As an organ unparalleled in anatomical architecture, the tongue has the versatility to effect regional deformations and positional changes with multiple potential degrees of freedom. Despite an abundance of studies on the tongue and its functions, as well as numerous proposed tongue models over the years, much of the anatomical and biomechanical details of the in vivo human tongue remain poorly understood. Physiologically based biomechanical modeling of the tongue in swallowing is the ultimate objective of this protocol. However, before such modeling can be accurately pursued, a substantial database must be established, and several important, unaddressed issues regarding lingual anatomy and biomechanics must be resolved. These issues include: (1) the compressibility of the human tongue and its common, yet untested, reference as a muscular hydrostat; (2) task induced interactions between lingual musculature and vasculature and region-specific vascular demands; (3) changes in lingual fiber orientation, length, and strain distribution as a function of contraction tasks; and (4) effects of normal aging, disease processes, and task training on lingual myoarchitecture as well as the integration between structure and function. Using advanced 3D MRI, Doppler ultrasonography, and other MR imaging techniques (e.g., tagged MRI, diffusion tensor MRI), this protocol proposes to quantitatively address these issues and contribute to a better understanding of the functional biomechanical as well as myoarchitectural intricacies of the in vivo human tongue.

• INCLUSION CRITERIA

Volunteers must:

1. be older than 21 years in age;
2. reside in the Metropolitan Washington, D.C. Area;
3. have no speech, swallowing, respiratory, or cardiac problems;
4. be able to hold breath for at least 20-30 seconds;
5. be in good general health;
6. not be pregnant or nursing;
7. not be on medications that would adversely affect blood pressure, circulation, pulmonary function, speech, or swallowing ability.

Patients must:

1. be older than 21 years in age;
2. not be pregnant or nursing;
3. have tongue weakness, as confirmed in oral motor examination, associated with neurologic, degenerative, musculoskeletal, or other diseases.

EXCLUSION CRITERIA:

Healthy Volunteers:

1. Any contraindication for MRI, including:

   pacemaker or other implanted electronic device

   cochlear implants

   metal in the eye

   embedded shrapnel fragments

   cerebral aneurysm clips

   medical infusion pumps

   orthodontic braces, unremovable metal retainer, dental implants, crowns, long metal bridges, large or multiple amalgam fillings

   metal clips or wires in other parts of the body

2. Medical conditions that present elevated risks or reduced tolerance for an MRI procedure. Examples:

   angina

   severe and uncontrolled hypertension

   severe cardiovascular disorders

   dyspnea at rest

   severe claudication (less than 1 flight of steps)

   paralyzed hemidiaphragm

   symptoms of pheochromocytoma or insulinoma

   hemoglobinopathies

   severe asthma, allergies and postnasal drainage

   uncontrolled renal or hepatic disease

   severe back pain and inability to tolerate supine positioning

   claustrophobia

   morbid obesity

   pregnancy or lactation

3. History of swallowing problems or other conditions that adversely affect cardiac function, deglutitive function, tongue motility and control, hearing, language, and cognition.
4. Unsatisfactory performance status, as judged by the examining speech-language pathologist, that indicates poor compliance for the planned tasks (e.g., oral motor deficits, inability to hold breath for at least 20 seconds).

Patients:

1. Any contraindication for MRI, same as 5.2.1 (1);
2. Medical conditions that present high risks or severely reduced tolerance for an MRI procedure, as determined by or based on consultation with the medically responsible individual (or a designated substitute);
3. History of other conditions that have severely impaired cardiac function, hearing, language, and cognition.