Timothy Balmer, Ph.D.

Meet the Researcher

Balmer earned his doctorate in neuroscience from Georgia State University. He is an assistant professor in the School of Life Sciences at Arizona State University. His work investigates how neurons transmit signals to one another through synapses and how networks of neurons process information. His team uses in vitro and in vivo electrophysiology, optogenetics, immunohistochemistry, and computational modeling, to understand fundamental mechanisms of sensory processing. Balmer is a 2017 Emerging Research Grants scientist generously funded by the Les Paul Foundation.

Tinnitus may be caused by persistent cellular activity that leads to the false perception of a sound. My work focuses on understanding a type of neuron (nerve cell) in the auditory system that may underlie this activity.

Neurons send signals through neurotransmitters that travel across synapses, from a neuron’s axons to another’s dendrites. The cell type I am focusing on has a unique, single paintbrush-like dendrite, described in its name, the “unipolar brush cell.” This cell is found in the cochlear nucleus, the part of the brain linked by the auditory nerve to the inner ear.

The dendritic brush of these cells slows the neurotransmitters from leaving the synapse—they linger at these synapses. Using physiological recording techniques, we found that this leads to persistent excitatory activity, and we reasoned this may lead to tinnitus.

Unipolar brush cells have only recently been defined as a distinct cell type—most cell types were defined over 100 years ago. I am researching how they regulate their persistent activity and what signals they receive and process.

While studying psychology as an undergrad, I became interested in the fundamental biological mechanisms that underlie sensation, perception, and thought. My first lab experience was to study odor sensation in bumblebees. I felt at home in a lab, where I could explore how the brain works by looking at its component parts.

From an early age, I understood that taking things apart and putting them back together is an effective way to learn how they work. In high school I spent a lot of time rebuilding and modifying cars and engines, giving me experience in design and engineering that I use as a researcher.

Moreover, troubleshooting an engine that won’t start is an implicit lesson in problem-solving and the use of the scientific method. It starts with an observation (the engine won’t start), which leads to a hypothesis about the cause (there is no spark at the spark plugs) and testable predictions (if I can make them spark, the engine will start).

I have tinnitus myself. It is impossible to be certain what caused it, but my guess is that frequent use of power tools without hearing protection may have caused damage.

I still work on cars (using hearing protection!) and am restoring a 1969 MGB that I’ve been tinkering with since college. I also repair and modify mechanical watch movements, focusing on those worn by U.S. service members, including a Rolex that kept time on the wrist of a close friend during the Korean War, and an Elgin worn by a pilot in World War II. I also keep active by cycling to and from the lab, totaling over 1,000 miles a year.

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The Research

Chronic transmitter exposure in excitatory neurons of the cochlear nucleus generates persistent excitation and could underlie tinnitus

The dorsal cochlear nucleus in the brainstem receives not only auditory signals directly from the ear but also multisensory input from other areas of the brain. However, the sources of these inputs are unclear. We do know the inputs are processed through unipolar brush cells (UBC), a type of nerve cell in the cochlear nucleus that amplifies signals. This cell derives its name from its single paintbrush-like dendrite, which shows persistent excitation due to chronic neurotransmitter exposure. My project is to investigate whether problems with the multisensory inputs or with the chronic neurotransmitter at the UBC synapse lead to hyperactivity of the cochlear nucleus, which is associated with tinnitus.

Long-term goal: To investigate whether chronic transmitter exposure in nerve cells of the cochlear nucleus may be a cause of tinnitus, which eventually may lead to clinical tinnitus treatments.

Balmer’s 2017 ERG grant was generously funded by the Les Paul Foundation. We thank the Les Paul Foundation for its support of innovative research that will increase our understanding of the mechanisms, causes, diagnosis, and treatment of tinnitus.