Motor Unit Territories in the Human Perioral Musculature The perioral region was divided into four quadrants, and electromyograms (EMGs) were recorded from each area. The coherence function (i.e., the squared cross correlation between two signals computed at each frequency in the spectrum) was used to determine aspects of the organization of motor unit territories and to examine potential ... Research Article
Research Article  |   October 01, 1994
Motor Unit Territories in the Human Perioral Musculature
 
Author Affiliations & Notes
  • Lisa Goffman
    Department of Audiology and Speech Sciences, Purdue University, West Lafayette, IN
  • Anne Smith
    Department of Audiology and Speech Sciences, Purdue University, West Lafayette, IN
  • Contact author: A. Smith, PhD, Department of Audiology and Speech Sciences, Heavilon Hall, Purdue University, West Lafayette, IN 47907.
Article Information
Swallowing, Dysphagia & Feeding Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   October 01, 1994
Motor Unit Territories in the Human Perioral Musculature
Journal of Speech, Language, and Hearing Research, October 1994, Vol. 37, 975-984. doi:10.1044/jshr.3705.975
History: Received November 5, 1993 , Accepted March 10, 1994
 
Journal of Speech, Language, and Hearing Research, October 1994, Vol. 37, 975-984. doi:10.1044/jshr.3705.975
History: Received November 5, 1993; Accepted March 10, 1994

The perioral region was divided into four quadrants, and electromyograms (EMGs) were recorded from each area. The coherence function (i.e., the squared cross correlation between two signals computed at each frequency in the spectrum) was used to determine aspects of the organization of motor unit territories and to examine potential higher level sources of input in speech and nonspeech tasks. Coherence functions were computed between pairs of EMGs and were examined for significant values in the range of 20–240 Hz. When two pairs of electrodes were intentionally placed to record the activity from a common subset of motor units in a single quadrant of the lower lip, all subjects exhibited significant broad-band coherence in every frequency in all experimental tasks. Thus, the presence of such a pattern of broad-band significant coherence for EMG pairs recorded from different quadrants would indicate that single motor unit territories extended across perioral quadrants. When separate EMG recordings were obtained from the four quadrants of the lips, coherence functions computed between EMG pairs were typically zero across the entire frequency range. These findings suggest that perioral motor unit territories are organized into nonoverlapping quadrants. Further, the present analyses suggest that, unlike bilateral pairs of jaw-closing muscles during chewing, these motor units are not driven by any correlated oscillatory activity in chewing or other oral motor tasks.

Acknowledgments
This research was supported by grant DC00559 from the National Institutes of Hearth, Institute on Deafness and Other Communicative Disorders. The authors thank Margaret Denny for her assistance with this project and Erich Luschei and an anonymous reviewer for their insightful comments on an earlier draft of the manuscript.
Order a Subscription
Pay Per View
Entire Journal of Speech, Language, and Hearing Research content & archive
24-hour access
This Article
24-hour access