title: Effect of an 8-week practice of externally triggered speech on basal ganglia activity of stuttering and fluent speakers.
abstract: The neural mechanisms underlying stuttering are not well understood. It is known that stuttering appears when persons who stutter speak in a self-paced manner, but speech fluency is temporarily increased when they speak in unison with external trigger such as a metronome. This phenomenon is very similar to the behavioral improvement by external pacing in patients with Parkinson's disease. Recent imaging studies have also suggested that the basal ganglia are involved in the etiology of stuttering. In addition, previous studies have shown that the basal ganglia are involved in self-paced movement. Then, the present study focused on the basal ganglia and explored whether long-term speech-practice using external triggers can induce modification of the basal ganglia activity of stuttering speakers. Our study of functional magnetic resonance imaging revealed that stuttering speakers possessed significantly lower activity in the basal ganglia than fluent speakers before practice, especially when their speech was self-paced. After an 8-week speech practice of externally triggered speech using a metronome, the significant difference in activity between the two groups disappeared. The cerebellar vermis of stuttering speakers showed significantly decreased activity during the self-paced speech in the second compared to the first experiment. The speech fluency and naturalness of the stuttering speakers were also improved. These results suggest that stuttering is associated with defective motor control during self-paced speech, and that the basal ganglia and the cerebellum are involved in an improvement of speech fluency of stuttering by the use of external trigger.
authors.affiliation: Research Center for Advanced Technologies, Tokyo Denki University, Muzai-Gakuendai, Inzai, Chiba 270-1382, Japan; Graduate School of Health Sciences, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma 371-8514, Japan; Research and Education Center for Brain Science, Hokkaido University, Kita 15, Nishi 7 Kita-ku, Sapporo 060-8638, Japan. Electronic address: toyomura@rcat.dendai.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Toyomura
authors.affiliation: Department of Psychology, Hokkaido University, Kita 10, Nishi 7 Kita-ku, Sapporo 060-0810, Japan.
authors.forename: Tetsunoshin
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Research Center for Advanced Technologies, Tokyo Denki University, Muzai-Gakuendai, Inzai, Chiba 270-1382, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kuriki
mesh_terms: D000328:Adult; D001479:Basal Ganglia / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011214:Practice, Psychological; D013060:Speech / Q000502:physiology; D013070:Speech Therapy; D013342:Stuttering / Q000503:physiopathology* / Q000534:rehabilitation*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Basal ganglia; Brain; Externally triggered speech; Self-paced speech; Stuttering; fMRI