Although we are not usually aware of it, the ability to distinguish what the limits of our own body are – a skill that newborns develop through contact with others – is extremely important. Not only does it help us get a mental idea of ourselves, but, among other things, it allows us to detect whether it has been us or other individuals who have carried out a certain action.
Now a team of researchers at Linköping University in Sweden has examined what happens in different regions of the nervous system when one person caresses another or when they touch themselves in a similar way. Well, in an experiment, these scientists have been able to find out that the processing of sensory perception is reduced when we are the ones who touch each other. To determine this, they have examined the images obtained by functional magnetic resonance imaging of the brain activity of volunteers who, in some cases, were asked to hold on to an arm; in others, it was the experts who did it.
Different experiences
The skin has sensory receptors that react to pressure and temperature. When something touches it, the information is transmitted to the brain, where it is analyzed in different areas. The researchers wanted to see which ones “lit up” in the first case and which ones lit up in the second. “We found a clear disparity in both situations, even in the way the signals ran through the spinal cord, before being processed. Brain activity was less if it was the subject himself who was touching himself ”, indicates Rebecca Böhme, from the Department of Clinical and Experimental Medicine and the Center for Affective and Social Neuroscience, which has coordinated this initiative.
A statement from Linköping University indicates that the results seem to support a hypothesis that neuroscientists have been handling for a long time and that considers that our brain tries to anticipate our sensory interaction with what surrounds us. In essence, this means that it does not give as much importance to the perceptions originated by our body . The researchers, who have published their findings in the journal Proceedings of the National Academy of Sciences , found that this phenomenon was even more pronounced if the volunteer was subjected to different touches made simultaneously. “The results of the experiment are very interesting, especially with regard to those differences that occur in the first moments, in the spinal cord. In the case of the visual system, for example, processing begins already in the retina; it would be nice to examine in detail how tactile perceptions are modulated throughout the entire nervous system, ”says Böhme.
Reference: Distinction of self-produced touch and social touch at cortical and spinal cord levels. Rebecca Böhme et al. Proceedings of the National Academy of Sciences . DOI: doi.org/10.1073/pnas.1816278116
