The investigators hypothesize that individual differences exist in resting-state cortical attention, control, sensory, and emotion networks prior to noise exposure and these differences predispose some to the development of bothersome tinnitus. Furthermore, the investigators hypothesize that these changes in functional connectivity of these vulnerable systems after noise exposure are responsible for tinnitus. The proposed study will use a case-control cohort study design. Cases will be those soldiers who develop tinnitus and controls will be those who do not. This will be the first prospective study of tinnitus and will provide important information about the neurobiology of tinnitus.

If a cortical neural network etiology for bothersome tinnitus is confirmed, it will be an astounding, powerful, paradigm shifting model for the diagnosis, prevention and, most importantly, treatment of tinnitus. Furthermore, if a battery of neurocognitive tests can identify soldiers at risk for the development of tinnitus then appropriate primary prevention strategies can be introduced.

There are three Specific Aims to this project.

Specific Aim 1. To determine if soldiers who develop tinnitus display pre-deployment differences in a set of physical, functional, cognitive, vulnerability, perpetuating factors, pre-deployment neurocognitive scores, or neuroimaging features compared to soldiers who do not develop tinnitus ("control group").

Specific Aim 2. To determine if particular scores on neurocognitive tests or neuroimaging features of functional/structural connectivity networks are associated with the development of tinnitus.

Specific Aim 3. To identify a set of pre-deployment physical, functional, cognitive, vulnerability, and perpetuating factors, neurocognitive responses, and neuroimaging features that are associated with the development of tinnitus.

The investigators plan to recruit 200 soldiers, between the ages of 18 and 30 years who do not have hearing loss or tinnitus and have never been deployed to military theater. The soldier participants will undergo a variety of tests before and after deployment, which will include a hearing test, neurocognitive tests (i.e., brain function tests), and a variety of novel radiologic imaging studies of the brain. One of these novel radiologic imaging studies is functional connectivity Magnetic Resonance Imaging, a proven methodology that monitors changes in brain activity and connections based on blood flow between different brain areas and levels of consumption of oxygen. This information is used to describe the condition of important neural networks responsible for such things as attention, mood, sensation, vision, hearing, and introspection or self-contemplation.

Inclusion Criteria:

• Active duty or reserve military personnel with MOS job code 11B, 11C, 19D, or 19K
• Men and women between the ages of 18 and 30 years
• Scheduled for first deployment to military theater
• Must be able to read, write, and understand English
• Willing to sign Request Pertaining to Military Records (Form 180) to allow study personnel to access medical records for the purposes of this study.

Exclusion Criteria:

• History of hearing loss or tinnitus
• Currently taking medication for depression, anxiety, or other DSM IV Axis 1 disorder
• History of head trauma sufficient to cause loss of consciousness for 30 minutes or greater
• History of surgery to the brain
• History of claustrophobia
• Presence of metallic implants in the head and upper cervical region that are non-MRI compatible and would prohibit use of MRI.
• At any time in the past, prior deployment or employment in military theater
• Currently pregnant

Active-duty or reserve United States military personnel between the ages of 18 and 30 of either sex, all races and ethnicity, who are scheduled for initial deployment to theater with a Military Occupational Specialty code (MOS) of 11B Infantryman, 11C Indirect Fire Infantryman, 19D Calvary Scout, or 19K Armor Crewman.