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- Title
Concurrent Maturation of Inner Hair Cell Synaptic Ca2+ Influx and Auditory Nerve Spontaneous Activity around Hearing Onset in Mice.
- Authors
Wong, Aaron B.; Zhizi Jing; Rutherford, Mark A.; Frank, Thomas; Strenzke, Nicola; Moser, Tobias
- Abstract
Hearing over a wide range of sound intensities is thought to require complementary coding by functionally diverse spiral ganglion neurons (SGNs), each changing activity only over a subrange. The foundations of SGN diversity are not well understood but likely include differences among their inputs: the presynaptic active zones (AZs) of inner hair cells (IHCs). Here we studied one candidate mechanism for causing SGN diversity -- heterogeneity of Ca2+ influx among the AZs of IHCs -- during postnatal development of the mouse cochlea. Ca2+ imaging revealed a change from regenerative to graded synaptic Ca2+ signaling after the onset of hearing, when in vivo SGN spike timing changed from patterned to Poissonian. Furthermore, we detected the concurrent emergence of stronger synaptic Ca2+ signals in IHCs and higher spontaneous spike rates in SGNs. The strengthening of Ca2+ signaling at a subset of AZs primarily reflected a gain of Ca2+ channels. We hypothesize that the number of Ca2+ channels at each IHC AZ critically determines the firing properties of its corresponding SGN and propose that AZ heterogeneity enables IHCs to decompose auditory information into functionally diverse SGNs.
- Subjects
HAIR cells; ACOUSTIC nerve; AUDITORY pathways; HEARING disorders; RETINAL ganglion cells; PRESYNAPTIC receptors; LABORATORY mice
- Publication
Journal of Neuroscience, 2013, Vol 33, Issue 26, p10661
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.1215-13.2013