Key result
Smoking is linked to reduced effective connectivity from the PCC and right IPL to mPFC.
Cross-Sectional (n=28)
No
p-value: p=0.032
Smokers exhibit disrupted effective connectivity in the default mode network, specifically reduced connectivity from the posterior cingulate cortex and right inferior parietal lobule to the medial prefrontal cortex, suggesting a functional disconnection underlying addiction.
Smoking-DMN dysconnectivity association is hypothesis-generating; leaves open causality and precludes practice change without longitudinal confirmation.
Prefrontal and parietal cortex, including the default mode network (DMN; medial prefrontal cortex (mPFC), and posterior cingulate cortex, PCC), have been implicated in addiction. Nonetheless, it remains unclear which brain regions play a crucial role in smoking addiction and the relationship among these regions. Since functional connectivity only measures correlations, addiction-related changes in effective connectivity (directed information flow) among these distributed brain regions remain largely unknown. Here we applied spectral dynamic causal modeling (spDCM) to resting state fMRI to characterize changes in effective connectivity among core regions in smoking addiction. Compared to nonsmokers, smokers had reduced effective connectivity from PCC to mPFC and from RIPL to mPFC, a higher self-inhibition within PCC and a reduction in the amplitude of endogenous neuronal fluctuations driving the mPFC. These results indicate that spDCM can differentiate the functional architectures between the two groups, and may provide insight into the brain mechanisms underlying smoking addiction. Our results also suggest that future brain-based prevention and intervention in addiction should consider the amelioration of mPFC-PCC-IPL circuits.
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Tang et al. (2016) conducted a cross-sectional in Smoking addiction (n=28). Smoking vs. Nonsmokers was evaluated on Differences in effective connectivity among default mode network nodes (mPFC, PCC, L-IPL, R-IPL) (p=0.032). Smoking was associated with reduced effective connectivity from the posterior cingulate cortex and right inferior parietal lobule to the medial prefrontal cortex compared to nonsmokers (p=0.032).
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