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Re: mechanical cochlear model

Coincidence? A few days ago the Association for Research in Otolaryngology (ARO) published the abstracts of this year's meeting, which is closing today. In the field of cochlear mechanics several "unexpected" experimental findings were reported. Here are two of them.

Weddell et al. reported that in a genetically modified mouse where the tectorial membrane is detached from other tissues within the cochlea hearing sensitivity is almost normal. 2011 ARO abstract 616.
This result falsifies the ter Kuile theory from 1900. According to this theory hair cells are excited by a shear movement between the basilar membrane and the tectorial membrane. Such a shear movement was not possible in the experiments by Weddell et al. Hair cells must therefore be excited otherwise. The main implication, however, of the new finding is that a basilar membrane traveling wave cannot excite hair cells as suggested by ter Kuile and repeated by generations of hearing scientists until today.

Hakizimana et al. reported that the length of the "hairs" of hair cells changes during sound transduction and that the amplitude of the changes depends on the current going through the "hairs". 2011 ARO abstract 355.
Because "hair" length influences the mechanical behavior of the whole hair bundle, and thus of the whole hair cell, the current dependence of the length changes may be an important feature in the frequency selectivity of individual outer hair cells. Interestingly, inner hair cells, which are not assumed to be intrinsically tuned, showed no current dependence of "hair" length changes.


Martin Braun
Neuroscience of Music
S-671 95 Klässbol
email: nombraun@xxxxxxxxx
web site: http://www.neuroscience-of-music.se/index.htm

----- Original Message ----- From: "Jose Ignacio Alcantara" <jia10@xxxxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx>
Sent: Wednesday, February 23, 2011 12:03 AM
Subject: Re: mechanical cochlear model

A heartfelt ditto to this!  Long may they live and prosper on this list.

On 22 Feb 2011, at 21:59, Linda Seltzer wrote:

My vote is to keep the discussion on the list, and the postings do not
have to be short.  I believe that it is laudable when people want to
provide education to others and share the benefit of their expertise.
Hello !

I, too, would be glad if the cochlear-mechanics discussion on the Auditory List could continue. If possible, the postings should be kept short.