[MUSIC] Okay, so we're going to now spend this unit on the vestibular system, and the vestibular sy, one of the vestibular system's major outputs which is gaze control. So the vestibular system is an really interesting sensory system. It, it's not an obvious one. In fact, as opposed to sight and hearing and touch, which have been known since there, there has been language. The vestibular system was actually only discovered in the late 19th century. So it's a really unobvious one in, in large part because what it does for us is, is very understated. It drives our motor system. It enables us to do two really important things. One is to keep our balance. So we can keep our balance whether we're tight-roping, or whether I'm just standing here. Here's an individual who has, who's using his vestibular system to great advantage. And the other thing that it enables us to do is to keep our gaze steady. And what is gaze? Gaze is the place that we're looking at, so that the visual world stays steady. We don't want to the visual world to move every time our head or our eyes move a little bit. So we keep our gaze steady. So one of the things that you can see in this picture of my friend Peter, is that although he's banking around this curve, and his body and his, and the bike are at that angle, his head is at this angle. His head is at that angle because his eyes, his vestibular system is driving his head to keep the horizon horizontal. There's a reason why horizon and horizontal of the same route, because horizontal is the horizon. It should always be the horizon. It's always the horizon because we keep our head upright, even as we're banking around. Now he, Peter didn't make that choice. This is an unconscious action. He's keeping his head perpendicular to the ground in line with gravity as an unconscious action. So because all of this happens automatically and unconsciously, we're basically very unaware of our vestibular sense, ergo, the very late discovery of the vesti, vestibular sense. But when there is a problem with the vestibular sense, all of that goes out the window. Now, we're extraordinarily aware of it. So when, in individuals who have any kind of vestibular system dysfunction, there is it is an overwhelming feeling to not have your vestibular system, this automatic thing that we totally count on. It's it's a very disturbing situation to feel that one's not in balance, or that, say, the room is spil, spinning or that the self is spinning. And accompanying this, not only do we have these sensory feelings of not being in balance, but we also, that is accompanied by an, on, autonomic feeling of nausea. So nausea and vomiting can also aco, accompany, or often accompany vestibular dysfunction. Okay, so in the next segment, we're going to look at the, the stimulus. What's the stimulus for the vestibular system? [MUSIC]
