Fig. 1.

Different plausible hypotheses of the effective connectivity pattern in the network mediating emotional face perception. Forward and backward intrahemispheric endogenous connections were set between OFA and FFA, and between FFA and amygdala (Amy). Additional, reciprocal interhemispheric connections were set between bilateral OFA, bilateral FFA and bilateral amygdala. Driving inputs comprised all faces, regardless of the emotional valence, and were allowed to drive neuronal activity in the left and right OFA. While endogenous connectivity and driving inputs were identical for all models, they differed in the assumed modulatory influences of emotion processing. Emotion processing could either modulate (i) forward (models 1&4), (ii) backward (models 2&5), or (iii) forward and backward intrahemispheric connections (models 3&6). Additionally, emotion processing (i) modulated (models 1–3) or (ii) did not modulate interhemispheric connections among homotopic brain regions (models 4–6). Systematically varying all combinations resulted in six distinct models. Finally, we also included a “null” model (i.e., model 7, not shown) where none of the intra- and interhemispheric connections was modulate by emotion processing.