Cerebral Averaged Potentials Preceding Oral Movement The “readiness potential” is an event-related potential that shows increasing negativity at vertex and motor strip scalp recording sites prior to voluntary, unilateral limb movements. Though speech involves movement on both sides of the midline, recent recordings of prespeech potentials suggest a pattern of bilateral activation that lateralizes to the ... Research Article
Research Article  |   December 01, 1991
Cerebral Averaged Potentials Preceding Oral Movement
 
Author Affiliations & Notes
  • Amy B. Wohlert
    Northwestern University, Evanston, IL
  • Charles R. Larson
    Northwestern University, Evanston, IL
  • Requests for reprints should be sent to A. B. Wohlert, PhD, Division of Speech and Hearing Science, The Ohio State University, 1070 Carmack Road, Columbus, OH 43210-1002.
  • Currently affilliated with The Ohio State University.
    Currently affilliated with The Ohio State University.×
Article Information
Hearing / Research Articles
Research Article   |   December 01, 1991
Cerebral Averaged Potentials Preceding Oral Movement
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1387-1396. doi:10.1044/jshr.3406.1387
History: Received June 14, 1990 , Accepted February 26, 1991
 
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1387-1396. doi:10.1044/jshr.3406.1387
History: Received June 14, 1990; Accepted February 26, 1991

The “readiness potential” is an event-related potential that shows increasing negativity at vertex and motor strip scalp recording sites prior to voluntary, unilateral limb movements. Though speech involves movement on both sides of the midline, recent recordings of prespeech potentials suggest a pattern of bilateral activation that lateralizes to the dominant hemisphere just prior to the onset of articulatory movement. To determine whether this pattern of dominant hemisphere activation is present prior to a stereotyped, nonspeech movement of the mouth, the averaged potentials preceding a lip protrusion task were recorded at the cranial vertex and over the right and left motor cortex. Results were compared to potentials preceding a right finger extension task performed by the same subjects. Both the finger and the lip movements were initially preceded by slow negative potentials. Prior to the finger extension task, the negative amplitude became greatest over the left motor cortex, contralateral to the side of movement. Prior to the lip protrusion task, the amplitude of the potential remained even over the right and left motor cortices. The results suggest that, for this nonspeech movement of a midline structure, bilateral cortical control takes place. Control of lip movement is apparently not necessarily a dominant hemisphere function, though dominance may become part of the motor control strategy for more complex movements such as those used during speech.

Acknowledgments
This article is based on a doctoral dissertation by A. B. Wohlert that was supported in part by DYG 0100-510-147Y from the University Research Grants Committee at Northwestern University. Grateful acknowledgment is made to S. M. Barlow and two anonymous reviewers for comments on an earlier draft of this article.
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