Normal swallowing and functional magnetic resonance imaging: a systematic review.

Unknowns about the neurophysiology of normal and disordered swallowing have stimulated exciting and important research questions. Previously, these questions were answered using clinical and animal studies. However, recent technologic advances have moved brain-imaging techniques such as functional magnetic resonance imaging (fMRI) to the forefront of swallowing neurophysiology research. This systematic review has summarized the methods and results of studies of swallowing neurophysiology of healthy adults using fMRI. A comprehensive electronic and hand search for original research was conducted, including few search limitations to yield the maximum possible number of relevant studies. The participants, study design, tasks, and brain image acquisition were reviewed and the results indicate that the primary motor and sensory areas were most consistently active in the healthy adult participants across the relevant studies. Other prevalent areas of activation included the anterior cingulate cortex and insular cortex. Review limitations and suggested future directions are also discussed.