Analysis of High Frequency EEG-EMG Mouth Movement and
Speech Correlates in Parkinsonís Disease
J Caviness, J Liss, L Parsons, C Adler, V Evidente
Oscillations coherent between the contralateral sensorimotor cortex and muscle can be recorded during voluntary muscle contractions. The nature of the EEG-EMG coherence patterns have been used to hypothesize that synchronization at specific frequencies in both the spatial and time domain are combined to produce coordinated voluntary movement.† Abnormalities in these coherence relationships have been found in Parkinsonís disease, and are thought to relate to movement abnormalities. Coherence analysis to examine muscle and cortical activation relationships has not been previously conducted in the context of speech production.† This study evaluated wrist, speech, and nonspeech EEG-EMG coherence patterns in normal and PD patients. It was hypothesized that 1) cortico-muscular coherence is demonstrable between the orbicularis oris and scalp EEG and 2) abnormalities in Parkinsonís disease versus control subjects exist for the cortico-muscular coherence of orbicularis oris as increased and/or decreased coherence values in various topographies and frequency bands.† In general, the findings 1) confirmed the presence of EMG-EEG cohererence for some tasks; 2) revealed coherence differences between PD and controls for some tasks; 3) and revealed a trend for coherence and spectral differences between some speech and nonspeech tasks for both groups.† Though preliminary, the findings support the potential for coherence analysis to reveal cortical contributions to motor speech disorders.