Time Course of Lexicalization During Sentence Production in Parkinson's Disease: Eye-Tracking While Speaking Purpose Growing evidence suggests that sentence formulation is affected in Parkinson's disease (PD); however, how speakers with PD coordinate sentence planning and speaking remains unclear. Within 2 competing models of sentence production, this study examined whether speakers with PD show advanced buffering of words to minimize disfluencies and increased demands ... Research Article
Research Article  |   April 14, 2017
Time Course of Lexicalization During Sentence Production in Parkinson's Disease: Eye-Tracking While Speaking
 
Author Affiliations & Notes
  • Jiyeon Lee
    Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN
  • Disclosure: The author has declared that no competing interests existed at the time of publication.
    Disclosure: The author has declared that no competing interests existed at the time of publication. ×
  • Correspondence to Jiyeon Lee: lee1704@purdue.edu
  • Editor: Rhea Paul
    Editor: Rhea Paul×
  • Associate Editor: Swathi Kiran
    Associate Editor: Swathi Kiran×
Article Information
Development / Special Populations / Older Adults & Aging / Speech, Voice & Prosody / Language / Research Articles
Research Article   |   April 14, 2017
Time Course of Lexicalization During Sentence Production in Parkinson's Disease: Eye-Tracking While Speaking
Journal of Speech, Language, and Hearing Research, April 2017, Vol. 60, 924-936. doi:10.1044/2016_JSLHR-L-15-0350
History: Received October 5, 2015 , Revised March 24, 2016 , Accepted August 12, 2016
 
Journal of Speech, Language, and Hearing Research, April 2017, Vol. 60, 924-936. doi:10.1044/2016_JSLHR-L-15-0350
History: Received October 5, 2015; Revised March 24, 2016; Accepted August 12, 2016

Purpose Growing evidence suggests that sentence formulation is affected in Parkinson's disease (PD); however, how speakers with PD coordinate sentence planning and speaking remains unclear. Within 2 competing models of sentence production, this study examined whether speakers with PD show advanced buffering of words to minimize disfluencies and increased demands during speech or whether they plan one word at a time, compromising accuracy and fluency of speech.

Method Participants described 3 computer-displayed pictures using the sentence “the A and the B are above the C.” Name agreement (codability) was varied to be high (clock) or low (sofa/couch) for each object position (A, B, C), affecting difficulty of lexical selection. Participants' gaze durations to each object were recorded.

Results Speakers with PD showed incremental word-by-word planning, retrieving only the first lexical item (A) before speech onset, similar to controls. However, they produced greater word-finding errors and disfluencies compared to controls for the low-codable pictures, but not for high-codable pictures.

Conclusions These findings suggest that by following word-by-word incremental production, speakers with PD compromise fluency and accuracy of speech to a greater extent than healthy older speakers and that PD is associated with impaired inhibitory control during lexical selection.

Acknowledgments
This study was supported by an American Speech-Language-Hearing Foundation New Investigator's grant. The author would like to thank participants with PD and their caregivers for their participation in the study, the Motor Speech Laboratory at Purdue University (PI: Jessica Huber) for their assistance with participant recruitment, and Jessica Dick and Katie O'Connor for assisting with data collection and analysis. The author also thanks Drs. Jessica Huber and David Kemmerer for commenting on a previous version of this manuscript.
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