Even if we are not tired, if we see someone yawn, we do too. A very common reaction that we have all experienced. But why does this happen? The key lies in the activation of a very specific region of the brain , according to research from the University of Nottingham.
The study suggests that the propensity for involuntary yawning originates in the primary motor cortex of the brain , the area responsible for the execution of movement through neural impulses. The results shed light on the neural basis of this ecofenomenon (automatic repetition of the words or actions of others), unknown until now.
The study involved 36 adult volunteers who were taught to contain the contagion while watching video clips of people yawning. Subsequently, all his yawns, including repressed ones, were counted. To test the relationship between the neural basis of yawning and motor excitability, the group of researchers used transcranial magnetic stimulation (TMS) techniques, showing that through electrical stimulation yawning can also be prompted.
Thanks to the TMS they also proved that being more or less prone to contagious yawning depends on cortical excitability and physiological inhibition of the primary motor cortex of each person, for which the need to yawn is different in each one of us. However, our ability to resist contagion is limited, and even the attempt to suppress it increases the urge to yawn. Try as we might, our predisposition to yawn is not going to change.
The finding, published in the journal Current Biology , will allow researchers to better understand the causes of diseases related to an increase in cortical excitability and / or a decrease in physiological inhibition , where patients cannot stop the most common echophenomena: ecoalia, involuntary imitation of words, and echopraxia, automatic imitation of actions.
“We believe that these discoveries can serve to better understand a wide range of clinical conditions such as epilepsy, dementia, autism and Tourette syndrome,” said Stephen Jackson, Professor of Cognitive Neuroscience at the University of Nottingham and director of the study.
In search of personalized treatments
“This research has shown that the impulse increases when you try to stop. Using electrical stimulation it was possible to increase motor excitability and, by doing so, increased the tendency to catch yawning, so if in Tourette patients we could reduce excitability, we would reduce tics , and that’s what we’re working on, “explains Georgina Jackson, Professor of Cognitive Neuropsychology at the Nottingham Institute of Mental Health.
The study, which is part of the city’s new Biomedical Research Center (BRC), explores new personalized treatments through TMS techniques , without the need for drugs. “If we can understand how alterations in the excitability of the primary motor cortex cause neural disorders, we would potentially be able to reverse them,” says Professor Stephen Jackson.
Reference:
Georgina M. Jackson et al. A neural basis for contagious yawning. Current Biology. August 2017 DOI: 10.1016 / j.cub.2017.07.062
