Mapping the inner ear: Innovation uses sound to generate 3-D images

Understanding how hearing works has long been hampered by challenges associated with seeing inside the inner ear, but technology being developed by a team of researchers that includes a biomedical engineer from Texas A&M University is generating some of the most detailed images of the inner ear to date while offering new insight into the mechanics of hearing that could lead to new therapies for hearing loss.

Employing a technique that generates high-resolution, three-dimensional images, Brian Applegate, associate professor in the Department of Biomedical Engineering at Texas A&M, and colleagues from Stanford University are mapping the tissues within the cochlea, the portion of the inner ear responsible for hearing. Their research, which appears in the Journal of Neurophysiology, could lead to breakthroughs in understanding of cochlear function, Applegate says.

Capable of rendering detailed images of tissues within an intact cochlea, the system employs a technique known as “optical coherence tomography,” or OCT. OCT is similar to ultrasound but generates images with much higher resolution. The images are produced from measurements of the inner ear’s structure and the incredibly small vibrations within the cochlea, Applegate says.

Though the technology has been primarily used in animal models to date, it’s already resulted in the first vibration measurements from the apex of an unopened mouse cochlea, allowing researchers to image the portion of the cochlea responsible for low frequencies. Since mammalian hearing is similar across species, the model allows the researchers to use the technology on a hearing system similar to the one in humans, Applegate notes.

“We are the first to use this technique on mice in order to image the cochlea,” Applegate says. “We’re working on making measurements of the movement within the cochlea that have never before been made; we’re finding out new things about the mechanics of the inner ear that have not been known.”

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