Shared and differentiated motor skill impairments in children with dyslexia and/or attention deficit disorder: From simple to complex sequential coordination.
ABSTRACT: Dyslexia and Attention deficit disorder (AD) are prevalent neurodevelopmental conditions in children and adolescents. They have high comorbidity rates and have both been associated with motor difficulties. Little is known, however, about what is shared or differentiated in dyslexia and AD in terms of motor abilities. Even when motor skill problems are identified, few studies have used the same measurement tools, resulting in inconstant findings. The present study assessed increasingly complex gross motor skills in children and adolescents with dyslexia, AD, and with both Dyslexia and AD. Our results suggest normal performance on simple motor-speed tests, whereas all three groups share a common impairment on unimanual and bimanual sequential motor tasks. Children in these groups generally improve with practice to the same level as normal subjects, though they make more errors. In addition, children with AD are the most impaired on complex bimanual out-of-phase movements and with manual dexterity. These latter findings are examined in light of the Multiple Deficit Model.
Project description:<h4>Purpose</h4>Our objective was to delineate components of motor performance in specific language impairment (SLI); specifically, whether deficits in timing precision in one effector (unimanual tapping) and in two effectors (bimanual clapping) are observed in young children with SLI.<h4>Method</h4>Twenty-seven 4- to 5-year-old children with SLI and 21 age-matched peers with typical language development participated. All children engaged in a unimanual tapping and a bimanual clapping timing task. Standard measures of language and motor performance were also obtained.<h4>Results</h4>No group differences in timing variability were observed in the unimanual tapping task. However, compared with typically developing peers, children with SLI were more variable in their timing precision in the bimanual clapping task. Nine of the children with SLI performed greater than 1 SD below the mean on a standardized motor assessment. The children with low motor performance showed the same profile as observed across all children with SLI, with unaffected unimanual and impaired bimanual timing precision.<h4>Conclusions</h4>Although unimanual timing is unaffected, children with SLI show a deficit in timing that requires bimanual coordination. We propose that the timing deficits observed in children with SLI are associated with the increased demands inherent in bimanual performance.
Project description:Reaching and grasping (prehension) is one of the earliest developing motor skills in humans, but continued prehension development in childhood and adolescence enables the performance of increasingly complex manual tasks. In individuals with autism spectrum disorder (ASD) atypical unimanual reaching and grasping has been reported, but to date, no studies have investigated discrete bimanual movements. We examined unimanual and bimanual reach to grasp tasks in youth with ASD to better understand how motor performance might change with increasing complexity. Twenty youth with ASD (10.1 ± 2.4 years) and 17 youth with typical development (TD) (9.6 ± 2.6 years) were instructed to reach and grasp cubes that became illuminated. Participants were asked to reach out with the right and/or left hands to grasp and lift targets located at near (18 cm) and/or far (28 cm) distances. For the unimanual (simplest) condition, participants grasped one illuminated cube (with either the left or right hand). For the bimanual conditions, participants grasped two illuminated cubes located at the same distance from the start position (bimanual symmetric condition) or two illuminated cubes located at different distances (bimanual asymmetric condition). Significant interactions among diagnostic group, task complexity, and age were found for initiation time (IT) and movement time (MT). Specifically, the older children in both groups initiated and performed their movements faster in the unimanual condition than in the bimanual conditions, although the older children with ASD produced slower ITs and MTs compared to typically developing peers across all three conditions. Surprisingly, the younger children with ASD had similar ITs and MTs as their peers for the unimanual condition but did not considerably slow these times to adjust for the complexity of the bimanual tasks. We hypothesize that they chose to re-use the motor plans that were generated for the unimanual trials rather than generate more appropriate motor plans for the bimanual tasks. An atypical spatiotemporal relationship between MT and peak aperture (PA) was also found in the ASD group. Together, our results suggest deficits in motor planning that result in subtle effects on performance in younger children with ASD that become more pronounced with age.
Project description:Motor learning in unimanual and bimanual planar reaching movements has been intensively investigated. Although distinct theoretical frameworks have been proposed for each of these reaching movements, the relationship between these movements remains unclear. In particular, the generalization of motor learning effects (transfer of learning effects) between unimanual and bimanual movements has yet to be successfully explained. Here, by extending a motor primitive framework, we analytically proved that the motor primitive framework can reproduce the generalization of learning effects between unimanual and bimanual movements if the mean activity of each primitive for unimanual movements is balanced to the mean for bimanual movements. In this balanced condition, the activity of each primitive is consistent with previously reported neuronal activity. The unimanual-bimanual balance leads to the testable prediction that generalization between unimanual and bimanual movements is more widespread to different reaching directions than generalization within respective movements. Furthermore, the balanced motor primitive can reproduce another previously reported phenomenon: the learning of different force fields for unimanual and bimanual movements.
Project description:PURPOSE:To evaluate fine motor ability in children treated for unilateral congenital or infantile cataract. METHODS:Twenty-three children 3-13 years of age who were treated for unilateral congenital or infantile cataract and 38 age-similar control children were enrolled. Children completed five fine motor skills tasks (unimanual dexterity, bimanual dexterity, drawing trail, aiming, catching) from the Movement Assessment Battery for Children-2. Raw scores were converted into standardized scores, with higher scores indicating better performance. RESULTS:Compared with controls, children treated for unilateral cataract scored lower on drawing trail (P = 0.009), aiming (P = 0.009), and catching (P < 0.001) but not on unimanual (P = 0.77) or bimanual dexterity (P = 0.31). Poorer affected eye visual acuity was moderately related to poorer performance for unimanual dexterity (r = -0.47; P = 0.025), bimanual dexterity (r = -0.50; P = 0.014), and catching (r = -0.41; P = 0.051). Those with a poor visual outcome (>0.6 logMAR) had worse performance than those with a good visual outcome (?0.6 logMAR) for all tasks (all P values, 0.008-0.09) except aiming. Cataract type (congenital, 9; infantile, 14) and sensory fusion by Worth 4-Dot testing at 33 cm (pass, 10; fail, 13) had no effect on fine motor performance (all P values, 0.12-0.98). CONCLUSIONS:In our study cohort, fine motor deficits were found in children treated for congenital or infantile unilateral cataract.
Project description:<h4>Objective</h4>To determine similarities and differences in key predictors of recovery of bimanual hand use and unimanual motor impairment after stroke.<h4>Method</h4>In this prospective longitudinal study, 89 patients with first-ever stroke with arm paresis were assessed at 3 weeks and 3 and 6 months after stroke onset. Bimanual activity performance was assessed with the Adult Assisting Hand Assessment Stroke (Ad-AHA), and unimanual motor impairment was assessed with the Fugl-Meyer Assessment (FMA). Candidate predictors included shoulder abduction and finger extension measured by the corresponding FMA items (FMA-SAFE; range 0-4) and sensory and cognitive impairment. MRI was used to measure weighted corticospinal tract lesion load (wCST-LL) and resting-state interhemispheric functional connectivity (FC).<h4>Results</h4>Initial Ad-AHA performance was poor but improved over time in all (mild-severe) impairment subgroups. Ad-AHA correlated with FMA at each time point (<i>r</i> > 0.88, <i>p</i> < 0.001), and recovery trajectories were similar. In patients with moderate to severe initial FMA, FMA-SAFE score was the strongest predictor of Ad-AHA outcome (<i>R</i> <sup>2</sup> = 0.81) and degree of recovery (<i>R</i> <sup>2</sup> = 0.64). Two-point discrimination explained additional variance in Ad-AHA outcome (<i>R</i> <sup>2</sup> = 0.05). Repeated analyses without FMA-SAFE score identified wCST-LL and cognitive impairment as additional predictors. A wCST-LL >5.5 cm<sup>3</sup> strongly predicted low to minimal FMA/Ad-AHA recovery (≤10 and 20 points respectively, specificity = 0.91). FC explained some additional variance to FMA-SAFE score only in unimanual recovery.<h4>Conclusion</h4>Although recovery of bimanual activity depends on the extent of corticospinal tract injury and initial sensory and cognitive impairments, FMA-SAFE score captures most of the variance explained by these mechanisms. FMA-SAFE score, a straightforward clinical measure, strongly predicts bimanual recovery.<h4>Clinicaltrialsgov identifier</h4>NCT02878304.<h4>Classification of evidence</h4>This study provides Class I evidence that the FMA-SAFE score predicts bimanual recovery after stroke.
Project description:The aims of this study were twofold: first, to develop and validate a timed test of unimanual and bimanual dexterity suitable for those with disability affecting hand function; second, to explore relationships between unimanual and bimanual completion times.We developed the Tyneside Pegboard Test (TPT), an electronically timed test with three peg sizes, incorporating an asymmetrical bimanual task. Nine hundred and seventy-four participants (455 males, 519 females; age range 4-80y) provided normative data. Test-retest reliability and construct validity were assessed (50 adults: 14 males, 36 females; 15-73y) on two occasions 2 weeks apart. Bimanual and unimanual completion times were measured in 87 children (51 males, 36 females) with unilateral cerebral palsy (CP) and 498 individuals in a comparison group (238 males, 260 females; 5-15y).The comparison group showed an asymmetrical U-shaped relationship between completion times and age. Intraclass correlation coefficients ranged from 0.74 to 0.91, indicating moderate test-retest reliability. There was a negative relationship between average TPT bimanual times and Purdue pegboard bimanual scores (Spearman's rho -0.611, degrees of freedom 44, p<0.001). Children with unilateral CP had greater prolongation of bimanual than unimanual completion times compared with the comparison group (mean difference 20.31s, 95% confidence interval 18.13-22.49, p<0.001).The TPT is accessible for those with impaired hand function. Children with unilateral CP demonstrated disproportionate bimanual deficits, even allowing for unimanual dexterity: this has implications for therapy.We developed an adapted, electronically timed 9-hole pegboard test. Our modifications facilitate use by those with disability affecting hand function. The test incorporates an asymmetrical bimanual task. Children with unilateral cerebral palsy showed disproportionate bimanual dexterity deficits even allowing for unimanual dexterity.
Project description:The coordination of movement between the upper limbs is a function highly distributed across the animal kingdom. How the central nervous system generates such bilateral, synchronous movements, and how this differs from the generation of unilateral movements, remain uncertain. Electrophysiologic and functional imaging studies support that the activity of many brain regions during bimanual and unimanual movement is quite similar. Thus, the same brain regions (and indeed the same neurons) respond similarly during unimanual and bimanual movements as measured by electrophysiological responses. How then are different motor behaviors generated? To address this question, we studied unimanual and bimanual movements using fMRI and constructed networks of activation using Structural Equation Modeling (SEM). Our results suggest that (1) the dominant hemisphere appears to initiate activity responsible for bimanual movement; (2) activation during bimanual movement does not reflect the sum of right and left unimanual activation; (3) production of unimanual movement involves a network that is distinct from, and not a mirror of, the network for contralateral unimanual movement; and (4) using SEM, it is possible to obtain robust group networks representative of a population and to identify individual networks which can be used to detect subtle differences both between subjects as well as within a single subject over time. In summary, these results highlight a differential role for the dominant and non-dominant hemispheres during bimanual movements, further elaborating the concept of handedness and dominance. This knowledge increases our understanding of cortical motor physiology in health and after neurological damage.
Project description:This study investigated risk and protective factors associated with dyslexia and literacy development, both at the group and individual level, to gain more insight in underlying cognitive profiles and possibilities for compensation in high-IQ children. A sample of 73 Dutch primary school children included a dyslexic group, a gifted-dyslexic group, and a borderline-dyslexic group (i.e., gifted children with relative literacy problems). Children were assessed on literacy, phonology, language, and working memory. Competing hypotheses were formulated, comparing the core-deficit view to the twice-exceptionality view on compensation with giftedness-related strengths. The results showed no indication of compensation of dyslexia-related deficits by giftedness-related strengths in gifted children with dyslexia. The higher literacy levels of borderline children compared to gifted children with dyslexia seemed the result of both fewer combinations of risk factors and less severe phonological deficits in this group. There was no evidence for compensation by specific strengths more relevant to literacy development in the borderline group. Accordingly, the findings largely supported the core-deficit view, whereas no evidence for the twice-exceptionality view was found. Besides practical implications, the findings also add to knowledge about the different manifestations of dyslexia and associated underlying cognitive factors at the higher end of the intelligence spectrum.
Project description:<h4>Background</h4>Deficits in time perception (the ability to judge the duration of time intervals) have been found in children with both attention-deficit/hyperactivity disorder (ADHD) and dyslexia. This paper investigates time perception, phonological skills and executive functions in children with dyslexia and/or ADHD symptoms (AS).<h4>Method</h4>Children with dyslexia-only (n = 17), AS-only (n = 17), comorbid dyslexia+AS (n = 25), and typically developing controls (n = 42), matched for age and non-verbal ability, were assessed on measures of phonological skills, executive function and time perception (duration discrimination and time reproduction).<h4>Results</h4>Children with dyslexia were impaired on measures of phonological skill and duration discrimination compared to children without dyslexia (though problems on duration discrimination appeared to be attributable to mild symptoms of inattention in this group). In contrast, children with AS exhibited impairments on measures of both time perception and executive function compared to children without AS. Children with dyslexia+AS showed an additive combination of the deficits associated with dyslexia-only and AS-only.<h4>Conclusions</h4>Dyslexia and AS appear to be associated with distinct patterns of cognitive deficit, which are present in combination in children with dyslexia+AS.
Project description:An on-going debate surrounds the relationship between specific language impairment and developmental dyslexia, in particular with respect to their phonological abilities. Are these distinct disorders? To what extent do they overlap? Which cognitive and linguistic profiles correspond to specific language impairment, dyslexia and comorbid cases? At least three different models have been proposed: the severity model, the additional deficit model and the component model. We address this issue by comparing children with specific language impairment only, those with dyslexia-only, those with specific language impairment and dyslexia and those with no impairment, using a broad test battery of language skills. We find that specific language impairment and dyslexia do not always co-occur, and that some children with specific language impairment do not have a phonological deficit. Using factor analysis, we find that language abilities across the four groups of children have at least three independent sources of variance: one for non-phonological language skills and two for distinct sets of phonological abilities (which we term phonological skills versus phonological representations). Furthermore, children with specific language impairment and dyslexia show partly distinct profiles of phonological deficit along these two dimensions. We conclude that a multiple-component model of language abilities best explains the relationship between specific language impairment and dyslexia and the different profiles of impairment that are observed.