Acknowledgements The study was supported by the National Ins
The study was supported by the National Institute of Child Health and Human Development (NICHD) RO1 grant to Dr. Kramer and Dr. Hillman. We would like to thank the Biomedical Imaging Center for their help with data collection and the design of the ASL imaging protocol, in particular Ryan Larsen, Brad Sutton, Holly Tracy, and Nancy Dodge.
Introduction Episodic memory (EM) emerges and increases during childhood (e.g., Schneider and Pressley, 1997) and deteriorates in aging (e.g., Rönnlund et al., 2005). On the surface, children in middle childhood and older adults show comparable memory levels, with both groups performing worse than younger adults (Li et al., 2004). However, direct lifespan comparisons of neural correlates of EM are entirely lacking, leaving an untested assumption that neural mechanisms underlying memory in children and older adults are the same, given their similarities in performance (but see behavioral comparisons by Brehmer et al., 2007; Fandakova et al., 2013; Shing et al., 2008). Therefore, lifespan studies are strongly needed in the field of developmental cognitive neuroscience, which has tended to focus either on comparisons on the lower end (children vs. young adults) or the higher end (younger vs. older adults) of the developmental spectrum. Here, we examined the neural correlates of subsequent-memory effects (SME), defined as differences in fMRI activation between subsequently remembered and omitted trials during encoding, in 10–12 years old children, younger adults between 21 and 26 years, and older adults above 60 years of age. Our focus was to compare SME within the memory systems of the various age groups when they Talabostat mesylate operate successfully to form durable memory representation. According to the two-component framework of EM development, the ontogeny of EM reflects interactions between associative and strategic components (Shing et al., 2010; Shing et al., 2008; Werkle-Bergner et al., 2006). The associative component refers to binding mechanisms that integrate features of episodes into coherent representations (Treisman, 1996; Zimmer et al., 2006), and the strategic component refers to cognitive-control processes that aid and regulate memory functions (Simons and Spiers, 2003). In line with established conceptions of EM (Eichenbaum, 2002; Moscovitch, 1992; Simons and Spiers, 2003) and meta-analyses of fMRI studies on SME (Kim, 2011; Spaniol et al., 2009), we assume that the lateral PFC and MTL (particularly the hippocampus, HC) support strategic and associative components of EM, respectively. The HC and associated structures contribute to the formation of memory representations, particularly establishing associations between features (e.g., Davachi, 2006). Lateral PFC, on the other hand, supports cognitive control processes in service of memory (Fletcher and Henson, 2001), such as implementation of attention selection processes in the VLPFC and organization of information in working memory in the DLPFC (e.g., Blumenfeld and Ranganath, 2007). Both PFC and MTL undergo profound reorganization in childhood (Johnson, 2001; Nelson, 2001) and aging (Buckner, 2004; Cabeza et al., 2004). The structural integrity of PFC (particularly the dorsolateral regions) undergoes maturational changes well into adolescence. On the other hand, MTL regions mature at faster rates particularly in the first few years of life (Gogtay et al., 2006; Sowell et al., 2003). Therefore, we assume that successful memory formation in children should rely more on the associative component of MTL and less on the strategic component of PFC that is still developing (Ofen, 2012; Shing et al., 2010; but see Ghetti and Bunge, 2012). Thus far, results are mixed regarding MTL differences between childhood and young adulthood in SME, with some studies finding age differences (e.g., Ghetti et al., 2010) and others not (e.g., Ofen et al., 2007). This stands in contrast to the more consistent age differences found in PFC across development. Therefore, our empirical investigation will shed light on this topic.