Researched Why do some people stutter?

Stuttering mice could clarify why people develop such a speech disorder
That mice can not speak should be well known. For that reason, mice will not stutter, will they? Scientists are now changing the genes of some laboratory mice to alter rodents' communication in such a way that is very similar to human stuttering. By doing so, the researchers hope to better understand the background and causes of human stuttering.

Have you heard of stuttering mice? Probably not, because mice do not speak and their communication is incomprehensible to people anyway. Researchers from Washington University in St. Louis now changed the genes of some mice in their study, so that their offspring suffered from a disturbed communication that resembles the human stutter. The physicians published the results of their study in the journal "Current Biology".

Scientists are now changing the genes of mice so that their communication is disrupted and a state similar to human stuttering occurs. So the doctors wanted to fathom the causes of stuttering. (Image: efmukel / fotolia.com)

Researchers are changing the genes of mice and studying their communication
Stuttering is one of the most common language disorders in the world, affecting approximately one in every 100 adults in the United States alone, the researchers say. But the cause of this speech disorder is still completely unclear. Scientists discovered a few years ago that stuttering people often suffer from the mutation of a gene. This gene, called GNPTAB, encodes a protein that destroys waste products in animal cells and recycles the old cellular machinery, the experts explain. Mutations of other genes in this system cause the buildup of cellular waste products and often lead to debilitating diseases. How the GNPTAB mutation causes a stuttering language is still a mystery, the experts add. To explore the origins of stuttering, a team of neuroscientists from Washington University, led by Drs. Terra Barnes the genes of some mice. This resulted in a mutation in the GNPTAB gene. Afterwards, the doctors examined the newborn puppies of the mice, whether they showed signs of stuttering during their ultrasound communication with the mother. However, it is not an easy task to determine if a mouse is stuttering or not, explains dr. Barnes. It is even difficult for people to tell if a person is stuttering when they speak in a foreign language.

Computer program analyzes patterns of vocalization
For this reason, the team develops a computer program that could detect stuttering on the pattern of vocalization, regardless of the language spoken. The program pays attention to the number of vocalizations per minute and calculates the length of the pauses, explain the scientists. In humans, the program recognized 79 percent of all stuttering subjects. Mice with a mutated copy of the GNPTAB gene showed less vocalization and longer pauses than normal mice. The affected mice were still physically able to communicate normally. A series of cognitive and physical tests showed that the mice were otherwise completely healthy, explain the doctors. Although there are large differences in the complexity between humans and mice, mutated copies of GNPTAB have similar effects. Thus, the stuttering mice are a potentially valuable model. We can test each drug for its effect and then find out which parts of the brain are affected, the experts add.

Further research is needed to better understand causes
So far, the exact cause of stuttering is not yet clear. The build-up of undigested waste products from a malfunction of the lysosome system is only one possible cause of stuttering, explains co-author Dr. Tim Holy of the Washington University School of Medicine, St. Louis. Another possibility would be that the genes perform a different function whose relationship has not yet been understood. (As)