Indirect information on the developmental trajectory of the

Indirect information on the developmental trajectory of the BRS comes from resting state functional magnetic resonance imaging (fMRI) studies. The sensorimotor control network is already topologically adult-like by the age of two while higher-order networks including the fronto-parietal network are topologically incomplete, presenting a less specialized architecture compared to adults (Gao et al., 2015). Further studies reported that within-network connectivity changes stop in late childhood (∼10 years old) for the sensorimotor network and that they continue until adulthood for the frontal and parietal networks (Jolles et al., 2011; Kelly et al., 2009). Therefore, the fronto-parietal network supporting the BRS presents an extended development compared to the sensorimotor network. A recent fMRI study using tendon vibration also demonstrated that the proprioceptive order Madecassoside network still undergoes refinements during and beyond adolescence, mostly the fronto-striatal connections that exhibit functional pruning leading to a more restricted topology (Cignetti et al., 2016a). Therefore, although the sensorimotor network is likely earlier to mature compared to the fronto-parietal network, it may not yet be mature by late childhood. Outcomes from structural MRI studies would support this view. Studies on cortical grey matter development from childhood to adulthood reported a maturational sequence from sensorimotor to higher-order association regions, specifically from the precentral gyrus to the prefrontal cortex in the frontal lobe and from the postcentral gyrus to the angular/supramarginal gyri in the parietal lobe (e.g. Gogtay et al., 2004; Shaw et al., 2008). Likewise, a study by Zielinski et al. (2010) showed that grey matter networks establishing sensory and motor regions were already well-developed in early childhood, although not yet adult-like. In contrast, higher-level cognitive networks were undeveloped in early childhood and showed an important amount of change during adolescence. However, regional variations in the grey matter maturation pattern of the sensorimotor network appear to exist, especially in the subcortical regions that demonstrate important age-related changes in grey matter density during adolescence (Sowell et al., 1999). Considering white matter maturation, it is less clear whether the sensorimotor network reaches maturity before the fronto-parietal network. Diffusion tensor imaging (DTI) studies showed that the microstructural characteristics of association fibres, and especially the superior longitudinal fasciculus that connects the parietal cortex to the frontal gyrus, become adult-like by late adolescence (Asato et al., 2010; Lebel et al., 2008, 2012; Lebel and Beaulieu, 2011; Simmonds et al., 2014). This supports an extended development of the fronto-parietal network. However, late to mature in adolescence are also projection fibres, such as the corona radiatia connecting the basal ganglia to the cortex, as well as cerebellar connections (Asato et al., 2010; Lebel et al., 2008; Simmonds et al., 2014). Moreover, connections at terminal grey matter sites in basal ganglia were found to mature even in later adulthood (Lebel et al., 2008; Simmonds et al., 2014). Therefore, a set of white matter fibres involved in the sensorimotor network continue to mature during and beyond adolescence, suggesting once again that this network is not completely mature by late childhood. Using a protocol of kinaesthetic illusions in children (7–11 years) and adults (25–40 years) in fMRI, the aim of the present study was to evaluate the degree of maturation of the sensorimotor and fronto-parietal networks subtending the BRS by late childhood. We expected to find larger differences in activation levels between children and adults in fronto-parietal regions, i.e. a more immature fronto-parietal network by late childhood. A secondary objective was to examine the extent to which structural brain maturation influences the functional development of the networks that implement the BRS. To this end, we investigated group differences in fMRI results while statistically controlling for differences in grey and white matter between children and adults.