Tissue Sample Preparation Methods and Instruments and a Versatile and Efficient Interface for In-Situ Cochlear Mechanics Experiments

Jonathan Becker, MS Defense, Advised by Dr. Jong-Hoon Nam, Department of Mechanical Engineering

Hopeman 224

The cochlea is the frequency analyzer of the mammalian hearing organ. Within the cochlea, sounds produce cochlear travelling waves that peak at locations determined by the sound frequency, due to the graded stiffness of the cochlear partition along its length and cochlear amplification. Within the cochlear partition, the sensory epithelium called the organ of Corti contains inner and outer hair cells, the sensory receptors of the cochlea. Outer hair cells are known as the actuator for cochlear amplification, but how outer hair cell actuation is filtered to produce sharp tuning of the cochlea wave is the focus of active investigation by different experimental approaches.

As an object of experimental measurement, the cochlea presents challenges. The cochlea is fragile and geometrically complex, making preparation of intact and measurable cochlear tissue samples a difficult task. With suitable cochlear tissue samples, further challenge is found in efficiently applying appropriate stimuli and measuring kinematic response from the structures of the cochlear partition to identify the role of these structures in amplification. To address the challenges of cochlear tissue preparation, methods and instruments to consistently prepare intact and measurable in-situ cochlear tissue samples were developed. To address the challenge of efficient measurement of cochlear tissue samples across the span of the cochlea’s many structures, measurement systems were modified and integrated within a single efficient, versatile interface for the design and execution of cochlear tissue experiments.