SUMMARY
# Selective Neuronal Vulnerability to Aging — Mapping Why Specific Neurons Degenerate
## Background and Rationale
The phenomenon of selective neuronal vulnerability to aging represents one of the most fundamental and poorly understood aspects of brain aging and neurodegeneration. While the human brain contains approximately 86 billion neurons, only specific subpopulations exhibit dramatic age-related decline, creating distinct patterns of vulnerability that underlie age-associated cognitive chan
METHODOLOGY NOTES
1. **Human Brain Sample Collection**: Obtain post-mortem brain tissue from neurologically normal individuals across age groups (n=60): young adults (20-35 years, n=20), middle-aged (45-65 years, n=20), and elderly (75-95 years, n=20). Collect samples from vulnerable regions (substantia nigra, basal forebrain, entorhinal cortex layer II) and age-resistant regions (primary visual cortex, cerebellum) within 6-hour post-mortem intervals. 2. **Single-Cell RNA Sequencing**: Perform snRNA-seq on 50,000+ cells per region using 10x Genomics Chromium platform. Process fresh-frozen tissue using optimized nuclear isolation protocols for aged human brain. Generate comprehensive transcriptomic profiles of individual neurons. 3. **Laser Capture Microdissection**: Use LCM to isolate specific neuronal subtypes (dopaminergic, cholinergic, glutamatergic) from vulnerable and resistant regions. Extract RNA/protein for targeted molecular analysis. 4. **Proteomics and Metabolomics**: Perform mass spectrometr