How does proprioception work?
In: 3
To try and keep this simple:
Proprioception is a sense, one that gives information about body position and movement. It is often mainly attributed to two kinds of sensors, tension mechanical sensors in the tendons, muscles, and joints and acceleration sensors in the inner ear. But in reality, the brain also integrates information from many other sensors to form a coherent picture, such as mechanical receptors in the skin.
So how it works is quite simple. You have a sensor in your muscles, in your tendon/muscle interface, and in your joints (bone to bone connection), if you move your limbs whether you flex the muscle or without flexing (like you use your left arm to flex your relaxed right arm), at least one of these sensors will send a signal to the brain. They’re generally thought to operate with a mechanosensitive non selective cation channel, that’s basically a tiny hole in the membrane of the cells making up these sensors which, if the cell experiences tension due to stretching, stretch open, and they allow positive ions into the cell, which then change the voltage across the membrane (inside vs outside of cell), which then triggers voltage sensitive channels, which then triggers a cascade of events that lead to a release of a signal that eventually reaches the brain via neurons.
Now what about if you’re on a roller coaster, totally relaxed, and you’re being accelerated in three dimensional space? You also have sensors for that in your inner ear. Those are a bit more challenging to explain in just text. Think of them as essentially two sets of sensors, one is semi circular in shape and the other is just chunky semi rectangular ones. In the semi circular ones, you have fluid, and the semi circles are either vertical in one or other orientation or horizontal, if you rotate vertically or horizontally, the fluid in them will lag behind because of inertia, and so relative to the movement of walls of these semicircles (because you’re moving) the fluid is slower, pushing on some projections in the walls in one direction, triggering a signal. For the other set of sensors, they have tiny little crystals in them, while the bodies of the sensors are also in two orientations, such that if you accelerate linearly in one direction or another, the crystals lag behind, also triggering a signal. This way you can tell when you’re moving.
Really hard to explain the vestibular system simply enough here as I mentioned above. So here is a video you can watch to help clear it up: https://youtu.be/ryGMI3SpxCE
Latest Answers