The University of Chicago has published a new study that shows how people who have undergone an amputation are able to control a robotic device with their mind. This is possible thanks to an implant of electrodes in the brain of the affected.
Nicho Hatsopoulos, professor of Biology and Anatomy of the Agency and the study's principal author, assures that "this is a novelty", since, even after several years since the amputation, a person can perfectly develop the ability to handle a robotic arm .
Research shows that changes occur in both cerebral hemispheres after the implant. In this sense, both the affected area, responsible for the movement of the amputated limb, and the one that is intact create new connections with each other to learn how to move the robot. Therefore, after a long-term training, this connectivity is growing and evolving.
Previous experiments have shown that people with paralysis are also able to handle robotic limbs with this technique. However, this new study is among the first to make visible the effectiveness of this type of connection in amputees.
The first advances and results
Prior to human practice, it was investigated by helping three monkeys affected by an arm mutilation. Each primate was of a different age and their amputations happened in different periods. The first had been invalid for four years, the second nine and the last ten.
Two of the monkeys were implanted with electrodes on the side of the brain opposite the amputated extremity, the contralateral one. We must bear in mind that each cerebral hemisphere controls the opposite part of the human body. Thus, the movement that involves moving our right arm is controlled by the left hemisphere. In the third animal, the electrodes were implanted on the same side of the amputated limb, the ipsilateral.
The three subjects have been trained in the same way. His exercise consisted of being able to grab a ball and release it using a robotic arm using only his mental capacity. Meanwhile, the scientists recorded the activity of the neurons where the electrodes had been placed.
The results have shown the following:
The contralateral side connections were, at first, very weak as a result of the lack of exercise of the amputated area and with the passage of time, these were strengthened. On the other hand, the registration of the ipsilateral zone, that of the healthy area, revealed dense connections, but had previously gone through a period of reduction and subsequent regeneration during the study. A completely new and stable connectivity had been established.
Projection of the future
The next step for the team of scientists is to combine their work with research from other groups. The new challenge will be to equip the new robotic limbs with sensory feedback. Specifically, they will focus on touch and proprioception, the sense that informs the organism of the position of the muscles. According to Hatsopoulos, it is the next step to create true receptive members, since it affirms that people will obtain natural sensations through the interface placed in the brain.
Photo: Jean Lachat