Atypical inter‐hemispheric communication correlates with altered motor inhibition during learning of a new bimanual coordination pattern in developmental coordination disorder

Abstract

Impairment of motor learning skills in developmental coordination disorder (DCD) has been reported in several studies. Some hypotheses on neural mechanisms of motor learning deficits in DCD have emerged but, to date, brain-imaging investigations are scarce. The aim of the present study is to assess possible changes in communication between brain areas during practice of a new bimanual coordination task in teenagers with DCD (n = 10) compared to matched controls (n = 10). Accuracy, stability and number of mirror movements were computed as behavioural variables. Neural variables were assessed by electroencephalographic coherence analyses of intra-hemispheric and inter-hemispheric fronto-central electrodes. In both groups, accuracy of the new coordination increased concomitantly with right intra-hemispheric fronto-central coherence. Compared to typically developing teenagers, DCD teenagers presented learning difficulties expressed by less stability, no stabilization of the new coordination and a greater number of mirror movements despite practice. These measures correlated with reduced inter-hemispheric communication, even after practice of the new coordination. For the first time, these findings provide neuro-imaging evidence of a kind of inter-hemispheric 'disconnection' related to altered inhibition of mirror movements during motor learning in DCD.

Interhemispheric Cortical Inhibition Is Reduced in Young Adults With Developmental Coordination Disorder

“…Furthermore, the reduced interhemispheric cortical inhibition identified in our DCD group is consistent with the growing number of behavioral studies which have consistently found more unwanted activity of ipsilateral homologous muscles (i.e., mirror movements) during lateralized unimanual motor tasks ( 76 , 77 ) and bimanual coordination tasks ( 73 , 74 , 119 ) in DCD than TD controls. For example, during a recent finger tapping task which requires children to switch from bimanual to unimanual finger tapping, children with DCD made more additional taps of a non-cued finger when required to switch from tapping with both fingers to tapping with just one ( 119 ).…”

“…Our neurophysiological findings are also in line with recent structural MRI work showing functional anisotropy reductions in calossal regions in children with DCD, the major communication pathway between hemispheres ( 120 ). While speculative, the decreased interhemispheric cortical inhibition of M1 activity observed here in DCD could certainly be a plausible mechanism with which to explain the reduced interhemispheric communication in individuals with DCD ( 73 ) and the greater mirror movements observed.…”

“…Based on behavioral findings indicating that individuals with DCD often display phenotypes consistent with reduced intrahemispheric cortical inhibition within the M1 ( 73 – 80 , 84 – 87 ), we hypothesized that intrahemispheric cortical inhibition may be reduced in DCD. Contrary to expectations, comparisons between DCD and TD groups on a broad range of gold-standard indices of intrahemispheric cortical inhibition [i.e., SICI (%), LICI (%), and CSP ratio ] failed to reveal statistically meaningful differences.…”

“…However, despite the presence of such mirror movements, the authors of this particular fMRI study were unable to identify any activation deficits that could explain the presence of these unwanted actions. Interestingly a recent EEG study found that the increased incidence of mirror movements in DCD may be associated with reduced interhemispheric communication of inhibitory information ( 73 ). Specifically, children with DCD made more mirror movements during performance of a novel bimanual coordination task than their TD peers, with increased mirror movements correlating with lower cortico-cortical coherence between frontocentral regions of both hemispheres.…”

“…Recent experimental work is replete with evidence that individuals with DCD present with behavioral phenotypes that are traditionally associated with reduced intra- and interhemispheric cortical inhibition. For example, a number of studies have shown that individuals with DCD demonstrate an increased incidence of the type of “mirror movements” symptomatic of poor interhemispheric inhibition ( 73 – 77 ). Likewise, children with DCD have consistently shown difficulties performing tasks that require the sudden cancelation of both prepared or prepotent movements ( 78 – 87 ).…”