Aberrant Global and Regional Topological Organization of the Fractional Anisotropy-weighted Brain Structural Networks in Major Depressive Disorder

Background： Most previous neuroimaging studies have focused on the structural and functional abnormalities of local brain regions in major depressive disorder （MDD）. Moreover, the exactly topological organization of networks underlying MDD remains unclear. This study examined the aberrant global and regional topological patterns of the brain white matter networks in MDD patients. Methods： The diffusion tensor imaging data were obtained from 27 patients with MDD and 40 healthy controls. The brain fractional anisotropy-weighted structural networks were constructed, and the global network and regional nodal metrics of the networks were explored by the complex network theory. Results： Compared with the healthy controls, the brain structural network of MDD patients showed an intact small-world topology, but significantly abnormal global network topological organization and regional nodal characteristic of the network in MDD were found. Our findings also indicated that the brain structural networks in MDD patients become a less strongly integrated network with a reduced central role of some key brain regions. Conclusions： All these resulted in a less optimal topological organization of networks underlying MDD patients, including an impaired capability of local information processing, reduced centrality of some brain regions and limited capacity to integrate information across different regions. Thus, these global network and regional node-level aberrations might contribute to understanding the pathogenesis of MDD from the view of the brain network.

Quantum anomalous Hall effect in two-dimensional Cu-dicyanobenzene coloring-triangle lattice

Metrics details Abstract Magnetic two-dimensional(2D)topological insulators with spontaneous magnetization have been predicted to host quantum anomalous Hall effects(QAHEs).For organic topological insulators,the QAHE only exists in honeycomb or Kagome organometallic lattices based on theoretical calculations.Recently,coloring-triangle(CT)lattice has been found to be mathematically equivalent to a Kagome lattice,suggesting a potential 2D lattice to realize QAHE.Here,based on first-principles calculations,we predict an organometallic CT lattice,Cu-dicyanobenzene(DCB),to be a stable QAH insulator.It exhibits ferromagnetic(FM)properties as a result of the charge transfer from metal atoms to DCB molecules.Moreover,based on the Ising model,the Curie temperature of the FM ordering is calculated to be around 100 K.Both the Chern numbers and the chiral edge states of the semi-infinite Cu-DCB edge structure,which occur inside the spin-orbit coupling band gap,confirm its nontrivial topological properties.These make the Cu-DCB CT lattice an ideal candidate to enrich the family of QAH insulators.