Optometry and Vision Sciences - Research Publications

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Author: Ibbotson, Michael × Author: Maturana, Matias × Author: Tong, Wei × End date: 2023 × Start date: 2020 × Type: Journal Article ×

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    Preferential modulation of individual retinal ganglion cells by electrical stimulation
    Yunzab, M ; Soto-Breceda, A ; Maturana, M ; Kirkby, S ; Slattery, M ; Newgreen, A ; Meffin, H ; Kameneva, T ; Burkitt, AN ; Ibbotson, M ; Tong, W (IOP Publishing Ltd, 2022-08-01)
    Objective.Retinal prostheses have had limited success in vision restoration through electrical stimulation of surviving retinal ganglion cells (RGCs) in the degenerated retina. This is partly due to non-preferential stimulation of all RGCs near a single stimulating electrode, which include cells that conflict in their response properties and their contribution to visiual processing. Our study proposes a stimulation strategy to preferentially stimulate individual RGCs based on their temporal electrical receptive fields (tERFs).Approach.We recorded the responses of RGCs using whole-cell patch clamping and demonstrated the stimulation strategy, first using intracellular stimulation, then via extracellular stimulation.Main results. We successfully reconstructed the tERFs according to the RGC response to Gaussian white noise current stimulation. The characteristics of the tERFs were extracted and compared based on the morphological and light response types of the cells. By re-delivering stimulation trains that were composed of the tERFs obtained from different cells, we could preferentially stimulate individual RGCs as the cells showed lower activation thresholds to their own tERFs.Significance.This proposed stimulation strategy implemented in the next generation of recording and stimulating retinal prostheses may improve the quality of artificial vision.
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    Hybrid diamond/ carbon fiber microelectrodes enable multimodal electrical/chemical neural interfacing
    Hejazi, MA ; Tong, W ; Stacey, A ; Soto-Breceda, A ; Ibbotson, MR ; Yunzab, M ; Maturana, MI ; Almasi, A ; Jung, YJ ; Sun, S ; Meffin, H ; Fang, J ; Stamp, MEM ; Ganesan, K ; Fox, K ; Rifai, A ; Nadarajah, A ; Falahatdoost, S ; Prawer, S ; Apollo, NV ; Garrett, DJ (Elsevier, 2020-02-01)
    Implantable medical devices are now in regular use to treat or ameliorate medical conditions, including movement disorders, chronic pain, cardiac arrhythmias, and hearing or vision loss. Aside from offering alternatives to pharmaceuticals, one major advantage of device therapy is the potential to monitor treatment efficacy, disease progression, and perhaps begin to uncover elusive mechanisms of diseases pathology. In an ideal system, neural stimulation, neural recording, and electrochemical sensing would be conducted by the same electrode in the same anatomical region. Carbon fiber (CF) microelectrodes are the appropriate size to achieve this goal and have shown excellent performance, in vivo. Their electrochemical properties, however, are not suitable for neural stimulation and electrochemical sensing. Here, we present a method to deposit high surface area conducting diamond on CF microelectrodes. This unique hybrid microelectrode is capable of recording single-neuron action potentials, delivering effective electrical stimulation pulses, and exhibits excellent electrochemical dopamine detection. Such electrodes are needed for the next generation of miniaturized, closed-loop implants that can self-tune therapies by monitoring both electrophysiological and biochemical biomarkers.