The University of Chicago has published a new study showing how amputee people 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 person .
Nicho Hatsopoulos , professor of Biology and Anatomy of the Organism and main author of the study, assures that “it is a whole novelty”, since, even after several years since the amputation, a person can perfectly develop the ability to handle a robotic arm .
Research reveals that changes occur in both hemispheres of the brain after implantation . In this sense, both the affected area, responsible for the movement of the amputated limb, and the one that is intact create new connections between them to learn to move the robot. Therefore, after long-term training, this connectivity grows and evolves.
Previous experiments have shown that people with paralysis are also capable of handling robotic limbs with this technique . However, this new study is one of the first to make visible the effectiveness of this type of connection in amputees.
The first advances and results
Prior to the practice in humans, it was investigated helping three monkeys affected by a mutilation of an arm . Each primate was of a different age and their amputations happened at different times. The first had been an invalid for four years, the second nine and the last ten.
Two of the monkeys underwent electrode implantation on the side of the brain opposite to the amputated limb, the contralateral one . Keep in mind that each brain hemisphere controls the opposite part of the human body. Thus, the movement involved in 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 .
All three subjects have been trained in the same way. His exercise consisted of being able to grasp a ball and release it using a robotic arm using only his mental capacity . Meanwhile, the scientists recorded the activity of neurons where the electrodes had been placed.
The results have shown the following:
The connections on the contralateral side were, at first, very weak as a result of the lack of exercise of the amputated area and with the passage of time, these same were strengthened. On the other hand, the registration of the ipsilateral area, that of the healthy area, revealed dense connections, but which had previously undergone a period of reduction and subsequent regeneration during the study. A completely new and stable connectivity had been established .
Future projection
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 body of the position of the muscles. According to Hatsopoulos, it is the next step towards creating truly receptive limbs, since he affirms that people will obtain natural sensations through the interface placed in the brain.
Photo: Jean Lachat
Reference: Changes in Cortical Network Connectivity with Long-term Brain-Machine Interface Exposure after Chronic Amputation. University of Chicago ( https://www.eurekalert.org/pub_releases/2017-11/uocm-acl112717.php )
