For researchers studying hearing loss, critters promise breakthroughs

At any moment in nature, one may hear the screeches of bats overhead, the squeaks of mice along the ground or the swishes of fishes schooling underwater. The hearing and communication laboratories at Washington State University Vancouver offer the rare opportunity to study such animals: from bats to mice to zebrafish. Research in these labs is primarily focused on advancing the understanding of speech processing mechanisms in individuals with normal hearing and in those with different forms of hearing loss.

Known on campus as the “Rats, Bats and Fish Labs,” the hearing and communication laboratories are a collaborative effort among undergraduate and graduate students that work alongside postdoctoral and faculty members. Christine Portfors and Allison Coffin lead a group of neuroscientists who utilize fruit-eating bats from South America, mice and zebrafish as model systems that help provide insights into the human brain and body.

Although each lab utilizes different animals as models to facilitate research, the labs are often multi-functional in their purpose. The bat lab analyzes the mechanisms of vocal learning in the brains of bats; the mice lab focuses on the mechanisms of complex sound processing in the brains of mice; the fish lab uses external hair cells on zebrafish to study the mechanisms of hearing loss.

“We focus the majority of our studies on understanding how the brain detects, discriminates and categorizes different types of communication sounds,” Portfors said. “We conduct our studies in mice and bats because these mammals are great models for understanding the neural mechanisms of auditory processing.”

Like humans, bats possess an extremely rare trait found in nature: vocal learning. This trait makes them a great subject for researching speech and hearing. The vocal learning process includes the ability to learn, acquire and produce new sounds via imitation. Researchers study the vocal learning process that bats undergo in order to communicate with other bats and navigate their environment through supersonic sound, or echolocation.

By better understanding how communication sounds are detected, decoded and categorized by the auditory system, researchers aim to develop more effective prosthetic hearing devices. Their research includes studying how speech is processed by the auditory system in individuals with normal hearing and in those with various forms of hearing loss or disorders.

“The research that we are doing also is to enhance awareness about the causes of noise-induced hearing loss,” said Elena Mahrt, a doctorate-level researcher. “By doing this we can provide techniques to facilitate healthy listening habits for those who, for example, like to listen to loud music in the car or attend concerts.”

The bat lab has two different rooms, one of which houses 45 male and female bats intended for breeding, and another that houses 19 females for population control. Amongst the group of flying mammals there is an albino bat that has white hair and red eyes. These bats, including the red-eyed albino, will not attack your jugular for blood like vampire stereotypes would lead some to believe. The fruit eating bats, more technically the leaf-nosed bat, come from the humid regions of South America.

To replicate their original living conditions, the rooms are humid and the bats are fed fresh fruit and peach and apricot smoothies. Although the bats fly horizontally, they perform acrobatic feats to flip and land upside down quickly. Along with sharp teeth, these bats are equipped with an amazing signal processing ability that allows them to determine a target’s velocity, size, elevation and many more fine characteristics by echolocation. The high-pitched frequencies are indiscernible to the human ear.

“These bats are fun to work with, and very few universities even have the opportunity to research them,” said Alex Nevue, WSU Vancouver’s very own “Batman.”

According to Nevue there are a couple of different experiments being conducted with the bats utilizing a variety of different methods. These experiments include behavioral studies, ultrasonic sound and brain anatomy. The high dependency that bats have on echolocation means that a larger portion of the brain is devoted to auditory processing. By studying the brain and processing system of bats, researchers hope to learn more about the mysteries of the human mind.

For those involved, the research being conducted is much more than a step to gain skills necessary to succeed in scientific or health-related careers. By relying on teamwork, scientists in the hearing and communication labs hope to make an impact on the lives of the more than 275 million people worldwide that are affected by hearing loss.

To learn more about the hearing and communication lab, contact Christine Portfors at portfors@wsu.edu or visit https://labs.wsu.edu/hearcomm/.

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