No abstract

During human brain development, cortical gyrification, which is believed to facilitate compact wiring of neural circuits, has been shown to follow an inverted U-shaped curve, coinciding with the two-stage neurodevelopmental process of initial synaptic overproduction with subsequent pruning. This trajectory allows postnatal experiences to refine the wiring, which may manifest as endophenotypic changes in cortical gyrification. Diving experts, typical elite athletes who commence intensive motor training at a very young age in their early childhood, serve ideal models for examining the gyrification changes related to long-term intensive diving training. Using local gyrification index (LGI), we compared the cortical gyrification between 12 diving experts and 12 controls. Compared with controls, diving experts showed widespread LGI reductions in regions relevant to diving performance. Negative correlations between LGIs and years of diving training were also observed in diving experts. Further exploratory network efficiency analysis of structural cortical networks, inferred from interregional correlation of LGIs, revealed comparable global and local efficiency in diving experts relative to controls. These findings suggest that gyrification reductions in diving experts may be the result of long-term diving training which could refine the neural circuitry (via synaptic pruning) and might be the anatomical substrate underlying their extraordinary diving performance.

Calbindin-containing γ-aminobutyric acid (GABA)ergic interneurons in the prefrontal cortex (PFC) have been found to play an important role in working memory (WM) and their malfunctions have been linked to psychiatric disorders. A recent genome-wide association and expression-SNP study indicated that the RAB2A gene was associated with the density of prefrontal calbindin-positive neurons, suggesting this gene may have a broader influence on prefrontal structure and function. Using multimodal MRI and behavioral tasks, the current study investigated the effect of RAB2A on prefrontal morphology, resting-state functional connectivity, and WM performance in a large sample of healthy Han Chinese subjects. Results showed that the RAB2A AGCAAA haplotype was associated with improved WM accuracy, increased cortical thickness in the left inferior frontal gyrus, and decreased functional connectivity between the left inferior frontal gyrus and the left dorsolateral PFC. Our findings provide consistent evidence supporting the effect of RAB2A on the structure and function of the PFC and related cognitive functions. These results should provide new insights into the neural mechanisms underlying the GABAergic genes' role in WM as well as its dysfunction.

Unsaturated soil is a form of natural soil whose pores are filled by air and water. Different from saturated soil, the microstructure of unsaturated soil consists of three phases, namely, the solid phase (soil particle), vapor phase, and liquid phase. Due to the matric suction of soil pores, the hydraulic and mechanical behaviors of unsaturated soils present a significant dependence on the moisture condition, which usually results in a series of unpredictable risks, including foundation settlement, landslide, and dam collapse. Microbial-induced calcite precipitation (MICP) is a novel and environmentally friendly technology that can improve the water stability of unsaturated soft or expansive soils. This paper reviews the microscopic mechanisms of MICP and its effect on the mechanical properties of unsaturated soils. The MICP process is mainly affected by the concentration of calcium ions and urea, apart from the concentration of bacteria. The moisture-dependent properties were comparatively analyzed through mechanical models and influence factors on the experimental data among various unsaturated soils. It suggests that the variations in resilient modulus and permanent deformation are strongly related to the extent of MICP applied on unsaturated soils. Finally, the problems in the MICP application, environmental challenges, and further research directions are suggested.

No abstract