Structure and Function of the Human Tongue

This study will use magnetic resonance imaging (MRI) and ultrasound to examine changes in tongue volume and blood circulation during tongue exercises that require the use of different tongue muscle movements and contractions. More information on the structure and function of the human tongue is needed to develop better treatments for people with certain diseases affecting speech and swallowing. Normal volunteers between 21 and 80 years old who live in the metropolitan Washington, D.C., area may be eligible for this study. Candidates will be screened with a brief medical history and physical examination, including suitability for MRI testing, and a brief examination of tongue, lip and jaw movements. Participants will undergo ultrasound and MRI studies. During both tests, they will perform tongue exercises, such as holding a soft round object on the tongue or exerting tongue pressure against the back of the throat or roof of the mouth. During the ultrasound, the subject lies on a flattened dental chair. A small transducer is placed under the chin to take images of the tongue during the exercises. A thin rubber strip with air-filled pressure bulbs is attached to the roof of the mouth (with dental adhesive) to measure tongue pressure. For the MRI, the subject lies on a table that slides inside a donut's machine containing a magnetic field. MRI coils-special padded sensors that improve image quality-are placed around the head and neck. A pressure cuff placed around the arm measures blood pressure. The subject wears earplugs to muffle loud thumping noises that occur during electrical switching of the magnetic fields. The subject is in constant visual contact with the researchers and MR technologist and may request to stop the study at any time. Participants may undergo another procedure, called magnetic resonance diffusion tensor imaging, to examine how the fluid (water) in the tongue tissue shifts during tongue maneuvers. This procedure is essentially the same as the first MRI study, but two small round coils are placed in the mouth (one on each side) between the cheeks and the teeth.