2000 — 2008 |
Richter, Claus-Peter Koch, Dawn |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Micromechanics of the Mammalian Cochlea @ Northwestern University
The mammalian inner ear is exceptional in that it can process sound with high sensitivity and fine frequency resolution over a wide frequency range. The underlying mechanism for this remarkable ability is the "cochlear amplifier," which operates by modifying cochlear micromechanics. Although the exact mechanisms underlying mechanical modifications are unclear, it has been shown that the tectorial membrane plays an important role. In particular, it has been proposed that the tectorial membrane provides a second resonant system in the cochlea. Experiments are proposed to explore whether the tectorial membrane is, in fact, a resonant system and to examine its role in the cochlear-amplifier. To address this problem in an innovative way, an in vitro preparation will be used, the hemicochlea, which allows study of the tectorial membrane in situ. The specific aims of this study are (1) to determine the driving point stiffness of the tectorial at several locations along the cochlea in the hemicochlea, (2) to measure the bulk stiffness of the tectorial membrane in vitro, (3) to confirm the hemicochlea measurements by in vivo experiments at two locations in the basal and the middle turn, and (4) to determine the bending stiffness of the outer hair cell stereocilia bundles. The impedance and stiffness data will allow us to better describe the role of the tectorial membrane in the cochlear-amplifier feedback loop. These experimental results will contribute to our understanding how outer-hair-cell motility and the highly nonlinear cochlear amplifier are controlled, and ultimately, how sound is processed and encoded by the inner ear. This research has broad impact because students and high school teachers will be able to participate by making stiffness measurements of the tectorial membrane in the hemicochlea and in living animals, by interpreting the mechanical impedance measurements of the tectorial membrane and in the field of micromechanics the information may prove useful in developing micromechanical transducers of sound and motion.
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2011 — 2013 |
Fiebig, Torsten Richter, Claus-Peter |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Development of a Novel Laser Instrument For Advanced Medical Applications @ Northwestern University
DESCRIPTION (provided by applicant): The main objective of this project is to develop a completely new type of laser system, which will pave the way for significant advances in a variety of clinical applications that encompass minimally invasive procedures, surgeries and endoscopies. Currently, the application of medical lasers is starkly limited by the lack of flexibility and versatility of most commercial laser systems. These systems typically emit light at a single, fixed wavelength which renders each laser suitable for a very narrow range of applications. For example, the removal of tissue via ablation requires a wavelength in the infrared spectral region, typically between 2000 and 3000 nm. The exact wavelength that is optimal for a given surgical task depends on the structural properties and water content of the tissue, Thus, having the ability to tune the wavelength across a large spectral range to optimize the incision parameters (i.e. ablation profile, collateral cell damage etc.) would be highly beneficial. In addition, to maintain good visualization during any operation is key for the effectiveness and the outcome of the procedure. Control of homeostasis and coagulation can be achieved through laser light as well, however, in a different wavelength range than ablation. Our instrument will provide a simultaneous dual wavelengths output which allows tissue cutting and the control of wound bleeding at the same time. This proposal will focus on the assembly, testing and clinical characterization of the new table-top laser instrument. Due to its all-solid-state construction, the laser instrument will be very robust, reliable, compact and portable. Glass fiber optics will be used to deliver the power to a pen-size hand piece that enables flexible delivery of the laser output to the target tissue with high-precision and unprecedented control. Alternatively, the laser power can be delivered through an endoscope (or laparoscope) to both cut and control bleeding in confined spaces. It is our vision that procedures currently being done with more traditional surgical access, may be converted to minimal access. This is especially the case where wide exposure is retained principally for the control of hemorrhage. This concern would be alleviated by the flexibility of this new laser tool. Minimal access improves patient outcomes by reducing the morbidity and complications of brain manipulation. PUBLIC HEALTH RELEVANCE (provided by applicant): The aim of this research is to design a new laser instrument for advanced medical procedures, which involve any type of tissue removal and subsequent control of wound bleeding. By combining the advantages of multiple lasers in a single compact device, surgeons and endoscopists will have the opportunity to make very precise excisions in a large variety of different tissues while simultaneously controlling wound bleeding.
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2012 — 2016 |
Richter, Claus-Peter |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Understanding the Benefits of Infrared Nerve Stimulators For Neural Interfaces @ Northwestern University At Chicago
DESCRIPTION (provided by applicant): The goal for neuroprostheses is to restore neural function to a condition having the fidelity of a healthy system. However, contemporary neural prostheses, including cochlear implants, are not able to achieve this goal. The devices use electrical current to stimulate the neurons, which spreads in the tissue and consequently does not allow stimulation of focused populations of neurons. Therefore, high fidelity stimulation is no possible. In our model system, the cochlea, it has been argued that the performance of cochlear implant users could be increased significantly if more discrete locations of neurons situated along the electrode could be stimulated simultaneously. This might be possible with devices that use focal optical radiation to stimulate neurons. Today we know that infrared neural stimulation (INS) is possible, that stimulation rates can be achieved that allow encoding of acoustic information, that the spatial selectivity in the cochlea is about five times more selective than electrical stimulation, and that single channel stimulation in chronic experiments shows no functional damage of the cochlea over at least six weeks. The five-year project proposed here is a logical progression of our previous experiments. The aims include validating that the selectivity of INS will result in a larger number of independent channels, demonstrating that a three-channel device can safely stimulate an implanted cochlea over several weeks, and showing that each channel of multichannel INS can independently encode information to be perceived by the auditory system. At the conclusion of the project period we intend to present a prototype for a multi-channel neural interface for the human, here a cochlear implant. To determine the minimum channel separation for independent stimulation, we will implant a three-channel device in deaf cats. Recordings from the inferior colliculus will be used to construct spatial tuning curves (STCs). Non-overlapping STCs indicate separation of the channels. The distance between the stimulation sources will be altered systematically until independent stimulation at neighboring stimulation sources is obtained. By varying stimulus parameters such as the repetition rate, the pulse shape, and the delay between neighboring channels, the experiments will also provide information on the temporal properties of optical stimulation. Long-term stimulation after chronic implantation of a three-channel device into a cat cochlea will determine the safety. Evoked auditory responses will be measured and will provide information on cochlear function and safety. Results will be confirmed through histology. Measurements with temperature sensitive ink will provide important information on the heat load during stimulation. At the conclusion of this project, a prototype human optical cochlear implant will be constructed based on the physical and the optical requirements.
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2019 |
Richter, Claus-Peter |
R56Activity Code Description: To provide limited interim research support based on the merit of a pending R01 application while applicant gathers additional data to revise a new or competing renewal application. This grant will underwrite highly meritorious applications that if given the opportunity to revise their application could meet IC recommended standards and would be missed opportunities if not funded. Interim funded ends when the applicant succeeds in obtaining an R01 or other competing award built on the R56 grant. These awards are not renewable. |
Understanding the Benefits of Optical Nerve Stimulators For Neural Interfaces @ Northwestern University At Chicago
Project Summary / Abstract The goal for neuroprostheses is to restore neural function to a condition having the fidelity of a healthy system. However, contemporary neural prostheses, including cochlear implants, are not able to achieve this goal. The devices use electrical current to stimulate the neurons, which spreads in the tissue and consequently does not allow stimulation of focused neuron populations. Therefore, high fidelity stimulation is not possible. In our model system, the cochlea, it has been argued that the performance of cochlear implant users could be increased significantly if more discrete non-overlapping locations of neurons situated along the electrode could be stimulated simultaneously. This might be possible with devices that use focal optical radiation to stimulate neurons. Today we know that infrared neural stimulation (INS) is possible, that stimulation rates can be achieved that allow encoding of acoustic information, that the spatial selectivity in the cochlea is more selective than electrical stimulation, and that single channel stimulation in chronic experiments shows no functional damage of the cochlea over at least six weeks. The developments proposed in this R01 are a logical progression of previous experiments. The aims include the fabrication and testing of hybrid opto-electrical arrays to be surgically inserted into a cat cochlea and showing that each channel of multichannel INS can independently encode information to be perceived by the auditory system. Recordings from the inferior colliculus will be used to construct spatial tuning curves (STCs). Non-overlapping STCs indicate separation of the channels. The stimulation pattern will be changed systematically until an optimum match is achieved between and acoustically evoked response and the response obtained from the coding strategy. Long-term stimulation after chronic implantation of a multi-channel device into a cat cochlea will determine the safety. Strategies such as combined opto-electrical stimulation or shaping the optical pulses can reduce the power required for optical stimulation and will be explored. Results will be confirmed through histology. At the conclusion of this project, a prototype human optical cochlear implant will be available for a clinical study based on the physical and the optical requirements.
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2021 |
Richter, Claus-Peter |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Opto-Electrical Cochlear Implants @ Northwestern University At Chicago
Project Summary / Abstract Our goal is to develop an optical cochlear implant (oCI) that uses photons to stimulate surviving auditory neurons in severely-to-profoundly deaf. The benefit of optical stimulation is its spatial selectivity with the potential to create significantly more independent channels to encode acoustic information and to enhance the CI users? performance in challenging listening environments and to improve music appreciation. In previous experiments we have defined the parameter space for infrared neural stimulation (INS) in diverse animal models, including the cat. To translate the method into a clinical tool, an opto-electrical cochlear implant, we have to convert the parameter space defined for the cats to the larger cochlea of the humans. In preparation of the study we have communicated with the Food and Drug Administration (FDA) and have submitted a Q- submission for a study risk assessment for the first set of the proposed tests. The purpose of this study is to show that optical and combined opto-electrical stimulation is possible in humans using optical fibers, optical fiber bundles, and a hybrid opto-electrical cochlear implant. Furthermore, the tests will also validate that INS is possible at radiation wavelengths, which are used commercially in communication and for which the technology of optical sources and waveguides is well miniaturized and matured. Most importantly, we will use a forward masking method to validate the view that optical stimulation is spatially more selective than electrical stimulation by comparing the ability of a masking stimulus to reduce the response amplitude of a probe stimulus. Test subjects will be patients with large tumors of the skull base, who require a translabyrinthine craniotomy for tumor removal. For this surgical approach the cochlea and vestibular system will be damaged and the patients will be deaf after surgery. This surgery provides an unique opportunity to test optical stimulation in the human cochlea before it is removed during the tumor resection. Important data can be gathered, which will drive the development of an implantable opto-electrical cochlear implant system by our industrial collaborators. The measurements will take no longer than 30 minutes per patient, after which all the equipment will be removed from the surgical filed and the tumor resection surgery continues.
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