BME Seminar: Dr. Assimina A. Pelegri - Finite Element Simulation of White Matter Micromechanics

Armour College of Engineering's Biomedical Engineering Department will host a seminar featuring Assimina Pelegri, Ph.D., Professor of Mechanical and Aerospace Engineering at Rutgers School of Engineering on March 27, 2015. Lecture topic will be Finite Element Simulation of White Matter Micromechanics.

Abstract

Investigation of potential mechanisms of brain injury requires the development of a micromechanical structural representation of the white matter. Here, we are considering a biological composite material model for the white matter, in which the undulated, reinforcing axons are embedded within a supportive tissue matrix comprised primarily of glia. The multiscale microstructural kinematic model captures the mechanical response of the brain tissue at axonal level, with the aim to provide accurate insight into a spatial location of the injury for medical treatment. Contemporary studies have indicated that axon fibers’ kinematics during simple elongation follows neither pure affine nor non-affine models, and their behavior changes according to the level of macroscopic, tissue stretch. At low levels of macroscopic strain, axon’s behavior is shown to be predominantly non-affine. As strain increases, the behavior becomes increasingly affine. It has been suggested, that the unusual microstructure of white matter, where there is little to no structural extracellular matrix but instead axons are connected to a cellular matrix of asctrocytes and myelinating oligodendrocytes at Nodes of Ranvier, is responsible for the atypical behavior, and that the transition from non-affine to affine behavior is caused by the recruitment of cellular cross-links. To model the atypical white matter behavior and to determine the mechanical properties of the brain tissue, we adopt composite mechanics and micromechanics principles as well as a finite element analysis to the biomechanical and microstructure interacting model. Currently this framework enables us to obtain the strain and stress field of the brain tissue and to evaluate axonal damage with proper damage thresholds. The presented model constitutes a basis that can be scaled up for structural tissue analysis in subsequent work. With the use of multiscale techniques in combination with relatively simple microscale models, it is possible to perform many calculations in a short amount of computational time, lowering both the cost and time investment for complex models, while preserving the microstructural characteristics present in damage initiation and evolution in white matter.