Resting-State fMRI and Developmental Systems Neuroscience

Over the past several years, resting-state fMRI (rsfMRI) has emerged as a novel informative method for investigating the development of large-scale functional networks in the human brain. This method, first used to demonstrate coherent spontaneous low-frequency fluctuations in BOLD signal within the adult somatomotor system (Biswal et al., 1995), involves collecting functional imaging data from participants as they lay in the MRI scanner in the " resting state. " Participants are typically instructed to fixate on a cross-hair or to keep their eyes closed, and refrain from engaging in any particular cognitive task. This procedure allows for the assessment of resting-state functional connectivity using spontaneous synchronized fluctuations in BOLD signal to determine functional brain networks independent of transient task-induced correlations. The advantages of using rsfMRI in pediatric and clinical neuroscience are that functional brain organization can be examined independent of behavioral performance , and a full dataset can be collected in as little as 5 min (Van Dijk et al., 2009). The resting-state scanning procedure places a minimal cognitive burden on the participant , and requires relatively little time in the scanner compared to task fMRI studies, permitting neuroimaging data collection from very young populations without the need for sedation. For these reasons, developmental cognitive neuroscientists are increasingly incorporating resting-state fMRI into their research programs (see Uddin et al., 2010 for review). Functional connectivity measures derived from rsfMRI have been used to demonstrate age-related changes in the organization of networks across the whole brain (Fair et al., 2009; Supekar et al., 2009) as well as within specific systems (Kelly et al., 2009). The majority of research efforts have been directed at investigating the development of cortical systems, however cortical–subcortical and in particular thalamo-cortical connectivity has not been as well-studied. Thalamo-cortical changes are thought to occur throughout development (Giedd et al., 1999), yet very few studies have attempted to catalog these changes from childhood through adolescence and into adulthood. To address this, Fair and colleagues applied a novel method to characterize developing thalamo-cortical interactions. Using rsfMRI collected from children the investigators mapped thalamo-cortical interactions in a manner described in a previous publication from their group (Zhang et al., 2008). Briefly, known cortical anatomy was first used to identify functional boundaries in the thalamus. Next, regions of interest (ROIs) encompassing major cor-tical subdivisions (prefrontal cortex, motor/ premotor, somatosensory, parietal/occipital, and temporal) were identified. The average spontaneous rsfMRI signal generated within each cortical …