What Causes Stuttering?
During childhood, about one in 20 people go through a period of stuttering. Until the latter half of the 20th century, stuttering was believed to be a psychological problem stemming from lack of effort or from trauma.
Nowadays, neuroimaging techniques are leading to a much better understanding of brain function during speech and how stuttering arises. Frank Guenther, from Boston University, reported findings from a new study at the 181st Meeting of the Acoustical Society of America.
Guenther gives the example of speech being a jukebox that plays CDs. The jukebox has two circuits: one that chooses a CD and one that plays the CD.
In the brain, this corresponds to one circuit initiating the desired speech in the basal ganglia, while another circuit coordinates the muscles needed to generate the speech. Stuttering stems from the initiation of speech, so only the first of the two circuits is impaired.
“In stuttering, the CDs themselves are fine, but the mechanism for choosing them is impaired,” said Guenther.
This theory is in agreement with behavioural observations of stuttering: people will often speak words fluently later in a sentence, even if those same words cause stuttering at the start of a sentence.
Guenther and his team created computational models of how the speech initiation circuit performs in a non-stuttering individual. Since Parkinson’s disease also affects the initiation circuit, they can compare these models directly to data taken from the basal ganglia during deep brain stimulation surgery in patients with the disease.
“This gives us a fighting chance of finding the specific problems underlying stuttering and addressing them with highly targeted drugs or technological treatments that have minimal unwanted side effects,” said Guenther.
Source: EurekAlert!
