[MUSIC] Okay, so we're going to talk about myelin now. Myelin is a, is a fatty wrap that goes around some axons. Now, what's the difference between a myelinated axon and a naked axon? A naked axon is one that doesn't have mylelin, so it's unmylinated. so, an unmylinated, or naked axon, can only, transfer information at a slow rate. So the rate that it's transfers information is 0.2 to 1 meters per second. That means to go 1 and a half meters, which is roughly the distance between [COUGH] my toe, and right here. To go that distance would take me seconds. At least, a second and a half. And probably more like 5 seconds. [BLANK_AUDIO] Now, once we put on myelin, information transfers much much faster. It can go between 2 and 120 meters per second. If it goes at 120 meters per second, the whole game is over. Information is gone from here to here in 12 milliseconds. .012 seconds. So very short time, in perceptible to us. And that is a, obviously a very useful thing, so that we can get information in time to actually use it. So, the information that we need the, the fastest is information about keeping our balance. And so, as we walk along, if we bump into something and we stumble, we need that information fast. If we had to wait for a second or two, we'd be on the ground. All the neurons that support our posture against gravity, those neurons transfer information really fast. Alright, so let's talk a little bit more about the information that gets transferred. That information occurs in, it's a 0 or a 1. [BLANK_AUDIO] There's either an a point of information or not. And so it's very much like a computer code, where what we're seeing is a series of of 0s or 1s and what's important, the 0s are less important but the temporal pattern of these ones is very important. So, we want to know, at every millisecond, is there a 1 or is there a 0? If there's a 1 we want to know the temporal pattern of those ones. That's the neural code. And these ones are actually, I, I'm going to give you the name for that. That's an action potential, [BLANK_AUDIO] also called a spike. And we talk about firing spikes, neurons fire spikes. So, the timing of these spikes is what carries information. The spikes are going to travel down this axon, so lets now imagine in this situation that blue here is supposed to be the miling. These are wraps and their wraps that go around the axon. I, I've, I've drawn it as a cut away, but the wrap will go all the way around here. And the information, the spikes actually jump. That's what makes it so fast. They don't have to they don't have to, actually be carried through the places with the Myelin, they can actually jump. And so things, anthra, the spike information is transferred very quickly, down this axon. Now, if we lose this myelin, if we lose this myelin, just a little bit of myelin here, now, this is going to creep along. And it actually, it's either going to be really slowed or it may fail altogether. So, this if our original message is this. [SOUND]. And now, we have a demyelinating disease, what we're going to end up with is something that's spread out, because it's slower. And every once in a while, it's going to miss bits. And now, the neuron that we're talking to is getting a very incoherent message. This is very different from this and that is the problem with demyelination. By, because an [UNKNOWN] because axons are demyelinated, the information transfer is very degraded. It's a garbled message and that's a problem. And so in the next segment what we're going to look at is the two different major types of demyelinating diseases. [MUSIC]
