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Chapter 8: The Auditory System

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A person has unilateral hearing loss. Based only on this limited amount of information, which of the following statements best indicates a likely site of lesion?

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A. Acoustic division of the eighth cranial nerve

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B. Superior olivary complex

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C. Lateral lemniscus

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D. Primary auditory cortex

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Comment: Unilateral damage to the auditory pathway after the first synapse in central nervous system does not lead to unilateral deafness because of the extensive crossing of information. The only sites where a lesion can produce deafness in one ear are the peripheral auditory apparatus, eighth nerve, or cochlear nuclei.

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Preferential loss of perception of high-frequency sounds is best explained by which of the following conditions?

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A. Degeneration of hair cells at the apex of the cochlear

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B. Degeneration of hair cells at the base of the cochlear

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C. Damage to the lateral superior olivary nucleus

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D. Damage to the inferior colliculus

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Comment: Whereas the lateral superior olivary nucleus is important for localizing high-frequency sounds, this does not imply that it is where high-frequency sounds are selectively processed for perception. Indeed, there is a parallel path for all frequencies through the dorsal cochlear nucleus, which does not synapse in the lateral superior olivary nucleus. By contrast, when hair cells of the base of the cochlea have degenerated all transductive machinery for high-frequency sounds is lost.

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Which of the following contributes most of the axons in the trapezoid body?

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A. Inferior colliculus

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B. Superior olivary nucleus

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C. Dorsal cochlear nucleus

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D. Anteroventral cochlear nucleus

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Comment: The superior olivary nucleus contributes a small number of axons to the trapezoid body. But by far, most axons come from the anteroventral cochlear nucleus.

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Which is not a property of the medial superior olivary nucleus?

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A. Important for processing low-frequency sounds

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B. Receives an inhibitory input from the nucleus of the trapezoid body

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C. Receives monosynaptic input from the ipsilateral and contralateral anteroventral nucleus

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D. Projects to the inferior colliculus

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Comment: Neurons of the nucleus of the ...

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