title: Filtering of acoustic signals within the hearing organ.
abstract: The detection of sound by the mammalian hearing organ involves a complex mechanical interplay among different cell types. The inner hair cells, which are the primary sensory receptors, are stimulated by the structural vibrations of the entire organ of Corti. The outer hair cells are thought to modulate these sound-evoked vibrations to enhance hearing sensitivity and frequency resolution, but it remains unclear whether other structures also contribute to frequency tuning. In the current study, sound-evoked vibrations were measured at the stereociliary side of inner and outer hair cells and their surrounding supporting cells, using optical coherence tomography interferometry in living anesthetized guinea pigs. Our measurements demonstrate the presence of multiple vibration modes as well as significant differences in frequency tuning and response phase among different cell types. In particular, the frequency tuning at the inner hair cells differs from other cell types, causing the locus of maximum inner hair cell activation to be shifted toward the apex of the cochlea compared with the outer hair cells. These observations show that additional processing and filtering of acoustic signals occur within the organ of Corti before inner hair cell excitation, representing a departure from established theories.
authors.affiliation: Oregon Health & Science University, Oregon Hearing Research Center, Portland, Oregon 97239-3098.
authors.forename: Sripriya
authors.initials: S
authors.lastname: Ramamoorthy
authors.affiliation: Oregon Health & Science University, Oregon Hearing Research Center, Portland, Oregon 97239-3098, Xijing Hospital, Fourth Military Medical University, Department of Otolaryngology/Head & Neck Surgery, Xi'an 710032, People's Republic of China, nuttall@ohsu.edu zhadjun@fmmu.edu.cn.
authors.forename: Dingjun
authors.initials: D
authors.lastname: Zha
authors.affiliation: Oregon Health & Science University, Oregon Hearing Research Center, Portland, Oregon 97239-3098, South University of Science & Technology of China, Department of Biology, Shenzhen, Guandong, People's Republic of China.
authors.forename: Fangyi
authors.initials: F
authors.lastname: Chen
authors.affiliation: Oregon Health & Science University, Department of Biomedical Engineering, Portland, Oregon 97239-3098.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Jacques
authors.affiliation: University of Washington, Seattle, Washington 98195-5061, and.
authors.forename: Ruikang
authors.initials: R
authors.lastname: Wang
authors.affiliation: Oregon Health & Science University, Oregon Hearing Research Center, Portland, Oregon 97239-3098.
authors.forename: Niloy
authors.initials: N
authors.lastname: Choudhury
authors.affiliation: Oregon Health & Science University, Oregon Hearing Research Center, Portland, Oregon 97239-3098, nuttall@ohsu.edu zhadjun@fmmu.edu.cn.
authors.forename: Alfred L
authors.initials: AL
authors.lastname: Nuttall
authors.affiliation: Oregon Health & Science University, Oregon Hearing Research Center, Portland, Oregon 97239-3098, Linköping University, Department of Clinical and Experimental Medicine, Cell Biology, SE-58185 Linköping, Sweden.
authors.forename: Anders
authors.identifier: http://orcid.org/0000-0002-7960-1559
authors.initials: A
authors.lastname: Fridberger
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001306:Auditory Pathways / Q000502:physiology; D001489:Basilar Membrane / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000502:physiology*; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D006309:Hearing / Q000502:physiology*; D008297:Male; D008959:Models, Neurological; D041623:Tomography, Optical Coherence; D014732:Vibration
keywords: basilar membrane; cochlea; cochlear amplifier; inner hair cells; outer hair cells; reticular lamina