Mechanical characterization of human versus porcine brain tissue under large strains.

Due to the limited availability of human body donor brains, biomechanical testing for material parameter identification is often done on animal tissue. So far, only one study has compared human and animal brain tissue under indentation, which provides data for the small strain regime and hence is not applicable to large-strain scenarios like surgery. Here, we compare the large-strain behavior of human and porcine brain tissue from four anatomical regions (corona radiata, putamen, cerebellar white matter, and brain stem) under compression, tension, and shear. Our results from cyclic loading tests show that samples from the cerebral white matter behave similarly for both species under all loading modes, whereas samples from the cerebellar white matter are similar only under compression-tension, but not shear loading. For regions with mixed gray and white matter, we observe a softer behavior for porcine samples under all loading modes. The stress relaxation behavior is similar in both species, except for samples from the putamen. These findings indicate that porcine brain tissue can be used as an alternative for human tissue to study general tissue mechanics. However, since the porcine brain is much smaller and therefore, less brain regions can be characterized mechanically, human brain data are still needed to calibrate full brain simulation models.