Brain Imaging of Respiratory Overloads

Respiration is controlled involuntarily by medullary respiratory centers in the pons and voluntarily through the motor cortex. It also has an intimate relation to emotions. The aim of this study was to examine effects of respiration on regional brain activities by using a brain imaging technique, positron emission tomography (PET) and statistical parametric mapping. Twenty-eight male normal volunteers, 30.2 years (SD 8.6), were divided into three groups: control (without resistance), group 30 (mild inspiratory resistance of 30 cm H2O/L/sec), group 70 (moderate inspiratory resistance of 70 cm H2O/L/sec). PET studies were carried out by injecting 191.51 MBq (SD 69.42) of FDG at one minute after applying the inspiratory resistance (groups 30 and 70) which lasted for 30 min or during resting breathing (control group) using a PET scanner. Image processing and statistical analyses were carried out using the statistical parametric mapping software (SPM99; Wellcome Department of Cognitive Neurology, Queens Square, London, UK)1. Comparison among all groups showed extensive activation and deactivation. Respiratory loads activated the motor area, frontal lobe and temporal pole bilaterally; an extensive reduction in brain metabolism was found in the posterior part of the brain including the parietal lobe.