Single-unit labeling of medial olivocochlear neurons: the cochlear frequency map for efferent axons

摘要: Medial olivocochlear (MOC) neurons are efferent that project axons from the brain to cochlea. Their action on outer hair cells reduces gain of “cochlear amplifier,” which shifts dynamic range hearing and effects noise masking. The MOC in one ear can be elicited by sound ipsilateral or contralateral ear. To study how onto cochlea mediate these effects, single-unit labeling guinea pigs was used mapping for responsive vs. those sound. were sharply tuned frequency with a well-defined characteristic (CF). However, their labeled termination spans organ Corti ranged narrow broad, innervating between 14 69 per axon “patchy” pattern. For units sound, midpoint innervation mapped according CF relationship generally similar to, but more variability than, auditory-nerve fibers. Thus, based mappings, most terminations miss involved cochlear amplifier CF, located basally. Compared ipsilaterally neurons, contralaterally had an apical offset larger span (an average 10.41% distance), suggesting when activates reflex, actions different than