External Network Error <peer-error at excite.com> wrote:
> 1a. Is there is a disorder[s] in the auditory cortex of the brain that
> would cause sudden and total deafness -- without evidence of physical
No if it's just auditory cortex. If you had a bilateral lesion of your
auditory cortex, you could still perform certain simple tasks, such as tone
discrimination. You perception (esp of complex events like music) would be
altered, to put it mildly, but you would not be deaf in the sense of not
being able to react to sounds.
> 1b.Can this be due to complete relaxation of neurons in the auditory
> cortex [thus rendering these neurons unexcitable]?
Uh? What does 'relaxation' mean in this context? Usually, damage to auditory
cortex is due to a local infarct, or to removal for treatment of intractable
epilepsy. A nice paper of Zatorre, for instance, showed that people whose
right auditory was removed for epilepsy could not hear the pitch of a
> 2. Are there ways to hear without ears -- i.e. through the brain [via
> radio and electromagnetic neuron stimulation]?
Without "ears", yes. If for instance your ossicles are non-functioning, you
can be made to hear through bone conduction. Apply a high-frequency RF
field near the temporal bone, and amplitude-modulate it by an audio signal,
and the person will be able to hear.
> 3. What symptoms would occur if blood entering the cochlear
> capillaries was cyanosed [blue due to absense of oxygen]?
For how long? Or, how slowly does the oxygen deprivation occur? There's more
than one blood vessel in that region. As a guess, I would think your outer
hair cells would die first, leading to a serious increase in hearing
thresholda. After that, I would imagine the whole cochlea would go dead,
though through the mysteries of the auditory nerve, you might be left deaf
but with a strong case of tinnitus.
Wow, you are asking a lot of questions...
Didier A Depireux ddepi001 at umaryland.edudidier at isr.umd.edu
685 W.Baltimore Str http://neurobiology.umaryland.edu/depireux.htm
Anatomy and Neurobiology Phone: 410-706-1272 (off)
University of Maryland -1273 (lab)
Baltimore MD 21201 USA Fax: 1-410-706-2512