Hemispheric Dominance and Neurodevelopmental Disorders: Global Effects for Intensive Motor Training on White Matter Plasticity.

Cerebral maturation is characterized by different age-dependent molecular and cellular processes and follows a different course for grey matter (GM) and white matter (WM). During brain development, a crucial point seems to be represented by the establishment of a hemispheric specialization with the left hemisphere dominant for language and motor control and the right hemisphere dominant for visuospatial processing and attention. Therefore, motor and cognitive development are strongly connected. Atypical motor development and lateralization can be associated with neurodevelopmental disorders, such as Language Disorder, Learning Disorders (Dysgraphia and Dyslexia), Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder. The aim of our research was to investigate the possible effects of intensive motor training on WM plasticity and writing skills in children with Developmental Dysgraphia through a tractography study of the main WM tracts. Considering the effect of training for the Mean Diffusivity (MD) over 18 WM tracts, in 6 collaborating dysgraphic patient MD decrease (-4.3%) and in 3 not. Intensive motor training affects both stimulated and not stimulated WM tracts and showed a double not-specificity: for not stimulated hemilate and for not directly stimulated WM tracts. Intensive motor training improves both some lateralized brain functions and intra- and inter-hemispheric connectivity in our patients with good compliance with motor treatment. Moreover, our findings have shown that WM plasticity improvement concerned cortical areas responsible for both motor and cognitive functions.