Electroencephalographic evidence for pre-motor cortex activation during inspiratory loading in humans.
Faced with mechanical inspiratory loading, awake animals and anaesthetized humans develop alveolar hypoventilation, whereas awake humans do defend ventilation. This points to a suprapontine compensatory mechanism instead of or in addition to the 'traditional' brainstem respiratory regulation. This study assesses the role of the cortical pre-motor representation of inspiratory muscles in this behaviour. Ten healthy subjects (age 19-34 years, three men) were studied during quiet breathing, CO2-stimulated breathing, inspiratory resistive loading, inspiratory threshold loading, and during self-paced voluntary sniffs. Pre-triggered ensemble averaging of Cz EEG epochs starting 2.5 s before the onset of inspiration was used to look for pre-motor activity. Pre-motor potentials were present during voluntary sniffs in all subjects (average latency (+/-s.d.): 1325 +/- 521 ms), but also during inspiratory threshold loading (1427 +/- 537 ms) and during inspiratory resistive loading (1109 +/- 465 ms). Pre-motor potentials were systematically followed by motor potentials during inspiratory loading. Pre-motor potentials were lacking during quiet breathing (except in one case) and during CO2-stimulated breathing (except in two cases). The same pattern was observed during repeated experiments at an interval of several weeks in a subset of three subjects. The behavioural component of inspiratory loading compensation in awake humans could thus depend on higher cortical motor areas. Demonstrating a similar role of the cerebral cortex in the compensation of disease-related inspiratory loads (e.g. asthma attacks) would have important pathophysiological implications: it could for example contribute to explain why sleep is both altered and deleterious in such situations.
Raux
Mathieu
M
Université Pierre et Marie Curie-Paris6, UPRES EA 2397, Paris, France.
Straus
Christian
C
Redolfi
Stefania
S
Morelot-Panzini
Capucine
C
Couturier
Antoine
A
Hug
François
F
Similowski
Thomas
T
D000328:Adult; D002245:Carbon Dioxide / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D015203:Reproducibility of Results; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology
D002245:Carbon Dioxide