A network approach to the topological organization of the Brodmann map

Abstract

Brain morphology is the result of functional factors associated with cortical areas, but it is also influenced by structural aspects due to physical and spatial constraints. Despite the noticeable advances in brain mapping, Brodmann's map is still used in many research fields that rely on macroscopic cortical features for practical or theoretical issues. Here, the topological relationships among the Brodmann areas were modeled according to the principles of network analysis, in order to provide a synthetic view of their spatial properties following a criterion of contiguity. The model evidences the importance of the parieto-temporal region in terms of biological burden and topological complexity. The retrosplenial region is particularly influenced by spatial constraints, and the cingulate cortex occupies a position that bridges the anterior and posterior topological blocks. Such spatial framework should be taken into account when dealing with brain morphology in both ontogeny and phylogeny.

A comprehensive anatomical network analysis of human brain topology

“…In the present study, we also detected the presence of the small‐world effect, which is most commonly discussed, within the broader field of neurology, in neural connectivity research. Nevertheless, this property applies to all networks, including models of macroscopic anatomical systems such as the one here presented (Bruner, 2022; Esteve‐Altava, Marugán‐Lobón, Botella, Bastir, & Rasskin‐Gutman, 2013; Rasskin‐Gutman & Esteve‐Altava, 2014). Regarding its morphology, the simpler geometry of regularity increases the cost efficiency of the brain in ontogeny and phylogeny.…”

“…In two preliminary studies, anatomical network analysis was used to identify spatial constraints that influence the morphology and morphogenesis of macroscopic brain regions according to the endocranial surface and Brodmann's map respectively (Bruner, 2022; Bruner et al, 2019). The present work aims to supply a more extensive topological understanding of the human brain's spatial arrangement as a whole.…”

“…When considering only the external brain regions (Bruner et al, 2019), the model suggests a separation between an anterior block, formed by the frontal lobe, and a posterior block, formed by the rest of the brain. When most areas are included from the lateral and sagittal regions (the Brodmann map; Bruner, 2022), the modular analysis reveals five clusters: prefrontal, parietal (including the paracentral regions), lateral temporal, deep temporal and occipito‐medial (occipital lobe plus restrosplenial and cingulate cortex) blocks. In the current analysis, the main separation concerns the superior (vault) and inferior (base) regions.…”

“…Namely, in this case, we can conclude that the antero‐posterior separation is a topological condition associated with the external regions only, while a superior–inferior gradient is present when the internal and subcortical regions are also considered. A mixed situation is associated when only the cortical areas are taken into consideration (e.g., Bruner, 2022). All these results are ‘true’, when referred to the different models employed.…”

“…The model also suggested that the lateral temporal cortex is particularly influenced by the general brain architecture, due to its longitudinal disposition, while the parietal cortex presented a low topological burden because of its peripheral location. The second study modelled the human brain's topology according to Brodmann's map, as well as introducing a version of the model with weighted edges (Bruner, 2022). This second study also found a separation between the anterior and posterior aspects of the brain, but here the cingulate cortex was the bridge between the two blocks.…”