Auditory Cortical Network Changes in Tinnitus
Abstract
Tinnitus is the persistent perception of a sound in the absence of an external sound source. Often described as a "ringing in the ears," this condition can have a profound negative impact on the quality of life of those chronically affected by it. The American Tinnitus Association estimates that up to ~50 million people in the United States experience tinnitus to some degree, a portion of whom have symptoms so severe that they interfere with daily lives. Tinnitus can affect an individual s ability to concentrate, negatively impact sleep patterns, and reduce the desire for social interactions, leading to depression and anxiety, thus adding an "impact to society" to its list of consequences. According to the American Tinnitus Association, nearly 60% of military personnel returning from combat have impairment of auditory activity and tinnitus, thus designating it as the most common war wound, ranking higher than post-traumatic stress disorder. The problems associated with tinnitus are on the rise. For example, according to the Department of Veteran Affairs, in 2009, there were 760,000 Veterans receiving Service-connected tinnitus disability compensation and this number was projected to nearly double to 1.5 million Veterans by the current calendar year. Disability compensation for these Service men and women translated into $1.12 billion in dispensed disability compensation in 2009 and a projected value of $2.26 billion in the current year. These sobering statistics indicate that hearing loss/tinnitus represents an increasingly pressing problem for not only the U.S. Armed Forces but for the U.S. population as a whole. Despite its prevalence, growing incidence, and impact, the mechanisms underlying tinnitus and a strategy for curing this condition remain elusive. Our studies are aimed at identifying microcircuit mechanisms underlying the neuronal circuit level changes associated with the tinnitus percept. It is believed that the percept of "ringing in the ears" is generated by increased spontaneous activity and hyper-synchrony in response to sound stimulation in brain circuits. One target brain structure implicated in the formation of tinnitus percept is the primary auditory cortex (A1). However, because of limitations of current and traditional methods of sampling brain activity, the role of spontaneous activity and hyper-synchrony in local populations of individual A1 neurons has not been investigated directly. Here, we propose to apply state-of-the art optical imaging techniques to understand the precise nature of the neuronal circuit level changes in populations of individual neurons. The results will provide unprecedented insight into the changes that occur in the brain as a result of noise trauma and will significantly advance the fields of tinnitus research and neuroscience. Here, we propose to study the impact of noise trauma on neuronal circuits in the auditory cortex. We expect that spontaneous activity and local connectivity of populations of individual neurons within the neocortex are dramatically elevated after noise trauma. In addition, we propose to monitor specific classes of inhibitory neurons for evidence that specific properties of their activity (spontaneous or stimulus evoked) are altered after noise trauma. Moreover, we expect that the network balance between excitation and inhibition to be severely disrupted in animals with tinnitus-like behavior. In total, advances like the ones we expect will alter the outlook for military personnel suffering from tinnitus from one in which they are destined to a life filled with these symptoms to one in which, when proper therapies are applied, there is a hope for a cure.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610143
Entities
People
- Patrick Kanold
Organizations
- United States Army
- University of Maryland