description): The objective is to identify the brain structures that are deficient in patients afflicted with Congenital Central Hypoventilation Syndrome (CCHS), a disorder characterized by absence of central chemoreception, loss of breathing drive during sleep, and occasional waking hypotonia. Brain areas will be visualized with functional magnetic resonance procedures in normal subjects and CCHS patients during baseline conditions and during challenges of mild hypoxia, hypercapnia, and transient elevation of blood pressure. Blood oxygen level dependent (BOLD) functional magnetic resonance images will be collected from fifteen CCHS patients and 15 age-matched controls during baseline, and 100% 02, 5% CO2 in 95% 02, and 15% 02 ventilatory challenges, and during Valsalva pressor maneuvers, while respiration, heart rate and variability, non-invasive blood pressure, and an index of sympathetic outflow (sweating) are measured. Brain images from baseline conditions will be subtracted from images collected during experimental challenges. The extent of activation and time course of changes in activated brain regions during challenges and recovery will be compared in CCHS patients and controls. The timing of activation of different brain sites will be correlated with physiological changes accompanying the challenges.
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