Speech is a major disturbance to automatic breathing control. Speech occurs during exhalation, involving controlled inhibition of automatic inspiration. Additionally, utterances are preceded by prephonatory inspirations that must be prepared to account for prosody and loudness. We hypothesized that the speech-related breathing control activities shaping prephonatory breaths originate in cortical pre-motor areas and should be associated with corresponding EEG evidence. We studied 10 normal subjects (4 men, age 23-27) during spontaneous breathing, sniff manoeuvres, and while reading out loud. Fronto-median inspiratory potentials (Cz EEG derivation) were consistently present before voluntary inspirations and large prephonatory breaths, while these potentials were generally absent during resting breathing or small prephonatory breaths. We conclude that the preparation of prephonatory breaths during speech has a cortical substrate, involving the cortical sources of premotor potentials. These results have important implications to validate whether co-modulation of the pre-motor cortex and breathing during speech are incidental or whether these cortical modulations are necessary for initiation of "speech breathing".
Keywords: Cerebral cortex; Control of breathing; Speech; Speech breathing; Supplementary motor area.
Copyright © 2014 Elsevier B.V. All rights reserved.