Kelsey N. Hom
Neural Adaptations of Filtering Social Acoustic Signals in a Noisy Environment
Kelsey N. Hom is a doctoral student in the Biology Department at The Graduate Center, CUNY. She conducts research in the Forlano Lab and teaches at Brooklyn College. Her research focuses on how hormones, like dopamine, affect auditory driven social behavior in vocal toadfish. She is interested in how a local species, oyster toadfish, are able to localize mates in a noisy environment. Prior to coming to the program, Kelsey received her Bachelor’s of Science with Honors at Brown University in Psychology. Her work at Brown examined resistance to noise-induced hearing loss in echolocating bats.
Animals that rely on acoustic communication need to filter out relevant sounds from the natural noise surrounding them. While the adaptation to filter signals is crucial for an organism’s survival and reproduction, the mechanism of such filtering is not known. The oyster toadfish provides an excellent means of understanding the mechanisms of signal filtering because they are a local species that use acoustic advertisement calls to localize mates. We know that dopamine is found in the central and peripheral auditory system of these animals and that they share homologies with other vertebrates. However, the specific role of dopamine in the ear is unknown. Therefore, we propose to study how the dopaminergic neurons and their targets in the central and peripheral auditory system of midshipman females are differentially activated when listening to the male’s advertisement call in noise.
Imagine you’re at a bar with a friend trying to hear the details about their weekend. When listening, you’re still able to hear your friend’s voice amongst all the laughter, words, and music around you. How does your brain do that? Well, in other animals, hearing is used for communication with members of the same species, prey avoidance, finding food, or finding a mate. Being able to hear the relative signal within noise can mean life or death. While this is an important evolutionary adaptation for animal, including humans, it is not clear how your brain and ear are able to do this.
This is the topic that I have centered my dissertation around. To test this, I use the oyster toadfish (Opsanus tau), an animal that uses an acoustic advertisement call for finding a mate that lives in a typically noisy area, the Hudson River. This gives me a unique opportunity to see how these fish have adapted to find mates acoustically, even though they live by one of the loudest cities in the world. I’ve set up an experimental tank where I expose the female fish to the male advertisement call (also called a playback) in different noise conditions, similar to what they might experience in the wild. Also, I am able to see how their brains differ neurochemically from the brains of fish who did not receive playback or noise. Our lab predicts that dopamine might be the hormone that is helping the brain and ear increase the signal amongst noise (also known as signal to noise ratio). Therefore, we will be staining the brains with IEG markers (that show activation in the brain) and dopamine antibodies (that shows us where dopamine is in each neuron).
Playback experiments in the Forlano Lab have all been conducted on the West Coast at either UC Davis or the University of Washington. Not only is it expensive to fly to conduct work on the West Coast, but it also limits my ability to run experiments all summer and fall. This fellowship has given me an opportunity to purchase equipment so I could set up my own playback experiment, the first at Brooklyn College. With this fellowship, I’ve started to run pilot experiments to test my IEGs and different experimental parameters that will help shape the rest of my experiments for my dissertation. I have also been able to run the first experiment of my dissertation, which is looking at how dopamine activation and innervation changes depending on the different experimental condition. These tests can show a novel finding that dopamine helps animals hear signals amid noise.