Motor control factors that are specific to speech, which is a voluntary function overlaid on more basic reflex systems, must eventually be investigated at the cortical level. Aspects of cortical motor control for voluntary movements, including speech, can be visualized in averaged electroencephalographic potentials that occur prior to movement initiation. This psychophysiological technique attempts to relate variability in the physiological marker (the event-related EEG) to variations of the more complex behavioral task. Though stable patterns prior to hand and foot movements have been well described, standard event-related potential patterns preceding speech have not been ascertained. This research will evaluate the cortical activation patterns in 40 normal subjects prior to three oral tasks. Averaged potentials prior to a basic task (lip rounding), a word production task, and a sentence production task will be recorded from scalp electrodes. The EEG data will be computer averaged with respect to EMG onset measured at the lip, and analyzed in terms of differences in the waveform among subjects, tasks, and electrode sites. From these data, hypotheses of bilateral cortical control of midline oral movement, versus hypotheses of dominant hemisphere control for these muscles when they are engaged in complex or speech tasks, will be addressed. In addition, the results from this relatively large sample will provide a standard baseline for evaluation of small sample or individual results. The improved estimates of variability and guidelines for data collection developed in this project will support future clinical applications, including non-invasive description of upper motor neuron function following stroke and other diseases affecting motor and premotor cortex, and identification of cortical activation patterns in syndromes affecting voluntary motor output for speech, such as Parkinson's disease and apraxia of speech.
| Wohlert, A B (1996) Perioral muscle activity in young and older adults during speech and nonspeech tasks. J Speech Hear Res 39:761-70 |
| Wohlert, A B; Goffman, L (1994) Human perioral muscle activation patterns. J Speech Hear Res 37:1032-40 |
