Archives
cetrimonium bromide Several recent neuroimaging studies have
Several recent neuroimaging studies have used longitudinal measurements of neural activity to test for neurocognitive changes over development (Ordaz et al., 2013; Paulsen et al., 2015). Longitudinal designs have critical advantages over cross-sectional designs. For instance, previous studies demonstrated important individual differences in developmental trajectories that can be overlooked in cross-sectional designs (Koolschijn et al., 2011; Ordaz et al., 2013; Shaw et al., 2013). Furthermore, longitudinal designs have increased power to detect developmental change, because testing within-individual changes reduces error related to cohort differences (Fjell et al., 2010; Koolschijn et al., 2011). In the current study, neural changes in frontoparietal cortex activity were examined by testing whether frontoparietal activity during feedback learning follows a linear pattern (i.e. monotonic development over time, no adolescent-specific changes), a quadratic pattern (i.e., adolescent-specific effects) or a cubic pattern (adolescent-emergent; e.g. stable levels during childhood, steep changes in adolescence and stabilization in adulthood) (Braams et al., 2015; Somerville et al., 2013). Our longitudinal approach allows for a more specific test of the different hypotheses concerning the pattern of developmental change in frontoparietal areas.
Besides investigating age-related patterns of neural activity, a second goal of this study was to investigate other factors influencing time-related changes in frontoparietal activity in addition to age. There are multiple processes closely related to advancing age that may drive changes in neural activity. That is, an increase in age could be the sole factor explaining time-related increases or decreases in activity, but other factors might also play a role. The factors investigated in this study were task performance, working memory and structural cetrimonium bromide development. Task performance has been shown to influence neural activity, and there is evidence that a portion of developmental changes attributed to advancing age are related more to changes in performance (Church et al., 2010; Dumontheil et al., 2010; Koolschijn et al., 2011). Here we tested whether performance on a feedback learning task partly explained changes in neural activation over time. Working memory has previously been argued to be a core prerequisite for cognitive development (Case, 1992) and cognitive control functions (Huizinga et al., 2006), and as such was investigated as an important contributor to changes over time in neural activity during feedback learning. That is, we aimed to study whether a portion of changes in neural activity during feedback learning was explained by individual differences in working memory. A final factor that was investigated is cortical thickness. Several cross-sectional studies have suggested a link between functional activity and structural gray matter in adults (Harms et al., 2013; Hegarty et al., 2012) and children (Dumontheil et al., 2010; Lu et al., 2009; Wendelken et al., 2011). It is likely that developmental changes in neural activity are at least partly influenced by structural development of these brain regions, although the longitudinal relation between structural maturation and development of brain function is not well understood.
Taken together, in this study, we tested developmental trajectories of activation in the frontoparietal network during feedback learning in a large longitudinal fMRI sample across a wide age range (N=208, 8–27 years) with a two year interval between the first and second time point (see Peters et al., 2014a,b). Our aims were (1) to examine growth trajectories of core areas in the frontoparietal network (DLPFC, SMA, ACC and SPC) and to define the shape of age-related changes, (2) to test the additional contributions of task performance, working memory and structural development to changes over time in neural activity for feedback learning.
Methods