Major brain diseases (including neuroimmune diseases, neurodegenerative diseases, and cerebrovascular diseases) are leading causes of death and disability in humans. This research will gather brain imaging data from more than 10,000 participants across multiple age groups from multiple centers nationwide. Using standardized modeling methods, the investigators aim to establish normal brain imaging reference values for the Chinese population. (1) The study will reveal population-level patterns of brain structure changes and determine normal reference values for brain structure at different ages. (2) Non-invasive imaging methods will be applied to evaluate blood-brain barrier changes without the need for invasive procedures, establishing age-related permeability patterns and normal values in healthy populations. Additionally, functional magnetic resonance imaging (fMRI) will be combined to provide brain function indicators at various scales, creating comprehensive multi-dimensional function charts. (3) These brain structure and function charts will be applied to the individualized diagnosis and treatment of major brain diseases, including neuroimmune diseases (Multiple Sclerosis \[MS\], Neuromyelitis Optica Spectrum Disorders \[NMOSD\]), neurodegenerative diseases (Alzheimer's disease \[AD\], Parkinson's disease \[PD\]), and cerebrovascular diseases (Cerebral Small Vessel Diseases \[cSVD\]). This approach will facilitate early disease diagnosis and provide precise, individualized assessments of treatment efficacy and prognosis prediction. The established brain structure and function charts will be accessible via interactive websites or software, enabling real-time online data updates and individualized percentile outputs for brain structure and function. By inputting the target data, users can obtain individualized evaluation metrics for brain structure and function. The project's implementation and application hold great potential for broad use, promotion, and high translational potential.