Contribution of the speech musculature to apparent human EEG asymmetries prior to vocalization

Abstract Vocalizations are preceded by slow EEG waves over inferior frontal scalp regions, but some controversy exists as to whether these slow potentials are left-lateralized as a function of speech. In this study both speech and non-speech vocalizations were studied, under conditions of repetitive and variable production. Averaged responses over the speech musculature, including the temporalis, masseter, orbicularis oris, and mylohyoid muscles, as well as the eyes and tongue, were calculated simultaneously with scalp EEG averages. The responses of the temporalis and masseter muscles, as well as that of the tongue, were correlated with EEG sites at specific latencies prior to speech, suggesting that no part of the inferior frontal EEG record was free from myogenic confounds. In addition, all significant EEG differences between speech and non-speech conditions were subsequently eliminated by covariance analysis, using selected muscle channels as covariates. Previous reports of asymmetrical “speech potentials” in the EEG probably reflected a combination of several myogenic confounds.

[1]  R. S. Levy The Question of Electrophysiological Asymmetries Preceding Speech , 1977 .

[2]  Cortical potentials time-locked to speech production: Evidence for probable cerebral origin , 1972 .

[3]  L K Morrell,et al.  Electrocortical localization of language production. , 1971, Science.

[4]  H G Vaughan,et al.  Topography of the human motor potential. , 1968, Electroencephalography and clinical neurophysiology.

[5]  EDWARD W. P. SCHAFER Cortical Activity preceding Speech: Semantic Specificity , 1967, Nature.

[6]  E. Schafer,et al.  Cortical activity preceding speech. , 1967, Life sciences.

[7]  H. H. Kornhuber,et al.  Methodological problems in the investigation of cerebral potentials preceding speech: Determining the onset and suppressing artefacts caused by speech , 1975, Neuropsychologia.

[8]  D. Kimura The Neural Basis of Language Qua Gesture , 1976 .

[9]  H G Vaughan,et al.  Characteristics of cranial and facial potentials associated with speech production. , 1977, Electroencephalography and clinical neurophysiology.

[10]  F W Elliott,et al.  The electrophysiologic assessment of hemispheric asymmetries during speech. , 1974, Journal of speech and hearing research.

[11]  G. K. Karnavar,et al.  Some preliminary observations on the influence of faecal lipids on the induction of larval diapause in an insect. , 1969, Life sciences.

[12]  D. Mcadam,et al.  Bereitschaftspontential enhancement with increased level of motivation. , 1969, Electroencephalography and clinical neurophysiology.

[13]  H A Whitaker,et al.  Language Production: Electroencephalographic Localization in the Normal Human Brain , 1971, Science.