Toward neurobiological characterization of functional homogeneity in the human cortex: regional variation, morphological association and functional covariance network organization

Abstract

Local functional homogeneity of the human cortex indicates the boundaries between functionally heterogeneous regions and varies remarkably across the cortical mantle. It is unclear whether these variations have the neurobiological and structural basis. We employed structural and resting-state functional magnetic resonance imaging scans from 482 healthy subjects and computed the vertex-wise regional homogeneity of low-frequency fluctuations (2dReHo) and five measures of cortical morphology. We then used these metrics to examine regional variation, morphological association and functional covariance network of 2dReHo. Within the ventral visual stream, increases of 2dReHo reflect reduced complexity of information processing or functional hierarchies. Along the divisions of the prefrontal cortex and posteromedial cortex, the gradients of 2dReHo revealed the hierarchical organization within the two association areas, respectively. Individual differences in 2dReHo are associated with those of cortical morphology, and their whole-brain inter-regional covariation is organized into a functional covariance network, comprising five hierarchically organized modules with hubs of both primary sensory and high-order association areas. These highly reproducible observations suggest that local functional homogeneity has neurobiological relevance that is likely determined by anatomical, developmental and neurocognitive factors and should serve as a neuroimaging marker to investigate the human brain function.

Individual differences in verbal creative thinking are reflected in the precuneus

“…Changes in cortical volume or thickness may be driven in part by alterations at the synaptic level, such as synaptic and neuronal pruning or regeneration processes, which may be reflected in patterns of functional connectivity. Additionally, the biological implications of 2dReHo indicate that functional segregation and integration within brain regions may be linked to corresponding anatomical variation (Jiang et al, 2014). In light of these findings, we concluded that local functional homogeneity of verbal creative thinking has neurobiological relevance and an anatomical basis.…”

“…curve is the maximum and minimum bending of the cortical surface at a given vertex; and folding index is a metric that quantifies the amount of folding overall on a surface (Jiang et al, 2014).…”

“…Functional homogeneity can also assess correlations with regional cortical characterizations, including surface area, cortical thickness, volume, and others (Jiang et al, 2014). Considering 2dReHo's high test-retest reliability and biological meaning (Jiang et al, 2014;Zuo et al, 2013), we selected brain regions resulting from 2dReHo investigations as regions of interest (ROI) and extracted regional cortical indicators for further structural analysis.…”

“…In particular, structural MRI studies have shown that increased grey matter within the precuneus and prefrontal gyrus is associated with individual differences in creative potential, as measured by divergent thinking tasks (Fink et al, 2013;Jauk et al, 2015;Takeuchi et al, 2010). Besides, previous evidence has found that decreased regional functional homogeneity in high-level association areas (e.g., anterior cingulate cortex, prefrontal cortex, and precuneus) and increased functional homogeneity in the primary somatosensory cortex are associated with attention performance (Jiang et al, 2014;. Therefore, in the present study, we hypothesized that creative performance would be related to decreased functional homogeneity in DMN regions, including precuneus, posterior cingulate cortex, and medial prefrontal cortex, and increases in functional homogeneity in other areas involved in somatosensory and perceptual processes.…”

Unraveling the Miswired Connectome: A Developmental Perspective

“…Recent work has applied these regional metrics to index developmental and aging phenomena in the connectome, as well as to index inter-individual variation in behavior and cognition (Mennes et al, 2011). One caveat is that, while potentially valuable for biomarker development, the neurobiological meaning of these regional measures is yet to be determined (see an initial effort in Jiang et al, 2014). …”