The human brain considers tools as a sensory extension of the body, which gives people a new perception that scientists have called "extended perception by tools".
The results of this investigation, published in the journal Nature, confirm that we humans use the tools as if they were an extension of our members, and not as useful objects alien to the organism.
The ability to extend the processing of sensory information beyond the nervous system has been observed throughout the animal kingdom, for example when rodents feel objects using their whiskers or spiders locate prey through cobwebs. They use external elements to process information, informs Trends 21.
This study, carried out by scientists from the Center for Neuroscience Research in Lyon (France), has found that the ability to feel objects with tools represents an analogous scheme of information processing in humans.
Both behavioral psychophysics, structural mechanics and neuronal modeling show that the tools are treated by the nervous system as sensory extensions of the body, rather than as simple links between the hands and the environment, the researchers point out in their article. .
Where and how
The first thing they found was that tool users can accurately detect where an object comes in contact with a wooden cane, just as it happens on the skin. That is, in the same way that we feel when something hits our arm and we know in what part of the arm it has been, we can know where a stick we have in our hand has been hit.
The scientists also discovered that the characteristics of the vibration transmitted by the stick on the fist that holds the stick and on the skin of that hand, depend on the site where the stick has received the impact.
That means, according to the researchers, that the location we make of the impact site that the cane has suffered is not only predictable, but also reveals a pre-neuronal stage of the mechanical processing of information, similar to the detection with whiskers and cobwebs. that manifest themselves in mice and spiders.
The research has a third part no less surprising: the scientists treated the characteristics of the vibrations recorded by the fist at the moment of impact on the stick.
And they discovered that we know where the cane has been hit because the vibrations that the impact emits are encoded and contain information about the area where it has been hit. The human brain has the ability to interpret this information and to locate the area of impact, in the same way that happens when someone hits an arm.
The researchers conclude that this "extra" human sensory capacity arises from the functional coupling between the material, biomechanical and neural levels of information processing related to the impact suffered by the cane.
This discovery represents a new paradigm that could improve the understanding of the phenomena related to the tools that we humans use and the sensory perception of the blind, as well as the use of substitute prostheses of amputated limbs.
More information in Trends 21