This image is a close up of the rat hippocampus stained with a Nissl green stain (green color on the cell bodies of neurons with red for something else). The hippocampus has a unique structure that makes it stand out in all mammals- ours looks similar to this rat hippocampus, though it is located in a different part of the brain. Hippocampus is so named because it looks like a seahorse (now, this I don’t see, but they didn’t ask me when they were naming it).
Why do I bring up the hippocampus? Besides the awesome way it looks, it is my best friend as I enter into a 48hour exam this weekend. The hippocampus is responsible for the encoding of memories and also helpful in memory retrieval. As you study for exams (or in many cases, “cram”), you give your hippocampus quite a workout. It cycles information over and over, strengthening connections to help you remember facts, people, events, etc. A famous case of someone who lost hippocampus is HM (who died about a year ago)- he had it removed to stop terrible seizures, and after it was removed, he was completely unable to form new memories. He’s a pretty fascinating case, so I will talk more about him another time.