2024-03-14 14:48:34
“We can’t repair what we don’t understand,” says straight away. Sébastien Tremblay, new professor at the Faculty of Medicine and researcher at the CERVO Center. He is interested in neural activity in complex tasks, mainly during social interactions.
His study, published in the journal Nature, identifies the brain signatures of several social behaviors in primates. Sébastien Tremblay conducted this research while he was a researcher at the University of Pennsylvania in Philadelphia.
His goal was to shed light on the neural circuits responsible for social interactions to understand what happens when these circuits are damaged or fail due to disease.
Less restrictive technology
Using advanced technology, his team recorded brain activities with neuron-level spatial and temporal resolution, greater precision than magnetic resonance imaging.
Sébastien Tremblay’s approach also has the advantage of being wireless. Using an intracranial implant, he is able to record the brain activity of primates without restricting their movement.
“Until now, experiments required an absence of movement. When you can’t move, it’s difficult to study natural behaviors. There, we were able to study primates eating and interacting, for example,” explains the young researcher.
Un contexte social variable
In the study, two pairs of primates were present, but only the males carried the implant. The experiments made it possible to see the neural signature of all natural behaviors, and especially the way in which the social context influenced these behaviors. The answer varied, among other things, whether the primate was alone or with its partner.
For example, the lone male became aggressive when looked into his eyes, a sign of distrust among primates. This aggressiveness presented a specific signature. In the presence of his partner, however, he was less reactive. “Its neural signature was more like that at rest. It’s as if his partner is reducing his anxiety. We can recognize a social support mechanism,” underlines Sébastien Tremblay.
The male also became agitated when looking at his partner in the eyes. “The neural signal was similar to that observed when he himself was challenged. We see signs of empathy there.” According to the researcher, this is an avenue for understanding failures linked to empathy such as psychopathy or disengagement in autism disorders.
A result that surprised Sébastien Tremblay is that primates keep in memory a “report” of social interactions, to reciprocate signs of affection for example. “When one of the primates groomed its partner, the other returned the favor, but not always in the same way. We saw inequalities at the end of the day. But, the next day, we saw that the deficit was reversed, and so on until the interactions were balanced.”
It was not the same neuronal representation in the primate when it was he or his partner who was in an affection deficit. “It’s a clue to know how we establish equality in our interactions. We could understand why some people are more selfish or more generous,” suggests Sébastien Tremblay.
A promising path
With brain circuits targeted as a potential source of social behaviors, Sébastien Tremblay wishes to validate their role. To do this, he must modify them. “We are developing neuromodulation techniques in the brain, with optogenetics and chemogenetics. We make families of neurons sensitive to light or to a drug to study the changes.”
In his new laboratory at the CERVO center at Laval University, he wishes to optimize these techniques, eventually turning them into treatment avenues for mental illnesses, such as epilepsy and autism. He will also continue the study of complex behaviors in the brain and take advantage of the innovative technologies he has developed.
The study was published in the journal Nature. The signatories are Camille Testard, Sébastien Tremblay, Felipe Parodi, Ron W. DiTullio, Arianna Acevedo-Ithier, Kristin L. Gardiner, Konrad Kording and Michael L. Platt.
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