Today in the world there are people who are deprived of organs of vision, but have learned to successfully navigate using the echolocation technique. But there are very few of them, and this greatly complicates the study of this phenomenon. In 2011, to conduct an experiment to study the work of the brain of such unique creatures, it was possible to invite only two "sonar", this year, scientists have managed to collect already five. And they found out that the new skill changed the brain work of such people in a very interesting way.
When using echolocation, a person makes clicking sounds with his tongue and listens to where the reflected signal of this sound wave comes from and with what delay. Just like bats, dolphins, or military sonars do it. But when measuring brain activity, scientists saw that signal processing takes place in the primary visual cortex, despite the fact that vision in these people does not work in principle. It turns out that the brain has made a "readjustment" in order to allocate maximum resources for processing information in an alternative way.
In the mentioned experiment, three groups of five people each: the blind, sonar and sighted people, tried to determine from which directions different sounds in the room are emanating. At that time they themselves were studied on an MRI machine and it was found that the map of the activity of neuroimpulses in the brain of the sonar was identical to the map of sighted people. But it was radically different from the card of the ordinary blind.
Scientists already know that higher cortical regions gravitate towards signal processing in terms of the task at hand, rather than the nature of the signal itself. And experiments with human sonars confirm that their brains have learned to "see", to perceive the surrounding space in a three-dimensional form, just as a sighted person does. This is similar to how a computer builds a 3D picture of an object from a remote scan. With its help, you can distinguish everything in detail and make an effective decision. Simply the source of the signal in this case is sound, not light.