Neurobiology & Neurophysiology
Ever wonder how that squishy wrinkled gook called a brain works? Well wonder no more! Janilee talks about the structure and function of neurons in a basic and easy to understand way. With images included within the transcription, you’ll end this episode feeling like a champ at neurology basics. Important topics conclude this episode, weaving in things previously discussed as well as Janilee sharing her exposure to antidepressants and how she found one that works for her.
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JANILEE: Welcome friends! You have found Just Janilee at the corner of “Am I crazy?” and “No, you're not. Here's the science to prove it.” This is VILIFIED. These Just Janilee episodes are mini episodes that occur in between the main ones where we go into depth about topics that are touched on in the main episode. Today we are talking about neurobiology and neurophysiology of neurons.
Breaking that down a little bit. Neurobiology is the actual physical structures. Neurophysiology is how they interact with each other. So biology, physiology, easy enough to remember. I am going to start off this episode by highly, highly recommending that you go and check out our website, vilifiedpod.com. In the top right-hand corner, you'll see an option for main episodes and JJ episodes. Under JJ episodes, you'll want to go ahead and scroll down until you find this episode, which is 6.5. The reason I'm suggesting this early on in the episode is because I'm going to be inserting images in the middle of all of the text where we have the transcription of the audio. These images are going to really help you understand the basis of what we're talking about today. Even if you're not a visual learner, I still think the images will help. But if you are not in a place where you can go and pull up the website right now, not to worry. I have tried wording these things out in ways that you can visualize them in your head and check out the website later or whatever it may be that you want to do.
So to begin, I'm going to tell you what I'm hoping we'll accomplish throughout the course of this episode. Yes, it sounds a little bit like a thesis statement, but I kind of had to restrict myself to enough information that will fit into this little half hour episode. When we're done, I'm hoping we have a very basic understanding of what a neuron is, how neurons interact with each other and why on earth we care. Why, for this podcast in reference to mental health, specifically, why do we actually care what the neurobiology and neurophysiology is of our nervous systems? In the episode that came out on Monday. So episode six, there was reference to our central nervous system and our autonomic nervous system and our sympathetic and our parasympathetic nervous system. Now, all of these being nervous systems, they deal with nerves and specifically with neurons.
We begin with describing the structure of a neuron. I like to think of neurons in terms of the brain, even though the nervous systems run throughout the entire body, I work best thinking about this as the mass of fleshy tissue gunk that just exists in our head behind our skull, has the two halves that are connected together there, kind of wrinkly: the brain. So what that tissue stuff is made up of is just a bunch of neurons. And I say a bunch when in reality the number is billions, approximately 86 billion. So we're talking numbers that are just crazy big to think about. So if they're all really densely compacted together, does that mean that the only thing that our brain is made up of is neurons? No. There is also this thing called glia or glial cells. Basically glial cells are the canvas that the neurons are on. The paint is so thick and so dense that we don't see the canvas. But it is important to know that there are actual glial cells there.
IMAGE ONE
So, starting with the structure of a neuron, let's picture a circle. The circle part of a neuron is called the soma, or sometimes the cell body. Now, this cell body contains what all cells contain nucleus, all of that stuff. For our purposes today, we just care that there's a circle. Now, if we're imagining a whole bunch of circles altogether, that's just a whole bunch of neurons. But if we take each individual circle, they actually have little things attached to them.
IMAGE TWO
Picture, for instance, child's drawing of a basic scene. You have the sky, you have the ground, you have a house, maybe some flowers. You have the sun in the sky and the sun is like a circle... I always did it in the corner of the page with those lines coming off of it. Even if it wasn't in this corner of the page, you have that circle with straight lines coming off of it. Now, somas have a whole bunch of these things that come off of it. Most of them are called dendrites. One of them is called an axon. Now, the dendrites are relatively short and the axon relatively long in comparison to each other. Now, they all have different purposes. So dendrites will receive information and send it to the soma. The soma will interpret that information and convey it to the axon. The axon will take that information and they will send it on to the next neuron.
IMAGE THREE
So if we’re picturing a bunch of these neurons all together, we're going to have a bunch of axons that line up with dendrites because that is how they communicate with each other. You don't ever have dendrites communicating with dendrites for a reason that we will get to later on. {Editor’s Note: this is due to the structure of the axon terminal versus the dendrite receptors.} But you always have axons that communicate with dendrites. Now, where an axon ends and a dendrite begins, they don't actually physically touch. There is a space between those two things – the axon of the neuron that is sending the signal and the dendrite of the neuron that is receiving the signal. And that space between those two is called a synapse or plural synapses.
IMAGE FOUR
So now let's talk about what happens in that synapse. The process of what happens in the synapse is called synaptic function. What happens from the axon that is sending information, right? And then something happens and the dendrite receives the information. So on the left side we have an axon. If we're reading from left to right, on the left side we have an axon, on the right side we have a dendrite. And in between the two are a whole bunch of tiny little chemicals called neurotransmitters. Now, you've probably heard of the term before. Neurotransmitters is a pretty common thing to hear when we talk about mental health specifically. Just to name off a couple of neurotransmitters that probably are familiar to you, you have Serotonin and Norepinephrine. Those two are the most common because there are specific types of antidepressant medications that base around those two neurotransmitters. We will talk about how those work later at the end of the episode. Some other ones that are probably familiar: dopamine, histamine, glutamine, endorphins. We talked about this about more specific ones in a previous Just Janilee episode if you wanted to go check those out for more. But essentially these neurotransmitters is how the neurons within our brain communicate with each other. Let's just picture something, anything happening. Our eyes see an image. Our eyes send that information to the brain. And what we choose to do as a result of that image. Let's say we see an image of a cookie. For our body to decide, “I want to pick up and eat the cookie”. Our brain has to say, “I receive the stimulus of an image of a cookie and I will then tell the arms to tell the hand to reach out and pick up the cookie and give it to the mouth.” All of that is happening in our brains as one neuron talks to another neuron talks to another neuron. Billions of neurons all talking to each other with these complex webs woven together. These chemicals are being released into this synapse between the two neurons, between the axon and the dendrite.
IMAGE FIVE
What does this all look like put together? Well, we have a sending neuron and a receiving neuron. All the information goes from a dendrite to the soma, to the axon to the synapse, to a dendrite to soma, to an axon, to the synapse to the dendrite to the soma, to the axon, to the synapse to the dendrites, et cetera. On and on and on until the signal completes sending and our body is able to act on by our nervous system reaching out, picking up the cookie and enjoying it. Assuming it's a tasty cookie, of course. So we have this entire neural network from beginning to end. We have dendrites that send information, and the soma basically just determines what do I want to do with this information? And where else does this information need to go? But it does beg the question, why don't the neurons just touch each other then? The answer to that is in how different parts of the neuron communicate.
IMAGE SIX
Dendrites receive those chemicals, those neurotransmitters, which are chemicals from the synapse and sends it to the Soma. The problem there is that the Soma functions with electricity. Yes, you have electricity inside your body, and so chemicals can't talk to electricity directly. So the dendrites, as they receive information, they translate that information into electrical signals. Then the soma decides what to do with the information, where to send it, what actions to take, and it passes that information still via electric means to the axon. Now, the axon will translate that signal back into chemicals that will then be expelled back into the synapse. So we're getting a lot of this circular… it's just a neural network over and over and over again. It's just same thing dendrite, soma, axon, synapse, dendrite, et cetera. But now we know that the dendrites and the axons, in addition to just sending signals to and from the soma, they also translate [the signals] from a chemical language into an electricity based language and vice versa.
IMAGE SEVEN
If we zoom in on the synapse and what actually happens there, remember, we have the neuron that's sending the information. We have that axon on the left, and we have the neuron that's receiving the information that dendrite on the right. If we zoom into that space where they don't actually touch each other, but the chemicals exist. And yes, the chemicals aren't part of the neuron. They're just part of that canvas that glial cells that we talked about at the end of the axon, what's sending the information, there's a whole bunch of I'll call them pouches. Now, these pouches just contain a whole bunch of neurotransmitters. These neurotransmitters are sort of like a home base where chemicals will just chill. These neurotransmitter chemicals just chill and hang out until the axon says, “Okay, I'm trying to send this message to the next neuron. You're up, dopamine. Head on out or you're up serotonin. Off you go.” Now, where do they end up going? They go through these little divots on the end of the axon that are kind of like tunnels. They're called axon terminals. Think of a terminal at an airport or a subway, bus station, transportation, essentially. Now these tunnel-like parts of the axon, it's just where these chemicals go. And when they get to the end, when they get to that light at the end of the tunnel, boom. They're in the synapse. They just chill there. Okay? They chill there and they will just stay there eventually until the dendrite receives the information.
Now this is an interesting kind of scenario to think about. On the dendrite there's a whole bunch of receptors. Now these function almost like a sliding door. If you've ever been to any sort of store before it opens and you stand in front of the sliding door but it doesn't open, you kind of just sit there and wait. Because the motion sensor isn't working, because it hasn't been turned on if the store hasn't opened. But sometimes the doors are just broken and they don't work. And so if these neurotransmitters are chilling in the synapse and the dendrite doesn't open its sliding doors… The body tries to keep the. The body tries to conserve energy. And so what happens is, the axon will allow those neurotransmitters to go back into the tunnel and hang out in a pouch until they get sent out again. So when these dendrites are working properly, right, when these neurotransmitter receptors on the dendrite function properly, the motion sensor says, hey, there's a chemical out here you need to receive. The chemical goes through, and as soon as the dendrite has the gist, has the information it needs to send onto the soma to send onto the next neuron, and so forth, it will close its sliding doors, and then, to conserve energy, the axon will receive the rest of the neurotransmitters back. Now, that is how a healthy synapse works. Now, let's talk for a second about antidepressants.
IMAGE EIGHT
Antidepressants have a whole bunch of different forms. When I was first told by my doctor, “Hey, I want you to take antidepressants” I said, “No, not until I know what they are.” So I went home. I did some research. I found a really helpful YouTube video that I will link in the show notes that goes through kind of the history of antidepressants and how we got to where we are now, for the purpose of this podcast, in this episode, I'm only going to talk about SSRIs and SNRIs. SSRI stands for Selective Serotonin Reuptake Inhibitor. SNRI stands for Serotonin Norepinephrine Reuptake Inhibitor. Now, what does all of this mean? Well, that process of reuptake is just when the axon says, “Hey, your neurotransmitters chilling out in the synapse because the dendrite won't let you in, you can come back in.” That's called the reuptake process. So when we have systems in here where there's a reuptake inhibitor, all that means is that the axon puts out guard to not allow any neurotransmitters to make a return trip. The axon stops taking back these extra chemicals. There's often a… I don't know if warning is the right word, but like a cautionary label or you're usually told when you start taking antidepressants, “This will take about six to eight weeks to take effect.” Well, why can’t it just start working right now? The reason for that is because the way the antidepressants work is by refusing these chemicals to reenter the axon, they will eventually build up in the synapse and force the dendrite to open the door. Or it will continue to have the pressure built up until those neurotransmitter receptors allow these chemicals through, which then allows that dendrite to communicate with the soma to communicate with other neurons and so forth.
So when we [take] antidepressants, essentially we just have a broken sliding door and we can't really fix the motion sensors. So we just build up the synapse with a whole bunch of chemicals until they burst the door open. This is also why if you miss one day of an antidepressant, it doesn't have too much of an impact on you. And it's different for everybody. But for me, I don't really start noticing anything until two to three days of not taking my antidepressant in a row. And then I start to notice just little things that creep in here and there that I've known to be aware of. Certain triggers in my life that will make me extra depressed and then I can remember to take my antidepressant again. Fun little side note, if you struggle to remember to take your antidepressant, try linking it with something else. And I know this doesn't necessarily help, but for me, I take my antidepressants at the same time that I take a fiber supplement. And if you want to know what fiber does, it helps your pooping experience be really nice. So every single time I go to the bathroom, I'm reminded, “Oh, did I take my antidepressants?” And if my pooping experience is not nice, I know I forgot to take my fiber, which means I also forgot to take my antidepressants. So little things like that can help. But also know that if you miss a day or two, it's not going to be the worst because you're still going to have that build up in the synapse that you can rely on. But eventually that buildup will dissipate and the sliding doors will shut again and you will have to wait a couple of days for the effect to take charge again.
IMAGE NINE
Now, I did mention earlier on in an episode, something called myelin sheath. This is something that I find that is very important, especially in relation to building habits. If you remember the episode on developmental trauma disorder, at the end, I talked about a little nerd versus a big, strong athlete. If you don't remember it, go back and listen to it. I think it's great. I'm a little biased, but whatever. This myelin sheath is crucial when it comes to giving the nerd an advantage. So when we're talking about that big, buff athlete, those are going to be the neurons that have been used the most. Now, how do we know what neurons have been used the most? Well, around those axons, there are these little things that almost look like beads on a necklace, and those are called myelin sheaths. They essentially just buff up the axon and they allow that electrical signal that gets sent from the soma to reach the axon terminal, to reach those neurotransmitters that are just waiting in those little pouches faster. So the thicker the myelin, the faster and more efficient the neuron is. If you wanted to think of it as the more buff or the stronger the neuron is, that totally works.
So when we're thinking about, like, this nerd, we're thinking about an axon that has never been myelinated because we've never had a chance or even a thought to think or do this thing before. Referring back as well to the clip by Bessel Van der Kolk on the brains of people who've been chronically traumatized in the brains of those who have not, he mentions that there has to be somebody home. And essentially that Mohawk of self-awareness neurons is very well practiced in people who haven't been chronically traumatized. But for people who have been, those neurons have never been used. And the only neurons that have been used are the ones that say, “Hey, don't do anything.”
So coming around to the final point here, why do we even care about this? Why do we even care how neurons work? I found a lot of comfort in understanding how my physiological body was going to be impacted by starting to take antidepressants. Also, it helps for me to visually understand when I cannot, when I literally have no control over the action that happens, to understand that it's not for want of change. It's not because I don't want to do things differently. It's because my neurons aren't myelinated.
I mentioned earlier on about what my antidepressant journey was like, to try it, to try and find the correct one. I had a situation where my doctor was very concerned for my well-being, and so she started me on an antidepressant that worked for the majority of the population. But as I mentioned earlier, it did not work. It made everything worse. I started having manic episodes, and when I switched to the new antidepressant that worked for me, the manic episodes stopped within a week. Not because the new antidepressant had taken effect, but because the old antidepressant wasn't doing anything anymore. And it stopped forcing its way through those sliding doors that I didn't want the chemicals, the neurotransmitters, to get through. When I started taking the new antidepressant, it did take about six to eight weeks before I started seeing any kind of positive benefits.
A crucial part of this story that I don't believe I've told before on this podcast is how I knew what medication to take the second time. Was it a lucky guess? No. There is a test that you can take. It has to be ordered by a doctor. You can't order it on your own, unfortunately. But my doctor… I heard about this test and I went into my doctor and I said, “I will only take an antidepressant if you submit my DNA, (which is just spit from your mouth) to this laboratory so they can run this test.” Now, this test is called GeneSight, G-E-N-E-S-I-G-H-T. If you want to learn about it, you can go to genesight.com, which I will also link in the show notes. But essentially what this test does is your doctor will swab the inside of your cheeks and just get a little QTIP covered in your spit and send it into this laboratory. And then about a week or two later, you get the test results back. Well, your doctor will get them back. My doctor called and told me as soon as she got the results, and it has scientific jargon. So, for instance, I found out that I was homogeneous for the serotonin short promoter allele. Did I have any idea what that meant? No. Now I know. Essentially it means that SSR eyes don't work for me very well, but SNRIs work for me well. So my first antidepressant was an SSRI. My second antidepressant was an SNRI.
The test results also will dumb it down a little more, and it will list a whole bunch of common medications that treat a variety of issues. Everything from antidepressants, which is what I looked at, to antianxiety meds, to antipsychotics to mood stabilizers to… there’s a couple other ones that I don't remember the name of off the top of my head. But essentially what it will do is it will take all of the common medications for each of these categories, and it will split it into green, yellow, and red for you. Green medications are ones that will work well with your DNA makeup. Yellow ones are ones that will work well but might have some not so great side effects. And red ones are medications that won't work for you and may even, in fact, make things worse. True to form, when I got this result back, the first antidepressant I had taken was on the red list, and the antidepressant I took second and that I still take to this day, was on the green list. Now, there is a reason that I very carefully have never mentioned the name of the medication I take, because it doesn't matter what medication I take. What matters is that we find the medication that works for you. I do recommend taking this gene site test, and I am grateful that I heard about it. However, if that's not something you're able to do, you can at least talk to whoever is providing your medication and say, “Hey, I heard there's something different about SSRIs or SNRIs, this medication that you put me on that's not working. I know we have to guess another one. Can we at least try - let's say that you're on an SSRI - Can we at least try an SNRI?” So, having this information, it does provide us with more tools to be able to communicate with the medical professionals who are supposed to be there to improve our quality of life.
So use this information that you have. Feel free to share, download, share whatever you want, any of the images. I'm not going to come after you for copyright reasons, I just threw them together today. So do what you want with the information I've provided. Check out that YouTube video if you want to know more about the history of where antidepressants come from. But all in all, I hope that you leave this episode feeling more empowered and able to take charge of your own life and your own mental health and at least understand what's happening up in that noggin of yours. So until next Monday or until the next Just Janilee episode, remember that if you think you're crazy, you can check back here, and I'll keep throwing the science at you to show you that you're not. This is VILIFIED.
Show Notes
References to things Mentioned in this Episode