Memory in the Brain and the Hippocampus!

Good morning and happy February. I just have a few minutes between my morning sessions here at the office, so I thought I would jump on. And what I wanted to do is talk a little bit about the brain and also memory. So last month I was talking about this area of the brain that most people have never heard of, called the insula, that allows us to feel into internal experiences in the body. And I want to spend just a few minutes now, while I have the time to talk a little bit about memory and the brain, specifically focusing on the hippocampus, which is oftentimes called the memory center of the brain. Even though memory is in a lot of different places in the brain, but it's an area of the brain that's involved in explicit, declarative, autobiographical memory. Basically this just means the stuff that you can actually remember when you try to remember it, as opposed to implicit memory, which would be more stored in like the amygdala or basal ganglia, that system. So what I want to say about the hippocampus today is I want to say a little bit about its relationship to stress and how it can be impacted during stress. So you may have noticed that when you get really stressed out or anxious, or maybe if you're a clinician and you treat anxiety or other stress related conditions, that a lot of times people will come in and they'll complain about not being able to remember stuff. So well, I've had it happen many times actually, where somebody comes in and they say, oh my gosh, I think I have Alzheimer's, I think I have early onset dementia because I'm just not remembering stuff very well. Now the upside to that, the silver lining here is that if it is something like Alzheimer's, then you probably don't realize it is probably people around you are noticing some of the impairments that are happening, but you probably don't notice them yourself. So usually I tell folks, if you're actually noticing this, then it's probably not that, but it might be something else going on. And usually right away I'm thinking about some sort of stressor related disorder or maybe an anxiety disorder. So here in a nutshell is what is happening in the hippocampus when you get stressed. So the hippocampus is this little area of the brain. It's actually pretty deep in the brain, the amygdala, which is thought to be like that fear center, that center of the brain that detects danger. It's fear fairly, it's actually fairly close to that. It's a limbic structure, which means it's part of that limbic system or the emotional brain. And the way it works is that it consults oftentimes with the amygdala to determine whether or not something is dangerous based on past experience. It's also an area of the brain that's active. If you're trying to remember something, like you're trying to remember your birthday party from last year or something like that, it's kind of an explicit memory system. Bessel van der Kolk will also refer to this as the timekeeper of the brain, because this is the area that's responsible for putting the timestamp on your memories. So that when you remember something from the past, you have this sense that it's not happening right now. It's kind of hard to put in words, but you have this vague sense that it happened a long time ago or maybe last year, a short time ago, something like that. So it gives us this sense of time sequencing in our lives. So what can go wrong with this? Okay, so what can go wrong with the hippocampus is that when you get stressed, what happens is you have about 1400 biochemical reactions that happen in like a split second. So you have these chemicals surging through your body and surging through your brain. And it so happens that one of those chemicals is actually a structure stress chemical called cortisol. You may have heard of this before. And cortisol is great at kind of helping us mobilize our resources and, you know, go into fight or flight or freeze when we need it to help us with those things, those kinds of responses. But here's the thing about cortisol. We know if we have too much of it for too long, then we tend to have some medical issues, some stress related medical issues, and we can also have some psychological issues. So I'm not going to go into that quite as much today. But what I want to tell you about the hippocampus, this little memory center in the brain, is that it's kind of unusual in the way that it's built. Because it just so happens that the hippocampus is covered in cortisol receptors. Like all over, it's covered in cortisol receptors. Not a lot of areas of the brain are like this, okay, so it's like covered in this. So because it's covered in these receptors, what it means is that when cortisol is released and it's flooding through your brain and the body, the hippocampus is like a magnet to the cortisol and it all goes to the hippocampus and it floods the hippocampus. So again, this is when you're stressed or you're anxious, or of course, if you're experiencing like a traumatic event, that would be true as well. So anytime you're stressed, that cortisol increases, it floods through the hippocampus and it saturates the hippocampus. What this does to the hippocampus functioning is it makes it so that it can't fully activate. So it means that it doesn't fully light up when it needs to. So when you're trying to encode memories or remember things, it just doesn't quite light up the way we would like it to, which means we can't remember things super well. Okay. So that's one thing very broadly that happens. So in the short term, what this means is that things like eyewitness testimony are going to be somewhat controversial. Accurate memories are not always totally accurate, of course, they're never totally accurate anyway. But they're less accurate sometimes. Sometimes. And when they're encoded, when we're under stress, sometimes we can also lack the timestamp. So if the hippocampus is not working correctly, sometimes it does not put that timestamp on the memory. And what that means is that instead of remembering some really stressful or traumatic things as happening in the past, we experience them as though they're still happening in the present. So we don't remember stuff, we end up reliving stuff. This is largely a hippocampus problem. And again, this is because of that cortisol that's flooding it and making it so that it can't work properly. So in the short term that, that can be what happens. Where we also get into trouble, though, is not just with short term flooding of the cortisol to this area, but long term flooding of the cortisol and the hippocampus. So let's say you're under long term chronic stress. You may not be releasing as much cortisol. So it may not be flooding the hippocampus quite to the same degree. But even a fairly low level of cortisol is going to begin to impact the hippocampus over time. So what this is going to look like is long kind of longer term memory complaints and memory issues. So that's the relationship between these two things. So I don't want you to sit there and get really stressed out about being stressed out because, you know, you're thinking to yourself, oh my gosh, If I get too stressed out, it's going to under activate this area and eventually it can actually atrophy that area. So it's going to like the cortisol, like eats away at this brain area. And I know that as I'm telling you that that probably gets you really stressed out, which just makes the whole thing worse. Right? The more stressed you get, the more cortisol, the more it impacts the hippocampus. So don't want to present this as total doom and gloomy. Really good silver lining to this whole thing is that the hippocampus is one of the areas, one of the few areas of the brain where we know. I was going to say where we think, but we know that neurogenesis is possible, which is the generation of new neurons or taking old fragments or dendrites of damaged neurons and actually building from those old fragments that have been damaged by the cortisol. So we actually can heal our brain in this area. So what I'm going to do, it's actually time for me to run into session again, but I'm going to in the near future also write a blog telling you some ways that we can help neurogenesis happen in our own brains, in our hippocampuses, so that we don't have to have that atrophy of this area of the brain because, you know, we've just been stressed too long. So ways to help strengthen, strengthen and even rebuild the hippocampus. So stay tuned and thanks for listening and hope you have a good day. Bye.