Regional characterization of the dynamic mechanical properties of human brain tissue by microindentation

Abstract

Traumatic brain injury (TBI) is an important cause of mortality and morbidity worldwide. Finite element models of the human head are used widely to simulate TBI loading scenarios, to improve the understanding of the mechanical pathogenesis of head trauma. The reliability of such computational models depends strongly on the accuracy of the mechanical properties of the different components of the brain. Here, we address the shortage of high-quality data on the region-specific properties of human brain tissue at dynamic rates and under large deformation. We mechanically characterized 12 different regions of the human brain including cerebrum, cerebellum and brainstem through n=595 force-relaxation experiments with a custom-built micro-indentation apparatus. We imposed up to 35% strain at 10/s strain rate, i.e. values representative for TBI. Pronounced differences in mechanical response were observed across the brain. This work both highlights and addresses the need to assign accurate, region-specific viscoelastic properties to different brain regions in finite element head models.