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Author: David López de la Morena
Publisher:
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Languages : en
Pages : 0
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Optogenetic stimulation of the auditory nerve is a promising alternative to restore hearing. Since light can be focused on the target tissue, the optical cochlear implant (oCI) might support a major improvement in frequency resolution compared to current electrical CIs (eCIs). However, the slow kinetics of the first generation of optogenetic actuators hindered controlling the fast-spiking spiral ganglion neurons (SGNs) with high temporal fidelity. In this work, I evaluated the ability of two fast-gating opsins (Chronos-ES/TS and f-Chrimson) to improve temporal fidelity of optogenetic stimul...
Author: David López de la Morena
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Optogenetic stimulation of the auditory nerve is a promising alternative to restore hearing. Since light can be focused on the target tissue, the optical cochlear implant (oCI) might support a major improvement in frequency resolution compared to current electrical CIs (eCIs). However, the slow kinetics of the first generation of optogenetic actuators hindered controlling the fast-spiking spiral ganglion neurons (SGNs) with high temporal fidelity. In this work, I evaluated the ability of two fast-gating opsins (Chronos-ES/TS and f-Chrimson) to improve temporal fidelity of optogenetic stimul...
Author: Ajmal A. Azees
Publisher:
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Category :
Languages : en
Pages : 0
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Abstract: For individuals with severe to profound hearing loss resulting from irreversibly damaged hair cells, cochlear implants can be used to restore hearing by delivering electrical stimulation directly to the spiral ganglion neurons. However, current spread lowers the spatial resolution of neural activation. Since light can be easily confined, optogenetics is a technique that has the potential to improve the precision of neural activation, whereby visible light is used to stimulate neurons that are modified with light-sensitive opsins. This study compares the spread of neural activity across the inferior colliculus of the auditory midbrain during electrical and optical stimulation in the cochlea of acutely deafened mice with opsin-modified spiral ganglion neurons (H134R variant of the channelrhodopsin-2). Monopolar electrical stimulation was delivered via each of four 0.2 mm wide platinum electrode rings at 0.6 mm centre-to-centre spacing, whereas 453 nm wavelength light was delivered via each of five 0.22 × 0.27 mm micro-light emitting diodes (LEDs) at 0.52 mm centre-to-centre spacing. Channel interactions were also quantified by threshold changes during simultaneous stimulation by pairs of electrodes or micro-LEDs at different distances between the electrodes (0.6, 1.2 and 1.8 mm) or micro-LEDs (0.52, 1.04, 1.56 and 2.08 mm). The spread of activation resulting from single channel optical stimulation was approximately half that of monopolar electrical stimulation as measured at two levels of discrimination above threshold (p
Author: Daniel Keppeler
Publisher:
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Category :
Languages : en
Pages : 0
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In case of profound sensorineural hearing loss and deafness, cochlear implants (CIs) partially restore hearing and provide missing auditory information to the brain. Electrical stimulation of the spiral ganglion neurons (SGNs) enables speech understanding in the majority of the approximately 500,000 CI users. However, the utility of current clinical CIs is limited by their wide current spread resulting in limited coding of spectral information. As light can be better confined in space, optical CIs (oCIs) promise lower spread of excitation in the cochlea which might enable better speech comp...
Author: Michaël Charles Chalom Slama
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Languages : en
Pages :
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Auditory brainstem implants (ABIs) help provide some hearing to patients with non-functional auditory nerves or ossified cochleae. ABIs bypass the cochlea and electrically stimulate the surface of the cochlear nucleus (CN). Performance of ABI users in speech reception tasks is usually poor. One of the possible explanations for their limited performance is the poor spatial selectivity of electrical stimulation that limits frequency resolution. In this project, we show that spatial selectivity of electrical stimulation was usually poor in a rat model, as stimulation in one point of the CN surface led to activation of most of the tonotopic axis in the inferior colliculus (IC). These results point to the need for new stimulation strategies to improve frequency representation in the central auditory system of ABI users. An optogenetic approach is promising, as light may be more easily focused than electrical current. To test the feasibility of optogenetic control of the CN, we transfected the CN of mice with AAV2/8-Channelrhodopsin-2 (ChR2). We found a significant increase in activity in IC and primary auditory cortex during blue light stimulation in mice with successful ChR2 expression in the CN. Overall, these results lay the groundwork for a new generation opto-electronic ABI.
Author:
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Languages : en
Pages : 210
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Afferent synapses between inner hair cells (IHCs) and spiral ganglion neurons in the cochlea translate sound information into a discrete spike code, providing us the opportunity to directly observe the output of the cochlea. The availability of mutant strains with genetic hearing impairment makes the mouse a valuable species to investigate the molecular mechanisms of cochlear function. In this thesis, mouse was used as a model species to study cochlear sound encoding by recording single unit activities from auditory nerve fibers (ANFs) in vivo. First, developmental changes of ANF responses ...
Author: Alexander Christopher Thompson
Publisher: Swinburne University of Technology
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 241
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Book Description
The cochlear implant is a successful bionic device, restoring hearing to hundreds of thousands of patients worldwide. Despite its success, present devices are limited by the electrical interface with neurons. This thesis studied the ability of infrared light to stimulate the nerves of the cochlea. Experimental work was unable to replicate previously published results and suggests that those reports may be an acoustic artefact. However, modelling of light transport in tissue confirmed the ability of light to improve spatial localisation of stimulation, showing the potential of other optical stimulation techniques
Author: Carlos Javier Duque Afonso
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Category :
Languages : en
Pages :
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Book Description
Five per cent of the world population suffers nowadays from some kind of disabling hearing impairment, and 90% out of them is due to a defective functioning of the first step in the transduction of the soundwave into a neural code: the organ of Corti and the spiral ganglion neurons. The development of the most successful neuroprosthetic device, the cochlear implant, has allowed patients to accomplish fair speech comprehension, but has failed in providing speech comprehension in noisy environments, good frequency discrimination and music and prosody appreciation. The most prominent limitatio...
Author: Anupriya Thirumalai
Publisher:
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Languages : en
Pages : 0
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Book Description
Utilizing optogenetic stimulation to target type I spiral ganglion neurons (SGNs) could promise an alternative to the currently employed electrical stimulation by current cochlear implants (CIs). Given light's spatial confinement capabilities, the future optical cochlear implant (oCI) holds the promise of substantially increasing independently perceived stimulation channels. To date, the optogenetic modification of adult SGNs was performed by injection of a viral vector directly into the modiolus. However, this poses some challenges in achieving efficient SGN transduction, such that only a ...
Author: Alexander Dieter
Publisher:
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Category :
Languages : en
Pages : 0
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Cochlear implants (CIs) constitute the interface between the sound-deprived brain of patients suffering from sensorineural hearing loss and the auditory scene surrounding them. By electrically stimulating the auditory nerve (AN), CIs mimic coding principles of the cochlea and provide the user with auditory information, enabling speech comprehension in half a million implantees. Unfortunately, current is hard to steer in the cochlear fluids, limiting the spatial selectivity and thus the spectral resolution of electrical hearing restoration. As light can be conveniently confined in space, opt ...
Author: Peter Hegemann
Publisher: Walter de Gruyter
ISBN: 3110270722
Category : Science
Languages : en
Pages : 240
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Book Description
Optogenetics combines genetic engineering with optics to observe and control the function of cells using light, with clinical implications for restoration of vision and treatment of neurological diseases. As a new discipline much of the basic science and methods are currently under investigation and active development, thus there is a strong need for introductory literature in this field. This graduate level textbook provides an overview of the field of optogenetics in 5 concise chapters: Optogenetic tools, Applications in cellular systems, Mapping neuronal networks, Clinical applications and Restoration of vision and hearing. The concept and content was developed with top international researchers and students at a prestigious Dahlem Conference workshop.
