Investigating the Neurobiology of Tinnitus

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.