94 results found
Luo J, Nikolic K, Evans BD, et al., 2017, Optogenetics in Silicon: A Neural Processor for Predicting Optically Active Neural Networks, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 11, Pages: 15-27, ISSN: 1932-4545
Troiani F, Nikolic K, Constandinou TG, 2017, Optical coherence tomography for compound action potential detection: a computational study, SPIE/OSA European Conferences on Biomedical Optics (ECBO), Pages: 1-3
The feasibility of using time domain optical coherence tomography (TD-OCT)to detect compound action potential in a peripheral nerve and the setup characteristics, are studied through the use of finite-difference time-domain (FDTD) technique.
Evans BD, Jarvis S, Schultz SR, et al., 2016, PyRhO: A Multiscale Optogenetics Simulation Platform, FRONTIERS IN NEUROINFORMATICS, Vol: 10, ISSN: 1662-5196
Evans BD, Nikolic K, 2016, From Bytes to Insights with Modelling as a Service A new paradigm for computational modelling illustrated with PyRhO, 12th IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 316-319, ISSN: 2163-4025
Gaspar N, Sondhi A, Evans B, et al., 2016, A Low-power Neuromorphic System for Retinal Implants and Sensory Substitution, 12th IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 78-81, ISSN: 2163-4025
Katz ML, Viney TJ, Nikolic K, 2016, Receptive Field Vectors of Genetically-Identified Retinal Ganglion Cells Reveal Cell-Type-Dependent Visual Functions, PLOS ONE, Vol: 11, ISSN: 1932-6203
Nikolic K, Evans B, 2016, Identifying optimal feature transforms for classification and prediction in biological systems: recovering receptive field vectors from sparse recordings, International Conference on Machine Learning (ICML), Workshop on Computational Biology
With biological systems it is often hard to adequately sample the entire input space. With sensoryneural systems this can be a particularly acute problem, with very high dimensional natural inputs andtypically sparse spiking outputs. Here we present an information theory based approach to analysespiking data of an early sensory pathway, demonstrated on retinal ganglion cells (RGC) responding tonatural visual scene stimuli (Katz et al., 2016). We used a non-parametric technique based on theconcept of mutual information (MI), in particular, Quadratic Mutual Information (QMI). The QMIallowed us to very efficiently search the high dimensional space formed by the visual input for a muchsmaller dimensional subspace of Receptive Field Vectors (RFV). RFVs give the most informationabout the response of the cell to natural stimuli. This approach allows us to identify the RFVs far moreefficiently using limited data as we can search the complete stimulus space for multiple vectorssimultaneously. The RFVs were also used to predict the RGCs’ responses to any natural stimuli.Another suitable area of application of this algorithm is in diagnostic inference. Currently we areadapting the method to be used for identifying the cancer markers in the volatile organic compoundspresent in exhaled breath. Once the maximally informative features are established they can be usedfor diagnostic predictions on new breath samples. Preliminary results of the breathomics analysis willbe discussed at the conference.There are several other potential applications such as multiclass categorisation for bacterial strainsusing ISFET arrays for DNA sequencing. This algorithm can be part of a rapid point-of-care device foridentifying the specific infectious agents and recommending appropriate antibiotics.Here we will focus on presenting the algorithm using the example of RFVs of RGCs.
Troiani F, Nikolic K, Constandinou TG, 2016, Optical coherence tomography for detection of compound action potential in Xenopus Laevis sciatic nerve, Conference on Clinical and Translational Neurophotonics; Neural Imaging and Sensing; and Optogenetics and Optical Manipulation, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Gaspar N, Sondhi A, Evans B, et al., 2015, Live Demonstration: A Low-power Neuromorphic System for Retinal Implants and Sensory Substitution, 11th IEEE Annual Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 178-178, ISSN: 2163-4025
Leow HS, Nikolic K, 2015, Machine Vision Using Combined Frame-based and Event-based Vision Sensor, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 706-709, ISSN: 0271-4302
Rapeaux A, Nikolic K, Williams I, et al., 2015, Fiber Size-Selective Stimulation using Action Potential Filtering for a Peripheral Nerve Interface: A Simulation Study, 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Publisher: IEEE, Pages: 3411-3414, ISSN: 1557-170X
Wadehn F, Schieban K, Nikolic K, 2015, Motion Sensitivity Analysis of Retinal Ganglion Cells in Mouse Retina using Natural Visual Stimuli, 2015 37TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), Pages: 1658-1662, ISSN: 1557-170X
Jarvis SJ, Nikolic K, Schultz SR, 2014, Optical coactivation in cortical cells: reprogramming the excitation-inhibition balancing act to control neuronal gain in abstract and detailed models, BMC Neuroscience, Vol: 15, Pages: F1-F1, ISSN: 1471-2202
Neuromodulation has wide ranging potential applications in replacing impaired neural function (prosthetics), as a novel form of medical treatment (therapy), and as a tool for investigating neurons and neural function (research). Voltage and current controlled electrical neural stimulation (ENS) are methods that have already been widely applied in both neuroscience and clinical practice for neuroprosthetics. However, there are numerous alternative methods of stimulating or inhibiting neurons. This paper reviews the state-of-the-art in ENS as well as alternative neuromodulation techniques-presenting the operational concepts, technical implementation and limitations-in order to inform system design choices.
Reverter F, Prodromakis T, Liu Y, et al., 2014, Design Considerations for a CMOS Lab-on-Chip Microheater Array to Facilitate the in vitro Thermal Stimulation of Neurons, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 630-633, ISSN: 0271-4302
Grossman N, Simiaki V, Martinet C, et al., 2013, The spatial pattern of light determines the kinetics and modulates backpropagation of optogenetic action potentials, JOURNAL OF COMPUTATIONAL NEUROSCIENCE, Vol: 34, Pages: 477-488, ISSN: 0929-5313
Jarvis S, Nikolic K, Grossman N, et al., 2013, Controlling the neuronal balancing act: optical coactivation of excitation and inhibition in neuronal subdomains., Pages: P348-P348
Nikolic K, Jarvis S, Grossman N, et al., 2013, Computational Models of Optogenetic Tools for Controlling Neural Circuits with Light, 35th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 5934-5937, ISSN: 1557-170X
Nikolic K, Loizu J, 2013, Drosophila Photo-transduction Simulator, Journal of Open Research Software, Vol: 1, ISSN: 2049-9647
Katz ML, Lutterbeck C, Nikolic K, 2012, An Implementation of Magnocellular Pathways in Event-Based Retinomorphic Systems, IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 17-20, ISSN: 2163-4025
Katz ML, Nikolic K, Delbruck T, 2012, Behavioural Emulation of Event-Based Vision Sensors, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 737-740, ISSN: 0271-4302
Katz ML, Nikolic K, Delbruck T, 2012, Live Demonstration: Behavioural Emulation of Event-Based Vision Sensorsh, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 736-736, ISSN: 0271-4302
Mou Z, Triantis IF, Woods VM, et al., 2012, A Simulation Study of the Combined Thermoelectric Extracellular Stimulation of the Sciatic Nerve of the Xenopus Laevis: The Localized Transient Heat Block, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 59, Pages: 1758-1769, ISSN: 0018-9294
Grossman N, Degenaar P, Nikolic K, 2011, Spike engineering with Channelrhodopsin-2, Pages: e27-e27, ISSN: 0304-3940
Grossman N, Nikolic K, Grubb M, et al., 2011, High-frequency limit of neural stimulation with ChR2, Conf Proc IEEE Eng Med Biol Soc, Pages: 4167-4170, ISSN: 1557-170X
Optogenetic technology based on light activation of genetically targeted single component opsins such as Channelrhodopsin-2 (ChR2) has been changing the way neuroscience research is conducted. This technology is becoming increasingly important for neural engineering as well. The efficiency of neural stimulation with ChR2 drops at high frequencies, often before the natural limit of the neuron is reached. This study aims to investigate the underlying mechanisms that limit the efficiency of the stimulation at high frequencies. The study analyzes the dynamics of the spikes induced by ChR2 in comparison to control stimulations using patch clamp current injection. It shows that the stimulation dynamics is limited by two mechanisms: 1) a frequency independent reduction in the conductance-to-irradiance yield due to the ChR2 light adaptation process and 2) a frequency dependent reduction in the conductance-to-current yield due to a decrease in membrane re-polarization level between spikes that weakens the ionic driving force. The effect of the first mechanism can be minimized by using ChR2 mutants with lower irradiance threshold. In contrast the effect of the second mechanism is fundamentally limited by the rate the native ion channels re-polarize the membrane potential.
Grossman N, Nikolic K, Toumazou C, et al., 2011, Modeling Study of the Light Stimulation of a Neuron Cell With Channelrhodopsin-2 Mutants, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 58, Pages: 1742-1751, ISSN: 0018-9294
Nikolic K, Constandinou TG, Toumazou C, 2011, Method and Apparatus for Optically Outputting Information from a Semiconductor Device
A method of optically outputting information (e.g. digital data) from a semiconductor device, the method comprising: providing a semiconductor device having a semiconducting p-n junction, the p-n junction having a region of reduced free charge carrier density; applying an electrical signal to modulate the extent of the said region, the electrical signal being representative of the information to be outputted; arranging incident light to pass through at least part of the said region, such that the light is at least partially absorbed in dependence upon the modulated extent of the said region, thereby producing intensity-modulated output light; and detecting the intensity of the output light and thereby determining the outputted information. Also provided is an electro-optical assembly, a package module for mounting a semiconductor device on a printed circuit board, and an integrated circuit chip.
Nikolic K, San Segundo Bello D, Delbruck T, et al., 2011, High-sensitivity silicon retina for robotics and prosthetics, SPIE Newsroom
Nikolic K, Serb A, Constandinou TG, 2011, An Optical Modulator in Unmodified, Commercially Available CMOS Technology, IEEE PHOTONICS TECHNOLOGY LETTERS, Vol: 23, Pages: 1115-1117, ISSN: 1041-1135
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