Science Café Cleveland presents


"Deafness and Imbalance: Advances in Treatments and Understanding Using Zebrafish"


DECEMBER 14, 2009




Dr. Brian McDermott, Jr.  

(Otolaryngology, CWRU School of Medicine)



Dr. Cliff Megerian

 (Director of Otology and Neurotology, University Hospitals)




To hear a fire alarm in the middle of the night or to balance while playing a game of tennis, we rely on rare sensory receptor cells that reside deep in our internal ears. These cellular lynchpins are known as hair cells (Figure 1). These cells are specialists in mechanotransduction, a process where mechanical stimuli⎯such as those produced by sounds⎯are converted into electrical responses that are relayed to the brain. To accomplish its task in hearing and equilibrium, hair cells have unique subcellular structures, namely the ultrasensitive hair bundles that quiver with the slightest agitation. Despite this cell’s remarkable importance in the sensory modalities of hearing and equilibrium, much is yet undiscovered in relation to their mechanisms of functioning and development.


Figure 1. Schematic of a hair cell displaying the stereocilia of the hair bundle in orange, the cell body in blue, and a neuron that carries auditory information to the brain in green.


Figure 2. Image of a cochlear implant. Courtesy of Cochlear Americas Inc. 


The incidence of heritable deafness is high, with one child in a thousand being born deaf. Moreover, approximately 17% of American adults report some degree of hearing loss. Therefore, understandings of the causes of deafness that may lead to effective treatments and diagnoses are of substantial significance. There are many causes of deafness, a substantial proportion of these result from perturbations that affect the development and operation of the hair cell. Exciting technological advances accompanied by intricate surgical techniques have begun to dramatically affect the deaf; chief among these is the cochlear implant, a prosthetic device that can allow the deaf to hear (Figure 2). 


To understand the mechanisms of hearing, scientists use many tools and techniques, such as human genetics to identify damaged genes, mathematical modeling of ear functioning, and animal model systems to determine how particular forms of deafness occur. Because of a number of unique features, the zebrafish has emerged as an excellent animal model for the study of the development and function of the vertebrate ear (Figure 3). The eggs develop outside of the mother and the ear is transparent for the first few weeks of life; this allows for the imaging of the ears hair cells during their development. Moreover, the genes, that, when mutated in humans, which cause deafness, also cause deafness and imbalance in zebrafish when defective. Finally, this fish is a genetically tractable system that allows for the generation of forms of deafness in zebrafish that are similar to those found in humans. 


Figure 3. A schematic diagram of the zebrafish acousticolateralis system. (A) The zebrafish lateral line. The neuromasts of the lateral-line systems are displayed as orange dots. (B) The left ear of a four-day-old zebrafish larva depicts the sensory maculae (blue), cristae of the semicircular canals (green), and otoliths (gray). A red box delimits the anterior macula. (C) The organization of the anterior macula. (D) The organization of the neuromast organ. Hair cells are shown in orange.


Come to December's Science Café Cleveland to get the inside scoop on the ear and how it works!




If you have a few minutes, you can "prepare your mind" for the café by checking out these web resources:

Cochlear implants open deaf kids' ears to the world

Hearing (from the National Institutes of Health)




Date: December 14, 2009
Time: Drinks start at 6:30 PM, discussion starts around 7:00 PM
Location: Tasting Room, Great Lakes Brewing Company (2701 Carroll Ave, Cleveland)


Click here to download a pdf flyer for your office!