Julia Campbell, Ph.D., Au.D.
Julia Campbell, Ph.D., Au.D.
Meet the Researcher
Campbell received an Au.D. from the University of Colorado at Boulder, where she later received a triple Ph.D. in speech, language, and hearing sciences; behavioral neuroscience; and cognitive neuroscience while studying cortical plasticity in hearing loss. She is an assistant professor at the University of Texas at Austin in the department of communication sciences and disorders. Campbell’s 2016 Emerging Research Grant is generously funded by the Les Paul Foundation.
I’ve always been fascinated by tinnitus and how it largely remains a mystery. For instance, hearing loss and tinnitus are strongly related, but not everyone who acquires a clinical degree of hearing loss will develop tinnitus, and vice versa. We also have no way to objectively measure or diagnose tinnitus, depending instead on a patient’s report. Many physiological changes have been shown to take place in tinnitus patients, including at the inner ear, brainstem, and cortical levels of the central nervous system (CNS). But ultimately it is the individual’s conscious perception of the phantom sound that impacts their daily life.
A recent hypothesis holds that tinnitus perception may arise from faulty “gating mechanisms” in the brain. In other words, the brains of some individuals may be unable to filter out or ignore irrelevant auditory signals generated by the CNS. Though it has been documented for many years in the field of neuropsychology, surprisingly, gating function has not yet been examined in tinnitus. If sensory gating differs in individuals with tinnitus, it may be possible to develop an objective clinical measure for this disorder and eventually inform treatment options.
When I was a child I had an anatomy book that I spent hours looking through, always curious about how systems function. After working as a research assistant in various labs throughout high school and college, I realized that the brain is the ultimate system and that improved understanding of its function can positively impact people’s lives.
I experienced tinnitus in my left ear for three weeks as a graduate student. We were testing one another to pilot an experiment, and the sound was much too loud! My father had a repeat cholesteatoma (cyst), and a viral infection of the vestibular nerve, so he has a middle ear prosthetic as an ossicle replacement. I provided insights into the science while he shared the personal aspect of what patients go through.
Speaking with individuals suffering from tinnitus and/or hearing loss, as well as those with various neurological disorders, reminds one of the importance of research. It’s not about the grants or the papers. It’s about learning how to help people and improve their quality of life through the right kinds of scientific questions, leading to clinical breakthroughs.
Julia Campbell, Au.D., Ph.D., is generously funded by the Les Paul Foundation. We thank the foundation for its support of innovative research that will increase our understanding of the mechanisms, causes, diagnosis, and treatment of tinnitus.
The Research
University of Texas at Austin
Auditory gating in tinnitus
Tinnitus is the perception of sound, such as ringing or buzzing, without an external source. Though tinnitus likely arises, in part, from hearing loss in the inner ear, research has determined that the ongoing perception of tinnitus occurs in the brain. It has been suggested that auditory gating, a function carried out by the brain in filtering out unimportant auditory information, may be abnormal in individuals with tinnitus and contribute to the conscious perception of the phantom sound.
Auditory gating can be measured noninvasively through the brain’s cortical response to sound during recording of brainwave activity, known as EEG (electroencephalography). In typical auditory gating function, cortical auditory evoked potentials (CAEPs) recorded during EEG show a decrease in amplitude when sounds (e.g., tone pairs) are presented close together in time. This decrease in amplitude reflects the brain’s ability to filter out repetitive auditory input. In atypical gating function, CAEP amplitude remains the same across sound presentation or shows little change, again suggestive of the brain’s inability to filter out irrelevant input.
This study aims to evaluate auditory gating processes in tinnitus, including cortical sources of active gating networks as observed through source localization analyses. These results will be correlated with subject reports of tinnitus severity.
Research areas: high-density electroencephalography, cortical plasticity, hearing loss, tinnitus, sensory processing, source localization, auditory gating, perception, cognitive neuroscience
Long-term goal: To identify a possible biomarker of tinnitus that may be a viable clinical tool for assessment purposes as well as inform future treatment options.
Generously funded by the Les Paul Foundation