Multi-subject search correctly identifies causal connections and most causal directions in the DCM models of the Smith et al. simulation study

Modeling Causal Relationship Between Brain Regions Within the Drug-Cue Processing Network in Chronic Cocaine Smokers

“…Chronic cocaine smokers and control participants were scanned while they took part in a visual cue exposure task that involved cocaine and neutral cues. We utilized a graph theoretical approach (Ramsey et al, 2010;Ramsey et al, 2011) to model the effective connectivity between 10 ROIs implicated in drug-cue processing. Consistent with our hypothesis, we found that, during exposure to cocaine cues, cocaine smokers showed a feed-forward effective connectivity pattern between the ROIs of the drugcue processing network (amygdala → hippocampus → dorsal striatum → insula → medial frontal cortex, dorsolateral prefrontal cortex, anterior cingulate cortex) that was not present when the controls viewed the cocaine cues.…”

“…When additional links no longer improve the BIC score, a backward procedure is initiated. The backward procedure removes links using an analogous method (Ramsey et al, 2011). It exploits the strength of association between variables and cross-subject redundancy to eliminate spurious connections that result from indirect measurement of brain activity.…”

“…It exploits the strength of association between variables and cross-subject redundancy to eliminate spurious connections that result from indirect measurement of brain activity. IMaGES produces reliable and stable estimates of interactions between different ROIs and was recently validated on 28 benchmark simulations (Smith et al, 2011) where it performed ⩾ 90% accuracy of detecting connections and on recall of orientations (Ramsey et al, 2011).…”

“…Data were collected from non-treatment-seeking cocaine smokers abstinent from cocaine for 72 h and similarly aged healthy controls with no cocaine experience while they were presented with cocaine and neutral picture cues. We used a graph theoretic approach (IMaGES: Independent Multisample Greedy Equivalence Search; Ramsey et al, 2010;Ramsey et al, 2011) utilizing a Bayesian search algorithm to model effective connectivity. We further examined whether the activation in individual ROIs and the effective connectivity strength between the brain regions in the drug-cue processing network were positively correlated with cocaine smokers' subjective craving ratings.…”

“…We further examined whether the activation in individual ROIs and the effective connectivity strength between the brain regions in the drug-cue processing network were positively correlated with cocaine smokers' subjective craving ratings. Note: IMaGES offers a considerable methodological strength to the earlier effective connectivity study (Ma et al, 2012), as rather than utilizing an a priori specification of an anatomical network model, IMaGES uses an exploratory search method that does not require a model to be prescribed in advance but rather can accommodate any number of brain regions (Ramsey et al, 2011).…”