Question about Nucleus Laminaris

Didier A. Depireux didier at Glue.umd.edu
Tue Nov 24 10:15:37 EST 1998


I am sure I am not going to write your paper for you!
However, 

Yao-Yu E Wang (yew+ at andrew.cmu.edu) wrote:

: How was neural cross-correlation defined? and how was it measured 

For the Barn Owl, you can have locking to the incoming waveform up to very
high frequencies (6 KHz or so, depending on who you talk to). The owl has
asymmetric ears, one facing downwards and the other upwards.  When a sound
is heard in front (say) of the owl, there will be a time difference between
the sounds perceived at the ears, because of the azimuth of the source, and
an intensity difference because of the asymmetry of the ears and the
elevation of the source.

So: take an owl, and present a pure tone (its hearing range goes up to 8
KHz) to its ears and record in NL. You will find that the strenght of the
response of a given cell of the right Best Frequency depends on the phase
difference between the two ears, as though the cell was computing a
cross-correlation between the two sine waves.

: If NL or MSO is not the cross-correlator,  then which part of the
: auditory
: pathway could be the cross-correlator?

My point was that you don't _need_ a cross-correlator. In mammals,
especially, there 's a travelling wave along the cochlea, from high
frequencies to low frequencies. The phase accumulation in each cochlear
filter can serve to compute the delays for you. I recommend reading S.
Shamma, N. Shen, and P. Gopalaswamy, ``Stereausis: Binaural processing
without neural delays", J. Acoust. Soc. Am., 86, pp. 989-1006, 1989.  to
see an alternative to the common view that there _has_ to be a range of
neural delays to perform cross-correlations in the NL or the MSO.

: and what is ANOVA test?
You're kidding? Right? Pick up a book on statistics. 

					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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