Re: Place-based pitch

[Martin Braun <nombraun@xxxxxxxxx>]

On Thursday, March 25, 2004, David Mountain wrote:

> .... , the "tuning" properties of the inner hair cell or "pitch" neuron
> will depend on a host of anatomical and physiological parameters that
> would not be expected to be indentical on the two sides.

Thank you, David, this was the best about diplacusis that I could read so
far. The phenomenon also presents strong evidence that the temporal coding
of pitch is at some place written on a pitch map, as suggested by Gerald
Langner some two decades ago. Diplacusis would not occur, if pitch coding
remained in a temporal state throughout the auditory brain, as some seem to
think. Most of the time-place transformation seems to occur in the nuclei of
the inferior colliculus. Possibly some of it occurs in the auditory
thalamus.


> To me the wonder is how, it is that most of us have a pretty good match
> between the left and right ears when it comes to pitch and other salient
> perceptual qualities.

As to pitch, also this wonder seems to be located at the level of the two
nuclei of the inferior colliculus. There is a strongly developed tonotopic
commissure between them, which seems to level out all differences between
left and right for normal binaural hearing.

Malmierca, M.S., Rees, A., Le Beau, F.E.N., Bjaalie, J.G., 1995. Laminar
organization of frequency-defined local axons within and between the
inferior colliculi of the guinea pig. J. Comp. Neurol. 357, 124-144.

Martin

--------------------------------
Martin Braun
Neuroscience of Music
S-671 95 Klässbol
Sweden
web site: http://w1.570.telia.com/~u57011259/index.htm