Despite asking basically the same question (what is the developmental trajectory of dopamine-rich striatal circuitry in response to reward?), no two experimental paradigms described here are alike. While some focused on reward magnitude (Bjork et al., 2004; Galván et al., 2006), others manipulated reward probability (May et al., 2004; van Leijenhorst et al., 2009) or both (Ernst et al., 2005; Eshel et al., 2007). Further, in all but one study (van Leijenhorst et al., 2009), rewards were dependent on participants’ behavioral response including reaction time (e.g., Bjork et al., 2004) and response accuracy (Ernst et al., 2005; Galván et al., 2006; Eshel et al., 2007). Given known developmental differences in reaction time speed and accuracy ability, the difficulty of the task could have had large influence on neural activation patterns.
