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Edward F. Chang - One of the best experts on this subject based on the ideXlab platform.

  • seizure localization by chronic ambulatory electrocorticography
    Clinical Neurophysiology Practice, 2018
    Co-Authors: Alvin Y Chan, Robert C. Knowlton, Edward F. Chang
    Abstract:

    Abstract Aims To present two patients with medically-refractory focal epilepsy who, following non-diagnostic intracranial monitoring studies, had seizures localized by chronic ambulatory electrocorticography with an implanted neurostimulation device. Methods Case reports with clinical details and electrocorticograms showing seizures. Results Using electrodes placed at the suspected seizure onset zones, the Neurostimulator recorded seizures in both patients at long intervals following implantation (49 days and 7.5 months). Conclusions Chronic ambulatory electrocorticography can provide valuable diagnostic information when there is a narrow hypothesis about seizure localization, though there are important caveats related to limited spatial sampling.

  • Seizure localization by chronic ambulatory electrocorticography
    'Elsevier BV', 2018
    Co-Authors: Alvin Y Chan, Robert C. Knowlton, Edward F. Chang, Vikram R. Rao
    Abstract:

    Aims: To present two patients with medically-refractory focal epilepsy who, following non-diagnostic intracranial monitoring studies, had seizures localized by chronic ambulatory electrocorticography with an implanted neurostimulation device. Methods: Case reports with clinical details and electrocorticograms showing seizures. Results: Using electrodes placed at the suspected seizure onset zones, the Neurostimulator recorded seizures in both patients at long intervals following implantation (49 days and 7.5 months). Conclusions: Chronic ambulatory electrocorticography can provide valuable diagnostic information when there is a narrow hypothesis about seizure localization, though there are important caveats related to limited spatial sampling. Keywords: Epilepsy, RNS System, Chronic electrocorticography, Seizure localizatio

Dong Song - One of the best experts on this subject based on the ideXlab platform.

  • Neurostimulator for hippocampal memory prosthesis
    2021
    Co-Authors: Sahar Elyahoodayan, Wenxuan Jiang, Dong Song
    Abstract:

    In this chapter, we discuss the design, fabrication, and evaluation of a Neurostimulator for generating neural code–based electrical stimulation pulses. We show that, through multiplexing, this system can deliver constant current biphasic pulses, with arbitrary temporal patterns and pulse parameters to 32 electrodes using one pulse generator. Furthermore, a stimulus artifact suppression component is integrated with commercial amplifiers for recording short latency neural response to stimulation for feedback control. The key of this feature is to use CMOS switches to disconnect electrodes from recording amplifiers during stimulation, while shorting the recording system to ground through another CMOS switch to suppress ringing in the recording system. It is crucial to pay close attention to the timing of the switches used to block and suppress the stimulus artifact as it should be determined by the electrochemical properties of the electrode. Furthermore, the timing and stimulus magnitude of each pulse depends on the application and should be controlled by inputs from an external source that takes feedback commands from neural response from the region of stimulation. In this chapter, the reader will learn how to implement this system with low-power and compact packaged microchips to constitute an effective, cost-efficient, and miniaturized Neurostimulator. The reader will then learn how to evaluate the design in phantom preparations and then in rat hippocampus. This Neurostimulator design is desirable in a variety of neural interface applications, particularly hippocampal memory prosthesis aiming to restore cognitive functions by reinstating neural code transmissions in the brain.

  • A Multi-Channel Asynchronous Neurostimulator With Artifact Suppression for Neural Code-Based Stimulations
    Frontiers in neuroscience, 2019
    Co-Authors: Sahar Elyahoodayan, Wenxuan Jiang, Dong Song
    Abstract:

    A novel Neurostimulator for generating neural code-based, precise, asynchronous electrical stimulation pulses is designed, fabricated, and characterized. Through multiplexing, this system can deliver constant current biphasic pulses, with arbitrary temporal patterns, and pulse parameters to 32 electrodes using one pulse generator. The design also features a stimulus artifact suppression (SAS) technique that can be integrated with commercial amplifiers. Using an array of CMOS switches, electrodes are disconnected from recording amplifiers during stimulation, while the input of the recording system is shorted to ground through another CMOS switch to suppress ringing in the recording system. The timing of the switches used to block and suppress the stimulus artifact are crucial and are determined by the electrochemical properties of the electrode. This system allows stimulation and recording from the same electrodes to monitor local field potentials with short latencies from the region of stimulation for achieving feedback control of neural stimulation. In this way, timing between each pulse is controlled by inputs from an external source and stimulus magnitude is controlled by feed-back from neural response from the stimulated tissue. The system was implemented with low-power and compact packaged microchips to constitute an effective, cost-efficient, and miniaturized Neurostimulator. The device has been first evaluated in phantom preparations and then tested in hippocampi of behaving rats. Benchtop results demonstrate the capability of the stimulator to generate arbitrary spatio-temporal pattern of stimulation pulses dictated by random number generators (RNGs) to control magnitude and timing between each individual biphasic pulse. In vivo results show that evoked potentials elicited by the Neurostimulator can be recorded ∼2 ms after the termination of stimulus pulses from the same electrodes where stimulation pulses are delivered, whereas commercial amplifiers without such an artifact suppression typically result in tens to hundreds of milliseconds recovery period. This Neurostimulator design is desirable in a variety of neural interface applications, particularly hippocampal memory prosthesis aiming to restore cognitive functions by reinstating neural code transmissions in the brain.

  • A Closed-Loop Multi-Channel Asynchronous Neurostimulator to Mimic Neural Code for Cognitive Prosthesis.
    Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Inte, 2018
    Co-Authors: Sahar Elyahoodayan, Theodore W Berger, Dong Song
    Abstract:

    We describe a novel hardware and embedded system design of a closed loop Neurostimulator for generating precise neural code-like, multi-channel, asynchronous electrical stimulation pulses. Such stimulator will be used as the output unit of the cortical prosthesis that aims to restore cognitive functions by reinstating the neural signal transmission.

John C Sutcliffe - One of the best experts on this subject based on the ideXlab platform.

Roman Genov - One of the best experts on this subject based on the ideXlab platform.

  • closed loop Neurostimulators a survey and a seizure predicting design example for intractable epilepsy treatment
    IEEE Transactions on Biomedical Circuits and Systems, 2017
    Co-Authors: Hossein Kassiri, Sana Tonekaboni, Tariqus M Salam, Nima Soltani, Karim Abdelhalim, Jose Luis Perez Velazquez, Roman Genov
    Abstract:

    First, existing commercially available open-loop and closed-loop implantable Neurostimulators are reviewed and compared in terms of their targeted application, physical size, system-level features, and performance as a medical device. Next, signal processing algorithms as the primary strength point of the closed-loop Neurostimulators are reviewed, and various design and implementation requirements and trade-offs are discussed in details along with quantitative examples. The review results in a set of guidelines for algorithm selection and evaluation. Second, the implementation of an inductively-powered seizure-predicting microsystem for monitoring and treatment of intractable epilepsy is presented. The miniaturized system is comprised of two miniboards and a power receiver coil. The first board hosts a 24-channel Neurostimulator system on chip [15] fabricated in a $0.13\;\mu \text{m}$ CMOS technology and performs neural recording, on-chip digital signal processing, and electrical stimulation. The second board communicates recorded brain signals as well as signal processing results wirelessly. The multilayer flexible coil receives inductively-transmitted power. The system is sized at 2 $\times$ 2 $\times$ 0.7 $\text{cm}^3$ and weighs 6 g. The approach is validated in the control of chronic seizures in vivo in freely moving rats.

  • an impedance tracking battery less arbitrary waveform Neurostimulator with load adaptive 20v voltage compliance
    European Solid-State Circuits Conference, 2016
    Co-Authors: Hossein Kassiri, Nima Soltani, Gairik Dutta, Chang Liu, Roman Genov
    Abstract:

    A 4-channel wireless and battery-less Neurostimulator with impedance-tracking power-adaptive voltage compliance is presented. The device houses a 10 mm2 0.35µm HV-CMOS SoC (system on a chip) that performs current-mode arbitrary-waveform stimulation with voltage compliance of up to 20 V. An on-chip mixed-signal controller together with a 3-bit charge-pump maintain supply voltage at its minimum required value, resulting in up to 68.5% saving in power. An 8-bit current DAC is implemented in each channel, which together with adjustable supply voltage yield a current range from 23 µA to 95 mA (100Ω load). The device receives both power and configuration commands wirelessly using a near-field inductive link. The Neurostimulator SoC is wire-bonded on a 2×2 cm2 PCB. Additional rigid and flexible PCBs of the same size provide wireless command and power interface. The 3-board 2×2×0.7 cm3 stacked system weighs 6 grams.

  • battery less modular responsive Neurostimulator for prediction and abortion of epileptic seizures
    International Symposium on Circuits and Systems, 2016
    Co-Authors: Hossein Kassiri, Tariqus M Salam, Nima Soltani, Jose Luis Perez Velazquez, Roman Genov
    Abstract:

    An inductively-powered implantable microsystem for monitoring and treatment of intractable epilepsy is presented. The miniaturized system is comprised of two mini-boards and a power receiver coil. The first board hosts a 24-channel Neurostimulator SoC developed in a 0.13μm CMOS technology and performs neural recording, electrical stimulation and on-chip digit l signal processing. The second board communicates recorded brain signals as well as signal processing results wirelessly, and generates different supply and bias voltages for the Neurostimulator SoC and other external components. The multi-layer flexible coil receives inductively-transmitted power and sends it to the second board for power management. The system is sized at 2 × 2 × 0.7 cm3, weighs 6 grams, and is validated in control of chronic seizures in vivo in freely-moving rats.

  • inductively powered direct coupled 64 channel chopper stabilized epilepsy responsive Neurostimulator with digital offset cancellation and tri band radio
    European Solid-State Circuits Conference, 2014
    Co-Authors: Hossein Kassiri, Arezu Bagheri, Tariqus M Salam, Nima Soltani, Karim Abdelhalim, Jose Luis Perez Velazquez, Hamed Mazhab Jafari, Roman Genov
    Abstract:

    An inductively powered 0.13µm CMOS Neurostimulator SoC for intractable epilepsy treatment is presented. Digital offset cancellation yields a compact 0.018mm2 DC-coupled neural recording front-end. Input chopper stabilization is performed on all 64 channels resulting in a 4.2µVrms input-referred noise. A tri-band FSK/UWB radio provides a versatile transcutaneous interface. The inductive powering system includes a 20mm × 20mm 8-layer flexible receiver coil with 40% power transfer efficiency. In-vivo chronic epilepsy treatment experimental results show an average sensitivity and specificity of seizure detection of 87% and 95%, respectively, with over 76% of all seizures aborted.

  • Massively-Parallel Neuromonitoring and Neurostimulation Rodent Headset With Nanotextured Flexible Microelectrodes
    IEEE transactions on biomedical circuits and systems, 2013
    Co-Authors: Arezu Bagheri, S. R. I. Gabran, Muhammad Tariqus Salam, J. L. Perez Velazquez, Raafat R. Mansour, Magdy M. A. Salama, Roman Genov
    Abstract:

    We present a compact wireless headset for simultaneous multi-site neuromonitoring and neurostimulation in the rodent brain. The system comprises flexible-shaft microelectrodes, neural amplifiers, Neurostimulators, a digital time-division multiplexer (TDM), a micro-controller and a ZigBee wireless transceiver. The system is built by parallelizing up to four 0.35 μm CMOS integrated circuits (each having 256 neural amplifiers and 64 Neurostimulators) to provide a total maximum of 1024 neural amplifiers and 256 Neurostimulators. Each bipolar neural amplifier features 54 dB-72 dB adjustable gain, 1 Hz-5 kHz adjustable bandwidth with an input-referred noise of 7.99 μVrms and dissipates 12.9 μW. Each current-mode bipolar Neurostimulator generates programmable arbitrary-waveform biphasic current in the range of 20-250 μA and dissipates 2.6 μW in the stand-by mode. Reconfigurability is provided by stacking a set of dedicated mini-PCBs that share a common signaling bus within as small as 22×30×15 mm3 volume. The system features flexible polyimide-based microelectrode array design that is not brittle and increases pad packing density. Pad nanotexturing by electrodeposition reduces the electrode-tissue interface impedance from an average of 2 MΩ to 30 kΩ at 100 Hz. The rodent headset and the microelectrode array have been experimentally validated in vivo in freely moving rats for two months. We demonstrate 92.8 percent seizure rate reduction by responsive neurostimulation in an acute epilepsy rat model.

Dominique Grimaud - One of the best experts on this subject based on the ideXlab platform.