Mapping the dominant direction of the structural network of the macaque prefrontal cortex reveals its hierarchical structure

Various models have been put forth to explain the modus operandi of the prefrontal cortex (PFC). One such model postulates an hierarchical anterior-posterior gradient within the PFC[1]. The structural architecture of the macaque PFC seems to support such a model. The hierarchical model is characterized by the principles of asymmetry, i.e. more anterior regions (region 10) have more efferents towards posterior ones (region 8) than vice versa, and contiguity, reciprocal connections are “valid” among spatially adjacent regions. However, a formal quantification of the principles and the predictions of such an “asymmetry based hierarchical”(ABH) model is lacking. We thus aimed to perform such a quantification and also relate the ABH with another concept of hierarchy based on the laminar patterns of the PFC connections (LBH) [2].