In sum, rsFC provides a useful tool for studying multifaceted neuropsychiatric diseases like addiction at a systems-level of assessment. To efficiently leverage the capabilities of this tool, stronger, model-driven approaches need to be utilized. To this end, we attempt to formulate a framework of dynamic large-scale network interactions derived from recent advances in intrinsic functional connectivity to explain the consequences of acute nicotine abstinence and attention enhancing effects of nicotine administration. Complementing an interoceptive monitoring role, emerging evidence implicates insula involvement in directing attention towards either internal or external stimuli by mediating dynamic activity between two large-scale brain networks, the default-mode network (DMN) and the executive control network (ECN). These networks associated with endogenously oriented processes and exogenously oriented attention, respectively, competitively interact during task performance, with suppression of DMN activity often associated with optimal behavioral performance. By modulating dynamic network activity, the anterior insula is hypothesized to expedite processing of the most homeostatically relevant stimuli arising from either internal or external events. During nicotine abstinence, the insula may track withdrawal-induced bodily sensations and in turn direct attention towards this
