Articles by Gerhard Hoch in JoVE
Optogenetic Stimulation of the Auditory Nerve Victor H. Hernandez1,2,5, Anna Gehrt1,3, Zhizi Jing3, Gerhard Hoch1, Marcus Jeschke1, Nicola Strenzke3, Tobias Moser1,2,4 1InnerEarLab, Department of Otolaryngology, University Medical Center Goettingen, 2Bernstein Focus for Neurotechnology, University of Goettingen, 3Auditory Systems Physiology Group, Department of Otolaryngology, University Medical Center Goettingen, 4Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Goettingen, 5Department of Chemical, Electronic, and Biomedical Engineering, University of Guanajuato Cochlear implants (CIs) enable hearing by direct electrical stimulation of the auditory nerve. However, poor frequency and intensity resolution limits the quality of hearing with CIs. Here we describe optogenetic stimulation of the auditory nerve in mice as an alternative strategy for auditory research and developing future CIs.
Other articles by Gerhard Hoch on PubMed
Tuning of Synapse Number, Structure and Function in the Cochlea Nature Neuroscience. Apr, 2009 | Pubmed ID: 19270686 Cochlear inner hair cells (IHCs) transmit acoustic information to spiral ganglion neurons through ribbon synapses. Here we have used morphological and physiological techniques to ask whether synaptic mechanisms differ along the tonotopic axis and within IHCs in the mouse cochlea. We show that the number of ribbon synapses per IHC peaks where the cochlea is most sensitive to sound. Exocytosis, measured as membrane capacitance changes, scaled with synapse number when comparing apical and midcochlear IHCs. Synapses were distributed in the subnuclear portion of IHCs. High-resolution imaging of IHC synapses provided insights into presynaptic Ca(2+) channel clusters and Ca(2+) signals, synaptic ribbons and postsynaptic glutamate receptor clusters and revealed subtle differences in their average properties along the tonotopic axis. However, we observed substantial variability for presynaptic Ca(2+) signals, even within individual IHCs, providing a candidate presynaptic mechanism for the divergent dynamics of spiral ganglion neuron spiking.
Optogenetic Stimulation of the Auditory Pathway The Journal of Clinical Investigation. Mar, 2014 | Pubmed ID: 24509078 Auditory prostheses can partially restore speech comprehension when hearing fails. Sound coding with current prostheses is based on electrical stimulation of auditory neurons and has limited frequency resolution due to broad current spread within the cochlea. In contrast, optical stimulation can be spatially confined, which may improve frequency resolution. Here, we used animal models to characterize optogenetic stimulation, which is the optical stimulation of neurons genetically engineered to express the light-gated ion channel channelrhodopsin-2 (ChR2). Optogenetic stimulation of spiral ganglion neurons (SGNs) activated the auditory pathway, as demonstrated by recordings of single neuron and neuronal population responses. Furthermore, optogenetic stimulation of SGNs restored auditory activity in deaf mice. Approximation of the spatial spread of cochlear excitation by recording local field potentials (LFPs) in the inferior colliculus in response to suprathreshold optical, acoustic, and electrical stimuli indicated that optogenetic stimulation achieves better frequency resolution than monopolar electrical stimulation. Virus-mediated expression of a ChR2 variant with greater light sensitivity in SGNs reduced the amount of light required for responses and allowed neuronal spiking following stimulation up to 60 Hz. Our study demonstrates a strategy for optogenetic stimulation of the auditory pathway in rodents and lays the groundwork for future applications of cochlear optogenetics in auditory research and prosthetics.