Lateralization of cortical function in swallowing: a functional MR imaging study.

TLDR

Functional MR imaging has advanced brain localization, yet its application to the complex, poorly understood task of swallowing remains limited. The study aimed to map motor cortex activity during swallowing in healthy adults using fMRI. Eight healthy volunteers were scanned on a 1.5‑T MR system while performing three swallowing tasks and a finger‑tapping control; cortical and subcortical activation was quantified and a laterality index was calculated. Swallowing activated primary motor, sensory, association, and subcortical regions, with left‑hemisphere dominance more common but right‑hemisphere dominance showing stronger lateralization, demonstrating fMRI’s utility for mapping swallowing and aiding diagnosis of cerebral dysphagia.

Abstract

While functional MR imaging and other techniques have contributed to our knowledge of functional brain localization, these methods have not been extensively applied to the complex and incompletely understood task of swallowing. We used functional MR imaging to investigate motor cortex activity during swallowing in healthy human adults.Eight subjects were imaged on a 1.5-T MR system using blood oxygen level-dependent contrast mechanisms. Subjects performed three swallowing tasks and a finger-tapping task. Areas of activation in the cortex and subcortical areas were tabulated, and a laterality index, defined as LI = [sigmas left - sigmas right]/[sigmas left + sigmas right] x 100, was computed for the three tasks.Activation was observed in the primary motor and sensory cortices, motor processing and association areas, and subcortical sites. This activity was dominant for one hemisphere with left hemispheric dominance more prevalent among the subjects. Right hemispheric dominance, however, showed stronger lateralization than the left hemisphere.Our data indicate that specific sites in the motor cortex and other cortical and subcortical areas are activated with swallowing tasks and that hemispheric dominance is a feature of swallowing under these conditions. In addition, we demonstrate the utility of functional MR imaging in the study of the cortical representation of swallowing and suggest a role for functional MR imaging in the diagnosis of dysphagia of cerebral origin.