Investigating Granule Cell Layer Volume after Mild Traumatic Brain Injury

Nana with computer display of TBI damage to cell

Students

College

Faculty

Professor Of Neuroscience/anesthesiology and Critical Care Medicine

Project Summary

This summer, the College Alumni Society Research Grant allowed me to collect data in the lab of Dr. Amelia Eisch for my honors thesis on the effect of mild traumatic brain injury on the volume of the granule cell layer in the mouse hippocampus. The hippocampus is a region in the brain that plays an important role in the formation and storage of memories. Mild traumatic brain injuries (mTBI), more commonly referred to as concussions, often cause problems with memory, which suggests that the hippocampus is affected by the injury.  In my project, I was looking at one part of the mouse hippocampus, the granule cell layer (GCL),  to see if an mTBI affects its volume. We used the Lateral Fluid Percussion Injury (LFPI) model, which is a rodent model of mTBI. The mice were split into two groups: the LFPI mice received the injury, and the sham mice were given the preparatory surgery without the injury. Five mice each from the sham and LFPI groups (10 total) were sacrificed 3 days after the injury while the rest of the mice (10 total) were sacrificed 31 days after the injury. Once the brains were removed, sliced, and stained so that the GCL could be seen, I used the Cavalieri Principle via a special software to estimate the volume. I found that at 3 days post-injury, the GCL volumes in the LFPI mice and sham mice were similar, indicating that the injury had not changed anything. At 31 days post-injury, the GCL volumes remained similar in the LFPI and sham mice. However, I did see that the volume of the GCL was lower in both groups of mice at 31 days post-injury, particularly in the hemisphere that had received the injury and in the total GCL volume. I therefore concluded that the mTBI did not change the volume of the GCL immediately after the injury. There may, however, be a decrease in GCL volume over time. I would need a larger sample size to determine if there is a decrease, and if it is due to the traumatic brain injury.

Through my project, I learned that basic science research is a complex endeavor, and your results may not provide clear cut answers to your questions. I am now able to appreciate and wrestle with these complexities. I have also gained a greater understanding of the time and dedication that full-time research takes.

This research project has enriched my Penn education by deepening my knowledge of the hippocampus. I had learned a bit about it in my classes, but my time in the lab has taught me even more about the anatomy and circuitry. I’ve also gotten to see how the methods I learned about are actually applied in the field. I’m grateful to CURF and the Eisch lab for giving me the opportunity to continue my research and learn so much this summer.