Brain Structure & Function最新文献

Development of gray and white matter tissue microstructure is critical for the emergence of sensory and cognitive functions. However, it is unknown how microstructural tissue properties of the human visual system develop in the first year of human life. Across 85 infant sessions, we used tissue relaxation rate (R₁) obtained using quantitative MRI to measure the longitudinal development of gray and white matter in brain areas spanning three visual processing streams: dorsal, lateral, and ventral, during the first year of life. R₁ in gray and white matter of all visual regions in the three processing streams increases postnatally, indicating microstructural tissue growth. R₁ increases faster between 0-6 months than 6-12 months, and faster in white matter than gray matter, with white matter R₁ surpassing that of gray matter after two months of age. Notably, this microstructural growth is hierarchical: across all streams, early visual areas are more mature at birth than higher-level areas but develop more slowly postnatally than higher-level areas. The exception is TO1 (MT), which is similar to V1: it is microstructurally more mature at birth and develops more slowly than neighboring areas. Overall, our findings provide the first comprehensive measurement of microstructural tissue growth in infancy across three visual processing streams and propose a new hypothesis that functional development of the visual cortex may follow the hierarchical pattern of microstructural development.

The pineal gland is an organ that undergoes significant degeneration with age, and these degenerative changes lead to numerous physiological alterations. This study investigated age-related molecular changes and Alzheimer's disease (AD)-associated pathology in the human pineal gland using histopathological analyses. This study collected a total of 54 human pineal gland specimens. Of these, 47 were categorised into five age groups: 0-20, 21-40, 41-60, 61-80, and 81-100 years. A further 7 cases with confirmed AD-related neuropathological changes were assigned to the AD group, while matched to 7 controls. Our findings revealed that pineal calcification was initiated as early as age 3, with progressive accumulation of calcification and accompanying cellular loss during the ageing process. A remarkable degree of sexual dimorphism was observed: female-predominant patterns included lipofuscin deposition and pineal cysts, whereas male-predominant characteristics included glial fibrillary acidic protein (GFAP) immunoreactivity and connective tissue expression. Significantly, phosphorylated Tau (P-Tau) and amyloid-beta (Aβ) have recently been detected within the pineal gland. Aβ deposition was positively correlated with age and was markedly elevated in individuals with AD. Furthermore, individuals with AD exhibited marked pineal cellular depletion compared with controls, alongside elevated GFAP expression. Cerebro-spinal fluid analysis further revealed significantly reduced melatonin levels in the AD cohort. Overall, this study systematically elucidated the multidimensional pathological features of the pineal gland during ageing and AD progression, and these findings may open new avenues for mechanistic exploration and precision medicine in AD.

The cellular connectivity of the human visual cortex remains largely uncharted, with most insights derived from animal models. A custom-designed tracer electrophoresis setup for polar lipophilic tracers enabled the reconstruction of fiber tracts in fixed postmortem human brains, visualizing their trajectories across previously unmapped distances, from cellular origins to axonal terminations. Applied to the occipital lobe, four pathways of the calcarine cortex were demonstrated: the stratum calcarinum, stratum proprium cunei, fasciculus transversus cunei, and the fasciculus transversus gyri lingualis. Specifically, axonal projections from granular and supragranular layers of the calcarine cortex were traced to the granular and supragranular layers of the cuneus, inferior, middle, and superior occipital, lingual, and fusiform gyri. Additionally, infra- and supragranular feedback projections from the prestriate cortex to the supragranular layer of the calcarine cortex were identified. These results extend previous descriptions by offering the first cellular-level evidence for intrahemispheric pathways in the human occipital lobe.