Re: Efferent feedback to the organ of the Corti

[Matt Flax <flatmax@xxxxxxxx>]

David, please forgive me if I am incorrect.

I am referring to [1] Figure 5 where the VR/NP Synapses on VP/NR
NFs (Presumed Axodendritic Synapses) are depicted to become less numerous
towards the 3'rd turn.

Again, I am an electrical engineer, so please forgive me if I am
mistaken, but I am assuming that these are efferent neural connections.

I also refer to this posting to Auditory in 1996 :
http://www.auditory.org/postings/1996/74.html
Where it is stated ...
"There are also efferent fibers near the IHC's. These originate in the
lateral olivocochlear system, and make axodendritic synapses with the
afferent fibers [3]".

Matt

[3] Nadol J.B., Jr., Synaptic morphology of inner and outer hair cells of
the human organ of Corti, Journal of electron microscopy technique, 15,
187-196, 1990.
[1] @article{Thiers:2002,
author    = {Thiers, F.A. and Burgess, B.J. and Nadol, J.B.},
title     ={\href{http://www.elsevier.com/locate/issn/03785955}{Axodendritic and
dendrodendritic synapses within outer spiral bundles in a human}},
journal   = {Hearing Research},
pages     = {97-104},
year      = {2002},
volume    = {164},
issue     = {1-2}
}

On Thu, Oct 10, 2002 at 06:48:53AM -0400, David W. Smith, Ph.D. wrote:
> Matt,
> I think if you review Sato et al. (The innervation of outer hair cells:
> 3D reconstruction from TEM  serial sections in the Japanese macaque),
> Hearing res. 135,  29-38, 1999, you will see this is not precisely true.
> In  fact, the apex has a very robust, and perhaps qualitativiely
> different medial efferent supply than do more basal regions.  Your
> statement "In fact the afferent system is reported to be oversampled by
> the efferent system at high frequencies, one to one sampled for medium
> frequencies and under-sampled for low frequencies,"  I believe is incorrect.
> David SMith.
>
> Matt Flax wrote:
>
> >I would like to point researchers to the article [1] which slivers the
> >cochlea for electron microscope inspection. Of interest is the finding
> >that the efferent neural innervation is mostly in contact with the high
> >frequency portion of the spiral ganglion / organ of the Corti. There is
> >completely minimal contact for the low frequency portion of the  spiral
> >ganglion / organ of the Corti. There is medium contact for medium
> >frequencies.
> >In fact the afferent system is reported to be oversampled by
> >the efferent system at high frequencies, one to one sampled for medium
> >frequencies and under-sampled for low frequencies.
> >
> >This suggests that low frequencies are uniquely unaffected by the
> >efferent system. Medium frequencies are affected by efferent feedback and
> >high frequencies are seriously under the influence of the efferent
> >system.
> >
> >It is also noted that the efferent system is believed to develop post
> >birth.
> >
> >Matt
> >
> >[1]
> >@article{Thiers:2002,
> >  author    = {Thiers, F.A. and Burgess, B.J. and Nadol, J.B.},
> >  title     =
> >{\href{http://www.elsevier.com/locate/issn/03785955}{Axodendritic and
> >dendrodendritic synapses within outer spiral bundles in a human}},
> >  journal   = {Hearing Research},
> >  pages     = {97-104},
> >  year      = {2002},
> >  volume    = {164},
> >  issue     = {1-2}
> >}
> >
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> >
> >
> >
> >
>

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