Microstructural underpinnings and macroscale functional implications of temporal lobe connectivity gradients

Abstract

The temporal lobe is implicated in higher cognitive processes and is one of the regions that underwent substantial reorganization during primate evolution. Its functions are instantiated, in part, by its complex layout of structural connections. This study identified low-dimensional representations of structural connectivity variations in human temporal cortex and explored their microstructural underpinnings and associations to macroscale function. We identified three eigenmodes which described gradients in structural connectivity. These gradients reflected interregional variations in cortical microstructure derived from quantitative MRI and post-mortem histology. Gradient-informed models accurately predicted macroscale measures of temporal lobe function. Gradients aligned closely with established measures of functional reconfiguration and areal expansion between macaques and humans, highlighting the important role evolution has played in shaping temporal lobe function. Our results provide robust evidence for three axes of structural connectivity in human temporal cortex with consistent microstructural underpinnings and contributions to large-scale brain network function.

Marmoset Brain Mapping V5: an Anatomical and Connectivity Atlas of the Cerebellum

“…The topography, which shows roughly sensorimotor to trans-modal hierarchical changes, has been reported in brain cytoarchitecture, connectivity, and gene expression pattern 33,41,43,45,47 . The diffusion embedding method has proven useful for revealing the topographical pattern by recovering a low-dimensional spatial representation (functional gradients) from high-dimensional functional connectivity data 27,33,34,48 . Based on the diffusion embedding, our results and previous studies 25,26 revealed a similar functional gradient for the intra-cerebellar and the cerebello-cerebral functional connectivity of the human brain.…”

“…Previous human studies have revealed that the cerebellar cortex shows distinct topographic patterns of intrinsic functional connectivity more relevant to its functional domains than to the anatomical lobular parcellations 22,25 . To reveal the functional connectivity pattern of the marmoset cerebellar cortex, we calculated the functional gradients by analyzing the intra-cerebellar functional connectivity and the cerebellocerebral connectivity using diffusion map embedding 27,33,34 .…”

“…Based on our recently published resting-state fMRI resource (MBMv4) of the marmoset 15 The diffusion map embedding was used to estimate the functional-gradient patterns of the cerebellum 33,34 . Similar to a previous study on gradients of the human cerebellum 25 , we analyzed the functional gradients on two types of connectivity: 1) the intra-cerebellar functional connectivity that included only the vertices of the cerebellar cortex, emphasizing the intrinsic organization of the cerebellar cortex; and 2) the functional connectivity between the cerebellar cortex and the cerebral cortex, emphasizing the cerebello-cerebral communications.…”

“…The correlation between cerebellar ROIs and voxels of the cerebral cortex was calculated to form the matrix of cerebello-cerebral functional connectivity. The diffusion map embedding method was applied to these matrices by the BrainSpace 34 , which nonlinearly dimensionality reduced the matrices into several orthogonalized gradients accounting for as much data variance as possible. The gradient analysis was performed on population-averaged correlation matrices and on the correlation matrices of each marmoset to examine the individual variabilities for each gradient.…”

Functional divergence between the two cerebral hemispheres contributes to human fluid intelligence

“…We identified vertexwise hemispheric functional gradients for each hemisphere on the 10k cortical surface, providing a more detailed and gradual transition than in our previous work (23). Specifically, two sets of the top 10 gradients were extracted from individual left and right hemispheres (37). All individual hemispheric gradients were subsequently functional aligned through Procrustes rotation to a template representational space derived from the group-level left-right averaged functional connectivity (FC) profiles (Fig.…”