Brain – computer – spinal cord interface
Spinal implants made from an avatar monkey
James Cameron, in his Avatar, came up with a peculiar way to get rid of the hero from a wheelchair by placing his consciousness in an avatar – the body of an alien.
And this could be considered unattainable fiction, if not for the work of researchers from Cornell and Harvard Universities (both in the USA), who managed to do something similar for monkeys.
In the experiments of Ziv Williams and his colleagues, two monkeys were implanted with electrodes: one in the brain, the other in the spinal cord. The monkey, which had electrodes in its spinal cord, served as an avatar; it was treated so that it lost control of its own body. The avatar's hand was on the joystick, which could move the cursor on the screen, the screen itself was in front of the controlling animal, whose electrodes were inserted into the brain.
The scheme of the experience: the monkey-manager (above) follows the cursor on the screen
and tries to move his avatar monkey limb (below).
(Illustration by the authors of the work.)
Paralysis does not mean that motor neurons in the brain stop working: the individual still represents some movements, and nerve cells send the appropriate signals. Another thing is that these signals cannot pass through the damaged spinal cord. However, it is possible to pave a workaround and transmit impulses from the brain to those spinal neurons that lie after the injury site. With monkeys, they just tried to recreate such a situation, only the transmission of the impulse was carried out between different individuals. So, according to scientists, it was possible to recreate the picture of paralysis most fully when there is no communication between the brain and the limb – which is impossible with experimental temporary paralysis.
In order to transmit a signal from the brain, it needs to be decrypted, and then handed to the spinal neurons. The neurons of the cortex send a lot of impulses to the muscles, a detailed analysis of which can take a lot of time and effort, but the researchers did not set out to accurately compare the neural impulse and its kinetic effect, manifested in a particular muscle contraction. The movement of the avatar's hand did not occur from the summation of elementary instructions, but because of the appearance of a goal to be achieved through movement.
That is, scientists concentrated on those impulses that directed the limb to a certain goal. Simply put, it was not the movement that was deciphered, but the intention.
And they were successful: As the researchers write in Nature Communications, the control monkey was able to move the avatar monkey's arm and move the cursor around the screen so as to receive a reward (Shanechi et al., A cortical-spinal prosthesis for targeted limb movement in paralyzed primate avatars). The movements took place in the same plane, however, one must think that the possibility of manipulating the avatar's limb in all directions is only a matter of time. (The authors of the work, by the way, do not hide that they were inspired, among other things, by the famous Cameron movie.) And such avatars, of course, are only a transitional stage: in the future, this technology can be implemented, so to speak, within one body, so that the brain of a paralyzed person can again control his own limbs.
It is also worth noting that this is not the first work on the transmission of thoughts using neuroelectronic devices. Almost a year ago, we reported on the experiments of the research group of Miguel Nicolelis, who, together with colleagues, managed to establish a communication between the brains of two rats, and one of them did what the other was thinking. Among other well-known experiments by Mr. Nicolelis and his collaborators, one can mention the work on transferring the monkey's thought to an artificial arm in order to make it move. In short, the above-described results of experiments on the transmission of "thoughts" between the brain and spinal cord are based on very extensive developments.
Prepared based on the materials of Cornell University: Think to act: Brain signals move paralyzed limbs.
Portal "Eternal youth" http://vechnayamolodost.ru20.02.2014