to the DMN as smokers exhibited stronger anti-correlation. These results and the fact that smokers were abstinent for at least 3 hours before scanning seem concordant with the hypothesis that nicotine withdrawal might promote an enhancement in DMN functioning and shift network dynamics away from task positive areas in order to maintain homeostasis in a brain suffering from withdrawal effects (Sutherland et al., 2012). In contrast, hypo-connectivity in smokers was found within the reward system including the brain areas of thalamus and putamen. The thalamus is a main hub of information in the brain important in the study of nicotine addiction. It has been found that smoking reduces glutamate (one of the major neurotransmitters in the mammalian brain) in the thalamus (Durazzo et al., 2015; O’Neill et al., 2014), thus affecting its information relay function. Thalamic activity has been previously found to be correlated with FTND scores (Rose et al., 2007) and has been mentioned in many studies as part of affected brain networks (Hahn et al., 2007; Hong et al., 2009; Janes et al., 2012). Both putamen and thalamus have been found to be abnormally active during smoking cues presentation to abstinent smokers (McClernon et al., 2009). Lack of
