Browsing by Author "Kameneva, Tatiana"

Now showing 1 - 6 of 6
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    Biological Considerations of Optical Interfaces for Neuromodulation
    (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2019-07) Hart, William; Kameneva, Tatiana; Wise, Andrew; Stoddart, Paul
    The success of devices such as cochlear implants and pacemakers has led to increasing interest in new applications of artificial neural interfaces, ranging from brain–computer interfaces to vagus nerve stimulators. Both the established and emerging applications of neural interfaces have highlighted the need for improvements in spatial selectivity and reduced invasiveness, which in turn has driven growing interest in optical interfaces. The delivery of light to—and collection of light from—neural tissue presents distinct challenges for optical devices. This review presents the status of optical interface technologies with a focus on biological considerations, such as biocompatibility, thermal loading, and tissue response. Attention is also paid to factors affecting the portability of optical interfaces, and issues around reliability and manufacturing that need to be considered for successful translation. Indeed, it is imperative that engineers work closely with physiologists, clinicians, and patients when developing devices for research and the clinic. Finally, emerging trends and the potential for new technologies to disrupt the field are discussed. While many engineering challenges remain to be overcome, the achievements to date suggest that optical neuromodulation techniques have significant potential to be deployed in future for a wide range of practical therapeutic applications.
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    Combined optogenetic and electrical stimulation of auditory neurons increases effective stimulation frequency—an in vitro study
    (IOP Publishing, 2020-01) Hart, William; Richardson, Rachael; Kameneva, Tatiana; Thompson, Alex; Wise, Andrew; Fallon, James; Stoddart, Paul; Needham, Karina
    OBJECTIVE: The performance of neuroprostheses, including cochlear and retinal implants, is currently constrained by the spatial resolution of electrical stimulation. Optogenetics has improved the spatial control of neurons in vivo but lacks the fast-temporal dynamics required for auditory and retinal signalling. The objective of this study is to demonstrate that combining optical and electrical stimulation in vitro could address some of the limitations associated with each of the stimulus modes when used independently. APPROACH: The response of murine auditory neurons expressing ChR2-H134 to combined optical and electrical stimulation was characterised using whole cell patch clamp electrophysiology. MAIN RESULTS: Optogenetic costimulation produces a three-fold increase in peak firing rate compared to optical stimulation alone and allows spikes to be evoked by combined subthreshold optical and electrical inputs. Subthreshold optical depolarisation also facilitated spiking in auditory neurons for periods of up to 30 ms without evidence of wide-scale Na+ inactivation. Significance These findings may contribute to the development of spatially and temporally selective optogenetic-based neuroprosthetics and complement recent developments in "fast opsins".
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    Modeling experimental recordings of vagal afferent signaling of intestinal inflammation for neuromodulation
    (IOP Publishing, 2018-08) O'Sullivan-Greene, Elma; Kameneva, Tatiana; Trevaks, David; Shafton, Anthony; Payne, Sophie; McAllen, Robin; Furness, John; Grayden, David
    Objective Artificial modulation of peripheral nerve signals (neuromodulation) by electrical stimulation is an innovation with potential to develop treatments that replace or supplement drugs. One function of the nervous system that can be exploited by neuromodulation is regulation of disease intensity. Optimal interfacing of devices with the nervous system requires suitable models of peripheral nerve systems so that closed-loop control can be utilized for therapeutic benefit. Approach We use physiological data to model afferent signaling in the vagus nerve that carries information about inflammation in the small intestine to the brain. Main results The vagal nerve signaling system is distributed and complex; however, we propose a class of reductive models using a state-space formalism that can be tuned in a patient-specific manner. Significance These models provide excellent fits to a large range of nerve recording data but are computationally simple enough for feedback control in implantable neuromodulation devices.
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    Spectral distribution of local field potential responses to electrical stimulation of the retina
    (IOP Publishing, 2016-03) Wong, Yan; Halupka, Kerry; Kameneva, Tatiana; Cloherty, Shaun; Grayden, David; Burkitt, Anthony; Meffin, Hamish; Shivdasani, Mohit
    OBJECTIVE: Different frequency bands of the local field potential (LFP) have been shown to reflect neuronal activity occurring at varying cortical scales. As such, recordings of the LFP may offer a novel way to test the efficacy of neural prostheses and allow improvement of stimulation strategies via neural feedback. Here we use LFP measurements from visual cortex to characterize neural responses to electrical stimulation of the retina. We aim to show that the LFP is a viable signal that contains sufficient information to optimize the performance of sensory neural prostheses. APPROACH: Clinically relevant electrode arrays were implanted in the suprachoroidal space of one eye in four felines. LFPs were simultaneously recorded in response to stimulation of individual electrodes using penetrating microelectrode arrays from the visual cortex. The frequency response of each electrode was extracted using multi-taper spectral analysis and the uniqueness of the responses was determined via a linear decoder. MAIN RESULTS: We found that cortical LFPs are reliably modulated by electrical stimulation of the retina and that the responses are spatially localized. We further characterized the spectral distribution of responses, with maximum information being contained in the low and high gamma bands. Finally, we found that LFP responses are unique to a large range of stimulus parameters ( approximately 40) with a maximum conveyable information rate of 6.1 bits. SIGNIFICANCE: These results show that the LFP can be used to validate responses to electrical stimulation of the retina and we provide the first steps towards using these responses to provide more efficacious stimulation strategies.
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    Spike history neural response model
    (Springer US, 2015-06) Kameneva, Tatiana; Abramain, Miganoosh; Zarelli, Daniele; Nesic, Dragan; Burkitt, Anthony; Meffin, Hamish; Grayden, David
    There is a potential for improved efficacy of neural stimulation if stimulation levels can be modified dynamically based on the responses of neural tissue in real time. A neural model is developed that describes the response of neurons to electrical stimulation and that is suitable for feedback control neuroprosthetic stimulation. Experimental data from NZ white rabbit retinae is used with a data-driven technique to model neural dynamics. The linear-nonlinear approach is adapted to incorporate spike history and to predict the neural response of ganglion cells to electrical stimulation. To validate the fitness of the model, the penalty term is calculated based on the time difference between each simulated spike and the closest spike in time in the experimentally recorded train. The proposed model is able to robustly predict experimentally observed spike trains.
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    Thermal damage threshold of neurons during infrared stimulation
    (Biomedical Optics Express, 2020-04) Brown, William; Needham, Karina; Begeng, James; Thompson, Alexander; Nayagam, Bryony; Kameneva, Tatiana; Stoddart, Paul
    In infrared neural stimulation (INS), laser-evoked thermal transients are used to generate small depolarising currents in neurons. The laser exposure poses a moderate risk of thermal damage to the target neuron. Indeed, exogenous methods of neural stimulation often place the target neurons under stressful non-physiological conditions, which can hinder ordinary neuronal function and hasten cell death. Therefore, quantifying the exposure-dependent probability of neuronal damage is essential for identifying safe operating limits of INS and other interventions for therapeutic and prosthetic use. Using patch-clamp recordings in isolated spiral ganglion neurons, we describe a method for determining the dose-dependent damage probabilities of individual neurons in response to both acute and cumulative infrared exposure parameters based on changes in injection current. The results identify a local thermal damage threshold at approximately 60 °C, which is in keeping with previous literature and supports the claim that damage during INS is a purely thermal phenomenon. In principle this method can be applied to any potentially injurious stimuli, allowing for the calculation of a wide range of dose-dependent neural damage probabilities. Unlike histological analyses, the technique is well-suited to quantifying gradual neuronal damage, and critical threshold behaviour is not required.