Disorder (DCD) verified by the Movement Assessment Battery for Children-2 (MABC-2) are linked to their visual-perceptual abilities. Seventeen children with DCD and seventeen typically developing children (TD) aged 5-10 years screened from a total of 250 children were recruited. The assessments included MABC-2, traditional test of visual perceptual skills (TVPS-R), and computerized test for sequential coupling of eye and hand as well as motion coherence. The results indicated that children with DCD scored lower than TD in MABC-2, and their total scores were highly correlated with manual dexterity component scores. DCD group also showed poor visual-perceptual abilities in various aspects. The visual discrimination and visual sequential memory from the TVPS-R, the sequential coupling of eye and hand, and the motion coherence demonstrated a moderate or strong correlation with the MABC-2 in the DCD rather than the TD group. It was concluded that the motor problems screened by MABC-2 were significantly related to the visual-perceptual deficits of children with DCD. MABC-2 is suggested to be a prescreening tool to identify the visual-perceptual related motor deficits.

Developmental coordination disorder and overweight and obesity in children: a systematic review

Children with developmental coordination disorder (DCD) find themselves less competent than typically developing children with regard to their physical abilities and often experience failure. They are therefore likely to avoid physical activity. Physical inactivity is considered an important risk factor for developing overweight and obesity. The aim of this study is to assess the association between DCD and overweight and obesity in children and whether this association is influenced by age and/or gender. Six electronic databases were systematically searched. Titles and abstracts were screened for relevance. Remaining studies were subjected to full paper review. The quality of the included articles was assessed and relevant data were extracted for comparison. The search yielded 273 results. Twenty-one studies, based on 10 cohorts, were included. Participants' ages ranged from 4 to 14 years. In all cohorts, children with DCD had higher body mass index scores, larger waist circumference and greater percentage body fat compared with controls. Seven studies assessed the effect of gender and four studies provided information on the effect of age. Children with DCD seem to be at greater risk for overweight and obesity. This risk may be higher for boys and seems to increase with age and with the severity of motor impairment.

Global motion perception in 2-year-old children: a method for psychophysical assessment and relationships with clinical measures of visual function

PURPOSE

We developed and validated a technique for measuring global motion perception in 2-year-old children, and assessed the relationship between global motion perception and other measures of visual function.

METHODS

Random dot kinematogram (RDK) stimuli were used to measure motion coherence thresholds in 366 children at risk of neurodevelopmental problems at 24 ± 1 months of age. RDKs of variable coherence were presented and eye movements were analyzed offline to grade the direction of the optokinetic reflex (OKR) for each trial. Motion coherence thresholds were calculated by fitting psychometric functions to the resulting datasets. Test-retest reliability was assessed in 15 children, and motion coherence thresholds were measured in a group of 10 adults using OKR and behavioral responses. Standard age-appropriate optometric tests also were performed.

RESULTS

Motion coherence thresholds were measured successfully in 336 (91.8%) children using the OKR technique, but only 31 (8.5%) using behavioral responses. The mean threshold was 41.7 ± 13.5% for 2-year-old children and 3.3 ± 1.2% for adults. Within-assessor reliability and test-retest reliability were high in children. Children's motion coherence thresholds were significantly correlated with stereoacuity (LANG I & II test, ρ = 0.29, P < 0.001; Frisby, ρ = 0.17, P = 0.022), but not with binocular visual acuity (ρ = 0.11, P = 0.07). In adults OKR and behavioral motion coherence thresholds were highly correlated (intraclass correlation = 0.81, P = 0.001).

CONCLUSIONS

Global motion perception can be measured in 2-year-old children using the OKR. This technique is reliable and data from adults suggest that motion coherence thresholds based on the OKR are related to motion perception. Global motion perception was related to stereoacuity in children.

Visual control of manual actions: brain mechanisms in typical development and developmental disorders

Some key stages in the development of manual actions have been discussed in this supplement based on the idea of the dorsal cortical stream as the pathway for translating visual information into action control. We argue that visual information, transmitted through specialized visuomotor dorsal-stream modules, is required in the control of manual actions for selecting and attending to the target object of the action, translating visual spatial information into motor programmes and planning a coordinated sequence of actions so as to reach an optimal end-state. In typical development, we illustrate dorsal-stream processing through results on the use of stereoscopic information to guide infants' reaches, and changes in target selection and detailed kinematics of reaches depending on age, object size, and reaching in darkness (when dorsal-stream information rapidly decays). We hypothesize 'dorsal-stream vulnerability' as a widespread feature of neurodevelopmental disorders, such as autism, Williams syndrome, and children born very preterm. Such deficits, identified as abnormal visuomanual actions, are seen in bimanual coordination, visual guidance of action in the 'postbox' task, and failures in motor planning for end-state comfort. We discuss the possible application of these approaches to a wider range of disorders including developmental coordination disorder.

Developmental coordination disorders: state of art

In the literature, descriptions of children with motor coordination difficulties and clumsy movements have been discussed since the early 1900s. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), it is a marked impairment in the development of fine or global motor coordination, affecting 6% of school-age children. All these children are characterized for developmental coordination disorder (DCD) in motor learning and new motor skill acquisition, in contrast to adult apraxia which is a disorder in the execution of already learned movements. No consensus has been established about etiology of DCD. Intragroup approach through factor and cluster analysis highlights that motor impairment in DCD children varies both in severity and nature. Indeed, most studies have used screening measures of performance on some developmental milestones derived from global motor tests. A few studies have investigated different functions together with standardized assessments, such as neuromuscular tone and soft signs, qualitative and quantitative measures related to gross and fine motor coordination and the specific difficulties -academic, language, gnosic, visual motor/visual-perceptual, and attentional/executive- n order to allow a better identification of DCD subtypes with diagnostic criteria and to provide an understanding of the mechanisms and of the cerebral involvement.

Children's synchrony and rhythmicity in imitation of peers: toward a developmental model of empathy

The main mechanisms of children's imitative exchanges with peers are highlighted here through a developmental approach taking into account the importance of rhythmicity and synchrony. We focused on spontaneous motor imitation to describe a playful dynamic that is paradoxical: in the experience of play in which roles are not clearly distributed, mutual discovery of the self and others gradually arises. From an integrative perspective, this form of interaction, produced by positional reversal and turn taking, is apprehended through two axis. On the temporal plan, it can be considered as a rhythmic pattern with repetition and synchrony. Moreover, these mutual exchanges between the self and others challenge visuo-spatial abilities in children who must be able to change their reference point through an operation of mental rotation. Based on this description of the intersubjective experience produced through a succession of spatial and symbolic viewpoint changes, a developmental model of empathy is offered and discussed. According to this model, the capacity of empathy has two dimensions, emotional and cognitive, and is understood as a process involved in child development. In this article, we propose that empathy is more than the "mere" capacity of decentration corresponding to the acquisition of a theory of mind. It involves an individual in relationship with others and who has the ability to integrate perspectives.

Are Motor-free Visual Perception Skill Constructs Predictive of Visual-motor Integration Skill Constructs?

Background

Theoretical perspectives vary in considering whether visual perceptual skills and visual-motor integration (VMI) skills are related, interdependent skill sets, or two discrete skill constructs.

Objective

This study investigated whether motor-reduced/free visual perceptual skill constructs were predictive of motor-enhanced VMI skill constructs.

Method

A total of 45 typically developing children aged 6–12 years completed the Developmental Test of Visual Perception-Second Edition (DTVP-2) and the Test of Visual Perceptual Skills-Third Edition (TVPS-3). Four multiple linear regression analyses were completed with the four DTVP-2 motor-enhanced VMI subscales being the dependent (criterion) variables and the seven TVPS-3 motor-reduced subscales being the independent variables.

Results

The total variance accounted for in the four DTVP-2 VMI skill constructs by all the seven TVPS-3 skill constructs ranged from 29.3% to 60.10%. In the first regression analysis, the TVPS-3 Visual Sequential Memory and TVPS-3 Visual FigureGround constructs explained 5.40% and 4.90%, respectively, of the variance in the DTVP-2 Eye Hand Coordination construct. In the second regression, the TVPS-3 Visual Sequential Memory and TVPS-3 Visual Figure–Ground constructs accounted for 5.60% and 3.10%, respectively, of the DTVP-2 Copying construct's variance. The third analysis revealed that the TVPS-3 Visual Memory and TVPS-3 Visual Form Constancy constructs represented 6.20% and 7.90%, respectively, of the DTVP-2 Spatial Relations construct's variance. In the fourth and final regression analysis, the TVPS-3 Visual Sequential Memory and TVPS-3 Visual Figure–Ground construct explained 14.60% and 4.90%, respectively, of the variance in the DTVP-2 Visual-Motor Speed construct.

Conclusion

In the four regression analyses, specific types of motor-reduced visual perception constructs were predictive of the four specific types of motor-enhanced VMI constructs. Visual Sequential Memory and Visual FigureGround, specific types of motor-reduced visual perceptual constructs, were frequent and significant predictors of VMI skill constructs in children. It would appear that motor-reduced visual perceptual skills and motor-enhanced VMI skills as theoretical constructs are related and dependent on one another.

Probing the neurocognitive trajectories of children's reading skills

Emerging evidence of the high variability in the cognitive skills and deficits associated with reading achievement and dysfunction promotes both a more dimensional view of the risk factors involved, and the importance of discriminating between trajectories of impairment. Here we examined reading and component orthographic and phonological skills alongside measures of cognitive ability and auditory and visual sensory processing in a large group of primary school children between the ages of 7 and 12 years. We identified clusters of children with pseudoword or exception word reading scores at the 10th percentile or below relative to their age group, and a group with poor skills on both tasks. Compared to age-matched and reading-level controls, groups of children with more impaired exception word reading were best described by a trajectory of developmental delay, whereas readers with more impaired pseudoword reading or combined deficits corresponded more with a pattern of atypical development. Sensory processing deficits clustered within both of the groups with putative atypical development: auditory discrimination deficits with poor phonological awareness skills; impairments of visual motion processing in readers with broader and more severe patterns of reading and cognitive impairments. Sensory deficits have been variably associated with developmental impairments of literacy and language; these results suggest that such deficits are also likely to cluster in children with particular patterns of reading difficulty.

Development of multisensory reweighting is impaired for quiet stance control in children with developmental coordination disorder (DCD)

Background

Developmental Coordination Disorder (DCD) is a leading movement disorder in children that commonly involves poor postural control. Multisensory integration deficit, especially the inability to adaptively reweight to changing sensory conditions, has been proposed as a possible mechanism but with insufficient characterization. Empirical quantification of reweighting significantly advances our understanding of its developmental onset and improves the characterization of its difference in children with DCD compared to their typically developing (TD) peers.

Methodology/Principal Findings

Twenty children with DCD (6.6 to 11.8 years) were tested with a protocol in which visual scene and touch bar simultaneously oscillateded medio-laterally at different frequencies and various amplitudes. Their data were compared to data on TD children (4.2 to 10.8 years) from a previous study. Gains and phases were calculated for medio-lateral responses of the head and center of mass to both sensory stimuli. Gains and phases were simultaneously fitted by linear functions of age for each amplitude condition, segment, modality and group. Fitted gains and phases at two comparison ages (6.6 and 10.8 years) were tested for reweighting within each group and for group differences. Children with DCD reweight touch and vision at a later age (10.8 years) than their TD peers (4.2 years). Children with DCD demonstrate a weak visual reweighting, no advanced multisensory fusion and phase lags larger than those of TD children in response to both touch and vision.

Conclusions/Significance

Two developmental perspectives, postural body scheme and dorsal stream development, are provided to explain the weak vision reweighting. The lack of multisensory fusion supports the notion that optimal multisensory integration is a slow developmental process and is vulnerable in children with DCD.

Subtypes of developmental coordination disorder: research on their nature and etiology

Children with Developmental Coordination Disorder (DCD) are a group embracing clumsiness and developmental dyspraxia. Our study provides a better understanding of the nature of DCD and its etiology, and identifies subtypes of dyspraxia. Forty-three children with DCD (5-15 years) were enrolled on the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV-TR]; American Psychiatric Association, 2000) criteria. Extensive standardized evaluations were conducted. We distinguished from two patterns of "pure" developmental dyspraxia: ideomotor and visual-spatial/visual-constructional, and mix dyspraxia with more co-morbidities. Our study provides a better understanding of the nature of DCD, and sheds light on its etiology and brain dysfunction, so as to identify subtypes of developmental DCD/dyspraxia with specific clinical criteria.

Roadside judgments in children with Developmental Co-ordination Disorder

As pedestrians, the perceptual ability to accurately judge the relative rate of approaching vehicles and select a suitable crossing gap requires sensitivity to looming. It also requires that crossing judgments are synchronized with motoric capabilities. Previous research has suggested that children with Developmental Co-ordination Disorder (DCD) may have deficits in visual processing, specifically in detecting visual motion. It is possible, therefore that this population are at greater risk at the roadside. In a series of motion prediction tasks, several component roadside skills were assessed in 15 children with DCD, or at risk of DCD, aged between 6 and 11 years along with 15 typically developing age and gender matched controls. First, threshold errors for relative approach rate judgments (looming) were measured when vehicle size (car or truck) varied. Second, thresholds for crossing gap selection were measured for vehicle approach speeds of 32, 48, 64 and 80 km/h (20-50 mph). These were related to the walking speeds of children of different ages and profiles. We found that children with DCD showed a deficit in making relative approach rate judgments, using looming, which suggests they may not discern that a vehicle is travelling faster than the urban speed limit. Children with DCD also left considerably longer temporal crossing gaps than controls perhaps reflecting a lack of confidence in their ability, these preferred gaps were over twice the average inter-car gaps that occurred on roads around their school. Our findings raise a number of issues concerning children with DCD and their competence and potential limitations as pedestrians.

Coherent motion sensitivity predicts individual differences in subtraction

Recent findings suggest deficits in coherent motion sensitivity, an index of visual dorsal stream functioning, in children with poor mathematical skills or dyscalculia, a specific learning disability in mathematics. We extended these data using a longitudinal design to unravel whether visual dorsal stream functioning is able to predict individual differences in subsequent specific mathematical skills, i.e., single-digit subtraction and multiplication. We measured children's sensitivity to coherent motion in kindergarten (mean age: 5 years 8 months) and evaluated their subtraction and multiplication skills in third grade (mean age 8 years 3 months). Findings revealed an association between subtraction but not multiplication performance and coherent motion sensitivity. This association remained significant even when intellectual ability and reading ability were additionally controlled for. Subtractions are typically solved by means of quantity-based procedural strategies, which reliably recruit the intraparietal sulcus. Against the background of a neural overlap between the intraparietal sulcus and visual dorsal stream functioning, we hypothesize that low-level visuospatial mechanisms might set constraints on the development of quantity representations, which are used during calculation, particularly in subtraction.

Evidence review to investigate the support for subtypes of children with difficulty processing and integrating sensory information

We investigated the evidence for subtypes in children with difficulty processing and integrating sensory information. Fifty-seven articles were incorporated into a systematic literature review; only 4 articles provided direct evidence for subtypes. These studies did not provide a comprehensive assessment of all sensory functions and sensory-based motor functions (i.e., praxis) and included different diagnostic groups. Therefore, generalized conclusions about subtypes could not be drawn. The other 53 studies reviewed provided meaningful information about strengths and challenges that children with difficulty processing and integrating sensory information demonstrate, but these studies were limited in scope. A principal theme was the importance of conducting comprehensive assessments of sensory-based functions, including multiple measures of sensory integrative functions such as praxis, sensory modulation, and sensory discrimination in children and adolescents with various clinical disorders. In addition, more consistency in the use of specific assessment tools will allow for synthesis of data across studies.

Balance problems during obstacle crossing in children with Developmental Coordination Disorder

The present study investigated the visuomotor and balance limitations during obstacle crossing in typically developing (TD) children and those with Developmental Coordination Disorder (DCD) (7-9 years old; N=12 per group). Spatiotemporal gait parameters as well as range and velocity of the centre of mass (COM) were determined in three conditions: overground walking at a self-selected speed, crossing a low obstacle and crossing a high obstacle (5% or 30% of the leg length, respectively). Both groups walked more slowly during obstacle crossing than walking over level ground. In addition, both groups exhibited a significant decrease in the spatial variability of their foot placements as they approached the obstacle, which was then negotiated with a similar strategy. There were no differences in approach distance, length of lead and trail step, or lead and trail foot elevation. Compared to walking over level ground, obstacle crossing led to a longer swing phase of the lead and trail foot and increased maximal medio-lateral COM velocity. In children with DCD, however, medio-lateral COM velocity was higher and accompanied by significantly greater medio-lateral COM amplitude. In conclusion, the results indicate that while TD-children and those with DCD exhibit satisfactory anticipatory control and adequate visual guidance, the latter group have a reduced ability to control the momentum of the COM when crossing obstacles that impose increased balance demands.

Vision in developmental disorders: is there a dorsal stream deficit?

The main aim of this review is to evaluate the proposal that several developmental disorders affecting vision share an impairment of the dorsal visual stream. First, the current definitions and common measurement approaches used to assess differences in both local and global functioning within the visual system are considered. Next, studies assessing local and global processing in the dorsal and ventral visual pathways are reviewed for five developmental conditions for which early to mid level visual abilities have been assessed: developmental dyslexia, autism spectrum disorders, developmental dyspraxia, Williams syndrome and Fragile X syndrome. The reviewed evidence is broadly consistent with the idea that the dorsal visual stream is affected in developmental disorders. However, the potential for a unique profile of visual abilities that distinguish some of the conditions is posited, given that for some of these disorders ventral stream deficits have also been found. We conclude with ideas regarding future directions for the study of visual perception in children with developmental disorders using psychophysical measures.

Are poor mathematics skills associated with visual deficits in temporal processing?

Developmental learning disabilities such as dyslexia and dyscalculia have a high rate of co-occurrence in pediatric populations, suggesting that they share underlying cognitive and neurophysiological mechanisms. Dyslexia and other developmental disorders with a strong heritable component have been associated with reduced sensitivity to coherent motion stimuli, an index of visual temporal processing on a millisecond time-scale. Here we examined whether deficits in sensitivity to visual motion are evident in children who have poor mathematics skills relative to other children of the same age. We obtained psychophysical thresholds for visual coherent motion and a control task from two groups of children who differed in their performance on a test of mathematics achievement. Children with math skills in the lowest 10% in their cohort were less sensitive than age-matched controls to coherent motion, but they had statistically equivalent thresholds to controls on a coherent form control measure. Children with mathematics difficulties therefore tend to present a similar pattern of visual processing deficit to those that have been reported previously in other developmental disorders. We speculate that reduced sensitivity to temporally defined stimuli such as coherent motion represents a common processing deficit apparent across a range of commonly co-occurring developmental disorders.

Auditory and visual processing in children with dyslexia

This study investigated the temporal stability and longitudinal replicability of visual and auditory sensory processes found to be poor in children with dyslexia. Seventy children with dyslexia and 52 normal readers were tested twice, 9 months apart, on measures of visual and auditory sensory processing and on phonological and orthographic skills. About 30% of children with dyslexia were found to have sensory deficits. Associations were found between sensory and cognitive skills. Based on analyses of agreement, the temporal stability of the sensory tasks was poor. Future research should develop sensory measures with high temporal stability that can control for maturation.

Judgment of action capabilities in children at risk for developmental coordination disorder

PURPOSE

To evaluate the ability to accurately perceive the limits of action capabilities in children at risk for developmental coordination disorder (DCD).

METHODS

In Study 1, 9 to 12-year-old children (mean = 10.6 years, SD = 1.09) were identified as at risk for DCD and the accuracy of their perceptual judgments was compared with the judgments of a group of typically developing children (TDC). Two judgment tasks were used: Maximum vertical reach and maximum sitting height. Study 2 tested the hypothesis that a significant correlation would be found between a specific movement task and a related judgment task. Participants were randomly selected (n = 24) 10 and 11-year-old children (mean = 10.5 years, SD = 0.51).

RESULTS

Magnitude of judgment error (absolute error) on all tasks was significantly (p < 0.05) greater in the DCD group than in the TDC group. Study 2 revealed a significant (p < 0.05) correlation between the movement task and the related perceptual task (r = 0.70).

CONCLUSION

Compared to a typically developing group, children at risk for DCD made less accurate judgments of the limits of their action capabilities. The accuracy of a perceptual judgment was found to correlate with a related movement skill.

Relationship of Visual Perceptual Deficit and Motor Impairment in Children with Developmental Coordination Disorder

The study explored the relations of visual perceptual deficits and motor impairments in 60 children with Developmental Coordination Disorder (120.8 ± 4.0 mo.) and 60 controls (121.0 ± 5.3 mo.), who were matched by sex (29 boys and 31 girls) and age. They were separately assessed on fine and gross motor-dexterity tasks of the Movement Assessment Battery for Children, static balance and reaction time of lower extremities with eyes open or closed, and the Test of Visual-Perceptual Skills–Revised. Analysis showed the children with Developmental Coordination Disorder performed significantly worse than the control group, but only the visual perception and motor skills with timed responses were significantly correlated. When visual information was controlled, no significant correlation was noted, so motor-free visual perception appears to be significantly related to motor performance having a speed component in these children.

The use of predictive information is impaired in the actions of children and young adults with Developmental Coordination Disorder

The need for a movement response may often be preceded by some advance information regarding direction or extent. We examined the ability of individuals with Developmental Coordination Disorder (DCD) to organise a movement in response to advance information. Pre-cues were presented and varied in the extent to which they indicated the response target. Both eye movement latencies and hand movements were measured. In the absence of pre-cues, individuals with DCD were as fast in initial hand movements as the typically developing (TD) participants, but were less efficient at correcting initial directional errors. A major difference was seen in the degree to which each group could use advance pre-cue information. TD participants were able to use pre-cue information to refine their actions. For the individuals with DCD this was only effective if there was no ambiguity in the advance cue and they had particular difficulty in using predictive motion cues. There were no differences in the speed of gaze responses which excluded an explanation relating to the dynamic allocation of attention. Individuals with DCD continued to rely on the slower strategy of fixating the target prior to initiating a hand movement, rather than using advance information to set initial movement parameters.

[Non-verbal learning disabilities: developmental dyspraxia]

Dyspraxia is a non verbal neuropsychological dysfunction still unrecognized but which can generate scholar learning and behavioural disabilities. We propose, at first time, to do a state of art with the various terminologies and typologies which lead to put together clumsiness, motor coordination disorder and the different types of dyspraxia. Then, we will bring an integrative model and clinical data in children with developmental dyspraxia, allowing a better pointing, to make a diagnostic and then we suggest some advices for remediations.

Impaired balance in developmental dyslexia? A meta-analysis of the contending evidence

BACKGROUND

Developmental dyslexia is typically defined by deficits in phonological skills, but it is also associated with anomalous performance on measures of balance. Although balance assessments are included in several screening batteries for dyslexia, the association between impairments in literacy and deficits in postural stability could be due to the high co-occurrence of dyslexia with other developmental disorders in which impairments of motor behaviour are also prevalent.

METHODS

We identified 17 published studies that compared balance function between dyslexia and control samples and obtained effect-sizes for each. Contrast and association analyses were used to quantify the influence of hypothesised moderator variables on differences in effects across studies.

RESULTS

The mean effect-size of the balance deficit in dyslexia was .64 (95% CI = .44-.78) with heterogeneous findings across the population of studies. Probable co-occurrence of other developmental disorders and variability in intelligence scores in the dyslexia samples were the strongest moderator variables of effect-size.

CONCLUSIONS

Balance deficits are associated with dyslexia, but these effects are apparently more strongly related to third variables other than to reading ability. Deficits of balance may indicate increased risk of developmental disorder, but are unlikely to be uniquely associated with dyslexia.

Disorders of motor development (clumsy child syndrome)

This presentation will focus on motor competence, the clumsy child, perceptual deficits in clumsy children and possible neurological dysfunction in this group of children. Motor competence not only allows children to carry out everyday practical tasks, but it is also an important determinant of their level of self-esteem and of their popularity and status in their peer group. Research has shown that about 6-10% of children have motor competences well below the norm. It is unusual for motor problems to simply disappear over time. In the absence of intervention the syndrome is likely to manifest itself. In the clinical literature attempts have been made to establish causal links between surface manifestations of clumsiness and underlying perceptual deficits. In this respect the attention is primarily directed towards the concept of inter- and intra-modal matching, particularly with respect to vision and proprioception, an ability deemed to underlie many real-life motor skills. Neurobehavioural model of inter- and intra-modal matching and deficit model is presented. Findings from studies using this paradigm are discussed and it is argued that clumsiness must be seen as a neurological dysfunction (insufficiency).

Children with low motor ability have lower visual-motor integration ability but unaffected perceptual skills

The purpose of this study was to examine perceptual, visual-motor abilities and intellectual skills in children with low, average and above average motor abilities. The participants were 144 children (aged 6-10 years) attending elementary school. Three groups of children were identified on the basis of their performance at the TGMD (Test of Gross Motor Development; [Ulrich, D.A. (1985). TGMD, Test of Gross Motor Development. Austin, Texas: PRO-ED. Edizione Italiana a cura di D. Ianes, TEST TGM. Test di valutazione delle abilita grosso-motorie. 1994, Trento: Edizioni Centro Studi Erickson]). Each child received an intelligence test (K-BIT; [Kaufman, A.S., & Kaufman, N.L. (1990). K-BIT. Kaufman Brief Intelligence Test. Circle Pines, MN: American Guidance Service]) and was evaluated for perceptual and visual-motor integration abilities (DTVP; [Hammill, D.D., Pearson, N.A., & Voress, J.K. (1993). Developmental Test of Visual Perception (2nd ed.). Austin, Texas: PRO-ED. Edizione Italiana a cura di D. Ianes, TEST TPV. Test di percezione visiva e integrazione visuo-motoria. Trento: Edizioni Centro Studi Erickson]). Results highlight a significant difference in visual-motor integration between children with high and low gross-motor abilities, in the absence of significant differences in perceptual skills or intellectual ability. The findings are discussed with reference to the concept of atypical brain development [Gilger, J.W., & Kaplan, B.J. (2001). Atypical brain development: A conceptual framework for understanding developmental learning disabilities. Developmental Neuropsychology, 20, 465].

Do 'clumsy' children have visual recognition problems?

OBJECTIVE

Visual recognition by 8-year-old children with hand-eye co-ordination problems (HECP), and by a control group of children without such problems was tested using a task of visual closure.

DESIGN

The task required the children to identify common objects from an incomplete visual presentation.

RESULT

As predicted, it was found that the HECP children, who were designated as such solely on the basis of their motor difficulties, identified significantly fewer correct objects than their control counterparts.

CONCLUSIONS

This finding raises the possibility that the visual processing problems of clumsy children contribute to, or even strongly determine, not only their movement problems but also their learning difficulties.

Do visual processing deficits cause problem on response time task for dyslexics?

This study was set out to explore the prediction that dyslexics would be likely to have particular problems compared to control group, on response time task when 'driving' a car simulator. The reason for doing so stems from the fact that there is considerable body of research on visual processing difficulties manifested by dyslexics. The task was to drive a car and at the same time, the driver had to use either signal button on the right side of the wheel (condition 1) or a voice-activated microphone (condition 2) immediately when a road sign appears. In condition 1, the sign appears only in the mid-field zone and in condition 2, it appears in one of six possible positions in relations to the car ahead. As predicted, it was found that the dyslexics had significantly higher response time in both conditions than their controls. Dyslexics may have visual processing deficit which not only cause reading problems but also problems perceiving rapid changes in their environment such as responding on a sign when driving.

Motorische Ungeschicklichkeit

Zusammenfassung. Das Kind mit koordinativen Problemen in der Motorik benötigt spezielle Aufmerksamkeit im frühen Kindesalter. Rechtzeitige Diagnose und konsequente Intervention der motorischen Ungeschicklichkeit (DCD) wirken sich positiv auf die weitere motorische Entwicklung aus. Darüber hinaus lässt sich durch eine frühe Intervention das psycho-soziale Stigma, das durch ungeschickte Bewegungen sowie dem Problem in Sport und Spiel mit anderen Kindern mitzuhalten, begegnen. Die Möglichkeit für diese Kinder, am Sport mit Gleichaltrigen teilzuhaben, hilft ihnen in ihrer Sozialisation. Das Ziel dieses Überblicksbeitrages ist es, motorische Ungeschicklichkeit zu definieren, typische Erscheinungsformen, Diagnosekriterien sowie bestehende Therapien vorzustellen.