Another study which used rs-fMRI also showed that smokers exhibited reduced connectivity in DMN regions and SR 1001 increased activity in the network related to attention after nicotine administration. These results showed that nicotine was associated with decreased activity in DMN regions and increased activity in the regions related to executive control and attention. Nicotine, which is a main chemical substance in cigarettes, can alter neural activity by activating nicotinic cholinergic receptors. However, information on the effects of acute cigarette smoking on neural circuits remains insufficient. Increasing evidence has shown that distributed neural circuits in the brain exhibit spontaneous activity while people are at rest. These slow frequency fluctuations in brain activity are temporally correlated within functionally related networks. Such evidence provides an opportunity to investigate and characterize neural circuit abnormalities in smokers. However, no study has investigated global functional connectivity patterns after acute cigarette smoking, although prior findings constitute important advances in our understanding of addiction to smoking. Such a global, data-driven approach is important to comprehensively examine the changes in global brain connectivity after acute cigarette smoking. Thus, the present study applied a recently developed GBC method that could identify specific nodes or hubs influenced by smoking. Moreover, whether the regions influenced by acute cigarette smoking are related to structural change remains unknown. Although previous studies have used VBM based on the RS 45041-190 hydrochloride analysis of regions of interest to explore the changes caused by chronic cigarette smoking to some extent, this method excludes some key regions. Therefore, a whole-brain analysis without an ROI-based hypothesis could be conducted to comprehensively investigate the structural brain changes in smokers and their relation to acute cigarette smoking. To examine the effect of acute cigarette smoking on brain function and its relation to the regions that show structural changes, this study compared the GBC of smokers when they abstained from smoking for 12 hours and after acute cigarette smoking and the GMV between smokers and non-smokers. On the basis of previous studies, we developed two a priori hypotheses. First, we hypothesized that smokers would display structural changes in prefrontal cortex and brain regions in DMN.