Brain Imaging of Tinnitus
Condition: Hearing Disorder
MeSH terms: Tinnitus; Hearing Disorders
Study type: Observational

Summary: 
      This study will use magnetic resonance imaging (MRI) to compare brain function in three
      groups of people: hearing-impaired people with tinnitus; hearing-impaired people without
      tinnitus; and people with normal hearing and without tinnitus. Also known as "ringing in the
      ears," tinnitus is the false sensation of sounds.

      Adults between 30 and 65 years of age who meet the following criteria may be eligible for
      this study:

        -  Mild to moderate hearing loss who have experienced tinnitus daily for at least 1 year

        -  Mild to moderate hearing loss who have never or rarely experienced tinnitus

        -  Normal hearing who have never or rarely experienced tinnitus

      Candidates are screened with a medical history and questionnaires.

      Participants have a detailed hearing test to measure hearing and the nature of tinnitus. In a
      second visit, subjects have a brief physical examination, followed by MRI scanning. MRI uses
      a magnetic field and radio waves to produce images of body tissues and organs. For this
      procedure, the subject lies on a table that can slide in and out of the scanner (a narrow
      cylinder), wearing earplugs to muffle loud knocking and thumping sounds that occur during the
      scanning process. The subject may be asked to lie still for up to 8 minutes at a time. During
      the MRI, the subject performs computer-based tasks that involve listening to sounds. Another
      hearing test is done after the MRI.
    

Detailed description: 
      Subjective tinnitus, the false perception of sound in the absence of an acoustic stimulus,
      occurs frequently as a consequence of noise-induced deafness. The purpose of this study is to
      investigate the brain sites and mechanisms underlying tinnitus using a combined mathematical
      modeling and functional brain imaging experimental approach. Although studies have focused on
      the neural bases of tinnitus, it is not known why tinnitus arises only in certain cases of
      hearing loss, and the contribution of different brain regions in tinnitus perception is
      poorly understood. This in turn, prevents the development of better studies and new treatment
      methods for tinnitus. The primary hypothesis is that a network of brain regions, from
      auditory processing areas to emotional processing areas, contributes to, and modulates,
      tinnitus perception. The brain imaging study will be used to study differences in the network
      of brain regions involved in listening and discriminating sounds for tinnitus sufferers as
      compared to a control group of subjects with similar hearing loss but without tinnitus. This
      comparison should permit the identification of brain regions most active in tinnitus. An age
      matched control group without hearing loss and tinnitus will be included to determine those
      effects due to hearing loss alone. The mathematical computational modeling will use a
      previously developed large-scale neural network model of auditory processing in the cerebral
      cortex, which will be modified to induce tinnitus via different neural mechanisms. The
      modeling study should allow us to evaluate the contribution of different cortical regions and
      mechanisms to tinnitus perception; some changes in the model will be more successful than
      others in inducing tinnitus and in matching simulated brain imaging data with experimental
      brain imaging data. The modeling study will use the same stimuli and experimental paradigm as
      the functional brain imaging study. Comparing the experimental and modeling results will
      provide hypotheses about the most likely mechanism mediating tinnitus. Together, the modeling
      and experimental studies will advance our knowledge of the brain regions and mechanisms
      underlying tinnitus.
    

Observational model: Cohort
Time perspective: Other
Keywords: Neural Networks; Mathematical Modeling; Auditory Processing; Tinnitis; Hearing Loss