Space-independent community and hub structure of functional brain networks

Abstract

Coordinated brain activity reflects underlying cognitive processes and can be modeled as a network of inter-regional functional connections. The most costly connections in the network are long-distance correlations that, in the absence of underlying structural connections, are maintained by sustained energetic inputs. Here, we present a spatial modeling approach that amplifies contributions made by long-distance functional connections to whole-brain network architecture, while simultaneously suppressing contributions made by short-range connections. We use this method to characterize the long-distance architecture of functional networks and to identify aspects of community and hub structure that are driven by long-distance correlations and that, we argue, are of greater functional significance. We find that based only on patterns of long-distance connectivity, primary sensory cortices occupy increasingly central positions and appear more "hub-like". Additionally, we show that the community structure of long-distance connections spans multiple topological levels and differs from the community structure detected in networks that include both short-range and long-distance connections. In summary, these findings highlight the complex relationship between the brain's physical layout and its functional architecture. The results presented here inform future analyses of community structure and network hubs in health, across development, and in the case of neuropsychiatric disorders.

Hubs of long‐distance co‐alteration characterize brain pathology

“…In general, regions of long‐distance co‐alteration, such as the precentral and postcentral gyri and the insula, exhibit high consistency with the map of co‐activation centrality (Figure 4). Of note, precentral and postcentral gyri were recently found to be hubs of long‐distance connectivity when short‐rage connections are subtracted from the connectome (Esfahlani, Bertolero, Bassett, & Betzel, 2019). The values of co‐alteration distance are also correlated with those of co‐activation distance, highlighting the relation between pathology and connectivity.…”

Edge-centric functional network representations of human cerebral cortex reveal overlapping system-level architecture

“…We found evidence of a weak negative relationship between surface area and eFC (r = −0.056, p < 10 −15 ; Fig. 2d), suggesting that unlike traditional nFC, whose connection weights are more strongly influenced by spatial relationships of brain areas to one another [30][31][32], eFC is less constrained by the brain's geometry.…”

“…Next, we asked whether eFC exhibits any clear spatial dependence, as nFC is known to decay as a function of Euclidean distance [30,31]. This requires computing a spatial relationship between two pairs of brain regions; hence the traditional metric of Euclidean distance is insufficient.…”

A co-alteration parceling of the cingulate cortex

“…However, local co-alteration between different sections of the cingulate cortex itself (i.e. within-cingulate cortex) may have a role in shaping the whole brain MCN (Cauda et al 2020;Zamani Esfahlani et al 2020). In order to evaluate if local co-alteration was driving the observed effect, the node-wise clustering procedure was repeated after discarding the edges among root nodes.…”