salience disruption that shifts network dynamic towards the DMN in order to resolve withdrawal effects in the brain (Sutherland et al., 2012). Our observations seem to lack the ECN emphasis previously found by alcohol studies (Weiland et al., 2014). Only one ECN RSN embracing the left IPL showed significant hypo-connectivity with the left IOG. In our data, reduced ECN-visual connectivity resembles the sensorimotor-visual hypo-connectivity pattern in smoking and drinking subjects. The similar hypo-connectivity effect in ECN and sensorimotor areas may be related to the hypothesis of a network dynamic that shifts away from exogenous information processing (Fedota and Stein, 2015). In addition, results support the existence of a putamen-thalamus dysfunction that might be involved in nicotine craving behavior as previously observed in (McClernon et al., 2009). The different effects observed in our study indicate that alcohol, nicotine and their interaction affect the brain in particular ways that may help understand the specific or interactive mechanisms of substance use on brain function. These results also show that concurrent use of substances must be carefully controlled when studying substance specific effects on the brain.
