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Application of Targeting-Optimized Chronos for Stimulation of the Auditory Pathway

Part of the Methods in Molecular Biology book series (MIMB,volume 2191)


In the last 15 years, optogenetics has revolutionized the life sciences and enabled studies of complex biological systems such as the brain. Applying optogenetics also has great potential for restorative medicine, such as hearing restoration, by stimulating genetically modified spiral ganglion neurons of the cochlea with light. To this end, opsins with short closing kinetics are required, given the high firing rates and utmost temporal precision of spiking in these neurons. Chronos is the fastest native blue channelrhodopsin (ChR) reported so far with a closing kinetics bellow 1 ms at body temperature and an interesting candidate for the development of the future optogenetic cochlear implants. This book chapter explains in more details the development and application of Chronos with optimized membrane targeting for temporally precise optical stimulation of spiral ganglion neurons. In addition, the generation of adeno-associated virus (AAV) and AAV delivery to the cochlea of postnatal mice and the procedure to record optically evoked auditory brainstem responses are described.

Key words

  • Channelrhodopsin
  • Cochlear optogenetics and gene therapy
  • Cochlear implant
  • Trafficking
  • Spiral ganglion

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  • DOI: 10.1007/978-1-0716-0830-2_16
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    The direction to the cochlea and the position of the stapedial artery is preliminary defined by the approach described in [19].


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We thank Daniela Gerke for expert help with virus and histology preparations. We thank Tobias Moser for critical reading of the manuscript and useful suggestions. We thank Ben Deverman and Viviana Gradinaru for providing the PHP.B construct, Edward S. Boyden for providing Chronos construct. The work was funded by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 670759—advanced grant “OptoHear”) to Tobias Moser.

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Correspondence to Vladan Rankovic .

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Huet, A.T., Rankovic, V. (2021). Application of Targeting-Optimized Chronos for Stimulation of the Auditory Pathway. In: Dempski, R. (eds) Channelrhodopsin. Methods in Molecular Biology, vol 2191. Humana, New York, NY.

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