Inspiratory resistances facilitate the diaphragm response to transcranial stimulation in humansReport as inadecuate




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BMC Physiology

, 6:7

First Online: 29 July 2006Received: 16 May 2006Accepted: 29 July 2006

Abstract

BackgroundBreathing in humans is dually controlled for metabolic brainstem commands and behavioral purposes suprapontine commands with reciprocal modulation through spinal integration. Whereas the ventilatory response to chemical stimuli arises from the brainstem, the compensation of mechanical loads in awake humans is thought to involve suprapontine mechanisms. The aim of this study was to test this hypothesis by examining the effects of inspiratory resistive loading on the response of the diaphragm to transcranial magnetic stimulation.

ResultsSix healthy volunteers breathed room air without load R0 and then against inspiratory resistances 5 and 20 cmH2O-L-s, R5 and R20. Ventilatory variables were recorded. Transcranial magnetic stimulation TMS was performed during early inspiration I or late expiration E, giving rise to motor evoked potentials MEPs in the diaphragm Di and abductor pollicis brevis APB. Breathing frequency significantly decreased during R20 without any other change. Resistive breathing had no effect on the amplitude of Di MEPs, but shortened their latency R20: -0.903 ms, p = 0.03 when TMS was superimposed on inspiration. There was no change in APB MEPs.

ConclusionInspiratory resistive breathing facilitates the diaphragm response to TMS while it does not increase the automatic drive to breathe. We interpret these findings as a neurophysiological substratum of the suprapontine nature of inspiratory load compensation in awake humans.

Electronic supplementary materialThe online version of this article doi:10.1186-1472-6793-6-7 contains supplementary material, which is available to authorized users.

Thomas Similowski and Christian Straus contributed equally to this work.

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Author: Chrystèle Locher - Mathieu Raux - Marie-Noelle Fiamma - Capucine Morélot-Panzini - Marc Zelter - Jean-Philippe Derenne - T

Source: https://link.springer.com/







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