reader’s question Aline Comerio, Colatina, ES
illustrates Pri Wi
edition Felipe van Deursen
Because our brain processes outdated information. Everything happens in the ear. One of the internal parts of the organ is responsible for providing us with balance and spatial orientation, that is, the place we occupy in an environment and the directions we take when moving. The ear is made up of three interconnected semicircular canals, each accounting for one dimension, top-bottom, left-right, and front-back. These channels are filled with a fluid called endolymph. When the head turns to one side, the fluid follows the displacement and pushes against specific structures that have microhairs, the hair cells. These cells then send an impulse to the brain. According to the inclination of the hairs, the brain identifies that there is movement.
burning tire
When turning in circles, inertia causes the endolymph to go against the movement and drag the hair cells, which are in a structure called the ampulla. It’s the same reaction as when accelerating in a car: you are thrown backwards when it goes forward.
cadenced rhythm
In moments, the liquid starts to follow the same speed as the head’s rotation and enters into synchrony. This causes the little hairs to return to their original position and the brain no longer receives movement information – only vision and other senses identify that the body is rotating.
little stars in the sky
When stopped abruptly, the fluid continues its normal movement through the channels until it loses strength and stops. During this time, the cells send information back to the brain that the body is still spinning despite being stationary. It is these conflicting data that provoke the dizziness.
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SOURCES Review of Clinical and Functional Neuroscience, by Rand Swenson; highlightskids.com, science.howstuffworks.com, livescience.com, scienceabc.com, neurophys.wisc.edu