Neurodevelopmental changes in verbal working memory load-dependency: An fMRI investigation

Abstract

Development of working memory (WM) aptitude parallels structural changes in the frontal-parietal association cortices important for performance within this cognitive domain. The cerebellum has been proposed to function in support of the postulated phonological loop component of verbal WM, and along with frontal and parietal cortices, has been shown to exhibit linear WM load-dependent activation in adults. It is not known if these kinds of WM load-dependent relationships exist for cerebro-cerebellar networks in developmental populations, and whether there are age-related changes in the nature of load-dependency between childhood, adolescence, and adulthood. The present study used fMRI and a verbal Sternberg WM task with three load levels to investigate developmental changes in WM load-dependent cerebro-cerebellar activation in a sample of 30 children, adolescents, and young adults between the ages of 7 and 28. The neural substrates of linear load-dependency were found to change with age. Among adolescents and adults, frontal, parietal and cerebellar regions showed linear load-dependency, or increasing activation under conditions of increasing WM load. In contrast, children recruited only left ventral prefrontal cortex in response to increasing WM load. These results demonstrate that, while children, adolescents, and young adults activate similar cerebro-cerebellar verbal working memory networks, the extent to which they rely on parietal and cerebellar regions in response to increasing task difficulty changes significantly between childhood and adolescence.

Frontoparietal function in young people with dysthymic disorder (DSM-5: Persistent depressive disorder) during spatial working memory

“…In addition, patients showed less activation in regions of left vlPFC but also in dmPFC regions (BA 9) including dorsal ACC (BA 32) and the rostral ACC/frontal pole (BA 32/10) compared to typically developing participants. These regions all form part of a working memory network (Braver et al, 1997;Bunge and Wright, 2007;Ciesielski et al, 2006;O'Hare et al, 2008;Rottschy et al, 2012) that has previously been identified in patients with MDD to function abnormally (Bench et al, 1993;Harvey et al, 2005;Matsuo et al, 2007;Vasic et al, 2009;Walter et al, 2007b). In contrast, during the DMTS task patients showed increased activation of right posterior medial regions including the precuneus (BA7) and the PCC (BA31).…”

“…The precuneus is involved in a variety of processes including visuo-spatial imagery, episodic memory retrieval, self-processing and consciousness (Cavanna and Trimble, 2006). In addition, activation in this region has been found to depend on working memory load (Jahn et al, 2012;O'Hare et al, 2008;Stollstorff et al, 2010).…”

Constructivist developmental theory is needed in developmental neuroscience

“…4 However, in some studies researchers find a wider set of areas activated for children than in adults, 5 but in other studies the number of brain regions showing linear load dependency expands with increasing age. 6 Studies also show that children who exhibit better performance on cognitive tasks exhibit more activity in task-relevant brain regions, 7 although better performance is associated as well with fewer activated regions. 8 These results would benefit from a developmental framework that explains the global and less differentiated performance in younger children in terms of processing limits in mental/executive attentional capacity in younger children.…”

Working Memory and Corpus Callosum Microstructural Integrity after Pediatric Traumatic Brain Injury: A Diffusion Tensor Tractography Study

“…[17][18][19][20] Although the majority of functional neuroimaging research on WM has been conducted with adults, developmental studies suggest that children recruit similar cortical networks. [21][22][23][24][25][26] With regard to white-matter pathways underlying WM, the few studies conducted in healthy individuals have identified the involvement of both intra-and interhemispheric tracts. In addition to the superior longitudinal fasciculi (the major white-matter pathways connecting frontal and parietal cortices), [27][28][29][30] investigations of typically developing (TD) 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).…”