Combined analysis of DTI and fMRI data reveals a joint maturation of white and grey matter in a fronto-parietal network.

“In addition, evidence from fiber tracking techniques indicates that the discussed area is part of a parietal--frontal network involved in spatial WM ( Olesen et al. 2003; Klingberg 2006).”

“…associations between WM microstructure of specific anatomical structures and a number of cognitive functions, e.g., visuo-spatial working memory [Klingberg, 2006; Olesen et al., 2003; Vestergaard et al., 2011], visual search [Mabbott et al., 2006], and response inhibition [Madsen et al., 2010].”

“We used the same regions in superior frontal cortex (left and right hemisphere) shown above to relate to hemispheric asymmetry of alpha and gamma and reported previously in [19].”

“In the field of learning disabilities, variations in WM tract measures have been associated with both general cognitive ability and specific cognitive domains.”

“…structural connectivity between parietal and frontal regions is related to brain activation during working memory performance in children between the ages of 8 and 18 years [Olesen et al., 2003], which is relevant here because working memory is highly related to intelligence [Conway et al., 2003].”

“The uncinate fasciculus, a late-myelinated control region not implicated in cognitive control, did not mediate this effect.”

“, 2004] and early emerging adulthood [Olesen et al., 2003].”

“In children, diffusion tensor imaging studies suggest that developmental increases in gray matter activation in frontal and parietal cortices could be due to maturation of white matter connections (Olesen et al., 2003).”

“Although there are no suitable answers yet for both questions (Poldrack, 2010), our findings build upon recent developmental studies in which increased activation patterns were associated with increased performance (Klingberg et al., 2002; Olesen et al., 2003; Vannest et al., 2010).”

“Most studies found enhanced activation with age (8 or 9 yo through 18 yo) in the circuits already identified in adults for supporting this process: dorsal or lateral prefrontal cortex and intra- or posterior parietal cortex (Klingberg et al., 2002; Kwon et al., 2002; Olesen et al., 2003).”

“…and cognitive performance (Madden et al. 2004; O’Sullivan et al. 2005; Tuch et al. 2005; Charlton et al. 2006, forthcoming; Persson et al. 2006; Grieve et al. 2007) and the blood oxygenation level-- dependent (BOLD) response (Olesen et al. 2003; Seghier et al. 2004; Schlösser et al. 2007).”

“The corona radiata has ascending and descending tracts rom the cerebral cortex that integrate information throughout the rain, and these tracts are known to play a role in processing speed, ognitive control and memory (Bendlin et al., 2010; Niogi et al., 010; Olesen et al., 2003).”

“Further, in a recent study using a variety of tasks, Ozonoff and Strayer (2001) failed to find working memory deficits in high-ability children and adolescents with autism.”

“Although, more systematic study is needed, it is likely that improvements in cognitive control are supported primarily by increases in structural and functional connectivity across and between cortical and subcortical regions (Olesen et al., 2003; Liston et al., 2006; Vincent et al., 2008; Schmithorst and Yuan, 2010).”

“, 2010), as well as the visuo-spatial aspects of working memory (Olesen et al., 2003; Nagy et al., 2004; Klingberg, 2006; Vestergaard et al., 2011) and visuo-spatial attention (Hoeft et al.”

“Interestingly, increased structural connectivity between frontal, parietal and striatal regions with age has been linked to improvements in cognitive functioning, like working memory capacity (Nagy et al., 2004; Olesen et al., 2003) and cognitive control (Liston et al.”

“Developmental changes in white matter may be associated with these activation changes as fractional anisotropy in fronto-parietal cortex is correlated with activation in intra-parietal cortex and behavioral performance during a working memory task [Nagy et al., 2004; Olesen et al., 2003].”

“Frontoparietal white matter maturation correlates with an increase in grey matter activity in both lobes during performance of a working memory (WM) task indicating the close functional connection [10].”

“Moreover, these FA values were positively correlated with the BOLD response in superior frontal sulcus and intraparietal cortex (Olesen et al. 2003).”

“To this aim we applied PAS over the DLPFC and the PPC, given the crucial role of the connections between these two areas in largescale memory and attention processes (Olesen et al., 2003; 2004; Sauseng et al., 2005).”

“The fossil record provides evidence about the rate, duration, and timing of brain growth.”

“Even in normal patients, DTI imaging shows a significant correlation between working memory function and maturation of white matter tract connectivity between the PFC and the parietal lobe.(92) PFC and IPL have reciprocal connections with the cerebellum with input passing through the internal capsule and pons and outp…”

“Similarly, a multi-modal diffusion tensor imaging and fMRI study found that the degree of white matter maturation is positively correlated with brain activity in superior fronto and intraparietal cortex, which contribute to the WM functional network (Olesen et al., 2003).”

“Moreover, a comparison of fMRI data and diffusion tensor imaging data reveals that increased fractional anisotropy in fronto-parietal white matter – suggestive of increased strength of anatomical connectivity between these regions – is positively correlated with blood-oxygen-level-dependent (BOLD) activation in the SF…”

“…studies have linked increasing myelination of major white matter tracts across adolescence (Barnea-Goraly et al., 2005; Schmithorst et al., 2008) to both brain activation maturation and cognitive test performance (Nagy et al., 2004; Olesen et al., 2003), ch Center, Whitehall Building, 06106, USA.”

“Similarly, developmental imaging of visuospatial working memory has shown that both age and working memory ability are positively correlated with activation in parietal and superior frontal cortices (Klingberg, Forssberg, & Westerberg, 2002; Kwon, Reiss, & Menon, 2002) as well as maturation of white matter tracts link…”

“Finally, it has been reported that FA values in frontoparietal white matter correlate strongly with BOLD response (during a working memory task) in closely located gray matter in the superior frontal sulcus and inferior parietal lobe ( Oleson, Nagy, Westerberg, & Klingberg, 2003 ).”

“, 2008), and across normal development (Olesen et al., 2003; Klingberg, 2006).”

“Gerstmann syndrome is also characterized by disruption of spatial discrimination as well as finger agnosia, and inferior parietal cortexplaysa role in spatialworkingmemory (Leunget al., 2007; Olesen et al., 2007; Olesen et al., 2003; for a review see Vallar, 2007).”

“There have been several studies investigating age-related changes of white matter and the corresponding changes in cognitive measures (e.g., Olesen et al., 2003; Nagy et al., 2004; Zahr et al., 2009; Bava, et al., 2010).”

“This methodology may allow us to determine if developmental changes in separate regions of activation are associated with simultaneous developmental changes in connectivity between those regions (70,71).”

“…connectivity between frontal and cortical or subcortical regions (Asato et al., 2010; Barnea-Goraly et al., 2005; Gogtay et al., 2004; Huttenlocher and Dabholkar, 1997; Hwang et al., 2010; Lenroot et al., 2007; Olesen et al., 2003; Snook et al., 2005; Sowell et al., 1999; Sowell et al., 2002).”

“Furthermore, normative developmental studies suggest that the dorsal pathway has a more protracted maturational trajectory than the ventral stream [66], and WM fMRI studies demonstrate greater parietal [4,73] but less fusiform recruitment [66] with age.”

“children have identified significant correlations between visual WM performance and development of white matter in left frontoparietal regions, as well as in the anterior corpus callosum (CC).(31,32)”

“These findings support the hypothesis that the frontoparietal network, with the SLF as an important constituent, provides a neurobiological foundation for psychological regulation [17].”

“Higher FA and lower diffusivity are functionally significant (Deutsch et al., 2005; Dougherty et al., 2007; Olesen et al., 2003) and have been described as markers of developmental progress (Barnea-Goraly et al., 2005b; Eluvathingal et al., 2007; Lebel et al., 2008b; McGraw et al., 2002; Morriss et…”

“Correlations between maturation of white matter and increased brain activity during performance of a working memory task have been reported in a normative sample (Olesen et al., 2003).”

“, 2007] or to examine correlations across modalities but within only one or several regions of interest [Barkovich et al., 2006; Nitkunan et al., 2008; Olesen et al., 2003; Toosy et al., 2004].”

“There exists another report pointing to the associated myelination of the long-range cortical connections and activation of their target areas in children aged 8–18 years (Olesen et al., 2003).”

“network (Olesen et al. 2003), while better visuospatial construction and psychomotor performance is associated with high corpus callosum fractional anisotropy (Fryer et al.”

“Maturation of the gray and white matter of the frontoparietal network is seen in healthy children (Olesen et al., 2003) and is related to working memory performance (Nagy et al., 2004; Ostby et al., 2011).”

“…factors, such as crossing fibers, is commonly used and has been successful in identifying the neuro-anatomical correlates of cognitive functions, such as working memory (e.g., Olesen et al., 2003), intelligence (e.g., Schmithorst et al., 2005) and reading (Vandermosten et al., 2012b, for a review).”

“Importantly, subcortical regions (Giedd et al., 1996) and lateral prefrontal (Ordaz et al., 2013) and posterior parietal cortices (PPC) (Olesen et al., 2003) undergo significant maturation during adolescence.”

“The combination of both techniques (fMRI and DTI) has opened up the opportunity to investigate structure-function relationships non-invasively in children [6,7].”

“Most previous studies that have investigated white matter contributions to individual WMC differences focused on local white matter integrity of individual regions (Olesen et al., 2003; Nagy et al., 2004).”

“To this end, the ACB analysis was run by choosing as reference regions bilateral frontal areas, in proximity of the FEFs (Olesen et al., 2003; Marshall et al., 2015).”

“The development of gray matter activity seems to be mediated by the maturation of white matter (Olesen et al., 2003).”

“It is possible that the younger, low-performing very preterm born children cannot engage the same widespread network seen in controls, because they are still in the process of functional organization of working memory, leading to different network characteristics (Olesen et al., 2003).”

“Olesen et al. (2003) combined data from DTI and fMRI from children (8–18 years) and showed positive correlations between WM maturation (FA measures) and neural activity (BOLD responses) in a number of regions important for spatial working memory and the development of working memory capacity (e.g.,…”

“Thus, findings from structural and functional MRI studies have demonstrated that the FPN regions undergo protracted development (Johnson 2001; Klingberg et al. 2002; Olesen et al. 2003; Alvarez and Emory 2006; Fair et al. 2007), with slower maturation than the DMN from childhood to adulthood (Supekar et al.”

“LDLPFC to LPPC Substantial evidence demonstrates that the connections between the dorsolateral prefrontal cortex (DLPFC) and PPC are relevant for memory, attentional processes, and choice (Essex et al., 2012; Olesen et al., 2003; Sauseng et al., 2005).”

“…task that has been shown, at least in typically developing adults, to depend heavily on the posterior aspects of the frontoparietal attention network (Piazza et al., 2002; Sathian et al., 1999) was found to directly relate tomeasures of the anterior corpus callosum in children with DS22q11.”

“…associated with both memory and language deficits in temporal lobe epilepsy and white matter maturation within the arcuate fasciculus including the temporoparietal segment is a predictor of visuospatial memory capacity in childhood (McDonald et al., 2008; Olesen et al., 2003; Short et al., 2013).”

“Continued development of this circuitry throughout adolescence (Fair et al., 2007; Klingberg et al., 2002; Olesen et al., 2003) may lead to differences in how incentives can modulate decisions in adolescents relative to adults (van den Bos et al.”

“WM integrity, found in nonclinical samples is associated with cognitive function with reference to nonsocial and nonemotional thought processes [Jung et al., 2010a; Olesen et al., 2003; Schmithorst et al., 2005; Takeuchi et al., 2010d].”

“Anatomical changes in the prefrontal cortex that continue throughout adolescence include increases in grey and white matter volumes, and in myelination of axon fibres within the prefrontal cortex and between the prefrontal cortex and other brain areas 6–13 .”

“Later studies of TD children reported fronto-parietal activation during visuospatial working memory tasks (Klingberg et al., 2002; Olesen et al., 2003; Thomas et al., 1999), with evidence for an age-related increase in working memory activation between 9 and 18 years (Klingberg et al., 2002).”

“Studies have illustrated that the maturation of white matter fibre tracts, such as the superior longitudinal fasciculus, positively correlate with the functional activation of frontal and parietal regions involved with working memory [48,59].”

“…as the amplitude of steady-state visual evoked potentials (Butler et al., 2005), measures of functional connectivity (Boorman et al., 2007), and task-related BOLD signal (Baird et al., 2005; Olesen et al., 2003), this is the first report of relations between FA and the timing of evoked responses.”

“…verbal skills in girls than in boys and diffusivity decreasing with typical brain development (Bonekamp et al., 2007), we interpret low left relative to right temporal diffusivity as an indication of brain maturation in boys, a condition that may enhance reading comprehension (Olesen et al., 2003).”

“While children have been shown to activate similar brain regions as adults [Nelson et al., 2000; Olesen et al., 2003] there are several distinct developmental differences, although the findings are inconsistent.”

“WM processes are associated with the PFC, and in children and adolescents a higher FA in the genu of corpus callosum and in the temporo-occipital node is associated with a better WM performance (Nagy et al., 2004; Olesen et al., 2003).”