- #1
andrewr
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Hi,
I've been studying the cochlea, and how the hair cells (IHCs) receive sound, and some amplify it (OHCs) ; and am trying to get an idea of the density profile of hair cells acting as a spatial filter.
The smallest discrimination in frequency that is positional (not temporal) coded, would be the frequency difference of the position of one hair cell ; so I want to know the profile (density) change of cells along the whole cochlea.
After looking at photomicrographs/sem online, I was only able to measure the spacing between cells in one (arbitrary/unknown) place in the cochlea; and it was about 10microns -- center to center -- axially along a single row of OHC's.
That good enough for a crude estimate test (assuming it was constant everywhere); for a human can discriminate a pitch change of about 5 "cents" near middle "C"; which works out to ~.77Hz ;
I used human cadaver data from ( Greenwood // or // Zwisloski ) to make a curve fit of resonance distance along the cochlea (passive resonance) vs. frequency -- and I get a result that .77Hz is roughly 15microns of distance near middle "C". -- So, about 1.5 hair cells... ( which is what I would expect 1 to 2 cells... )
Now, I just want to improve on that:
Does anyone know of a source that shows cell spacings from one end of the cochlea (basal/oval window) to the other (helicotrema) ?
I know it doesn't vary a lot, eg: it's less than 2:1 ratio ; but I can't seem to find any photographs of more than just one end of the cochlea at a time...
Thanks!
P.S. Here's my estimate of passive resonance frequency as a function of distance along the cochlea.
f( x[cm] ) [Hz] ~= 10**( -0.069*x**3 + 0.3293*x**2 - 1.115*x + 4.522 )
:)
I've been studying the cochlea, and how the hair cells (IHCs) receive sound, and some amplify it (OHCs) ; and am trying to get an idea of the density profile of hair cells acting as a spatial filter.
The smallest discrimination in frequency that is positional (not temporal) coded, would be the frequency difference of the position of one hair cell ; so I want to know the profile (density) change of cells along the whole cochlea.
After looking at photomicrographs/sem online, I was only able to measure the spacing between cells in one (arbitrary/unknown) place in the cochlea; and it was about 10microns -- center to center -- axially along a single row of OHC's.
That good enough for a crude estimate test (assuming it was constant everywhere); for a human can discriminate a pitch change of about 5 "cents" near middle "C"; which works out to ~.77Hz ;
I used human cadaver data from ( Greenwood // or // Zwisloski ) to make a curve fit of resonance distance along the cochlea (passive resonance) vs. frequency -- and I get a result that .77Hz is roughly 15microns of distance near middle "C". -- So, about 1.5 hair cells... ( which is what I would expect 1 to 2 cells... )
Now, I just want to improve on that:
Does anyone know of a source that shows cell spacings from one end of the cochlea (basal/oval window) to the other (helicotrema) ?
I know it doesn't vary a lot, eg: it's less than 2:1 ratio ; but I can't seem to find any photographs of more than just one end of the cochlea at a time...
Thanks!
P.S. Here's my estimate of passive resonance frequency as a function of distance along the cochlea.
f( x[cm] ) [Hz] ~= 10**( -0.069*x**3 + 0.3293*x**2 - 1.115*x + 4.522 )
:)