Lateralization of cortical function in swallowing: A functional MR imagingstudy

BACKGROUND AND PURPOSE: While functional MR imaging and other techniques ha ve contributed to our knowledge of functional brain localization, these met hods have not been extensively applied to the complex and incompletely unde rstood task of swallowing. We used functional MR imaging to investigate mot or cortex activity during swallowing in healthy human adults. METHODS: Eight subjects were imaged on a 1.5-T MR system using blood oxygen level-dependent contrast mechanisms. Subjects performed three swallowing t asks and a finger-tapping task. Areas of activation in the cortex and subco rtical areas were tabulated, and a laterality index, defined as LI = [Sigma s left - Sigma s right]/[Sigma s left + Sigma s right] x 100, was computed for the three tasks. RESULTS: Activation was observed in the primary motor and sensory cortices, motor processing and association areas, and subcortical sites. This activi ty was dominant for one hemisphere with left hemispheric dominance more pre valent among the subjects. Right hemispheric dominance, however, showed str onger lateralization than the left hemisphere. CONCLUSION: Our data indicate that specific sites in the motor cortex and o ther cortical and subcortical areas are activated with swallowing tasks and that hemispheric: dominance is a feature of swallowing under these conditi ons. In addition, we demonstrate the utility of functional MR imaging in th e study of the cortical representation of swallowing and suggest a role for functional MR imaging in the diagnosis of dysphagia of cerebral origin.