Re: Auditory efferents and phase locking

[Matt Flax <flatmax@xxxxxxxx>]

Indeed,

We gave birth to the "Multi-mode Cochlear Amplifier" theory of hearing
based on this paradigm (originally about 12 years ago). It goes much
further and deeper then simple phase locking. This is regarded as a
non-classical theory of hearing, as it suggests paradigms which are very
different to the classical active travelling wave theory (which
typically doesn't incorporate any form of efferent activity).

Liberman originally indicated that there was little effect due to
severing of the COCB in cats [1].
This was countered 8 years later by Walsh (in conjunction with Liberman)
[2], again in cats.
This countering was confirmed a year later by Zheng in Chinchillas [3].

There is currently a huge amount of work into efferent shocking from the
IV'th ventricle in the brain ... whilst it is most often referred to as
'suppression', this is misleading as the SEVERE efferent shocking
effects do not resemble the subtle signalling which occurs naturally in
the COCB. Refer to Guinan's huge body of work in this area and also
refer to Guinan's most recent material on 'non-classical' effects. The
non-classical effects refer to regions in the apex (and possibly the
middle) of the Cochlea. This is - of course - the region where the best
phase locking occurs.

Current experimental evidence supports our multi-mode theory of active
hearing - where the base of the cochlea experiences active travelling
waves and the apex of the Cochlea experiences active compression waves.

Matt

[1] Liberman, M.C., "Effects of chronic cochlear de-efferentation on
auditory-nerve response.", Hearing Research 49, 1-3 (1990), pp. 209--23.
[2] Walsh, E.J. and McGee, J.A. and McFadden, S.L. and Liberman, M.C.,
"Long-Term Effects of Sectioning the Olivocochlear Bundle in Neonatal
Cats", Journal of Neuroscience 18, 10 (1998), pp. 3859--3869.
[3] Zheng, X.Y. and Henderson, D. and Salvi, R.J., "Auditory nerve fiber
responses following chronic cochlear de-efferentation", Journal of
comparative neurology 406, 1 (1999), pp. 72--86.


On Tue, 2011-08-30 at 00:28 +0100, Josà Ignacio AlcÃntara wrote:
> Dear List,
> 
> Might anyone know of any physiological and/or psychophysical studies that 
> have investigated the role of the efferent system, specifically the MOCB, 
> on IHC neural phase locking/perception of temporal fine structure? For the 
> latter, I guess I'm looking for studies that might show changes in pitch 
> perception of sinusoids and/or harmonic tone complexes - preferably 
> containing only unresolved harmonics - and/or sound localisation abilities 
> in patients who have undergone vestibular (and efferent) nerve sectioning.
> 
> On a more general note, is there are good reason to suppose that MOCB 
> stimulation might improve the accuracy of IHC phase locking either in quiet 
> or in noise?
> 
> Thanks for any help you can provide.
> 
> Cheers, JosÃ
> _________________________________
> 
> Josà Ignacio AlcÃntara, PhD
> University Lecturer
> Department of Experimental Psychology
> University of Cambridge
> Downing Street
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> Tel: +44 (0)1223 764412
> 
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