A Swedish scientist explained why people feel pain in amputated limbs. This became possible thanks to the previous development of the same author - a method of treating such pain using an augmented reality system. The research is published in the journal Frontires in Neurology.
After an arm or leg is amputated, the patient may feel as if their nonexistent limb is still in pain. This phenomenon is called phantom pain, and it still cannot be explained. Swedish scientist Max Ortiz-Catalan, in his previous research, developed a method for treating these pains using machine learning and augmented reality technology. In the new work, the author, based on his development, offered a theoretical explanation for phantom pains.
After amputation of a limb, those neurons that were usually involved in its control become, as it were, unemployed. The cells themselves and the connections between them can function, but they no longer perform any work: they do not receive signals from sensitive neurons and do not process them into commands for movement. At the same time, according to the author, they do not "subside". Sometimes a burst of their activity can coincide with the activity of neurons responsible for the perception of pain. As a result of such a coincidence, a person has sensations of pain in the arm or leg, which are absent.
Such coincidences regularly occur in all people, this is a kind of noise that no one notices in a normal situation. In patients with an amputated limb, the sensation of phantom pain, due to its unusualness, cannot be forgotten. Moreover, each such joint burst of activity more and more "binds" the work of neurons.
Ortiz-Catalan made similar conclusions based on the method of treating phantom pain, which he himself developed. The scientist connected electrodes to the rest of the patients' amputated limb and monitored the transmitted nerve impulses. Then the artificial intelligence "translated" the signal from the electrodes into the movement of a virtual limb, which could be seen on a computer monitor. The patient saw himself on the screen, but with a limb drawn using augmented reality technology, while he could control a virtual arm or leg in real time. With this exercise, the neurons responsible for the movement of the missing limb become working again, their connection with the neurons responsible for pain is weakened, and phantom pains disappear.