Arun Palghat Udayashankar
The vertebrate cochlea has been and continues to be the classic model system used to study mechanotransduction (MET) in auditory systems. However there are several questions with regard to MET in audition that have been difficult to address using the vertebrate cochlea. These include the biophysical origins of cochlear amplification and acoustic emissions (which are thought to be tightly coupled with MET) among others. In particular, the mechanism of action of calcium during the signal transduction process continues to be a matter of extensive debate.
By employing what is commonly referred to as the reductionist approach in biology I use bush-crickets as model organisms to understand mechanotransduction at the cellular and at the organ level. The hearing organ in bush-crickets is located in their forelegs and is known as the crista-acustica. A characteristic feature of the hearing organ is that it is lined with an array of auditory receptors in a tonotopic fashion. The receptors, graded in size, are directly involved in the mechanics of transduction. Each receptor is associated with a sensory neuron. The sensory neurons are spiking neurons and are thought to convey sensory information to the auditory ganglion and higher processing centers.
Just like their vertebrate counterparts, it is believed that bush-crickets also have an MET channel associated with the transduction apparatus. Furthermore, the MET current associated with transduction displays adaptation, a very characteristic phenomenon observed in vertebrate hair cells. On the whole organ level as well one finds several similarities with the vertebrate cochlea such as frequency selectivity and distortion product otacoustic emissions.
In my project I intend to throw some light on mechanotransduction both at the organ level and the cellular level in the auditory receptors of bush-crickets. To this end I use laser doppler vibrometry to measure mechanical responses and electrophysiology to measure electrical responses during MET. Furthermore I intend to combine the experimental measurements with mathematical modeling to further our understanding of the measured data and the system in general.
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Druckversion: 02. März 2012, 16:19