Petros Karamanides, COL ’26, Radnor, PA
For ten weeks this summer I conducted research as a member of the Eisch Lab at CHOP. Our translationally-relevant neuroscience research centers around the role of a critical brain region, the dentate gyrus, and how changes to it can alter cognition. The lab has a variety of projects using rodent models, including ketamine’s ability to ameliorate depressive symptoms, the role of the dentate gyrus circuitry in contextual memories involving substance use, and the effects of high-energy space radiation on hippocampal health.
My project, however, takes an in-depth look at how pattern separation, a critical aspect of our episodic memory necessary for distinguishing memories with many overlapping features, functions as a result of manipulations to inputs into the dentate gyrus. By inhibiting the axon terminals of upstream lateral entorhinal cortex neurons to the dentate gyrus during different memory stages (encoding, consolidation, and retrieval), we can gain mechanistic insights into the nature of pattern separation, an ability that is dysfunctional in various neurological disorders and diseases such as PTSD and Alzheimer’s.
I have been working on this project for over a year and continued with it this summer. I spent the first few weeks conducting the live mice experimentation. We utilized the spontaneous location recognition (SLR) test to assess mice’s pattern separation abilities with and without inhibition to a key circuit of interest during the retrieval phase of memory (the encoding and consolidation versions of the experiment have already been completed). Our goal is to observe if memory-stage-specific inhibition results in SLR task performance differences compared to a control group, indicating variation in pattern separation ability.
I followed this up by taking part in perfusing the mice and collecting their brains. We used optogenetics to inhibit the axon terminals of lateral entorhinal cortex fan cells, which required us to implant fiber optic cables bilaterally into the mice’s brains. Therefore, one of my principal goals this summer was to mount and stain slides of brain tissue to verify accurate optic fiber placement within the molecular layer of the dentate gyrus.
After analyzing fiber placements, I used a machine learning pipeline to evaluate the mice’s performance during the SLR task. The first part of the pipeline was SLEAP, which allows for frame-by-frame tracking of various labeled keypoints on the mice’s bodies. This keypoint data was then fed into SimBA, an open-source platform capable of drawing regions of interest (ROIs) atop various parts of the SLR arena. Overlapping the SLEAP tracking data with SimBA’s ROIs enabled me to precisely evaluate each mouse’s time spent in different parts of the arena. Statistical analysis was then completed to compare control versus inhibited group performance (preliminary results are ongoing).
I thank Penn Career Services for funding my research experience, and I am forever grateful to Dr. Amelia Eisch and Dr. Sanghee Yun for giving me the opportunity to be a part of such a fantastic team of neuroscientists. Being a member of the Eisch Lab has been one of the highlights of my experience as an undergrad and I am excited to continue our work this upcoming year.
This is part of a series of posts by recipients of the 2025 Career Services Summer Funding Grant. We’ve asked funding recipients to reflect on their summer experiences and talk about the industries in which they spent their summer. You can read the entire series here
