Despite decades of research into neurotrauma prevention and treatment, the underlying mechanisms responsible for Traumatic Brain Injury (TBI) are not well understood. This is a result of inadequate mechanical characterization of the brain during the traumatic event (e.g. blunt head impact), the resulting biochemical cascade occurring that the cellular level, and the following neurocognitive deficits that evolve over time. Traumatic Axonal Injury (TAI) can lead to widespread white matter disruption and is believed to play a large role in the neurocognitive outcomes of TBI patients, but the ability to assess TAI in humans is limited since most pathologies are only observable post-mortem. This creates a fundamental problem in the TBI research community: how can the deformations of the brain be linked with the pathological outcomes if both are difficult to measure in living humans?
One solution to this problem is to evaluate TAI using animal models. Mouse models are commonly used together with blunt impact experiments to understand the pathologies and neurophysiological deficits related to TAI at different times post-injury, but the relationships between the initial impact, the subsequent motion of the mouse head, and the brain tissue distortion are not well established. To address this gap, this work examines the mechanics of the mouse brain during dynamic head rotations, which occur during head impacts in both the mouse and human. The first portion of the current work presents optical measurements of post-mortem mouse brain tissue during forced dynamic rotations. Using the experimental strain field measurements as a validation source, a Finite Element Model (FEM) of the mouse brain is developed in the second portion of the current work. The purpose of the mouse brain FEM is to calculate tissue strains that occur for a given rigid-body motion of the skull. In the third portion of current work, the FEM brain strain calculations are presented for a recent CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration) mouse experiments, and the axonal strains calculated by the model are compared TAI patterns observed in the experiments. The results here give insight to TAI mechanisms and thresholds, which is critical to better understanding TBI in humans
