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.