Central swallowing in normal adults using functional magnetic resonance imaging

BACKGROUND: While brain-imaging studies in healthy adults have indicated that multiple cortical regions are involved in swallowing, these functional imaging techniques have not been extensively applied to the complete understand neurophysiology of swallowing in China. A full understanding of normal swallowing neurophysiology is important for improving functional outcomes for dysphagia due to neurologic disorders or damage with increasing age. Thus the interpretations of the functional contributions of various brain areas in swallowing should be scientifically researched. OBJECTIVE: To identify the activation and characteristic of swallowing center in healthy adults using functional magnetic resonance imaging. DESIGN TIME AND SETTING: An uncontrolled neuroimaging study was performed at the Outpatient Clinic, Department of Radiology, West China Hospital of Sichuan University between March and November 2008. PARTICIPANTS: Ten healthy right-handed volunteers, aged over 20 years With a mean age of (34.2 +/- 8.1) years, a range of 25-45 years and including five males and five females participated. A medical history was obtained from all potential subjects and all subjects were free of systemic diseases and neurological disorders. METHODS: The healthy volunteers were examined With event-related functional magnetic resonance imaging of blood oxygenation level-dependent while laryngeal swallow-related movements were recorded. Subjects were scanned during voluntary saliva swallowing and water bolus swallowing activation tasks. Data was processed using the General Linear Model. A voxel by voxel group comparison was performed using random effect analysis. Any cluster With a corrected P < 0.05 for spatial extent was considered significant. MAIN OUTCOME MEASURES: The cerebral cortical activation maps of voluntary swallowing of saliva and swallowing of water bolus in healthy adults were observed. RESULTS: A multifocal cortical representation of swallowing was in the precentral gyrus, postcentral gyrus, insula, anterior cingulate gyrus, thalamus, basal ganglia and cerebellum, in a bilateral and asymmetrical manner, predominantly on the left hemisphere in the volunteers (P < 0.05). CONCLUSION: Activation of the cortex during normal swallowing tasks may be functionally linked to basal nuclei, thalamus, and cerebellum, greatly appearing in the left hemisphere.