The present study examines age related differences in

The present study examines age-related differences in ventral striatal (VS) iFC and dorsal striatal (DS) iFC. This approach permits us to define and contrast the VS iFC and DS iFC networks, which are broadly linked to motivation and cognitive function, respectively (Haber, 2003), and to examine the influence of age on these systems. Resting-state iFC reflects phasic activity coupling between regions in an idle state. It is thought to provide a measure of both the history of use of a connection (more use may strengthen iFC; Buckner and Vincent, 2007) and the network\'s readiness to respond when challenged (Deco et al., 2011). Accordingly, we would expect generally a more strongly linked motivation network and a less strongly linked cognitive network in adolescents compared to adults. In this study, we examined iFC of the VS and DS across the whole Atglistatin in a sample of 106 healthy individuals spanning the ages of 9–44 years. In keeping with the extant literature, we expected to observe a segregation of functional connections for each striatal region regardless of age, such that DS would be more strongly connected with higher cortical association areas in the frontal and parietal lobes, while VS would be more strongly connected with the ventral prefrontal cortex (PFC), the amygdala, midbrain, and anterior cingulate cortex (Choi et al., 2012; Di Martino et al., 2008). Based on a dual neural systems model (Luciana et al., 2012; Steinberg, 2010) and strong evidence of a decline in VS activation and associated behaviors from adolescence into adulthood (Urosevic et al., 2012), we expected decreasing VS iFC and increasing DS iFC in the transition from adolescence to adulthood. The age at which striatal connectivity changes stabilize is assumed to be in the mid-twenties, given recent structural findings as observed throughout the brain (Giedd et al., 1999; Giorgio et al., 2008; Lebel and Beaulieau, 2011), but no studies have yet reported on striatal iFC in the transition from adolescence to early adulthood and into mid-adulthood.
Methods
Results
Discussion With respect to the first set of findings, striatal iFC across the whole sample cohered with other reports in adults on iFC patterns for the ventral striatum (VS) and dorsal striatum (DS) (Barnes et al., 2010; Choi et al., 2012; Di Martino et al., 2008). In line with the proposal of a dorsal–ventral striatal functional dichotomy (e.g., Fareri et al., 2008), these resting state studies in adults showed the DS to be more strongly connected with higher cortical association areas in frontal and parietal cortices, and the VS to be more strongly connected with ventral PFC, amygdala, midbrain, and anterior cingulate regions. Here, we showed that the direct comparison of DS iFC with VS iFC confirmed a preferential link of VS to ventral PFC, a region associated with stimulus value coding, emotion processing, and emotion regulation, and of DS to premotor/motor and parietal cortices, regions associated with motor and cognitive processes. This striatal iFC pattern parallels animal and human studies, broadly supporting a role of VS in motivation and emotion, and DS in motor and cognitive processes (see review, Fareri et al., 2008). Based on the dual neural systems model of motivated behavior in adolescence, according to which behavioral patterns evolve from two distinct maturational trajectories of motivation and cognitive function (Casey et al., 2008; Luciana et al., 2012; Steinberg, 2010), we predicted that age would differently affect VS iFC and DS iFC, i.e., our second set of findings. In line with predictions, age differentially impacted VS iFC and DS iFC, both qualitatively (location of the target regions), and quantitatively (direction of age effects). Qualitatively, age influenced VS iFC with bilateral anterior insula (extending into orbital frontal cortex) and dACC (extending into supplementary motor area), and DS iFC with pCC (extending into precuneus). Quantitatively, increasing age was associated with decreased VS–aIns and VS–dACC iFC, but with increased DS–pCC iFC.