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SUMMARY:Hearing the light: Optogenetic Stimulation of the Auditory Nerve
DTSTART:20170405T110000
DTEND:20170405T120000
DTSTAMP:20260921T101728Z
UID:66f1ea16a6bfed72c3aaee9944f2f178b9b5b2f729339f8f26b7dda0
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Tobias Moser\, University of Göttingen Medical Center
 \, Germany.\nDISTINGUISHED LECTURES in NEUROPROSTHETICS\n\nAbstract\nWhen 
 hearing fails\, speech comprehension can be restored by auditory prosthese
 s. However\, sound coding with current prostheses\, based on electrical st
 imulation of auditory neurons\, has limited frequency resolution due to br
 oad current spread. We aim to improve frequency and intensity resolution o
 f cochlear implant coding by establishing spatially confined optical stimu
 lation of spiral ganglion neurons (SGNs). We have established optogenetic 
 stimulation of the auditory pathway in rodents using virus-mediated expres
 sion of channelrhodopsins to render SGNs light-sensitive. Optogenetic stim
 ulation of spiral ganglion neurons activated the auditory pathway\, as dem
 onstrated by recordings of single neuron and neuronal population responses
  at various stages of the auditory system. Fast opsins enabled SGN firing 
 at physiological rates (hundreds per second). We approximated the spatial 
 spread of cochlear excitation by recording local field potentials in the i
 nferior colliculus in response to suprathreshold optical and electrical st
 imuli\, which suggested a better frequency resolution for optogenetic than
  for electrical stimulation.\nTowards characterizing the percept induced b
 y cochlear optogenetics we studied activation of neurons in primary audito
 ry cortex and performed a behavioral analysis in virus-injected gerbils. V
 arious types of optogenetic responses were observed in auditory cortex. Fo
 r the behavioral analysis we implanted an optical fiber into the round win
 dow of the injected cochlea. Subsequently\, animals were trained in a dete
 ction task using the shuttle box paradigm. In parallel\, optically driven 
 auditory brainstem responses (oABRs) were measured during the period of be
 havioral testing to monitor the physiological response to optical stimulat
 ion of SGNs. We found that amplitudes\, latencies and thresholds of oABRs 
 stayed stable for a period of at least 3 weeks. During this period gerbils
  learned to avoid electric aversive stimuli cued by optical SGN stimulatio
 n within a few days and obtained response rates of up to 95%. Behavioral t
 hresholds of light amplitude were found to be below physiological threshol
 ds (< 3mW\, close to the threshold of the neurons in auditory cortex) and 
 thresholds of light pulse duration were as short as 0.1ms. This study demo
 nstrates that stimulation of channelrhodopsin-expressing spiral ganglion n
 eurons with blue light creates both a stable physiological response and a 
 robust auditory percept over several weeks. In summary\, optogenetic stimu
 lation of the auditory nerve is feasible and bears substantial potential f
 or future application in research and hearing restoration.\n\nBio\nTobias 
 Moser is a professor at University of Göttingen Medical Center where he d
 irects the Institute of Auditory Neuroscience. He also is heading research
  groups at the German Primate Center and at Max-Planck-Institutes in Gött
 ingen. His work focuses on the molecular anatomy\, physiology and pathophy
 siology of sound encoding and information processing in the auditory syste
 m as well as the restoration of hearing by gene replacement therapy and op
 togenetic stimulation. His team combines various techniques to characteriz
 e synapses of hair cells and the auditory brainstem from the molecular to 
 the systems level. This way they have contributed to the understanding of 
 structure and function of auditory synapses and initiated the concept of a
 uditory synaptopathy. Towards restoration of hearing Moser's team aims to 
 establish virus-mediated gene replacement therapy of auditory synaptopathy
  and pursue the optogenetic stimulation of auditory nerve for improving th
 e performance of the cochlear implant.\n 
LOCATION:Campus Biotech H8 Auditorium http://cnp.epfl.ch/files/content/sit
 es/cnp/files/Seminars/PlanSallesCampusBiotechH8-01.pdf
STATUS:CONFIRMED
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