Stuttering and the basal ganglia circuits: a critical review of possible relations Per A. Alm a,b,* a Department of Clinical Neuroscience, Lund University, Lund, Sweden b Department of Clinical Psychology, Lund University, Box 213, SE-221 00, Lund, Sweden Received 8 April 2003; received in revised form 12 February 2004; accepted 16 March 2004 Abstract The possible relation between stuttering and the basal ganglia is discussed. Important clues to the pathophysiology of stuttering are given by conditions known to alleviate dysfluency, like the rhythm effect, chorus speech, and singing. Information regarding pharmacologic trials, lesion studies, brain imaging, genetics, and developmental changes of the nervous system is reviewed. The symptoms of stuttering are compared with basal ganglia motor disorders like Parkinson’s disease and dystonia. It is proposed that the basal ganglia-thalamocortical motor circuits through the putamen are likely to play a key role in stuttering. The core dysfunction in stuttering is suggested to be impaired ability of the basal ganglia to produce timing cues for the initiation of the next motor segment in speech. Similarities between stuttering and dystonia are indicated, and possible relations to the dopamine system are discussed, as well as the interaction between the cerebral cortex and the basal ganglia. Behavioral and pharmacologic information suggests the existence of subtypes of stuttering. Learning outcomes: As a result of this activity, the reader will (1) become familiar with the research regarding the basal ganglia system relating to speech motor control; (2) become familiar with the research on stuttering with indications of basal ganglia involvement; and (3) be able to discuss basal ganglia mechanisms with relevance for theory of stuttering. # 2004 Elsevier Inc. All rights reserved. Keywords: Stuttering; Basal ganglia; Dopamine; Dystonia; Cluttering 1. Introduction Research concerning the nature of stuttering has produced an extensive amount of data during the past century, but the mechanisms behind the speech disruptions and the speech Journal of Communication Disorders 37 (2004) 325–369 * Tel.: þ46-46-177907; fax: þ46-46-177906. E-mail address: per.alm@psykiatr.lu.se (P.A. Alm). 0021-9924/$ – see front matter # 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.jcomdis.2004.03.001