02311nas a2200181 4500008004100000245006200041210006200103520174300165653002101908653001301929653001901942100002101961700003201982700001902014700002102033700002002054856005502074 2011 eng d00aSound Transduction in the Auditory System of Bushcrickets0 aSound Transduction in the Auditory System of Bushcrickets3 a

Place based frequency representation, called tonotopy,is a typical property of hearing organs for the discrimination of different frequencies. Due to its coiled structure and secure housing, it is difficult access the mammalian cochlea. Hence, our knowledge about in vivo inner-ear mechanics is restricted to small regions. In this study, we present in vivo measurements that focus on the easily accessible, uncoiled auditory organs in bushcrickets, which are located in their foreleg tibiae. Sound enters the body via an opening at the lateral side of the thorax and passes through a horn-shaped acoustic trachea before reaching the high frequency hearing organ called crista acustica. In addition to the acoustic trachea as structure that transmits incoming sound towards the hearing organ, bushcrickets also possess two tympana, specialized plate-like structures, on the anterior and posterior side of each tibia. They provide a secondary path of excitation for the sensory receptors at low frequencies. We investigated the mechanics of the crista acustica in the tropical bushcricket Mecopoda elongata. The frequency-dependent motion of the crista acustica was captured using a laser-Doppler-vibrometer system. Using pure tone stimulation of the crista acustica, we could elicit traveling waves along the length of the hearing organ that move from the distal high frequency to the proximal low frequency region. In addition, distinct maxima in the velocity response of the crista acustica could be measured at ̃7 and ̃17 kHz. The travelling-wave-based tonotopy provides the basis for mechanical frequency discrimination along the crista acustica and opens up new possibility to investigate traveling wave mechanics in vivo.

10aLDV-measurements10atonotopy10atraveling wave1 aNowotny, Manuela1 aUdayashankar, Arun, Palghat1 aWeber, Melanie1 aHummel, Jennifer1 aKössl, Manfred uhttp://aip.scitation.org/doi/abs/10.1063/1.365813100620nas a2200181 4500008004100000245009100041210006900132653002300201653001900224653001200243653002700255100002100282700002100303700001900324700002000343700002000363856005500383 2010 eng d00aAcoustic-induced motion of the bushcricket (Mecopoda elongata, Tettigoniidae) tympanum0 aAcousticinduced motion of the bushcricket Mecopoda elongata Tett10aAcoustic resonance10ainsect hearing10atrachea10aVibration measurements1 aNowotny, Manuela1 aHummel, Jennifer1 aWeber, Melanie1 aMöckel, Doreen1 aKössl, Manfred uhttp://link.springer.com/10.1007/s00359-010-0577-602072nas a2200205 4500008004100000245008700041210006900128520133100197653001601528653002001544653002201564653001901586653002901605653001801634100002101652700002101673700002001694700002101714856013101735 2014 eng d00aProcessing of simple and complex acoustic signals in a tonotopically organized ear0 aProcessing of simple and complex acoustic signals in a tonotopic3 a

Processing of complex signals in the hearing organ remains poorly understood. This paper aims to contribute to this topic by presenting investigations on the mechanical and neuronal response of the hearing organ of the tropical bushcricket species Mecopoda elongata to simple pure tone signals as well as to the conspecific song as a complex acoustic signal. The high-frequency hearing organ of bushcrickets, the crista acustica (CA), is tonotopically tuned to frequencies between about 4 and 70 kHz. Laser Doppler vibrometer measurements revealed a strong and dominant low-frequency-induced motion of the CA when stimulated with either pure tone or complex stimuli. Consequently, the high-frequency distal area of the CA is more strongly deflected by low-frequency-induced waves than by high-frequency-induced waves. This low-frequency dominance will have strong effects on the processing of complex signals. Therefore, we additionally studied the neuronal response of the CA to native and frequency-manipulated chirps. Again, we found a dominant influence of low-frequency components within the conspecific song, indicating that the mechanical vibration pattern highly determines the neuronal response of the sensory cells. Thus, we conclude that the encoding of communication signals is modulated by ear mechanics.

10abushcricket10acrista acustica10aElectrophysiology10ainsect hearing10alaser Doppler vibrometry10aTettigoniidae1 aHummel, Jennifer1 aWolf, Konstantin1 aKössl, Manfred1 aNowotny, Manuela uhttps://royalsocietypublishing.org/doi/10.1098/rspb.2014.1872https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2014.187201893nas a2200181 4500008004100000022001300041245010200054210006900156260001600225300001800241490000700259520129300266100002101559700002101580700002301601700002101624856006601645 2016 eng d a0960982200aAuditory fovea in the ear of a duetting katydid shows male-specific adaptation to the female call0 aAuditory fovea in the ear of a duetting katydid shows malespecif cJan-12-2016 aR1222 - R12230 v263 a

Convergent evolution has led to surprising functional and mechanistic similarities between the vertebrate cochlea and some katydid ears 1 ;  2. Here we report on an ‘auditory fovea’ (Figure 1A) in the duetting katydid Ancylecha fenestrata (Tettigoniidae). The auditory fovea is a specialized inner-ear region with a disproportionate number of receptor cells tuned to a narrow frequency range, and has been described in the cochlea of some vertebrates, such as bats and mole rats 3 ;  4. In tonotopically organized ears, the location in the hearing organ of the optimal neuronal response to a tone changes gradually with the frequency of the stimulation tone. However, in the ears of A. fenestrata, the sensory cells in the auditory fovea are tuned to the dominant frequency of the female call; this area of the hearing organ is extensively expanded in males to provide an overrepresentation of this behaviorally important auditory input. Vertebrates developed an auditory fovea for improved prey or predator detection. In A. fenestrata, however, the foveal region facilitates acoustic pair finding, and the sexual dimorphism of sound-producing and hearing organs reflects the asymmetry in the mutual communication system between the sexes ( Figures 1B, S1).

1 aScherberich, Jan1 aHummel, Jennifer1 aSchöneich, Stefan1 aNowotny, Manuela uhttp://linkinghub.elsevier.com/retrieve/pii/S0960982216312611