Mapping the Hierarchical Layout of the Structural Network of the Macaque Prefrontal Cortex

Abstract

A consensus on the prefrontal cortex (PFC) holds that it is pivotal for flexible behavior and the integration of the cognitive, affective, and motivational domains. Certain models have been put forth and a dominant model postulates a hierarchical anterior-posterior gradient. The structural connectivity principles of this model dictate that increasingly anterior PFC regions exhibit more efferent connections toward posterior ones than vice versa. Such hierarchical asymmetry principles are thought to pertain to the macaque PFC. Additionally, the laminar patterns of the connectivity of PFC regions can be used for defining hierarchies. In the current study, we formally tested the asymmetry-based hierarchical principles of the anterior-posterior model by employing an exhaustive dataset on macaque PFC connectivity and tools from network science. On the one hand, the asymmetry-based principles and predictions of the hierarchical anterior-posterior model were not confirmed. The wiring of the macaque PFC does not fully correspond to the principles of the model, and its asymmetry-based hierarchical layout does not follow a strict anterior-posterior gradient. On the other hand, our results suggest that the laminar-based hierarchy seems a more tenable working hypothesis for models advocating an anterior-posterior gradient. Our results can inform models of the human PFC.

Situating the default-mode network along a principal gradient of macroscale cortical organization

“…1, showing that these hierarchies are not isolated local phenomena; they emerge as elements of a spectrum that begins within input-output systems and ends with the DMN. Notably, our results are consistent with a recent modification of the rostral-caudal processing gradient described within lateral frontal cortex (59,60). Rather than the more rostral areas located farther along in the processing hierarchy (18,19), two distinct hierarchical gradients of temporal-and feature-related abstraction converge in middle lateral prefrontal cortex (60).…”

Individual differences in visual motion perception and neurotransmitter concentrations in the human brain

“…Our further speculation is based on the fact that the BA 46 region of the PFC is located at the top of the anatomical hierarchy of the prefrontal areas [36,45]. As motion assimilation and contrast are perceived antagonistically (figure 1b), a final percept must be determined at a higher stage of visual motion processing.…”

Visuomotor Functions in the Frontal Lobe

“…Recent studies have refined our understanding of many details of the connectivity among frontal areas and between frontal and extrastriate visual areas; many new insights have been earned from quantitative methods and graph theory algorithms (Barbas & Rempel-Clower 1997;Medalla & Barbas 2006;Modha & Singh 2010;Markov et al 2013Markov et al , 2014Goulas et al 2014;Saleem et al 2014). Areas in the prefrontal cortex (PFC) form central nodes in the cortical network (Figure 2a).…”

“…Area 8A, which includes the FEF is the lowest lateral frontal area. Panel adapted with permission from Modha & Singh (2010) and Goulas et al (2014). Division into 10 levels is arbitrary.…”