A lamb that has lost sight of the rest of its family members can even locate them even in the framework of huge herds of sheep. Likewise, salmon move through huge stretches of sea and, once they have matured and must spawn, they end up returning to the native river where they were born – and even to the exact place of their birth – with astonishing precision .
Scientists have long been aware of these animal kinship attachments, some of them known as “imprinting,” but the mechanisms that govern these behaviors are more mysterious at the cellular and molecular level. Now, biologists at the University of California, San Diego (USA) have managed to uncover some key elements that will serve to understand social attraction – and aversion – in certain animals and in humans .
Thus, Associate Professor Davide Dulcis, from the Department of Psychiatry at the University of California, San Diego School of Medicine, as well as Giordano Lippi, Darwin Berg and Nick Spitzer, who work in the Division of Biological Sciences, and others colleagues have published the results of their study in the journal Neuron .
Researchers, who have carried out a series of neurobiological studies for eight years – they began in 2009 – have examined tadpoles, as they are known to swim in groups alongside family members. They focused on studying the familiar olfactory signals (kinship odors), and thanks to this they identified the mechanisms that led the tadpoles between two and four days old to choose to swim with family members rather than with members who did not belong to that. Likewise, their tests revealed that tadpoles that were exposed early to forming odors from a group outside their family were also inclined to swim with that group that generated the odor, thus expanding their social preference beyond kinship. real.
Neurotransmitter switch
According to the researchers, everything is based on a process called “neurotransmitter switching,” an area of brain research initiated by Nick Spitzer and developed by Davide Dulcis in the context of psychostimulants and the diseased brain. The neurotransmitter dopamine – often associated with sensations of pleasure and relaxation – was found at high levels when the normal bonding of family kinship occurred , but it changed to the neurotransmitter GABA in the case of kinship with artificial odor or “non-parental” attraction.
“In the inverted conditions there is a clear sign of neurotransmitter change, so now we can see that these neurotransmitters are actually controlling a specific behavior ,” explains Dulcis on the website of his university. “We can imagine how important this is to social preference and behavior. We have innate responses in relationships, falling in love, and deciding if we like someone. We use a variety of signals and these odor receptors can be part of the equation for social preference, “he continues.
This group of researchers took the study further to try to decipher how this mechanism develops at the genetic level , and they identified microRNA-375 and microRNA-200b – a class of small molecules involved in the coordination of gene expression – as the Key regulators that mediate neurotransmitter switching for social attraction and aversion, affecting the expression of genes known as Pax6 and Bcl11b, which control tadpole swimming behavior.
“Social interaction, whether it’s with people where we work or with family and friends, has many determinants,” says Spitzer. “As humans, we are complicated and we have multiple mechanisms to achieve social bonding , but it seems likely that this mechanism for changing social preference in response to olfactory stimuli contributes to some extent,” he concludes.
