Sound-Evoked Radial Strain in the Hearing Organ

AbstractThe hearing organ contains sensory hair cells, which convert sound-evoked vibration into action potentials in the auditory nerve. This process is greatly enhanced by molecular motors that reside within the outer hair cells, but the performance also depends on passive mechanical properties, such as the stiffness, mass, and friction of the structures within the organ of Corti. We used resampled confocal imaging to study the mechanical properties of the low-frequency regions of the cochlea. The data allowed us to estimate an important mechanical parameter, the radial strain, which was found to be 0.1% near the inner hair cells and 0.3% near the third row of outer hair cells during moderate-level sound stimulation. The strain was caused by differences in the motion trajectories of inner and outer hair cells. Motion perpendicular to the reticular lamina was greater at the outer hair cells, but inner hair cells showed greater radial vibration. These differences led to deformation of the reticular lamina, which connects the apex of the outer and inner hair cells. These results are important for understanding how the molecular motors of the outer hair cells can so profoundly affect auditory sensitivity

Successor Liability in Bankruptcy: Some Unifying Themes of Intertemporal Creditor Priorities Created by Running Covenants, Products Liability, and Toxic-Waste Cleanup

The exceptional sensitivity of mammalian hearing organs is attributed to an active process, where force produced by sensory cells boost sound-induced vibrations, making soft sounds audible. This process is thought to be local, with each section of the hearing organ capable of amplifying sound-evoked movement, and nearly instantaneous, since amplification can work for sounds at frequencies up to 100 kHz in some species. To test these fundamental precepts, we developed a method for focally stimulating the living hearing organ with light. Light pulses caused intense and highly damped mechanical responses followed by traveling waves that developed with considerable delay. The delayed response was identical to movements evoked by click-like sounds. This shows that the active process is neither local nor instantaneous, but requires mechanical waves traveling from the cochlear base toward its apex. A physiologically-based mathematical model shows that such waves engage the active process, enhancing hearing sensitivity.Funding Agencies|NIH [DC-004554, DC-004084]; Swedish Research Council [K2011-63X-14061-11-39]; Research Council for Health, Working Life and Welfare [2006-1526]; Horselskadades Riksforbund; Tysta skolan foundation</p

Розробка модуля Ethernet контролю для дистанційного керування електроживильною установкою

Sound processing in the inner ear involves separation of the constituent frequencies along the length of the cochlea. Frequencies relevant to human speech (100 to 500 Hz) are processed in the apex region. Among mammals, the guinea pig cochlear apex processes similar frequencies and is thus relevant for the study of speech processing in the cochlea. However, the requirement for extensive surgery has challenged the optical accessibility of this area to investigate cochlear processing of signals without significant intrusion. A simple method is developed to provide optical access to the guinea pig cochlear apex in two directions with minimal surgery. Furthermore, all prior vibration measurements in the guinea pig apex involved opening an observation hole in the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here, this limitation is overcome by measuring the vibrations through the unopened otic capsule using phase-sensitive Fourier domain optical coherence tomography. The optically and surgically advanced method described here lays the foundation to perform minimally invasive investigation of speech-related signal processing in the cochlea. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.Funding Agencies|NIH NIDCD [R01DC000141]; NIH [R01DC004554, R01DC010201, R01DC011796]; Swedish Research Council [K2014-63X-14061-14-5]; Torsten Soderberg Foundation</p

Влияние параметров торцовой фрезы на характер обработанной поверхности

Материалы ХI Международной науч.-техн. конф. студентов, магистрантов и аспирантов [28-29 апреля 2011 г., г. Гомель]. - Гомель, 2011

A mechanoelectrical mechanism for detection of sound envelopes in the hearing organ

To understand speech, the slowly varying outline, or envelope, of the acoustic stimulus is used to distinguish words. A small amount of information about the envelope is sufficient for speech recognition, but the mechanism used by the auditory system to extract the envelope is not known. Several different theories have been proposed, including envelope detection by auditory nerve dendrites as well as various mechanisms involving the sensory hair cells. We used recordings from human and animal inner ears to show that the dominant mechanism for envelope detection is distortion introduced by mechanoelectrical transduction channels. This electrical distortion, which is not apparent in the sound-evoked vibrations of the basilar membrane, tracks the envelope, excites the auditory nerve, and transmits information about the shape of the envelope to the brain.Funding Agencies|Swedish Research Council [K2014-63X-14061-14-5, 2017-06092]; Torsten Soderberg foundation; Strategic research area for systems neurobiology (Region Ostergotland); Linkoping University; NIH-NIDCD [R01 DC-004554, R01 DC 000141]</p

In Vivo Outer Hair Cell Length Changes Expose the Active Process in the Cochlea

BACKGROUND: Mammalian hearing is refined by amplification of the sound-evoked vibration of the cochlear partition. This amplification is at least partly due to forces produced by protein motors residing in the cylindrical body of the outer hair cell. To transmit power to the cochlear partition, it is required that the outer hair cells dynamically change their length, in addition to generating force. These length changes, which have not previously been measured in vivo, must be correctly timed with the acoustic stimulus to produce amplification. METHODOLOGY/PRINCIPAL FINDINGS: Using in vivo optical coherence tomography, we demonstrate that outer hair cells in living guinea pigs have length changes with unexpected timing and magnitudes that depend on the stimulus level in the sensitive cochlea. CONCLUSIONS/SIGNIFICANCE: The level-dependent length change is a necessary condition for directly validating that power is expended by the active process presumed to underlie normal hearing

Antioxidanter vid stapedotomi

Background: Otosclerosis is a disorder that impairs middle ear function, leading to conductive hearing loss. Surgical treatment results in large improvement of hearing at low sound frequencies, but high-frequency hearing often suffers. A likely reason for this is that inner ear sensory cells are damaged by surgical trauma and loud sounds generated during the operation. Animal studies have shown that antioxidants such as N-Acetylcysteine can protect the inner ear from noise, surgical trauma, and some ototoxic substances, but it is not known if this works in humans. This trial was performed to determine whether antioxidants improve surgical results at high frequencies. Methods: We performed a randomized, double-blind and placebo-controlled parallel group clinical trial at three Swedish university clinics. Using block-stratified randomization, 156 adult patients undergoing stapedotomy were assigned to intravenous N-Acetylcysteine (150 mg/kg body weight) or matching placebo (1:1 ratio), starting one hour before surgery. The primary outcome was the hearing threshold at 6 and 8 kHz; secondary outcomes included the severity of tinnitus and vertigo. Findings: One year after surgery, high-frequency hearing had improved 2.7 ± 3.8 dB in the placebo group (67 patients analysed) and 2.4 ± 3.7 dB in the treated group (72 patients; means ± 95% confidence interval, p=0.54; linear mixed model). Surgery improved tinnitus, but there was no significant intergroup difference. Post-operative balance disturbance was common but improved during the first year, without significant difference between groups. Four patients receiving N-Acetylcysteine experienced mild side effects such as nausea and vomiting. Conclusions: N-Acetylcysteine has no effect on hearing thresholds, tinnitus, or balance disturbance after stapedotomy Purpose: Otosclerosis is a disease of the middle ear that causes gradually increasing hearing loss. The stapes is gradually fixed inside the oval window, which leads to hearing impairment. The conventional treatment is surgical (stapedotomy): The stapes is partially replaced by drilling on its footplate and connecting a prosthesis. This results in great improvement of low-frequency hearing, but at frequencies above 4000 Hz, there is less improvement and in some cases even decline of hearing after surgery (see e.g. Meyer, 1999). This is considered a consequence of trauma to the high-frequency parts of the inner ear during drilling on the stapes footplate. During drilling, patients report loud sounds, often described as ”the worst sound I ever heard”. In animals, antioxidants such as N-Acetylcysteine can protect the inner ear against noise-induced hearing loss. We will examine whether antioxidants lead to improved high-frequency hearing after stapedotomy. Our hypothesis is that antioxidants protect the inner ear against the trauma caused by the operation. The dataset contains 9 variables: "id" is a number with range 1 - 145, unique for each patient. "medicin" denotes the type of treatment given (possible values are "N-Acetylcysteine" or "Placebo"). "beta" denotes whether the steroid betametason was given before surgery. "gender" is "f" for female patients and "m" for males. "weight" is each patient's weight in kg. "age" is the age (in years, at the time of surgery). "freq" denotes the type of measurement performed. There are several possible values. "Tinnitus" means that "air1" and "air2" contains the difference in tinnitus scores before and after surgery. "tmv" denotes that air1 contains the average hearing threshold across the frequencies 0.5 - 3 kHz. "disk" means that "air1" contains the difference in discrimination scores before and after surgery "dizziness" means that "air1" contains the difference in dizziness scores before and after surgery. "hearq" means that "air1" contains the difference in hearing quality scores before and after surgery "surgery" means that "air1" contains the patient's assessment of the outcome of the operation (10 is the best, 0 is the worst) Numbers "250", "500", "1000", "2000", "3000","4000", "6000" and "8000" means that "air1" contains the difference in hearing thresholds before and after surgery at this particular stimulus frequency. "air1" contains measurements acquired 6 - 8 weeks after surgery. "air2" contains measurements acquired 1 year after surgery.Bakgrund: Otoskleros är en sjukdom som försämrar mellanörats funktion, vilket leder till hörselnedsättning. Kirurgisk behandling förbättrar hörseln vid låga stimuleringsfrekvenser, men högfrekvenshörseln förbättras inte. En trolig anledning till de sämre resultaten vid höga frekvenser är att innerörats sinnesceller skadas av det kirurgiska traumat och ljud som alstras under operationen. Djurstudier har visat att antioxidanter, tex N-Acetylcystein, kan skydda innerörat mot bullerskador, kirurgiskt trauma, och vissa ototoxiska substanser, men det är inte känt om detta fungerar hos människa. Syftet med denna studie är att undersöka om antioxidanter förbättrar kirurgiska resultat vid höga frekvenser. Metoder: Vi har genomfört en randomiserad, dubbelblind och placebokontrollerad klinisk studie vid tre svenska universitetskliniker. Stratifierad randomisering användes för att slumpa 156 patienter till behandling med antingen intravenöst N-Acetylcystein (150 mg/kg kroppsvikt) eller matchande placebo (kvot 1:1), med start en timme innan operationen. Primärt utfallsmått var hörtröskeln vid 6 och 8 kHz, sekundära effektmått tinnitus och yrsel. Resultat: Ett år efter operationen hade högfrekvenshörseln förbättrats med 2.7 ± 3.8 dB i placebogruppen (67 patienter analyserade) och med 2.4 ± 3.7 dB i den behandlade gruppen (72 patienter; medelvärde ± 95% konfidensintervall, p=0.54, linjär mixad modell). Operationen förbättrade patienternas tinnitus, men utan signifikant skillnad mellan grupperna. Balansstörningar var vanligt förekommande, men förbättrades under det första året, utan att någon signifikant skillnad mellan grupperna förelåg. Milda biverkningar observerades hos fyra patienter i N-Acetylcysteingruppen (illamående och kräkningar). Slutsats: N-Acetylcystein påverkar inte hörtrösklar, tinnitus eller balansstörningar efter stapedotomi. Syfte: Otoskleros är en öronsjukdom som ger en långsamt tilltagande hörselnedsättning. Stigbygeln fixeras gradvis i ovala fönstret och dess rörelser hämmas, vilket leder till hörselnedsättning. Den gängse behandlingen är kirurgisk (stapedotomi): stigbygelns platta borras upp och man kopplar in en protes som delvis ersätter stigbygeln. Detta ger en stor förbättring av hörseln framförallt vid låga frekvenser, men vid frekvenser ovanför 4000 Hz ses en mindre förbättring och i en del fall tom en försämring efter operationen (se tex Meyer, 1999). Detta anses bero på det trauma som innerörats högfrekvensdelar utsätts för då stigbygelns platta borras upp. Under borrningen upplever patienten starka ljud, som ofta beskrivs som "det värsta jag någonsin hört". Hos försöksdjur kan antioxidanter, tex acetylcystein, skydda innerörat mot bullerskador. Vi vill undersöka om tillförsel av antioxidanter kan ge förbättrad högfrekvenshörsel efter stapedotomi. Vår hypotes är att antioxidanterna skyddar innerörat mot det trauma som operationen innebär. The dataset contains 9 variables: "id" is a number with range 1 - 145, unique for each patient. "medicin" denotes the type of treatment given (possible values are "N-Acetylcysteine" or "Placebo"). "beta" denotes whether the steroid betametason was given before surgery. "gender" is "f" for female patients and "m" for males. "weight" is each patient's weight in kg. "age" is the age (in years, at the time of surgery). "freq" denotes the type of measurement performed. There are several possible values. "Tinnitus" means that "air1" and "air2" contains the difference in tinnitus scores before and after surgery. "tmv" denotes that air1 contains the average hearing threshold across the frequencies 0.5 - 3 kHz. "disk" means that "air1" contains the difference in discrimination scores before and after surgery. "dizziness" means that "air1" contains the difference in dizziness scores before and after surgery. "hearq" means that "air1" contains the difference in hearing quality scores before and after surgery. "surgery" means that "air1" contains the patient's assessment of the outcome of the operation (10 is the best, 0 is the worst). Numbers "250", "500", "1000", "2000", "3000","4000", "6000" and "8000" means that "air1" contains the difference in hearing thresholds before and after surgery at this particular stimulus frequency. "air1" contains measurements acquired 6 - 8 weeks after surgery. "air2" contains measurements acquired 1 year after surgery