Functional connectivity of the affective network

Introduction: A recent fMRI-study [1] revealed automated affective processing to be reduced in medial orbitofrontal cortex (OFC) and bilateral amygdala (AMY) by increased concurrent cognitive demand. Here, we further characterize these regions, where affective processing is susceptible to cognitive modulation, with respect to their functional properties and connectivity patterns. Materials & Methods : Functional characteristics were obtained via behavioural meta-data of the BrainMap database; connectivity was characterized using meta-analytic connectivity modelling (MACM) of significant co-activation based on the same database. The identified connectivity patterns were then cross-validated by analysing resting-state correlations of the seed regions in an independent sample of 100 healthy subjects [50 female]. Results: All three seed regions co-activated with subgenual cingulum (SGC), precuneus (PCu), nucleus accumbens (NAcc) and the amygdala but not the OFC. This asymmetry indicates a hierarchical organization between AMY and the OFC. Analysis of resting-state connectivity confirmed significant coupling of all seeds with the SGC. The latter area moreover showed significant resting-state connectivity with all other regions implicated in the network connected to regions where emotional processing may be modulated by a cognitive distractor. Conclusion: Only the SGC shows robust task-based and task-free connectivity with regions where cognitive demand may modulate emotional processing. This relates well to the proposed involvement of this region in the pathophysiology of depression. Based on its functional profile and connectivity pattern, we suggest that the SGC might link autobiographic information [PCu], reward [NAcc], (reinforce) values [OFC] and emotional significance [AMY]. Such a role, in turn, may allow SGC to exert modulating influences on the latter two structures, modulating affective processing.

Literatur: [1] Kellermann, T.S., Sternkopf, M.A., Schneider, F., Habel, U. Turetsky, B.I., Zillles, K., Eickhoff, S.B. Modulating the processing of emotional stimuli by cognitive demand. SCAN (in press)