 Last summer, me and my husband went tracking and we were so slow that we fell far, far behind from the group that we went with and soon we realized that we were all alone and we were lost. I started to panic. I was so scared that some wild animal will come out of nowhere and would eat us. On the other hand, my husband was super thrilled. He was like, Yay, we will be, we will be finding our roots ourselves and it will be a whole different adventure. Well, thankfully that day we came back home safe. But the thing that stayed with me was how differently me and my husband reacted to the same situation. Well, upon some Google research, I found out that it was all the play of the limbic system. A system made of various small parts in our brain which is responsible for our emotions and memory. And that's the reason I have made so many icons of different emotions here, including a brain that indicates memory. Well, the word limbic comes from a Latin word which means border or edge. And it is called so because it sits in the edge of two different parts of the brain. One is the neocortex and the other is the brainstem and it sits somewhere in the border of the two. Now, this limbic system is not an isolated part of the brain. They are all interconnected to all different parts. Behavior or response of one particular part, it triggers the response in other parts of the brain. And also there is a confusion as to which parts to be included in the limbic system and which parts to not. And researchers have yet not reached the conclusion. But there are certain parts of the brain which are inevitable from the limbic system. They are the thalamus, hypothalamus, amygdala, and the hippocampus. Now, the picture you see on the screen is just half the brain. We have longitudinally sectioned it so that we can look at the limbic system. But in reality, if we consider the entire brain, all these parts that I mentioned are actually present in pairs except for the hypothalamus. And to judge the positions of these different parts of limbic system better, we will make our own limbic system. We will start with the thalamus. As you can see, it is present in a pair. And below the thalamus, we have a small kidney bean shaped hypothalamus. Don't go by its size because it is also the most powerful one. Edges into the hypothalamus, we have two amygdali. And attached to the amygdali, we have hippocampus. Hope this helps you understand their locations better. Now let's dive into their functions. And we will begin with the thalamus. Thalamus is the relay center of the brain. It is the part where all the inputs from the sensory organs are gathered and the thalamus decides which information should go where. So the information that we gather through sight, through hearing, through touch, it is all sent to the thalamus first and the thalamus forwards it to the other parts of the brain for logical reasoning. But remember, the sense of smell do not follow the same path. It has its own separate root to reach the brain. So apart from the sense of smell, all other senses reach the thalamus first and the thalamus forwards it to the processing parts of the brain. So if I had to use just one word for the actions of the thalamus, I would say it takes care of the consciousness, the consciousness that we have through our sense organs. Okay, moving forward, let's talk about the hypothalamus. Hypo means underneath and it is underneath the thalamus. That is why it's called hypothalamus. Now you must have studied about the hypothalamus in the endocrine system, in the autonomic nervous system and now again in the limbic system. So the hypothalamus has got multiple functions. But talking in context with the limbic system, it takes care of the body's homeostasis. That means it maintains a proper body temperature. It takes care of the person's sleep and wake cycle, of the sexual drive of a person, of the appetite and also a sense of satisfaction that one achieves after maybe completing a work or having food. It is all derived by the hypothalamus. And during an emergency if triggered by the amygdala, hypothalamus also initiates the flight or fight response and also because of its role in the endocrine system due to some hormones, it also impacts the mood and behavior of a person. So this was about the hypothalamus. Now moving ahead to amygdala. Amygdala or plural amygdali are responsible for a lot of emotional responses like fear, anxiety, sadness and aggression. So if the amygdala of a person is damaged, he will not be able to feel any of these emotions. So I read a case study about a woman whose amygdala was surgically removed and then she was made to watch a horror movie and was taken to a haunted house but she could not feel a thing. Now this story might motivate you to get rid of your amygdala and become the fearless one in this world but before you dive deep into that thought, let me give you another scenario. Imagine you got rid of your amygdala and you visited a zoo and now that you don't fear anything, you open the cage of the lion and you went straight inside to have a closed look. What will happen? You will be killed. So having an amygdala, a proper functioning amygdala is essential for survival. Now we understood how important amygdala is for survival but having an overstimulated amygdala can cause phobias. Phobias is when a person is scared of something which is not at all harmful, something which do not have the potential to kill the person but even then the person is super scared of that particular thing or that particular situation. Now there are so many phobias in this world that you could literally Google about phobia for, let's say, write anything that's present on your desk. And you will get a name for it because there are so many phobias and it is because the overstimulation of amygdala it initiates a full-blown threat response towards something that is not harmful. Now before you start associating amygdala with all these unpleasant emotions let me show you a few positive aspects of amygdala. Amygdala helps in the alertness of a person. It is responsible for the alertness that we have and maybe that day during trekking it was my amygdala that kicked in really bad alerting me from any potential danger that could arise if we go all alone in the jungle, right? On the other hand, the amygdala of my husband was pretty much calm that day and he could go ahead without fear. Apart from alertness, it also helps us in emotionally connecting with others and I need not tell you how important emotional connection is. Imagine a friend walked up to you and was narrating his sad story and you just sit there feeling nothing. How terrible will that be, right? So all the emotional connections that we feel or the emotional touch that our conversations get it is all because of the amygdala. And it was particularly essential in the ancient times because people then would stick together in a tribe because they were emotionally connected to each other. If they were not emotionally connected and they would have stayed all alone then they could be easily predated upon, right? So this was about amygdala. Now let's move ahead to hippocampus. The word hippocampus is taken from a Greek word which meant sea horse and it is because of the shape it has, the curved shape which pretty much looks like a sea horse. Now this hippocampus is crucial for the memory. It converts short-term memory into a long-term memory. Now there is a very famous case study on a man called Henry Molisson whose hippocampus was surgically removed and after the surgery, scientists found that he was unable to learn any new words, facts or remember new faces. But he retained memories prior to the surgery. So this helps scientists understand that this part of the brain do not store memories but only help to convert them into a long-term memory. Now if you are a fan of Bollywood movies, you must have watched Ghajani. Here the protagonist of the movie was beaten badly and his brain was damaged and he lost his short-term memory. But he did remember stuff prior to the head injury. So maybe it was his hippocampus that was badly damaged when he was beaten up, right? So this was all about the four important parts of the limbic system. It is a system essential for the sanity of an individual and it also contributes to the continuation and the preservation of an individual.