Jaw-phonatory coordination in chronic developmental stuttering Torrey M.J. Loucks 1, * , Luc F. De Nil 1,2 , Jayanthi Sasisekaran 1 Graduate Department of Speech-Language Pathology, Rehabilitation Sciences Building, Room 160, University of Toronto, 500 University Avenue, Toronto, Ont. M5G1V7, Canada Received 19 December 2005; received in revised form 14 June 2006; accepted 26 June 2006 Abstract A deficiency in sensorimotor integration in a person who stutters may be a factor in the pathophysiology of developmental stuttering. To test oral sensorimotor function in adults who stutter, we used a task that requires the coordination of a jaw-opening movement with phonation onset. The task was adapted from previous limb coordination studies, which show that movement coordination depends on intact proprioception. We hypothesized that adult stutterers would show deficient jaw-phonatory coordination relative to control participants. The task required initiation of phonation as a jaw-opening movement passed through a narrow spatial target. Target amplitude and jaw movement speed were varied. The stuttering group showed significantly higher movement error and spatial variability in jaw-phonatory coordination compared to the control group, but group differences in movement velocity or duration were not found. The aberrant jaw-phonatory coordina- tion of the stuttering participants suggests that stuttering is associated with an oral proprioceptive limitation, although, the findings are also consistent with a motor control deficit. Learning outcomes: As a result of this activity, reader will (1) learn about a hypothesis and evidence supporting the view that a sensorimotor deficit contributes to chronic developmental Journal of Communication Disorders 40 (2007) 257–272 * Corresponding author at: Laryngeal & Speech Section, Building 10, Room 5D38, National Institutes of Neurological Disorders & Stroke, Bethesda, MD 20896, United States. Tel.: +1 301 402 0762; fax: +1 301 480 0803. E-mail addresses: louckst@ninds.nih.gov (T.M.J. Loucks), luc.denil@utoronto.ca (L.F. De Nil), jsasisek@purdue.edu (J. Sasisekaran). 1 Tel.: +1 416 978 1789. 2 Principal Investigator and Senior Author. 0021-9924/$ – see front matter # 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jcomdis.2006.06.016