According to a 2024 study by the National Institutes of Health, approximately 55% of adults over the age of 75 experience some type of hearing loss. That is why, for the past 30 years, Maria Eulalia (Lania) Rubio, professor of neurobiology, School of Medicine, has been working to better understand the molecular basis of hearing loss and uncover new scientific data that may one day reduce the extent of this age-related phenomenon.
In her lab in the Biomedical Science Tower 3, Rubio studies the synaptic circuitries in the cochlear nucleus, the cerebellum and the hippocampus as well as the Organ of Corti, an essential structure in the cochlea.
“There is considerable research done on genetics as well as anatomical and environmental causes of hearing loss,” notes Rubio. “But little is known about how the molecular structure of the brain, the unique role each synapse plays, and why the presence of certain proteins affect hearing.”
Taking a multidisciplinary approach, Rubio has developed expertise in the assessment of hearing function, anatomy, ultrastructure and quantitative immunolabeling of a variety of proteins. She utilizes state-of-the-art anatomical approaches at the light and electron microscopy levels. She is also interested in determining the role of glial cells in auditory function, in particular the relationship of astrocyte processes to auditory nerve synapses in the normal hearing and in the hearing impaired.
Her goal is to determine the molecular mechanisms that allow cochlear nerve fibers to be ultrafast and transmit sound reliably.
Rubio’s studies have shown that the presence or absence of certain proteins—for example, neurotransmitter receptors at synapses—can lead to deficits in hearing throughout the life span. Most recently, she has been investigating the differences in hearing sensitivity in adolescent male and female mice.
The aim of this novel research is to test the hypothesis of a distinct structural and molecular refinement of cochlear ribbon synapses and to examine the role that sex hormones play in normal hearing in response to changes in auditory experience and hearing loss.
Rubio says this project will provide unique information to understand the sex-specific cellular and molecular mechanisms underlying sound coding's temporal precision in normal and hearing-impaired adolescent mice, which are still largely unknown and may correlate to human hearing.