 Hey everybody, Dr. O here, in this video we're going to cover the limbic system. So we'll talk about the anatomy and the structure and then the function of the limbic system. But it's important to note this is a functional grouping. So all the parts of the limbic system, they function together, but they're not one structure. The limbic system is actually going to be all these different structures that are sitting right where the subcortical structure. So the things below the cerebral cortex meet the cerebral cortex. I like to say this is where our lizard brain is being connected to our human brain. So the parts of the limbic system that we're going to focus on here, we'll talk about the amygdala and you see here the cingulate gyrus and the hippocampus will be the three main ones we talk about. There are a couple more that I'll bring up at the end, the dentate gyrus and the parahippocampal gyrus, but they're not that big of a deal. So the amygdala, the cingulate gyrus and the hippocampus are the three key ones we're going to talk about here. So what does it do? I like to think of it this way. The limbic system is what gives our emotions and our fear so much power because it's the part of the brain that's involved in our behavioral and emotional responses, especially with things that are really important for survival. Think about things like the fight or flight response, caring for our young, feeding, reproduction, those kind of things. So the limbic system helps establish our emotional states and then also it links all these subconscious structures to our conscious mind and that works both directions. So that means that fear and other emotions can influence our thinking, but then on the flip side our thinking can hopefully influence fear and our emotions as well. And then another major function we'll talk about with the hippocampus is the limbic system plays a big role in memory, in memory storage and retrieval. And this is kind of, this is good news, bad news, right? You remember things that are really emotionally powerful. You remember things that are really bad. So hopefully you won't do them again in the future, right? You won't put yourself in that situation, but it also gives a lot of extra strength to our fear-based memories. Bad memories stick with us in a way that other memories don't seem to. All right, so I put this image up here just to show you that the limbic system is tightly connected to our prefrontal cortex and that is what makes us human, right? This is what, so fear and emotion drives us and it also, but it also drives our conscious decisions. So when you, for example, when the amygdala there senses fear, it's going to actually decrease the functioning of your prefrontal cortex. So your thinking gets foggy and it's hard to make good clear decisions when you're scared, when your emotions are running high. So you may see this called the elephant and the rider, but I'm not going to go through that right now. But if you ever hear anybody talking about the elephant and the rider, they're basically talking about the limbic system and your instinctual parts of your brain are the elephant, which is, which is driving, you know, driving you forward. The human brain, the prefrontal cortex would be the rider and our job is to try to influence this emotional instinctive brain. We cannot overpower it. This limbic system is very, very powerful. All right, so the parts here, you have the amygdala, main thing here is emotional states, motivation, these types of things. It does play a role, though, in memory consolidation. When you think memory, though, I want you thinking hippocampus, but the amygdala is important in, in fear-based memories and really emotional memories. This is why we remember the really bad stuff the most, sadly. So amygdala just think fear, emotions, motivation, and then also these fear-based memories. The cingulate gyrus is kind of a neat one because there's been a lot of research done on this because we all have different, different amounts of cingulate gyrus and it can influence our behavior. So a big picture here is what I like to think of, you know, you could say the cingulate gyrus, it helps regulate our behavior. So when something bad happens, maybe somebody cuts you off in traffic, you might have an instinct, right? You might have an instinct for some sort of violent outbursts like road rage or emotional outbraces. So cursing someone, flipping them off, you know, wanting to do harm to them. Well, those, those initial impulses strike us all. But then as this information travels through the cingulate gyrus, your other, the other parts of your brain get to weigh in like, oh, you wouldn't really like it in prison and you don't want to leave your family and you really don't want to hurt somebody over something like that. So this, so while information travels through the cingulate gyrus, it helps to regulate your behavior. So if your cingulate gyrus works well, is functioning well, then you'll be less impulsive, you'll be less prone to violent outbursts. You know, some studies have even shown that serial killers and people like that, people that do actually do things like road rage and hurt other people, they may have smaller cingulate gyruses, which mean they do, they're, they're going to act on these initial impulses in a way that you and I don't. So the cingulate gyrus helps to regulate aggressive behavior and outbursts and that's plenty there. The hippocampus, so the hippocampus, the word actually means seahorse because of what it looks like. You can't see it right here, but when you hear hippocampus, I want you thinking memory consolidation. That's how short-term memories are moved into long-term storage. So, so the entire limbic system plays a role in emotion or in memory, sorry, but the hippocampus is the primary place where your typical memories are going to be consolidated. It also seems to play a role in the type of memories that help us with navigation, like spatial memories as well. The last two, not a big deal, but I just want to note them. The dentate gyrus, what's cool about this, it hasn't been shown in humans, but in mammals from rodents to primates. The dentate gyrus has been shown to have adult neurogenesis, meaning nerve, so a part of the brain that actually does regenerate. And that's very, very rare. So that's kind of the only cool thing about the dentate gyrus. And then the parahippocampal gyrus just plays a role in all the other things we've talked about there, so nothing new to add. So that's your limbic system, this functional system that connects our really instinctual behavior-driven brain to our human brain, the prefrontal cortex and the rest of the cerebrum, playing large roles in our behavior and our emotions. One last thing, you know, I've done a lot of research and done a lot of presentations on sleep. This is something where when you're tired, the connection between the two really gets severed. So you make worse decisions when you're tired. You're way more likely for violent outbursts and aggressive behavior when you're tired. I know what I say all the time is the reason I need to sleep as a parent than a husband is that when I'm tired, I react to my environment. I am like a caged animal. I react to my environment in ways that I'm not proud of. So I know that if my temper gets a little short, these types of things, I know I have to get some more sleep because when I'm well rested, I respond to my environment. Whatever's happening around me, I make conscious, you know, clear decisions about it and I respond to my environment. So to me that the reacting to the environment is the limbic system, responding to the environment is your cerebrum, what makes us human. So when you're tired, you're not as good of a human being as when you're not basically. Okay, so that's the limbic system. I do hope this helps. Have a wonderful day. Be blessed.