1. John S. Oghalai

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    1. Mentioned In 28 Articles

    2. Noise and sensitivity in optical coherence tomography based vibrometry

      Noise and sensitivity in optical coherence tomography based vibrometry
      There is growing interest in using the exquisite phase sensitivity of optical coherence tomography (OCT) to measure the vibratory response in organ systems such as the middle and inner ear. Using frequency domain analysis, it is possible to achieve picometer sensitivity to vibration over a wide frequency band. Here we explore the limits of the frequency domain vibratory sensitivity due to additive noise and consider the implication of phase noise ...
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    3. Postdoc Position at the University of Southern California

      Postdoc Position at the University of Southern California
      A postdoctoral researcher position is available immediately in the Department of Otolaryngology at the University of Southern California. The principal project will be to develop Optical Coherence Tomography (OCT) systems for functional and morphological imaging in the human ear. The utilization of OCT for imaging in the human ear is a growing field with a range of applications from basic science research to the diagnosis and monitoring of disease. The ...
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    4. Picometer scale vibrometry in the human middle ear using a surgical microscope based optical coherence tomography and vibrometry system

      Picometer scale vibrometry in the human middle ear using a surgical microscope based optical coherence tomography and vibrometry system
      We have developed a highly phase stable optical coherence tomography and vibrometry system that attaches directly to the accessory area of a surgical microscope common to both the otology clinic and operating room. Careful attention to minimizing sources of phase noise has enabled a system capable of measuring vibrations of the middle ear with a sensitivity of 5 pm in an awake human patient. The system is shown to be ...
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    5. University of Southern California Receives NIH Grant for Cochlear Mechanics in the Mouse

      University of Southern California Receives NIH Grant for Cochlear Mechanics in the Mouse
      University of Southern California Receives a 2019 NIH Grant for $215,469 for Cochlear Mechanics in the Mouse. The principal investigator is John Oghalai. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. Sound pressure produces force across the mammalian cochlear partition, ultimately creating a vibratory traveling wave that propagates longitudinally up the cochlear duct. The key feature distinguishing this process from ...
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    6. University of Southern California Receives NIH Grant for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo

      University of Southern California Receives NIH Grant for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo
      University of Southern California Receives a 2019 NIH Grant for $408,735 for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo. The principal investigator is John Oghalai. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. The function of the cochlea is to transduce complex sound pressure waves into electrical signals. Organ of Corti vibration is based upon a ...
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    7. Organ of Corti vibration within the intact gerbil cochlea measured by volumetric optical coherence tomography and vibrometry

      Organ of Corti vibration within the intact gerbil cochlea measured by volumetric optical coherence tomography and vibrometry
      There is indirect evidence that the mammalian cochlea in the low-frequency apical and the more commonly-studied high-frequency basal regions function in fundamentally different ways. Here, we directly tested this hypothesis by measuring sound-induced vibrations of the organ of Corti (OoC) at three turns of the gerbil cochlea using volumetric optical coherence tomography vibrometry (VOCTV), an approach that permits non-invasive imaging through the bone. In the apical turn, there was little ...
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    8. Osmotic stabilization prevents cochlear synaptopathy after blast trauma

      Osmotic stabilization prevents cochlear synaptopathy after blast trauma
      Traumatic noise causes hearing loss by damaging sensory hair cells and their auditory synapses. There are no treatments. Here, we investigated mice exposed to a blast wave approximating a roadside bomb. In vivo cochlear imaging revealed an increase in the volume of endolymph, the fluid within scala media, termed endolymphatic hydrops. Endolymphatic hydrops, hair cell loss, and cochlear synaptopathy were initiated by trauma to the mechanosensitive hair cell stereocilia and ...
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    9. Endoscopic optical coherence tomography enables morphological and subnanometer vibratory imaging of the porcine cochlea through the round window

      Endoscopic optical coherence tomography enables morphological and subnanometer vibratory imaging of the porcine cochlea through the round window
      A highly phase stable hand-held (HH) endoscopic system has been developed for optical coherence tomography and vibrometry. Designed to transit the ear canal to the middle ear space and peer through the round window (RW), it is capable of imaging the vibratory function of the cochlear soft tissues with subnanometer scale sensitivity. A side-looking, 9 cm long rigid endoscope with a distal diameter of 1.2 mm, was able to ...
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    10. ELHnet: a convolutional neural network for classifying cochlear endolymphatic hydrops imaged with optical coherence tomography

      ELHnet: a convolutional neural network for classifying cochlear endolymphatic hydrops imaged with optical coherence tomography
      Detection of endolymphatic hydrops is important for diagnosing Menieres disease, and can be performed non-invasively using optical coherence tomography (OCT) in animal models as well as potentially in the clinic. Here, we developed ELHnet, a convolutional neural network to classify endolymphatic hydrops in a mouse model using learned features from OCT images of mice cochleae. We trained ELHnet on 2159 training and validation images from 17 mice, using only the ...
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    11. University of Southern California Receives NIH Grant for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo.

      University of Southern California Receives NIH Grant for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo.
      University of Southern California Receives a 2017 NIH Grant $317,544 for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo. The principal investigator is John Oghalai. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. The function of the cochlea is to transduce complex sound pressure waves into electrical signals. Organ of Corti vibration is based upon a complex ...
      Read Full Article
    12. Computer-aided detection and quantification of endolymphatic hydrops within the mouse cochlea in vivo using optical coherence tomography

      Computer-aided detection and quantification of endolymphatic hydrops within the mouse cochlea in vivo using optical coherence tomography
      Diseases that cause hearing loss and/or vertigo in humans such as Menieres disease are often studied using animal models. The volume of endolymph within the inner ear varies with these diseases. Here, we used a mouse model of increased endolymph volume, endolymphatic hydrops, to develop a computer-aided objective approach to measure endolymph volume from images collected in vivo using optical coherence tomography. The displacement of Reissners membrane from its ...
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    13. Stanford University Receives NIH Grant for Cochlear Mechanics in the Mouse

      Stanford University Receives NIH Grant for Cochlear Mechanics in the Mouse
      Stanford University Receives a 2017 NIH Grant for $307,982 for Cochlear Mechanics in the Mouse. The principal investigator is John Oghalai. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. Sound pressure produces force across the mammalian cochlear partition, ultimately creating a vibratory traveling wave that propagates longitudinally up the cochlear duct. The key feature distinguishing this process from the non-mammalian ...
      Read Full Article
    14. Stanford Receives NIH Grant for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo

      Stanford Receives NIH Grant for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo
      Stanford University Receives a 2017 NIH Grant for $364,249 for Optical Coherence Tomography for 3D Measures of Cochlear Mechanics In Vivo. The principal investigator is John Oghalai. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. The function of the cochlea is to transduce complex sound pressure waves into electrical signals. Organ of Corti vibration is based upon a complex interplay ...
      Read Full Article
    15. High-speed spectral calibration by complex FIR filter in phase-sensitive optical coherence tomography

      High-speed spectral calibration by complex FIR filter in phase-sensitive optical coherence tomography
      Swept-laser sources offer a number of advantages for Phase-sensitive Optical Coherence Tomography (PhOCT). However, inter- and intra-sweep variability leads to calibration errors that adversely affect phase sensitivity. While there are several approaches to overcoming this problem, our preferred method is to simply calibrate every sweep of the laser. This approach offers high accuracy and phase stability at the expense of a substantial processing burden. In this approach, the Hilbert phase ...
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    16. Phase-sensitive optical coherence tomography-based vibrometry using a highly phase-stable akinetic swept laser source

      Phase-sensitive optical coherence tomography-based vibrometry using a highly phase-stable akinetic swept laser source
      Phase-sensitive Optical Coherence Tomography (PhOCT) is an emerging tool for in vivo investigation of the vibratory function of the intact middle and inner ear. PhOCT is able to resolve micron scale tissue morphology in three dimensions as well as measure picometer scale motion at each spatial position. Most PhOCT systems to date have relied upon the phase stability offered by spectrometer detection. On the other hand swept laser source based ...
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  2. About John S. Oghalai

    John S. Oghalai

    John S. Oghalai, MD, has been recruited to serve as the new chair of the USC Tina and Rick Caruso Department of Otolaryngology – Head and Neck Surgery, effective Aug. 1.