Auditory mechanics in the Grig (Cyphoderris monstrosa): Tympanal travelling waves and frequency discrimination as a precursor to inner ear tonotopy

Woodrow, Charlie, Pulver, Christian, Song, Hojun and Montealegre-Z, Fernando (2022) Auditory mechanics in the Grig (Cyphoderris monstrosa): Tympanal travelling waves and frequency discrimination as a precursor to inner ear tonotopy. Proceedings of the Royal Society B: Biological Sciences, 289 (1973). ISSN 0962-8452

Full content URL: https://doi.org/10.1098/rspb.2022.0398

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Auditory mechanics in the Grig (Cyphoderris monstrosa): Tympanal travelling waves and frequency discrimination as a precursor to inner ear tonotopy
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Abstract

Ensiferan orthopterans offer a key study system for acoustic communication and the process of insect hearing. Cyphoderris monstrosa (Hagloidea) belongs to a relict ensiferan family and is often used for evolutionary comparisons between bushcrickets (Tettigoniidae) and their ancestors. Understanding how this species processes sound is therefore vital to reconstructing the evolutionary history of ensiferan hearing. Previous investigations have found a mismatch in the ear of this species, whereby neurophysiological and tympanal tuning does not match the conspecific communication frequency. However, the role of the whole tympanum in signal reception remains unknown. Using laser-Doppler vibrometry, we show that the tympana are tonotopic, with higher frequencies being received more distally. The tympana utilize two key modalities to mechanically separate sounds into two auditory receptor populations. Frequencies below ~ 8 kHz generate a basic resonant mode in the proximal end of the tympanum, whereas frequencies above ~ 8 kHz generate travelling waves in the distal region. Micro-CT imaging of the ear and the presented data suggest that this tonotopy of the tympana drive the tonotopic mechanotransduction of the crista acustica. This mechanism represents a functional intermediate between simple tuned tympana and the complex tonotopy of the bushcricket crista acustica.

Keywords:Hearing, Tonotopic, ear, Orthoptera, Haglid, Relic
Subjects:H Engineering > H340 Acoustics and Vibration
C Biological Sciences > C182 Evolution
D Veterinary Sciences, Agriculture and related subjects > D322 Animal Physiology
F Physical Sciences > F380 Acoustics
Divisions:College of Science > School of Life Sciences
ID Code:48799
Deposited On:11 Apr 2022 14:56

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