Brain scans do not capture all forms of tinnitus ... Re: AUDITORY Digest - 6 Oct 2009 to 7 Oct 2009 (#2009-230)

[Matt Flax <flatmax@xxxxxxxx>]

I have copied the original context of Jont's statement in response to
Didier's statement below ... [1]

The point being made by Jont in analogy was that nerve section is not an
indicator for tinnitus. I hope that people don't take offense to each
other on this list ... it is really a waste of valuable time ...

The original comments by Arnaud were that nerve section does not always
solve problems to do with tinnitus ...
I then supported Arnaud's comments and introduced the literature which
points out that tinnitus may either be peripheral (in the ear labrynth /
neural connections) OR  central (auditory cortex).

I am aware of the wider opinion from Robert's statement "Most people I
think believe that it [tinnitus] is caused by some kind of maladaptive
reorganization in the central nervous system."

This concept is that plasticity is the sole cause for tinnitus ...
however it simply doesn't hold enough water ... the articles I posted
references to previously are proof that tinnitus is generated by EITHER
peripheral malfunctions OR central malfunctions ...

Further, in similarity to the processes of the compression wave cochlear
amplifier (which captures the peripheral form of tinnitus) ... neural
loops may form in the auditory cortex which is discussed here [2]. These
neural loops could be caused by plasticity, however on a physiological
level ... the general concept that 'all of tinnitus is due to central
reorganisation' is not valid in my opinion.

One can go further into the detail of how tinnitus can take the form of
tonal or 'cricket' or roaring perceptions ... these perceptions may
actually be due to real signals ... also discussed briefly in [2] ...
there is no reason why such signals must be produced centrally ... they
can be produced peripherally OR centrally ... all that is needed are
unstable limit cycles in well connected systems, such as the compression
wave cochlear amplifier in the periphery OR neural loops in the
cortex ...
Incidently the connection between physical signals (eg OAEs in the
periphery) and the perception of tinnitus appears to go back to 1931 [1]
as pointed out by Jont. I would assume that the cortex will have a
similar relationship between signals and perception ... although some of
you will find my statement contentious !

Matt

[2] @PhdThesis{flax:2008phd,
  author = {Flax, M.R.},
  title = {The active compression wave cochlear amplifier},
  school = {Electrical Engineering \& Telecommunications, UNSW},
  year = {2008},
}


[1] ........... original statement and response ....

> The idea of the relationship between some measure from OAEs and
> tinnitus is still progressing. Recently, Glenis Long and Lucas Parra
> (and co-authors, sorry) gave very convincing evidence that even the
> spectral profile of tinnitus, i.e. a tinnitus likeness spectrum, can
> be predicted by measures of a high resolution audiogram and the growth
> of DPOAE as a function of level. This was true for a subset of their
> tinnitus sufferers, particularly those who have stable tinnitus.

This is just one more paper in a long line, that shows the correlation
between tinnitus and OAE. How about the one that started it all:

http://auditorymodels.org/jba/PAPERS/Wegel31.djvu

@article{Wegel31
,author={Wegel, R.L.}
,title={Study of tinnitus}
,journal="Archives Otolaryngology"
,year=1931
,month=aug
,volume=14
,pages={158-165}

> However, remember that, as pointed out earlier by Arnaud in this
> thread, people who have their 8th nerve resected (for surgical
> resolution of a vestibular schwannoma, typically) often have tinnitus.

This is a meaningless indicator. If you drive a truck over someone's 
head and crush their skull, they will become blind. Does it follow that 
you see with your skull?


On Thu, 2009-10-08 at 20:37 -0400, R. Zatorre, Dr. wrote:
> *************
> You reply: "This is a meaningless indicator. If you drive a truck over
> someone's head and crush their skull, they will become blind. Does it
> follow that you see with your skull?"
> 
> I don't get it.
> 
>                             Didier
> ***************
> I didn't get it either...
> 
> ...and according to that logic, phantom limb pain is generated...in the missing limb!?
> Most people I think believe that it is caused by some kind of maladaptive reorganization in the central nervous system. I only bring it up because phantom phenomena have been often proposed as a model for tinnitus. 
> 
> But it's not my idea, so if you don't like it, don't yell at me, ok?
> 
> Robert
> 
> 
> Robert Zatorre
> Montreal Neurological Institute
> McGill University
> 514-398-8903
> fax: 514-398-1338
> www.zlab.mcgill.ca