Cortical Representation of Swallowing: A Modified Dual Task Paradigm

Abstract

It is unclear whether the cortical representation of swallowing is lateralized to the left cerebral hemisphere, right hemisphere, or bilaterally represented. As dysphagia is common in acute stroke, it is important to elucidate swallowing lateralization to facilitate earlier detection of stroke patients who may be at greater risk for dysphagia and aspiration. In this study, a modified dual task paradigm was designed to study laterality of swallowing in a group of 14 healthy, young, right-handed, male adults. The subjects were studied at baseline and with interference. Baseline conditions, performed separately, were continuous swallowing, finger tapping using the right and left index fingers, and word repetition. Interference tasks, including tapping with the right index finger, tapping with the left index finger, and word repetition, were completed with and without swallowing. Finger-tapping rate was measured, and x-ray samples of the swallowing task were taped to measure swallowing rate and volume swallowed. At baseline, the rate of tapping the right index finger was significantly faster than that of the left index finger. There was a significant decline in the tapping rates of both left and right index fingers with swallowing interference. The volume per swallow was significantly reduced during the interfering language task of silent repetition. These results offer partial support for a bilateral representation of swallowing as well as suggest an important left hemispheric contribution to swallowing. However, it cannot be concluded that the left hemisphere is more important than the right, as a comparable right hemisphere task was not studied.