A team of five researchers led by Miguel Nicolelis of Duke University has recently published a study showing that when monkeys perform a collaborative task, their brains synchronize: in the same area of their motor cortex, their neurons unload at the same time . A state called “inter-cerebral cortical synchronization” (ICS).
This phenomenon is related to mirror neurons, which neuroscientists think are essential to human interactions and especially to how we can identify with each other. Conversely, failures of mirror neurons are probably involved in autistic syndromes and other disorders that affect our social skills and behaviors.
Moreover, Nicolelis and his colleagues observe that the ICS is modulated by the hierarchical links that the monkeys maintain between themselves.
“We believe that our study could open a completely new field of investigation,” says the scientist, demonstrating that even the simplest functions of the motor cortex, such as the production of body movements, are strongly influenced by the type of social relations that the animals have woven. ”
To arrive at this conclusion, the researchers recorded the activity of the motor cortex of two monkeys during this experiment: a first animal (the observer) was installed on a fixed chair while another (the passenger) was sitting on a Wheelchair. While crossing the room, the passenger was followed by the eyes by the observer. Once the programmed trajectory was completed, the passenger was rewarded with grapes and the observer with fruit juice.
Scientists have observed that ICS episodes help predict wheelchair location and speed. The cerebral activity of monkeys also seems to depend on the distance between them and the distance that remains to be traveled to obtain the reward. An activity that is also modulated by the social rank of animals in their colony — Rhesus macaques being among the most hierarchical primates.
Thus, when a dominant monkey was observed by a subordinate, ICS increased in intensity as the passenger approached the observer. Synchronization peaked when the animals were close enough to touch each other.
However, when the positions were reversed, the phenomenon did not occur and synchronization did not increase as the apes approached each other. This suggests that the social hierarchy plays a role in the brain synchronization of monkeys.
Such an approach, explains Nicolelis, could thus be used to “quantify the collaboration of athletes, musicians or dancers (…) and to improve the social cohesion” of a group. From a medical perspective, this study could also contribute to better diagnoses of autism spectrum disorders and a better evaluation of their treatments.