Study suggests neural mechanism behind contagious yawning

A study named “A neural basis for contagious yawning” conducted at the University of Nottingham suggests that primitive reflexes that originate in the primary motor cortex, a section of the brain accountable for motor function, are responsible for automatically initiating the human tendency for contagious yawning.

This study is part of the University’s research in determining the biological mechanisms behind neuropsychiatric disorders and their search for novel treatment approaches.

The findings indicate that a someone’s ability to resist yawning when a nearby person yawns is restricted and when a person is instructed to resist yawning, an increasing urge to yawn has been observed.

It has also been seen that the tendency to suppress a yawn only changes the way of yawning, but not whether it will happen. The researchers have also noted that the tendency for contagious yawning is unique for each individual.

Stephen Jackson, the lead author and a Professor of Cognitive Neuroscience in the School of Psychology said that these findings might be helpful in the further understanding of the link between motor excitability and the incidence of echophenomena in a wide range of clinical conditions associated with augmented cortical excitability and reduced physiological inhibition like dementia, epilepsy, autism, and Tourette syndrome.

Contagious yawning, which is a common form of echophenomena, is involuntarily triggered when one observes another person yawning. It is not particular to humans alone; dogs and chimpanzees also exhibit this characteristic.

Echophenomena is also caused due to various clinical conditions associated with raised cortical excitability and reduced physiological inhibition like dementia, epilespsy, autism and Tourette syndrome.

The neural basis behind echophenomena is not known. In order to find the connection between motor excitability and the neural basis for contagious yawning and quantify the same, transcranial magnetic stimulation (TMS) was used by the team of researchers.

The 36 participants were asked to view video clips of other people yawning and were instructed to resist yawning or allow themselves to yawn; the number of their yawns, stifled yawns as well as the intensity of their apparent urge to yawn were continuously recorded in a video.  

The researchers could also increase the urge to yawn by using electrical stimulation.

Georgina Jackson, Professor of Cognitive Neuropsychology in the Institute of Mental Health, commented: “In Tourettes if we could reduce the excitability we might reduce the ticks and that’s what we are working on.”

The findings suggested that the TMS measures used to quantify the physical inhibition and excitability of the motor cortex are significant forecasters of the volunteers’ tendency to experience contagious yawning.

According to Professor Stephen Jackson, if the way by which alterations in cortical excitability give rise to neural disorders is understood, it can possibly be reversed. The study further aims at developing non-drug, personalized treatments for such conditions.

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