02067nas a2200133   4500008004100000245017300041210006900214520150800283100002001791700002201811700001201833700002001845856006801865       2012                        eng d00aTraveling Waves on the Organ of Corti of the Chinchilla Cochlea: Spatial Trajectories of Inner Hair Cell Depolarization Inferred from Responses of Auditory-Nerve Fibers0 aTraveling Waves on the Organ of Corti of the Chinchilla Cochlea 3 a<p>Spatial magnitude and phase profiles for inner hair cell depolarization throughout the chinchilla cochlea were inferred from responses of auditory-nerve fibers to threshold- and moderate-level tones and tone complexes. Firing-rate profiles for frequencies &le; 2 kHz are bimodal, with the major peak at the characteristic place and a secondary peak at 3&ndash;5 mm from the extreme base. Response- phase trajectories are synchronous with peak outward stapes displacement at the extreme cochlear base and accumulate 1.5-period lags at the characteristic places. High-frequency phase trajectories are very similar to the trajectories of basilar-membrane peak velocity toward scala tympani. Low- frequency phase trajectories undergo a polarity flip in a region, 6.5&ndash;9 mm from the cochlear base, where traveling-wave phase velocity attains a local minimum and a local maximum and where the onset latencies of near-threshold impulse responses computed from responses to near-threshold white noise exhibit a local minimum. That region is the same where frequency-threshold tuning curves of auditory-nerve fibers undergo a shape transition. Since depolarization of inner hair cells presumably indicates the mechanical stimulus to their stereocilia, the present results suggest that distinct low-frequency forward waves of organ of Corti vibration are launched simultaneously at the extreme base of the cochlea and at the 6.5&ndash;9 mm transition region, from where antiphasic reflections arise.</p>
1 aTemchin, A., N.1 aRecio-Spinoso, A.1 aCai, H.1 aRuggero, M., A.  uhttp://www.jneurosci.org/cgi/doi/10.1523/JNEUROSCI.1138-12.2012