Fw: Mechanisms of hearing question
rcb5 at msn.com
Wed Dec 16 09:38:50 EST 1998
From: F. Frank LeFever <flefever at ix.netcom.com>
To: neur-sci at net.bio.net <neur-sci at net.bio.net>
Date: Sunday, December 13, 1998 8:28 PM
Subject: Re: Mechanisms of hearing question
>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
>>My understanding is that the 'dead' cochlea has a frequency resolution
>>around 1/2 an octave, and in vivo it is the 'lateral inhibition'
>>the motile outer hair cells (OHCs) that refines this frequency
>>Now consider the following:
>>IHCs initially detect a sound pressure wave and send the information
>>brain. The brain processes this data, and send instructions back to
>>appropriate OHCs. The OHCs do their 'fine tuning' work, enabling the
>>appropriate IHCs to accurately identify the frequency of the incoming
>>If that is approximately correct, I see a problem:-:
>>There would be a delay of the order of milliseconds while (1) the
>>information is relayed to appropriate brain nuclei, (2) The
>>processed, (3) instructions are sent to the OHCs.
>>Several milliseconds delay seems rather a long time, particularly as I
>>(?) we can hear sounds of a shorter duration than this.
>>Is my description along the right lines? I suspect I'm missing
>>Could there really such a delay?
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