The purpose of this study is to examine the influence of the brain shape factor on the strain distribution in deep brain by comparing the distribution of the three differently-shaped head physical models in rotational impact. One of the brain model used in this study was shaped actual human brain including the cerebral sulci, gyri and ventricles. Another was no-ventricle brain model with sulci. The other was simple-shaped brain model removed theose structures. All models were induced to rotational acceleration by impactor collision causing 4500 rad/s^2 peak angular acceleration with 8 ms pulse duration. After rotating 60 degree, all models were decelerated with 1500 rad/s^2 peak, 30 ms duration. As the results of the experiments, the maximum principal strain at brainstem in no-ventricle model was larger than the actual model. And the strain in simple model was small compared with the others. Therefore the cerebral ventricles had a strain-relieving effect on deep brain. On the other hand, the sulci had a strain-increasing effect on deep brain.
