Say Again

SPEECH

The mystery of stuttering may soon be unraveled. New evidence suggests an anatomical basis for the speech disorder, previously thought to have an emotional or learned component. A recent study headed by Anne Foundas, Ph.D., at Tulane University in New Orleans found differences in the "language centers" of the brain between persistent developmental stutterers and non-stutterers.

Foundas and her colleagues used magnetic resonance imaging to measure the brain surfaces of 16 stutterers and 16 control subjects. They found that a portion of Wernicke's area, which is believed to control language comprehension and auditory processing, was significantly enlarged in stutterers.

Strikingly, there were no size differences in Broca's area, which is considered the brain's motor-speech production center.

The researchers postulate that stuttering may result from disordered auditory processing, because when auditory feedback is delayed, stutterers become temporarily fluent and non-stutterers are temporarily stymied.

Foundas cautions that it is too early to draw definitive conclusions: "We cannot say whether the anatomical abnormalities cause the stuttering or whether years of stuttering cause brain anomalies," she says. However, there is evidence of neurological asymmetry in fetuses as young as 29 weeks. So, even before birth, much less language acquisition, a region crucial to language is anomalous.