Insect 'cochlea' mechanics and sensitivity
To better understand the functional micromechanics of the crista acustica, we are also investigating the sensitivity and mechanical tuning of the organ, by laser-doppler vibrometry, in various transparent bush cricket species. To measure mechanical function, we are testing for indicators of active amplification – a well-known mechanism by which an ear uses physiological energy to enhance hearing sensitivity. Such mechanisms are known in vertebrates, and some insects, but have not yet been investigated in insects with a cochlea-like inner ear. So far, we have discovered the generation of place-dependant distortion products in the ear – suggesting that the mechanics of the crista acustica function just like the mammalian cochlea. Currently, we are testing the physiological vulnerability of these distortions, testing for spontaneous oscillations (the strongest indicator of active amplification), and testing the sensitivity of ears across many species.
|
Non-invasive measurement of auditory processes
We will also exploit the transparent cuticle of our model bush-crickets by developing calcium imaging techniques for visualising the function of the ear in a non-destructive manner. By injecting calcium-sensitive dyes into the auditory nerve further up the leg, we will be able to image the hearing process in an intact acoustic organ for the first time.