Experimental investigation of mechano-electrical signal transduction in a simple auditory organ [in the hearing organ of bushcrickets]

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Critical to our understanding of the hearing process is the conversion of a sound signal into a receptor potential in the auditory sensory cells, the mechano-electrical transduction (MET). To date this process is still not fully understood. In this context, the sensitivity and sharply-tuned perception of high-frequency sound is of particular interest. The hearing organ of bushcrickets, the crista acustica, is functionally similar to the basilar membrane of mammals. It is characterized by tonotopically arranged sensory cells and a very good high-frequency hearing. In contrast to the cochlea of mammals, the straight shape of the crista acustica allows in-vivo experiments along the whole length of the organ and thus the entire frequency tuning of it. To obtain information about the signal transduction process we will measure sound-induced motion of single sensory cell complexes (scolopidia) in addition to changes in the potential of the sensory cells. Once we have examined the fundamental processes involved in the signal transduction and tuning throughout the entire hearing organ, we will investigate the influence of the mechanical and electrical components on the transduction process with the aid of physical and chemical manipulations. The collected data will provide information about potential active feedback of cellular micromechanics on the vibration characteristics of the crista acustica. Using the crista acustica as a simple model system, we will understand the fundamental processes of MET, tonotop interactions and mechanical reaction of sensory cells in the hearing organ.