Do you yawn when you read an Astromart News posting? I hope not. But if you do, does your spouse or significant other also yawn even though he or she is across the room? Why is that so? Is this what Albert Einstein would label "Spooky action at a distance?" Nah. But still, why do we yawn if someone else does? Researchers at the University of Nottingham suggest that the human propensity for contagious yawning is triggered automatically by primitive reflexes in the primary motor cortex -- an area of the brain responsible for motor function.
Their study, "A Neural Basis for Contagious Yawning," is part of their research into the underlying biology of neuro-psychiatric disorders and their search for new methods of treatment.
The latest findings show that our ability to resist yawning when someone else near us yawns is limited... And our urge to yawn is increased if we are instructed to resist yawning. But, no matter how hard we try to stifle a yawn, it might change how we yawn but it won't alter our propensity to yawn. Importantly, they have discovered that the urge to yawn -- our propensity for contagious yawning -- is individual to each one of us.
Contagious yawning is triggered involuntarily when we observe another person yawn. It is a common form of echophenomena -- the automatic imitation of another's words (echolalia) or actions (echopraxia). And it's not just humans who have a propensity for contagious yawning. Chimpanzees and dogs do it too.
Echophenomena can also be seen in a wide range of clinical conditions linked to increased cortical excitability and/or decreased physiological inhibition such as epilepsy, dementia, autism, and Tourette syndrome.
The neural basis for echophenomena is unknown. To test the link between motor excitability and the neural basis for contagious yawning the Nottingham research team used Trans-cranial Magnetic Stimulation (TMS). They recruited 36 adults to help with their study. These volunteers viewed video clips showing someone else yawning and were instructed to either resist yawning or to allow themselves to yawn.
The participants were videoed throughout and their yawns and stifled yawns were counted. In addition, the intensity of each participant's perceived urge to yawn was continuously recorded.
Using electrical stimulation they were also able to increase the urge to yawn.
Georgina Jackson, Professor of Cognitive Neuropsychology in the Institute of Mental Health, said: "This research has shown that the urge is increased by trying to stop yourself. Using electrical stimulation we were able to increase excitability and in doing so increase the propensity for contagious yawning. In Tourettes if we could reduce the excitability we might reduce the ticks and that's what we are working on."
TMS was used to quantify motor cortical excitability and physiological inhibition for each participant and predict the propensity for contagious yawning across all the volunteers.
The TMS measures proved to be significant predictors of contagious yawning and demonstrated that each individual's propensity for contagious yawning is determined by cortical excitability and physiological inhibition of the primary motor cortex.
The research was funded by an ESRC doctoral training award to Beverley Brown and is part of the University of Nottingham's new Biomedical Research Center (BRC), which is leading research into mental health technology with the aim of using brain imaging techniques to understand how neuro modulation works.
Professor Stephen Jackson said: "If we can understand how alterations in cortical excitability give rise to neural disorders we can potentially reverse them. We are looking for potential non-drug, personalized treatments, using TMS that might be effective in modulating inbalances in the brain networks."