Experimentally validated three-dimensional finite element model of the rat for mild traumatic brain injury.

The aim of our work was to expand on the knowledge concerning mild Traumatic Brain Injuries (TBI), by combining numerical modeling and animal experiments within a joint approach. A three-dimensional finite element model of the rat brain and braincase was developed, and experimental acceleration pulses were applied. Pulse data were obtained from tests conducted using anesthetized rats, subjected to coronal plane rotational acceleration loadings of varying amplitudes and durations, aimed to generate mild TBI. Times of loss of consciousness were obtained. Biomechanical response parameters generally associated with TBI (stresses and strains) in the three anatomical regions, i.e., hypothalamus, thalamus and parietal cortex were analyzed. While the parameters correlated well with changes in injury severity linked to peak rotational acceleration, they were relatively insensitive to the pulse duration or times of loss of consciousness. As a consequence, new stress-time and strain-time metrics were computed, and these metrics were more efficient in predicting changes in injury severity associated both with acceleration characteristics and loss of consciousness outcomes in all three anatomical regions controlling the aforementioned behavior. Results of our analysis tend to show that time-related metrics may be more suited for the explanation of mild TBI than commonly used peak metrics in the three anatomical regions of the brain.