Mouse brain elastography changes with sleep/wake cycles, aging, and Alzheimer's disease
Gary R. Ge,
Wei Song,
Michael J. Giannetto,
Jannick P. Rolland,
Maiken Nedergaard,
Kevin J. Parker
Affiliations
Gary R. Ge
The Institute of Optics, University of Rochester, 480 Intercampus Drive, Rochester, NY 14627, USA
Wei Song
Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
Michael J. Giannetto
Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
Jannick P. Rolland
The Institute of Optics, University of Rochester, 480 Intercampus Drive, Rochester, NY 14627, USA; Department of Biomedical Engineering, University of Rochester, 204 Robert B. Goergen Hall, Rochester, NY 14627, USA; Center for Visual Science, University of Rochester, 361 Meliora Hall, Rochester, NY 14627, USA
Maiken Nedergaard
Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA; Center for Translational Neuromedicine, University of Copenhagen, Blegdamsvej 3B, 2200-N, Denmark; Corresponding author at: Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
Kevin J. Parker
Department of Biomedical Engineering, University of Rochester, 204 Robert B. Goergen Hall, Rochester, NY 14627, USA; Department of Electrical and Computer Engineering, University of Rochester, 500 Computer Studies Building, Rochester, NY 14627, USA; Department of Imaging Sciences (Radiology), University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA; Corresponding author at: Department of Biomedical Engineering, University of Rochester, 204 Robert B. Goergen Hall, Rochester, NY 14627, USA.
Understanding the physiological processes in aging and how neurodegenerative disorders affect cognitive function is a high priority for advancing human health. One specific area of recently enabled research is the in vivo biomechanical state of the brain. This study utilized reverberant optical coherence elastography, a high-resolution elasticity imaging method, to investigate stiffness changes during the sleep/wake cycle, aging, and Alzheimer's disease in murine models. Four-dimensional scans of 44 wildtype mice, 13 mice with deletion of aquaporin-4 water channel, and 12 mice with Alzheimer-related pathology (APP/PS1) demonstrated that (1) cortical tissue became softer (on the order of a 10% decrease in shear wave speed) when young wildtype mice transitioned from wake to anesthetized, yet this effect was lost in aging and with mice overexpressing amyloid-β or lacking the water channel AQP4. (2) Cortical stiffness increased with age in all mice lines, but wildtype mice exhibited the most prominent changes as a function of aging. The study provides novel insight into the brain's biomechanics, the constraints of fluid flow, and how the state of brain activity affects basic properties of cortical tissues.
