That Neuroscience Guy - Neuroscience Bites-The Hippocampus

Episode Date: September 22, 2022

In this week's Neuroscience Bite, we narrow in on the Hippocampus and discuss its structure and functions.

Hi, my name is Olof Kurgolsen and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to another Neuroscience Byte. Now, you might have noticed in Season 3 we introduced the Bytes. And the idea was that on Sunday we'd do a full episode on like a big topic and then on Wednesdays we'd throw out this sort of quick hitter on just something short and interesting and we're going to continue that in season four and we're going to focus the bites primarily on brain regions and what they do and brain disorders and leave Sundays as they stand for larger more interesting topics. So on today's bite, the hippocampus. Now, we've talked about the hippocampus a lot,

but I just want to focus on the structure itself and what it does really quickly. Basically, the hippocampus is a bilateral structure. It means you've got one on either side. And at the front end, you have the amygdala. And at the back, it sort of comes together. And the easiest thing to think about the hippocampus is the gateway to memory. It's its primary role. So when we're encoding new memories, in particular episodic and semantic memories, our memories for facts and things that happen to us,

we see activation in this structure. And one of the biggest sort of proofs of that, and there's obviously a lot more, but there's a famous patient, H.M., who had damage to his hippocampus, and he lost the ability to form new memories. Now, what was interesting about H.M. was that he could recall old memories perfectly well, but he couldn't form new memories. And he could also only not form new semantic and episodic memories, but he could form new procedural memories. For instance, he could learn a new motor skill. So the hippocampus has been heavily tied to the formation of these new semantic and episodic memories. But like I just said, it's not involved in recall, at least after consolidation has occurred. Now, what is consolidation? Well, if you remember from our episode on memory, consolidation is the process where a memory

is sort of tied together. So if you think of what you did last night, there's a spatial location, there's sounds, there's smells, you know, there's words, there's objects, and the hippocampus sort of helps you tie all of those things together into a single memory. And while that memory is going through consolidation, basically firming up, if you will, the hippocampus plays a role in helping keep everything together. So it's playing a role in encoding the new memory, and it's also playing a role in consolidation, but it's not playing a role in memory formation. Now, there's one fine little piece on the hippocampus.

The hippocampus also seems to play a role in spatial memory. Basically, it helps encode a map of the world around us. Now, this is a relative map, so it doesn't have a map of the entire world in there. But say you're standing in your house, the hippocampus is helping you sort of form that map of where everything is in the house. And as you move through your house, then that relative map moves with you. So the hippocampus plays a massive role in memory formation and memory consolidation, not memory recall, but it also plays a role in spatial navigation. And one of my funny stories I always like to tell students that I'll share with you is I had one student on an exam who

basically wrote an entire essay on the role of the hippopotamus in memory formation. Anyway, that's it for this week's BITE. Remember, if you've got ideas, just follow me on Twitter and DM me or send an email to thatneuroscienceguy at gmail.com. And of course, there's our Etsy store where we're selling shirts. There's Patreon where you can support us. And please always listen to the podcast and subscribe if you can. It really helps out. My name is Olof Kregolsen, and I'm that neuroscience guy. I'll see you on Sunday for another full episode, and thank you for listening to this neuroscience bite.