x-no-archive:yes
wdr at world.std.com wrote in part:
>Has any work been done to determine whether the spurious signal in
>classic tinnititus is arising in the "signal processing" in the brain
>or if it is present in the nerve-bundle running to the brain? This
>would probably only be detectable in a patient for whom the tinititus
>was intermittent.
Such work has been done, but not enough of it. Spectral analysis of
auditory nerve activity has yielded some clues--enough to make more
research look promising, but not enough to answer the question you pose,
at least in the way you pose it.
Tinnitus can be turned on and off in a normal subject with drugs and
other means. There is a change in power spectra in the auditory nerve
when tinnitus is present. This same change is found when those with
normal hearing are compared with those with tinnitus.
However, the change is the addition of a 200 Hz peak amidst a complex
background extending up to about 1 kHz. For complex reasons, researchers
believe the peak is due to efferent neural activity--signals being sent
from brain to ear, rather than the expected reverse situation.
--
Jim Chinnis / Manassas, VA, USA / American Tinnitus Association member
Join the ATA at 800-634-8978. http://www.ata.org/
If replying by email, delete the X: Xjchinnis at alum.mit.edu
