Localization of pitch in the brain?

Didier A. Depireux didier at tango.isr.umd.edu
Mon Jul 23 08:58:51 EST 2001


Matt Jones <jonesmat at physiology.wisc.edu> wrote:

> But in your beating example, where the high frequency firing was
> modulated at 200 Hz, the all-interval distribution as used by Cariani
> & Delgutte wouldn't show the most prominent intervals at 200 Hz, would
> it? 

It actually would, but it becomes a little subltle. Once you consider a
2kHz fiber from the auditory nerve, it's fairly irrelevant that that fiber
was tuned to 2 kHz. The 2 kHz becomes more of a label than anything. This is
really well explained in an article by de Cheveigne, entitled "The auditory
system as a separation machine". The point is that what matters is what
happens in fibers that encode neighboring frequencies, and when you look at
it this way, there is all the information you need in the auditory nerve
firings (and the pitch even comes out of the 'pitchograms' kind of things
shows in Cariani and Delgutte). But you really should look at the
Cariani&Delgutte papers again, and the de Cheveigne.

> Another question though: is it necessary that there exist "pitch
> cells" by your definition at any level in the brain?  That is, can
> pitch not be represented as a population code, possibly even a
> multiplexed code where the same cells are also representing other
> aspects as well?

Absolutely, and that would definitely be the point of view of Cariani (with
his timing nets etc). It's explained in his homepage, http://www.cariani.com
 I think.

						Didier

-- 
Didier A Depireux                              didier at isr.umd.edu
Neural Systems Lab                 http://www.isr.umd.edu/~didier
Institute for Systems Research          Phone: 301-405-6557 (off)
University of Maryland                                -6596 (lab)
College Park MD 20742 USA                     Fax: 1-301-314-9920




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