Researchers believe that stuttering -- a potentially lifelong and debilitating speech disorder -- stems from problems with the circuits in the brain that control speech, but precisely how and where these problems occur is unknown. Using a mouse model of stuttering, scientists report that a loss of cells in the brain called astrocytes are associated with stuttering. The mice had been engineered with a human gene mutation previously linked to stuttering. The study offers insights into the neurological deficits associated with stuttering.