Brain mechanics and cognition: the role of rodent MR elastography in identifying cellular mechanisms

Magnetic resonance elastography (MRE) non-invasively quantifies brain tissue mechanical properties and has revealed an intriguing relationship between regional viscoelasticity and cognitive function across the lifespan. However, the biological basis of this relationship remains poorly understood as it is not yet clear which microstructural features generate the mechanical signal, whether brain mechanics are primarily structural or also dynamic on cognitive timescales, or how generalizable the current relationships observed in humans are across different brain regions and functions. We argue that resolving these questions requires preclinical MRE in rodents, where mechanical measurements can be linked directly to complementary analyses of cellular components and where structure and function can be experimentally perturbed. Although rodent MRE is well-established and has been productively applied to disease models, it has been little used in the contexts in which the human MRE-cognition findings are most concentrated including normal development and aging and cognitive variation in the otherwise-healthy brain. We review the human MRE-cognition literature, summarize what preclinical MRE has revealed to date, and outline experimental frameworks organized around the open questions through which rodent MRE could begin to clarify why brain mechanics relate to brain function.