The more our social relations were, the more certain structures of our brain would develop. This is a hypothesis at the heart of several research papers in neuroscience for several years. Researchers from Inserm and the UniversityLyon 1 within the Institute for Stem Cells and Brain, in collaboration with the University of Pennsylvania, focused more specifically on macaques including is comparable to human.
Observing animals in their natural state and analyzing images of their brains, they found that the number of companions of this non-human primate made it possible to predict the size of certain areas of his brain, which are particularly related tosocial and . The results of this study were published in the journal .
Connections betweeni have been the subject of previous studies in the field of neuroscience. From for example, they were already interested in variations in the size of the amygdala of the human brain, according to the number of friends which the individual has. In order to complete this research and try to better understand the organization and functions of neural networks in humans, the teams worked with an animal species with brain characteristics close to human, ie. rhesus.
Behavioral observations supported by scanners
In this new study, a team of researchers studied a group of thesenonhumans in their natural state and for several months before imaging their brain. The fact of studying animals in the wild enabled them to understand the social group in all its complexity. Scientists were thus able to measure the intensity of interactions (number of interactions, cooperative or aggressive, and ) with other individuals or identify the social hierarchical position of the animal within the group.
Part of the observation focused, for example, on grooming partners, who represent direct and important relationships for. In parallel with this work on observing behavior, scientists analyzed brains of individuals in the group, which consisted of 103 including 68 adults and 21 young macaques under 6 years of age. They found that, in adults, the more companions an animal had, the more parts of its brain were located in the lobe. were significant sizes.
The more companions the animal had, the more significant the parts of its brain located in the temporal lobe were.
This isanterior and middle part of the upper temporal sulcus which are regions considered essential for representation and perception of the behavior of others. To better understand how this phenomenon unfolds, scientists were also able to collect a brain scan of 21 young newborn macaques. The paper showed that they are not born with these differences in the size of cerebral structures, but that they are set during their development.
The brain develops over a lifetime
According to the researchers, therefore, there would be no correlation at birth between sizei brain. These results suggest that lifelong exposure to the social environment contributes to the maturation of brain networks.
“This aspect is interesting, because if we noticed the same correlation in young macaques, it could mean that the birth of a very popular mother (who has a lot of interaction with the group) could predispose the newborn to become popular. On the contrary, our data suggest that the differences we observe in adults will be strongly determined by our social environment, perhaps more than our innate predisposition. ” explains Jérôme Sallet, director of research at Inserm.
As a result of this study, researchers now want to study anatomical changes at the cellular level, to discover the mechanisms that work when areas of the brain identified by brain imaging increase in size.
Social networks increase the size (part) of your brain!
To find out if a person has a lot of friends, look at their Facebook profile or … brain! People with a large and complex social circle would indeed have a significant increase in tonsil volume.
Article by Claire Peltier, published on January 4, 2011
Use itdoes that imply that you have a special brain? A priori yes, according to Boston researchers. Named certain brain structures , in addition to being involved in emotions, they are also needed for the socialization of animal species. Indeed, this has been shown by previous studies based on brain comparisons where tonsil size correlated with the average number of persons making up the group.
But if the amygdala therefore seems to be important for the socialization of animals, does its size also differ among humans depending on their social network? Researchers from Northeastern University in Boston became interested in the question and decided to answer it by observing the size of the tonsils of 58 healthy adultsand psychological. To assess the complexity of these people’s social networks, the researchers used two variables: the first, which includes the total number of people with whom volunteers had regular contact, and the second, which indicates the number of different groups to which these contacts belonged (family, colleagues, etc.) .
Brain observation MR
The tonsils were then measured withobtained by recording on magnetic ( ) followed by computer reconstruction using programs developed at Harvard University (FreeSurfer). To serve as a control as a structure of the brain that is not included in social networks, are also measured. To avoid variations due to different sizes the measured volume of structures was related to total brain volume.
Linear regression analyzes have shown that people with larger and more complex social networks have a larger amygdala volume. This finding could be determined regardless of the age of the subjects (amygdala decreases with age), and regardless of the amygdala under consideration (no lateralization), while the hippocampus was completely independent of the complexity of the social network.
In contrast, amygdala size was not associated with other parameters such as life satisfaction or perceived social support, indicating that happiness of having friends was not included in this increase in tonsil volume.
Analyze better to work better
On the other hand, measuring othersand especially the thickness of the cortex made it possible to show that certain regions in addition to the amygdala are also associated with the complexity of the social network. Thus, the lower temporal sulcus gyrus caudal superior and the anterior subgenual cingulate is all three significantly thicker than the other parts of the cortex. These three regions would be developed together with the amygdala to ensure the management of a complex social network.
According to the authors, this would be the first demonstration of the correlation between the size of the amygdala and the size of the social network within the same species. But in what sense is that relationship established? Do larger tonsils favor social networks or, on the contrary, actively visiting social networks increases the size of tonsils? Study published in the journalhe does not say … What is certain is that the amygdala allows us, as social animals, to better understand our relatives, in order to establish strategies for better cooperation or entry into competition.