Differences between child and adult large‐scale functional brain networks for reading tasks

Abstract

Reading is an important high-level cognitive function of the human brain, requiring interaction among multiple brain regions. Revealing differences between children's large-scale functional brain networks for reading tasks and those of adults helps us to understand how the functional network changes over reading development. Here we used functional magnetic resonance imaging data of 17 adults (19-28 years old) and 16 children (11-13 years old), and graph theoretical analyses to investigate age-related changes in large-scale functional networks during rhyming and meaning judgment tasks on pairs of visually presented Chinese characters. We found that: (1) adults had stronger inter-regional connectivity and nodal degree in occipital regions, while children had stronger inter-regional connectivity in temporal regions, suggesting that adults rely more on visual orthographic processing whereas children rely more on auditory phonological processing during reading. (2) Only adults showed between-task differences in inter-regional connectivity and nodal degree, whereas children showed no task differences, suggesting the topological organization of adults' reading network is more specialized. (3) Children showed greater inter-regional connectivity and nodal degree than adults in multiple subcortical regions; the hubs in children were more distributed in subcortical regions while the hubs in adults were more distributed in cortical regions. These findings suggest that reading development is manifested by a shift from reliance on subcortical to cortical regions. Taken together, our study suggests that Chinese reading development is supported by developmental changes in brain connectivity properties, and some of these changes may be domain-general while others may be specific to the reading domain.

Longitudinal Task-Related Functional Connectivity Changes Predict Reading Development

“…This research provides evidence that improvements in reading skill over time are predicted by the nature and degree of changes among connectivity patterns within the reading network. This is consistent with broader theories of neural development that stipulate cognitive performance improves as a result of optimized connectivity throughout the lifespan ( Casey et al, 2005 ; Bassett et al, 2009 ), and connectionist models of reading development that propose a shift in interregional dependency within the reading network ( Koyama et al, 2011 ; Liu et al, 2018 ).…”

“…Indeed, this is supported by recent research using a rhyming judgment task that shows a decrease in dorsal stream connectivity, responsible for phonological processing, is important for the emergence of ventral stream dependent orthographic processing ( Younger et al, 2017 ). Comparison of task-related functional connectivity show disparate regional activation for children and adults, with children showing greater temporal functionality associated with phonological processing, and adults a greater task-related sensitivity with reliance on occipital regions associated with orthographic processing ( Liu et al, 2018 ), which provides convergent functional evidence in favor of developmentally dependent changes across the reading network.…”

Dyslexia on a continuum: A complex network approach

“…Moreover, connectivity between the IFG and posterior task-selective regions was weaker in children compared to adults when completing rhyming and spelling judgment tasks [53]. Converging evidence suggests that as reading becomes more automated reliance shifts from phonological specific regions to visuo-orthographic regions; however, stronger connectivity between phonological processing units and higher-level cognitive control regions is associated with better rhyming judgment in both groups [55]. This shift from a reliance on phonology to a reliance of orthography appears to be slower in dyslexic readers [36, 37].…”

Neural bases of phonological and semantic processing in early childhood

“…However, this study recruited adolescents in a wide age range (9 to 19 years); thus, the specialization of the semantic reading route might be biased by an age effect. On the contrary, the studies in Chinese (Cao et al 2009;Liu et al 2018) report no significant difference between visual phonological and semantic decision-making tasks for children within the age range of 9-12 years, suggesting the topological organization of children's reading network is not specialized. They report activation in leftlateralized brain areas, including left middle frontal gyrus (MFG), left inferior frontal gyrus (IFG), left fusiform gyrus (FG), and right middle occipital gyrus (MOG) for both semantic and phonological decision-making tasks.…”