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Hidden Hearing Loss: Cochlear Synaptopathy in Noise-Induced and Age-Related Hearing Loss

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1.  Auditory nerve fibers contacting inner hair cells: Are unbranched contacting a single hair cell by a single synaptic contact Have myelinated central axons Project to the cochlear nucleus All of the above

2.  Auditory nerve fibers contacting outer hair cells: Comprise only about 5% of the auditory nerve Have unmyelinated axons Are slow conducting and therefore unlikely to contribute to speech perception All of the above

3.  Which of the following structures tend to be the most vulnerable in noise-induced hearing loss: The hair cells The stria vascularis The spiral ganglion cells The synaptic connections between spiral ganglion cells and inner hair cells

4.  If a patient shows a prominent 4-kHz notch in the audiogram, which of the following is most likely true about the 4 kHz cochlear region: There is selective inner hair cell damage There is selective outer hair cell damage There is selective loss of auditory nerve fibers There is no damage to either hair cells or auditory nerve fibers

5.  In humans and animals, the synaptic connections between hair cells and auditory nerve fibers can be seen in the light microscope after immunostaining for: Proteins in the pre-synaptic ribbons Proteins in the post-synaptic glutamate receptors Proteins in the peripheral terminals of auditory nerve fibers All of the above

6.  After an auditory nerve fiber has lost its synaptic connection to the inner hair cell: The cell body and central axon can survive for years It will have no spontaneous activity and no response to sound It will remain electrically excitable, for example by a cochlear implant All of the above

7.  The phenomenon of cochlear synaptopathy has been called hidden hearing loss, because: Neural loss has little effect on audiometric thresholds until it becomes severe and cochlear synapses are not visible in routine histological material There are no tests to diagnosis it It only occurs in children No hearing loss actually exists

8.  In animal models, what type of pathophysiology is suggestive of cochlear synaptopathy? Pure synaptopathy causes no changes in any physiological measure Threshold elevation for the ABR without change in thresholds for DPOAEs Reduction in suprathreshold amplitudes of ABR wave 1 Threshold elevation for both ABRs and DPOAEs

9.  What types of hearing impairment should theoretically be caused by cochlear synaptopathy without hair cell damage? High-frequency threshold elevation Low-frequency threshold elevation Both high- and low-frequency threshold elevation Difficulty understanding speech in noise

10.  Cochlear synaptopathy might be a treatable condition, because: If stimulated with continuous low-level sounds, the auditory nerve fibers can send out new neuronal processes that re-connect to remaining inner hair cells If exposed to high levels of neurotrophin, auditory nerve fibers can send out new neuronal processes that re-connect to remaining inner hair cells If exposed to high levels of the neurotransmitter glutamate, auditory nerve fibers can send out new neuronal processes that re-connect to remaining inner hair cells All of the above