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Hearing in Drosophila.

Albert JT, Göpfert MC - Curr. Opin. Neurobiol. (2015)

Bottom Line: Recent studies have analyzed the operation of auditory sensory cells and the processing of sound in the fly's brain.Neuronal responses to sound have been characterized, and novel classes of auditory neurons have been defined; transient receptor potential (TRP) channels were implicated in auditory transduction, and genetic and environmental causes of auditory dysfunctions have been identified.This review discusses the implications of these recent advances on our understanding of how hearing happens in the fly.

View Article: PubMed Central - PubMed

Affiliation: Ear Institute, University College London, 332 Gray's Inn Rd, London WC1X 8EE, UK. Electronic address: joerg.albert@ucl.ac.uk.

No MeSH data available.


Related in: MedlinePlus

Transduction and amplification. (a) Left: mechanical sensitivity of the antenna (measured as antennal vibration velocity (m/s) normalized to the sound particle velocity (m/s)) as a function of the sound particle velocity (top), and corresponding relative amplitude of the sound-evoked antennal nerve potentials (bottom). Mechanical amplification by JONs maximally enhances the antenna's sensitivity to faint sounds (arrow, top) that, by themselves, would be too weak to evoke nerve potentials (arrow, bottom) (adopted from Ref. [15••]). Right: maximum sensitivity to faint sounds is also seen when the antenna's mechanical sensitivity is measured as the ratio between antennal displacement (nm) and the force (pN) that, during sound stimulation, is experienced by the antenna (Top). This mechanical behavior and also the amplitude characteristics of the nerve response (bottom) are reproduced by an active version of the gating spring model (orange circles) that links mechanical amplification by JONs to the open probability of MET channels (bottom) (adopted from Ref. [19]). (b) Localization of NOMPC and Nan–Iav in JON cilia (see also Refs. [28–30]). (c) Transduction models. According to the ‘NOMPC model’ (left), auditory JONs use NOMPC to transduce and mechanically amplify vibrations, and gravity/wind-sensitive JONs transduce antennal deflections with a second, unknown channel (‘X’). Downstream of transduction, electrical signals are amplified by Nan–Iav. The Nan–Iav model (bottom) posits that Nan–Iav mediates transduction in auditory and gravity/wind-sensitive JONs. NOMPC acts as a mechanical pre-amplifier in auditory JONs that, together with motor proteins, augments vibrations prior to transduction (see also Ref. [26]).
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fig0010: Transduction and amplification. (a) Left: mechanical sensitivity of the antenna (measured as antennal vibration velocity (m/s) normalized to the sound particle velocity (m/s)) as a function of the sound particle velocity (top), and corresponding relative amplitude of the sound-evoked antennal nerve potentials (bottom). Mechanical amplification by JONs maximally enhances the antenna's sensitivity to faint sounds (arrow, top) that, by themselves, would be too weak to evoke nerve potentials (arrow, bottom) (adopted from Ref. [15••]). Right: maximum sensitivity to faint sounds is also seen when the antenna's mechanical sensitivity is measured as the ratio between antennal displacement (nm) and the force (pN) that, during sound stimulation, is experienced by the antenna (Top). This mechanical behavior and also the amplitude characteristics of the nerve response (bottom) are reproduced by an active version of the gating spring model (orange circles) that links mechanical amplification by JONs to the open probability of MET channels (bottom) (adopted from Ref. [19]). (b) Localization of NOMPC and Nan–Iav in JON cilia (see also Refs. [28–30]). (c) Transduction models. According to the ‘NOMPC model’ (left), auditory JONs use NOMPC to transduce and mechanically amplify vibrations, and gravity/wind-sensitive JONs transduce antennal deflections with a second, unknown channel (‘X’). Downstream of transduction, electrical signals are amplified by Nan–Iav. The Nan–Iav model (bottom) posits that Nan–Iav mediates transduction in auditory and gravity/wind-sensitive JONs. NOMPC acts as a mechanical pre-amplifier in auditory JONs that, together with motor proteins, augments vibrations prior to transduction (see also Ref. [26]).

Mentions: Antennal displacements are coupled via the terminal threads to the mechanosensory cilia of JONs, where they gate mechano-electrical transduction (MET) channels [22]. This gating introduces a nonlinear compliance into the fly's antennal mechanics that, conforming to the gating spring model of vertebrate auditory transduction [23], suggests that the MET channels are directly gated by pull of gating springs. The interplay between this mechanogating and associated motor movements quantitatively explains mechanical amplification in Drosophila hearing [19], indicating that the same transducer-based mechanism that drives active hair bundle movements in vertebrate hair cells [24] also promotes the motility of JONs. The mechanistic link between transduction and amplification by JONs was recently put into question because ‘active amplification is observable for intensities below the threshold for antennal field potential responses’ [15••] (Figure 2a). Neither field potentials nor channel gating, however, possess thresholds, and a transduction-based model well captures the intensity-dependence of amplification in the fly's ear [19] (Figure 2a).


Hearing in Drosophila.

Albert JT, Göpfert MC - Curr. Opin. Neurobiol. (2015)

Transduction and amplification. (a) Left: mechanical sensitivity of the antenna (measured as antennal vibration velocity (m/s) normalized to the sound particle velocity (m/s)) as a function of the sound particle velocity (top), and corresponding relative amplitude of the sound-evoked antennal nerve potentials (bottom). Mechanical amplification by JONs maximally enhances the antenna's sensitivity to faint sounds (arrow, top) that, by themselves, would be too weak to evoke nerve potentials (arrow, bottom) (adopted from Ref. [15••]). Right: maximum sensitivity to faint sounds is also seen when the antenna's mechanical sensitivity is measured as the ratio between antennal displacement (nm) and the force (pN) that, during sound stimulation, is experienced by the antenna (Top). This mechanical behavior and also the amplitude characteristics of the nerve response (bottom) are reproduced by an active version of the gating spring model (orange circles) that links mechanical amplification by JONs to the open probability of MET channels (bottom) (adopted from Ref. [19]). (b) Localization of NOMPC and Nan–Iav in JON cilia (see also Refs. [28–30]). (c) Transduction models. According to the ‘NOMPC model’ (left), auditory JONs use NOMPC to transduce and mechanically amplify vibrations, and gravity/wind-sensitive JONs transduce antennal deflections with a second, unknown channel (‘X’). Downstream of transduction, electrical signals are amplified by Nan–Iav. The Nan–Iav model (bottom) posits that Nan–Iav mediates transduction in auditory and gravity/wind-sensitive JONs. NOMPC acts as a mechanical pre-amplifier in auditory JONs that, together with motor proteins, augments vibrations prior to transduction (see also Ref. [26]).
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4582067&req=5

fig0010: Transduction and amplification. (a) Left: mechanical sensitivity of the antenna (measured as antennal vibration velocity (m/s) normalized to the sound particle velocity (m/s)) as a function of the sound particle velocity (top), and corresponding relative amplitude of the sound-evoked antennal nerve potentials (bottom). Mechanical amplification by JONs maximally enhances the antenna's sensitivity to faint sounds (arrow, top) that, by themselves, would be too weak to evoke nerve potentials (arrow, bottom) (adopted from Ref. [15••]). Right: maximum sensitivity to faint sounds is also seen when the antenna's mechanical sensitivity is measured as the ratio between antennal displacement (nm) and the force (pN) that, during sound stimulation, is experienced by the antenna (Top). This mechanical behavior and also the amplitude characteristics of the nerve response (bottom) are reproduced by an active version of the gating spring model (orange circles) that links mechanical amplification by JONs to the open probability of MET channels (bottom) (adopted from Ref. [19]). (b) Localization of NOMPC and Nan–Iav in JON cilia (see also Refs. [28–30]). (c) Transduction models. According to the ‘NOMPC model’ (left), auditory JONs use NOMPC to transduce and mechanically amplify vibrations, and gravity/wind-sensitive JONs transduce antennal deflections with a second, unknown channel (‘X’). Downstream of transduction, electrical signals are amplified by Nan–Iav. The Nan–Iav model (bottom) posits that Nan–Iav mediates transduction in auditory and gravity/wind-sensitive JONs. NOMPC acts as a mechanical pre-amplifier in auditory JONs that, together with motor proteins, augments vibrations prior to transduction (see also Ref. [26]).
Mentions: Antennal displacements are coupled via the terminal threads to the mechanosensory cilia of JONs, where they gate mechano-electrical transduction (MET) channels [22]. This gating introduces a nonlinear compliance into the fly's antennal mechanics that, conforming to the gating spring model of vertebrate auditory transduction [23], suggests that the MET channels are directly gated by pull of gating springs. The interplay between this mechanogating and associated motor movements quantitatively explains mechanical amplification in Drosophila hearing [19], indicating that the same transducer-based mechanism that drives active hair bundle movements in vertebrate hair cells [24] also promotes the motility of JONs. The mechanistic link between transduction and amplification by JONs was recently put into question because ‘active amplification is observable for intensities below the threshold for antennal field potential responses’ [15••] (Figure 2a). Neither field potentials nor channel gating, however, possess thresholds, and a transduction-based model well captures the intensity-dependence of amplification in the fly's ear [19] (Figure 2a).

Bottom Line: Recent studies have analyzed the operation of auditory sensory cells and the processing of sound in the fly's brain.Neuronal responses to sound have been characterized, and novel classes of auditory neurons have been defined; transient receptor potential (TRP) channels were implicated in auditory transduction, and genetic and environmental causes of auditory dysfunctions have been identified.This review discusses the implications of these recent advances on our understanding of how hearing happens in the fly.

View Article: PubMed Central - PubMed

Affiliation: Ear Institute, University College London, 332 Gray's Inn Rd, London WC1X 8EE, UK. Electronic address: joerg.albert@ucl.ac.uk.

No MeSH data available.


Related in: MedlinePlus