Mechanisms of hearing question

F. Frank LeFever flefever at ix.netcom.com
Sun Dec 13 20:20:32 EST 1998


I'll admit to some ignorance about the fine details of auditory sense
mechanisms, but why do you invoke higher centers in this "tuning"? 
Lateral inhibition in the retina works at the retinal level, I believe.
Of course, the retina is ALREADY in the CNS (at the level of the
ganglion cells), so maybe this is not the best comparison, but is it
not possible that lateral inhibition and fine-tuning is at the level of
lateral inhibition between hair cells?  Someone out there with a better
grasp of cochlear funcction out there?  HELP!

F. Frank LeFever, Ph.D.
New York Neuropsychology Group


In <19981213062632.06806.00002674 at ngol06.aol.com> tonyjeffs at aol.com
(TONYJEFFS) writes: 
>
>
>
>My understanding is that the 'dead' cochlea has a frequency resolution
of
>around 1/2 an octave, and in vivo it is the 'lateral inhibition'
provided by
>the motile outer hair cells (OHCs) that refines this frequency
resolution.
>
>Now consider the following: 
>IHCs initially detect a sound pressure wave and send the information
to the
>brain. The brain processes this data, and send instructions back to
the
>appropriate OHCs.  The OHCs do their 'fine tuning' work, enabling the
>appropriate IHCs to accurately identify the frequency of the incoming
sound.
>
>If that is approximately correct, I see a  problem:-:
>There would be a delay of the order of milliseconds while (1) the
initial
>information is relayed to appropriate brain nuclei, (2) The
information is
>processed, (3) instructions are sent to the OHCs.
>
>Several milliseconds delay seems rather a long time, particularly as I
think
>(?) we can hear sounds of a shorter duration than this.
>
>Is my description along the right lines? I suspect I'm missing
something!
>Could  there really such a delay?
>
>Thanks
>Tony
>




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