Cortical representation of swallowing in normal adults: Functional implications

Objective: Dysphagia of neurogenic or postsurgical origin presents manageme nt and therapeutic challenges to the otolaryngologist. Improvements in mana gement and therapeutic approaches may be facilitated by understanding how t he central nervous system controls swallowing. The purpose of this investig ation was to utilize functional magnetic resonance imaging to determine pat terns of cortical activity during swallowing in normal, healthy adult subje cts. Study Design: Functional magnetic resonance imaging (fMRI) was perform ed on eight healthy adult subjects using conventional BOLD (blood oxygenati on level dependent) techniques. Methods: Subjects performed three different swallowing tasks including dry and bolus swallows, and performed a control finger movement task. Statistical maps of cortical activation were generat ed using a cross-correlation analysis. One-way and two-way ANOVA statistica l analyses were performed to compare activated areas among the different ta sks and to determine the effects of task sequence. Results: Activation duri ng the three swallowing tasks occurred in the primary motor cortex, primary somatosensory cortex, and other cortical and subcortical sites. Cortical r epresentation of swallowing and finger movement followed somatotopic maps. Differential distribution of cortical activation was observed for the diffe rent swallowing tasks. Conclusions: Activation of the primary motor and som atosensory cortices, as well as other sensory-motor areas, occurs with swal lowing in normal adults. Differential distribution of cortical activity wit h different swallowing tasks suggests differential functional organization for different swallowing tasks. Understanding these mechanisms may facilita te improved management and therapeutic intervention for neurogenic and post surgical dysphagia.