Structural alterations in whole-brain networks are driven by complex dynamics at the level of cells, including the disappearance or rewiring of neuronal synapses, fluctuations in myelin content, and the variable states of astrocytes and microglia. Disentangling cell-type specific signatures using accessible tools like in vivo MRI, and determining how these microstructural signatures vary across individuals, is crucial for advancing our mechanistic understanding of brain microstructure differences—and ultimately brain health—across the lifespan. To achieve this, a more precise ground truth mapping of brain networks and their cellular composition is required, utilizing specialized analytical techniques. My lab addresses this challenge by working across dimensions of resolution, MRI field strength, and data types to identify key features for tracking brain health in various conditions. Our past and ongoing projects have included atypical development in children and young people, models of infectious disease, and older age.