Rio de Janeiro, Brazil - Why sports fans can be so crazy about their teams? The answer lies deeply rooted in their brains, says a new study. Group belongingness is considered a basic human need and has been stated as a critical feature for hominin evolution. In the past decades, studies have shown our tendency to benefit ingroup over outgroup members during decisions, which can be explained by the reciprocal identification among members.

The study, published in Nature's Scientific Reports journal on November 23th, reveals for the first time the brain functioning involved in altruistic motivation among soccer fans - a "natural group" that shows strong bonds in real-life settings. The functional MRI study, which can be found here, sheds light into the neural basis of prosocial behaviour of ingroup attachment.

"Attachment to cultural groups is a unique property of humans, fundamental for our survival, which, in turn, makes the investigation of its neural basis very critical", states Dr. Jorge Moll, neuroscientist and senior author of the study. He is the head of the D'Or Institute for Research and Education (IDOR), where the research was conducted.

To do so, researchers recruited 27 soccer fans of brazilian teams for the experiment. Inside the functional Magnetic Resonance (fMR) scanner, supporters of the four most popular soccer clubs in Rio de Janeiro had to decide whether they want to donate a specific amount of money to (ii) anonymous fans of their own soccer teams, (ii) anonymous non-fans or (iii) to keep the amount to themselves. During these donation tasks, the fMR machine captured in detail their brain functioning in order to elucidate the neural underpinnings of ingroup motivation and altruistic decisions.

According to Dr. Tiago Bortolini, lead author of the study, from IDOR and the Federal University of Rio de Janeiro, "soccer fans constitutes an example of natural groups, which are reflected in daily life situations and thus provide an unique opportunity to investigate group belongingness in a more ecologic fashion."

The goal of the study was to investigate the neural mechanisms responsible for altruistic motivation among members of the same social group. In other words, what are the soccer fans' brain areas involved in this kind of behaviour?

Differently than most of the studies in the scientific literature, researchers designed a highly effortful task to probe participats engagement in obtaining money for themselves or to be donated to other participants. This was done by having participants squeezing a pressure device that they held in their hands during the experimental trials.

"This allowed us to measure their real motivation during the donation tasks, since greater amounts of money required lot of pressure effort on the handgrip device", explains Dr. Bortolini.

Results of the donation trials (measured by how strong they squeezed the handgrip device) showed that, on average, they invested more effort to benefit anonymous fans of their own soccer clubs than non-fans. Greater effort was observed to obtain money for themselves, however (yes, they did take better care of themselves!).

In order to elucidate what happens in the soccer fans' brain during the donation tasks, researchers analyzed brain activation in common for all three types of donation: to soccer fans, to non-fans or to themselves. Analyses showed that the medial orbitofrontal cortex (mOFC) a brain area extremely important for subjective value of choice alternatives, showed increased activity in all conditions.

Since this brain area plays a critical role in decision and values, researchers decided to investigate how this area (mOFC) interacts with other parts of the brain. This analysis revealed a close relationship (which means more "connectivity") of mOFC with the subgenual cingulate cortex - a region that has previously been implicated in altruistic decisions to charitable organizations and in family belongingness - only when donations were targeted to fans of the same soccer club. A straightforward interpretation is that fans respond to their team mates, even unknown ones, in a similar way that they respond to loved family members or when making noble altruistic choices.

"Understanding the neural mechanisms involved in group belongingness and pro-group behaviour can pave the way for developing novel brain modulation techniques able to address clinical problems, such as antisocial behaviors and other psychiatric symptoms, including sports-related agressive attitudes and behaviors", said Dr. Bortoloni.

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This study is a result of a fruitful collaboration between D'Or Institute for Research and Education, Max Planck Institute in Leipzig (Germany), King's College London (UK), Centre National de la Recherche Scientifique (France), and was funded by CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), ANR (Agence Nationale pour la Recherche) and D'Or Institute for Research and Education.