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[Altered effective connectivity of insula in nicotine addiction].

OBJECTIVE
To explore the changes of effective connectivity associated with insula in different nicotine addiction sessions so as to understand its role and function.


METHODS
A total of 20 smokers received the scans of resting-state functional magnetic resonance imaging in two sessions of different conditions: smoking abstinence followed by smoking satiety. Group ICA was initially adopted to obtain the independent component patterns. And paired t-test of ICA spatial patterns revealed such regions of interest as insula, parahippocampus, precuneus, dorsal anterior cingulate cortex, rostral anterior cingulate cortex, supplementary motor area and ventromedial/dorsolateral prefrontal cortex and effective connectivity from insula to other regions was examined subsequently with GCA.


RESULTS
In smoking abstinence, insula showed increased effective connectivity with dorsolateral prefrontal cortex, ventromedial prefrontal cortex, dorsal anterior cingulate cortex, rostral anterior cingulate cortex, precuneus; while in smoking satiety, there was no significant changes for effective connectivity. Referring to graph theory analysis, the insula was a causal output source in smoking abstinence.


CONCLUSION
Insula is a signal output node in smoking abstinence, with its interoceptive function monitoring the change of physiological state of body when in smoking abstinence, and then integrating each brain activity to produce subjective consciousness so as to facilitate addiction.