Volitional inspiration significantly increased fMRI BOLD signals in the superior motor, premotor, and supplementary motor cortices compared to mechanical ventilation.
Does voluntary breathing compared to mechanical ventilation activate specific central nervous system regions detectable by fMRI in healthy men?
This study demonstrates that fMRI can successfully identify and localize respiratory-related neuronal activity during volitional inspiration with high spatial and temporal resolution.
Functional magnetic resonance imaging (fMRI) provides a means of studying neuronal circuits that control respiratory muscles in humans with better spatial and temporal resolution than in previous positron emission tomography (PET) studies. 2. Whole brain blood oxygenation level-dependent (BOLD) changes determined by fMRI were used to identify areas of neuronal activation associated with volitional inspiration in five healthy men. Four series of scans of each subject were acquired during voluntary breathing (active task) and mechanical ventilation (passive task). Ventilation and end-tidal PCO2 were similar between tasks. Scan data were re-aligned to correct for movement artefacts and cross-referenced breath by breath to respiratory data for selective averaging of inspiratory and expiratory images. 3. Group analysis identified significant increases in the fMRI signal with volitional inspiration in the superior motor cortex, premotor cortex and supplementary motor area at loci similar to those detected in earlier studies that used PET. Additional regions activated by volitional inspiration included inferolateral sensorimotor cortex, prefrontal cortex and striatum (these foci were only revealed by PET under significant inspiratory load). 4. This study represents the first synchronised breath-by-breath analysis of respiratory-related neuronal activity with whole brain imaging in humans. Temporal resolution is sufficient to distinguish individual breaths at a normal breathing frequency.
Evans et al. (Fri,) conducted a other in Healthy volunteers (n=5). Voluntary breathing (volitional inspiration) vs. Mechanical ventilation (passive task) was evaluated on Neuronal activation (BOLD changes) associated with volitional inspiration. Volitional inspiration significantly increased fMRI BOLD signals in the superior motor, premotor, and supplementary motor cortices compared to mechanical ventilation.
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