Philip V. Bayly

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In humans and many other mammals, the cortex (the outer layer of the brain) folds during development. The mechanics of folding are not well understood; leading explanations are either incomplete or at odds with physical measurements. We propose a mathematical model in which (i) folding is driven by tangential expansion of the cortex and (ii) deeper layers(More)
The morphology of axonal and dendritic arbors in the immature cerebral cortex influences the degree of anisotropy in water diffusion. This enables cortical maturation to be monitored by the noninvasive technique of diffusion tensor magnetic resonance imaging (DTI). Herein, we utilized DTI of postmortem ferret brain to quantify regional and temporal patterns(More)
Animal models with complex cortical development are useful for improving our understanding of the wide spectrum of neurodevelopmental challenges facing human preterm infants. MRI techniques can define both cerebral injury and alterations in cerebral development with translation between animal models and the human infant. We hypothesized that the immature(More)
Genetically modified mice represent useful tools for traumatic brain injury (TBI) research and attractive preclinical models for the development of novel therapeutics. Experimental methods that minimize the number of mice needed may increase the pace of discovery. With this in mind, we developed and characterized a prototype electromagnetic (EM) controlled(More)
During human brain development, the cerebral cortex undergoes substantial folding, leading to its characteristic highly convoluted form. Folding is necessary to accommodate the expansion of the cerebral cortex; abnormal cortical folding is linked to various neurological disorders, including schizophrenia, epilepsy, autism, and mental retardation. Although(More)
Rapid deformation of brain matter caused by skull acceleration is most likely the cause of concussion, as well as more severe traumatic brain injury (TBI). The inability to measure deformation directly has led to disagreement and confusion about the biomechanics of concussion and TBI. In the present study, brain deformation in human volunteers was measured(More)
Folding of the cerebral cortical surface is a critical process in human brain development, yet despite decades of indirect study and speculation the mechanics of the process remain incompletely understood. Leading hypotheses have focused on the roles of circumferential expansion of the cortex, radial growth, and internal tension in neuronal fibers (axons).(More)
Rapid deformation of brain tissue in response to head impact or acceleration can lead to numerous pathological changes, both immediate and delayed. Modeling and simulation hold promise for illuminating the mechanisms of traumatic brain injury (TBI) and for developing preventive devices and strategies. However, mathematical models have predictive value only(More)
In this study, the magnetic resonance (MR) elastography technique was used to estimate the dynamic shear modulus of mouse brain tissue in vivo. The technique allows visualization and measurement of mechanical shear waves excited by lateral vibration of the skull. Quantitative measurements of displacement in three dimensions during vibration at 1200 Hz were(More)
The motion of flagella and cilia arises from the coordinated activity of dynein motor protein molecules arrayed along microtubule doublets that span the length of axoneme (the flagellar cytoskeleton). Dynein activity causes relative sliding between the doublets, which generates propulsive bending of the flagellum. The mechanism of dynein coordination(More)