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Sample records for optical neural recording

  1. Multiplexed neural recording along a single optical fiber via optical reflectometry

    Science.gov (United States)

    Rodriques, Samuel G.; Marblestone, Adam H.; Scholvin, Jorg; Dapello, Joel; Sarkar, Deblina; Mankin, Max; Gao, Ruixuan; Wood, Lowell; Boyden, Edward S.

    2016-05-01

    We introduce the design and theoretical analysis of a fiber-optic architecture for neural recording without contrast agents, which transduces neural electrical signals into a multiplexed optical readout. Our sensor design is inspired by electro-optic modulators, which modulate the refractive index of a waveguide by applying a voltage across an electro-optic core material. We estimate that this design would allow recording of the activities of individual neurons located at points along a 10-cm length of optical fiber with 40-μm axial resolution and sensitivity down to 100 μV using commercially available optical reflectometers as readout devices. Neural recording sites detect a potential difference against a reference and apply this potential to a capacitor. The waveguide serves as one of the plates of the capacitor, so charge accumulation across the capacitor results in an optical effect. A key concept of the design is that the sensitivity can be improved by increasing the capacitance. To maximize the capacitance, we utilize a microscopic layer of material with high relative permittivity. If suitable materials can be found-possessing high capacitance per unit area as well as favorable properties with respect to toxicity, optical attenuation, ohmic junctions, and surface capacitance-then such sensing fibers could, in principle, be scaled down to few-micron cross-sections for minimally invasive neural interfacing. We study these material requirements and propose potential material choices. Custom-designed multimaterial optical fibers, probed using a reflectometric readout, may, therefore, provide a powerful platform for neural sensing.

  2. In−Vitro and In−Vivo Noise Analysis for Optical Neural Recording

    Science.gov (United States)

    Foust, Amanda J.; Schei, Jennifer L.; Rojas, Manuel J.; Rector, David M.

    2008-01-01

    Laser diodes (LD) are commonly used for optical neural recordings in chronically recorded animals and humans, primarily due to their brightness and small size. However, noise introduced by LDs may counteract the benefits of brightness when compared to low−noise light emitting diodes (LEDs). To understand noise sources in optical recordings, we systematically compared instrument and physiological noise profiles in two recording paradigms. A better understanding of noise sources will help improve optical recordings and make them more practical with fewer averages. We stimulated lobster nerves and rat cortex, then compared the root mean square (RMS) noise and signal−to−noise ratios (SNRs) of data obtained with LED, superluminescent diode (SLD) and LD illumination for different numbers of averages. The LED data exhibited significantly higher SNRs in fewer averages than LD data in all recordings. In the absence of tissue, LED noise increased linearly with intensity, while LD noise increased sharply in the transition to lasing and settled to noise levels significantly higher than the LED’s, suggesting that speckle noise contributed to the LD’s higher noise and lower SNRs. Our data recommend low coherence and portable light sources for in−vivo chronic neural recording applications. PMID:19021365

  3. In vitro and in vivo noise analysis for optical neural recording.

    Science.gov (United States)

    Foust, Amanda J; Schei, Jennifer L; Rojas, Manuel J; Rector, David M

    2008-01-01

    Laser diodes (LD) are commonly used for optical neural recordings in chronically recorded animals and humans, primarily due to their brightness and small size. However, noise introduced by LDs may counteract the benefits of brightness when compared to low-noise light-emitting diodes (LEDs). To understand noise sources in optical recordings, we systematically compared instrument and physiological noise profiles in two recording paradigms. A better understanding of noise sources can help improve optical recordings and make them more practical with fewer averages. We stimulated lobster nerves and a rat cortex, then compared the root mean square (RMS) noise and signal-to-noise ratios (SNRs) of data obtained with LED, superluminescent diode (SLD), and LD illumination for different numbers of averages. The LED data exhibited significantly higher SNRs in fewer averages than LD data in all recordings. In the absence of tissue, LED noise increased linearly with intensity, while LD noise increased sharply in the transition to lasing and settled to noise levels significantly higher than the LED's, suggesting that speckle noise contributed to the LD's higher noise and lower SNRs. Our data recommend low coherence and portable light sources for in vivo chronic neural recording applications.

  4. Circular polarization intrinsic optical signal recording of stimulus-evoked neural activity.

    Science.gov (United States)

    Lu, Rong-Wen; Zhang, Qiu-Xiang; Yao, Xin-Cheng

    2011-05-15

    Linear polarization intrinsic optical signal (LP-IOS) measurement can provide sensitive detection of neural activities in stimulus-activated neural tissues. However, the LP-IOS magnitude and signal-to-noise ratio (SNR) are highly correlated with the nerve orientation relative to the polarization plane of the incident light. Because of the complexity of orientation dependency, LP-IOS optimization and outcome interpretation are time consuming and complicated. In this study, we demonstrate the feasibility of circular polarization intrinsic optical signal (CP-IOS) measurement. Our theoretical modeling and experimental investigation indicate that CP-IOS magnitude and SNR are independent from the nerve orientation. Therefore, CP-IOS promises a practical method for polarization IOS imaging of complex neural systems.

  5. Neural stimulation and recording electrodes.

    Science.gov (United States)

    Cogan, Stuart F

    2008-01-01

    Electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders. An understanding of the electrochemical mechanisms underlying the behavior of neural stimulation and recording electrodes is important for the development of chronically implanted devices, particularly those employing large numbers of microelectrodes. For stimulation, materials that support charge injection by capacitive and faradaic mechanisms are available. These include titanium nitride, platinum, and iridium oxide, each with certain advantages and limitations. The use of charge-balanced waveforms and maximum electrochemical potential excursions as criteria for reversible charge injection with these electrode materials are described and critiqued. Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.

  6. Neural recording and modulation technologies

    Science.gov (United States)

    Chen, Ritchie; Canales, Andres; Anikeeva, Polina

    2017-01-01

    In the mammalian nervous system, billions of neurons connected by quadrillions of synapses exchange electrical, chemical and mechanical signals. Disruptions to this network manifest as neurological or psychiatric conditions. Despite decades of neuroscience research, our ability to treat or even to understand these conditions is limited by the capability of tools to probe the signalling complexity of the nervous system. Although orders of magnitude smaller and computationally faster than neurons, conventional substrate-bound electronics do not recapitulate the chemical and mechanical properties of neural tissue. This mismatch results in a foreign-body response and the encapsulation of devices by glial scars, suggesting that the design of an interface between the nervous system and a synthetic sensor requires additional materials innovation. Advances in genetic tools for manipulating neural activity have fuelled the demand for devices that are capable of simultaneously recording and controlling individual neurons at unprecedented scales. Recently, flexible organic electronics and bio- and nanomaterials have been developed for multifunctional and minimally invasive probes for long-term interaction with the nervous system. In this Review, we discuss the design lessons from the quarter-century-old field of neural engineering, highlight recent materials-driven progress in neural probes and look at emergent directions inspired by the principles of neural transduction.

  7. Physical Principles for Scalable Neural Recording

    Directory of Open Access Journals (Sweden)

    Adam Henry Marblestone*

    2013-10-01

    Full Text Available Simultaneously measuring the activities of all neurons in a mammalian brain at millisecond resolution is a challenge beyond the limits of existing techniques in neuroscience. Entirely new approaches may be required, motivating an analysis of the fundamental physical constraints on the problem. We outline the physical principles governing brain activity mapping using optical, electrical,magnetic resonance, and molecular modalities of neural recording. Focusing on the mouse brain, we analyze the scalability of each method, concentrating on the limitations imposed by spatiotemporal resolution, energy dissipation, and volume displacement. We also study the physics of powering and communicating with microscale devices embedded in brain tissue.

  8. Fiber optic Adaline neural networks

    Science.gov (United States)

    Ghosh, Anjan K.; Trepka, Jim; Paparao, Palacharla

    1993-02-01

    Optoelectronic realization of adaptive filters and equalizers using fiber optic tapped delay lines and spatial light modulators has been discussed recently. We describe the design of a single layer fiber optic Adaline neural network which can be used as a bit pattern classifier. In our realization we employ as few electronic devices as possible and use optical computation to utilize the advantages of optics in processing speed, parallelism, and interconnection. The new optical neural network described in this paper is designed for optical processing of guided lightwave signals, not electronic signals. We analyzed the convergence or learning characteristics of the optically implemented Adaline in the presence of errors in the hardware, and we studied methods for improving the convergence rate of the Adaline.

  9. Optical sedimentation recorder

    Science.gov (United States)

    Bishop, James K.B.

    2014-05-06

    A robotic optical sedimentation recorder is described for the recordation of carbon flux in the oceans wherein both POC and PIC particles are captured at the open end of a submersible sampling platform, the captured particles allowed to drift down onto a collection plate where they can be imaged over time. The particles are imaged using three separate light sources, activated in sequence, one source being a back light, a second source being a side light to provide dark field illumination, and a third source comprising a cross polarized light source to illuminate birefringent particles. The recorder in one embodiment is attached to a buoyancy unit which is capable upon command for bringing the sedimentation recorder to a programmed depth below the ocean surface during recordation mode, and on command returning the unit to the ocean surface for transmission of recorded data and receipt of new instructions. The combined unit is provided with its own power source and is designed to operate autonomously in the ocean for extended periods of time.

  10. OptoZIF Drive: a 3D printed implant and assembly tool package for neural recording and optical stimulation in freely moving mice

    Science.gov (United States)

    Freedman, David S.; Schroeder, Joseph B.; Telian, Gregory I.; Zhang, Zhengyang; Sunil, Smrithi; Ritt, Jason T.

    2016-12-01

    Objective. Behavioral neuroscience studies in freely moving rodents require small, light-weight implants to facilitate neural recording and stimulation. Our goal was to develop an integrated package of 3D printed parts and assembly aids for labs to rapidly fabricate, with minimal training, an implant that combines individually positionable microelectrodes, an optical fiber, zero insertion force (ZIF-clip) headstage connection, and secondary recording electrodes, e.g. for electromyography (EMG). Approach. Starting from previous implant designs that position recording electrodes using a control screw, we developed an implant where the main drive body, protective shell, and non-metal components of the microdrives are 3D printed in parallel. We compared alternative shapes and orientations of circuit boards for electrode connection to the headstage, in terms of their size, weight, and ease of wire insertion. We iteratively refined assembly methods, and integrated additional assembly aids into the 3D printed casing. Main results. We demonstrate the effectiveness of the OptoZIF Drive by performing real time optogenetic feedback in behaving mice. A novel feature of the OptoZIF Drive is its vertical circuit board, which facilities direct ZIF-clip connection. This feature requires angled insertion of an optical fiber that still can exit the drive from the center of a ring of recording electrodes. We designed an innovative 2-part protective shell that can be installed during the implant surgery to facilitate making additional connections to the circuit board. We use this feature to show that facial EMG in mice can be used as a control signal to lock stimulation to the animal’s motion, with stable EMG signal over several months. To decrease assembly time, reduce assembly errors, and improve repeatability, we fabricate assembly aids including a drive holder, a drill guide, an implant fixture for microelectode ‘pinning’, and a gold plating fixture. Significance. The

  11. Optical implementation of neural networks

    Science.gov (United States)

    Yu, Francis T. S.; Guo, Ruyan

    2002-12-01

    An adaptive optical neuro-computing (ONC) using inexpensive pocket size liquid crystal televisions (LCTVs) had been developed by the graduate students in the Electro-Optics Laboratory at The Pennsylvania State University. Although this neuro-computing has only 8×8=64 neurons, it can be easily extended to 16×20=320 neurons. The major advantages of this LCTV architecture as compared with other reported ONCs, are low cost and the flexibility to operate. To test the performance, several neural net models are used. These models are Interpattern Association, Hetero-association and unsupervised learning algorithms. The system design considerations and experimental demonstrations are also included.

  12. Recent Advances in Neural Recording Microsystems

    Directory of Open Access Journals (Sweden)

    Benoit Gosselin

    2011-04-01

    Full Text Available The accelerating pace of research in neuroscience has created a considerable demand for neural interfacing microsystems capable of monitoring the activity of large groups of neurons. These emerging tools have revealed a tremendous potential for the advancement of knowledge in brain research and for the development of useful clinical applications. They can extract the relevant control signals directly from the brain enabling individuals with severe disabilities to communicate their intentions to other devices, like computers or various prostheses. Such microsystems are self-contained devices composed of a neural probe attached with an integrated circuit for extracting neural signals from multiple channels, and transferring the data outside the body. The greatest challenge facing development of such emerging devices into viable clinical systems involves addressing their small form factor and low-power consumption constraints, while providing superior resolution. In this paper, we survey the recent progress in the design and the implementation of multi-channel neural recording Microsystems, with particular emphasis on the design of recording and telemetry electronics. An overview of the numerous neural signal modalities is given and the existing microsystem topologies are covered. We present energy-efficient sensory circuits to retrieve weak signals from neural probes and we compare them. We cover data management and smart power scheduling approaches, and we review advances in low-power telemetry. Finally, we conclude by summarizing the remaining challenges and by highlighting the emerging trends in the field.

  13. Peripheral neural activity recording and stimulation system.

    Science.gov (United States)

    Loi, D; Carboni, C; Angius, G; Angotzi, G N; Barbaro, M; Raffo, L; Raspopovic, S; Navarro, X

    2011-08-01

    This paper presents a portable, embedded, microcontroller-based system for bidirectional communication (recording and stimulation) between an electrode, implanted in the peripheral nervous system, and a host computer. The device is able to record and digitize spontaneous and/or evoked neural activities and store them in data files on a PC. In addition, the system has the capability of providing electrical stimulation of peripheral nerves, injecting biphasic current pulses with programmable duration, intensity, and frequency. The recording system provides a highly selective band-pass filter from 800 Hz to 3 kHz, with a gain of 56 dB. The amplification range can be further extended to 96 dB with a variable gain amplifier. The proposed acquisition/stimulation circuitry has been successfully tested through in vivo measurements, implanting a tf-LIFE electrode in the sciatic nerve of a rat. Once implanted, the device showed an input referred noise of 0.83 μVrms, was capable of recording signals below 10 μ V, and generated muscle responses to injected stimuli. The results demonstrate the capability of processing and transmitting neural signals with very low distortion and with a power consumption lower than 1 W. A graphic, user-friendly interface has been developed to facilitate the configuration of the entire system, providing the possibility to activate stimulation and monitor recordings in real time.

  14. Design considerations for miniaturized optical neural probes

    Science.gov (United States)

    Rudmann, Linda; Ordonez, Juan S.; Stieglitz, Thomas

    2016-03-01

    Neural probes are designed to selectively record from or stimulate nerve cells. In optogenetics it is desirable to build miniaturized and long-term stable optical neural probes, in which the light sources can be directly and chronically implanted into the animals to allow free movement and behavior. Because of the size and the beam shape of the available light sources, it is difficult to target single cells as well as spatially localized networks. We therefore investigated design considerations for packages, which encapsulate the light source hermetically and have integrated hemispherical lens structures that enable to focus the light onto the desired region, by optical simulations. Integration of a biconvex lens into the package lid (diameter = 300 μm, material: silicon carbide) increased the averaged absolute irradiance ηA by 298 % compared to a system without a lens and had a spot size of around 120 μm. Solely integrating a plano-convex lens (same diameter and material) results in an ηA of up to 227 %.

  15. Optical imaging of neural and hemodynamic brain activity

    Science.gov (United States)

    Schei, Jennifer Lynn

    Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic

  16. Optically excited synapse for neural networks.

    Science.gov (United States)

    Boyd, G D

    1987-07-15

    What can optics with its promise of parallelism do for neural networks which require matrix multipliers? An all optical approach requires optical logic devices which are still in their infancy. An alternative is to retain electronic logic while optically addressing the synapse matrix. This paper considers several versions of an optically addressed neural network compatible with VLSI that could be fabricated with the synapse connection unspecified. This optical matrix multiplier circuit is compared to an all electronic matrix multiplier. For the optical version a synapse consisting of back-to-back photodiodes is found to have a suitable i-v characteristic for optical matrix multiplication (a linear region) plus a clipping or nonlinear region as required for neural networks. Four photodiodes per synapse are required. The strength of the synapse connection is controlled by the optical power and is thus an adjustable parameter. The synapse network can be programmed in various ways such as a shadow mask of metal, imaged mask (static), or light valve or an acoustooptic scanned laser beam or array of beams (dynamic). A milliwatt from LEDs or lasers is adequate power. The neuron has a linear transfer function and is either a summing amplifier, in which case the synapse signal is current, or an integrator, in which case the synapse signal is charge, the choice of which depends on the programming mode. Optical addressing and settling times of microseconds are anticipated. Electronic neural networks using single-value resistor synapses or single-bit programmable synapses have been demonstrated in the high-gain region of discrete single-value feedback. As an alternative to these networks and the above proposed optical synapses, an electronic analog-voltage vector matrix multiplier is considered using MOSFETS as the variable conductance in CMOS VLSI. It is concluded that a shadow mask addressed (static) optical neural network is promising.

  17. Design of fiber optic adaline neural networks

    Science.gov (United States)

    Ghosh, Anjan K.; Trepka, Jim

    1997-03-01

    Based on possible optoelectronic realization of adaptive filters and equalizers using fiber optic tapped delay lines and spatial light modulators we describe the design of a single-layer fiber optic Adaline neural network that can be used as a bit pattern classifier. In our design, we employ as few electronic devices as possible and use optical computation to utilize the advantages of optics in processing speed, parallelism, and interconnection. The described new optical neural network design is for optical processing of guided light wave signals, not electronic signals. We analyze the convergence or learning characteristics of the optoelectronic Adaline in the presence of errors in the hardware. We show that with such an optoelectronic Adaline it is possible to detect a desired code word/token/header with good accuracy.

  18. Novel digital optical tape recorder

    Science.gov (United States)

    Oakley, William S.

    1996-01-01

    A novel very high performance digital optical tape recorder is described. Linear tape motion at 4.2 meters per second and simultaneous writing of about 80 parallel bit tracks with a data density of three bits per micron per track enables a data rate of 1,000 Megabits per second, sufficient for a data rate of 100 megabytes per second with error correction. One micron track to track spacing gives a data capacity of one Terabyte (1,000 GB) in a single '3480' style tape cartridge shell. A single beam from a frequency doubled, laser diode pumped, solid state (2X- LDP-SS) laser is split into a multiplicity of like beams, each of which is then independently modulated at 12.5 MHz for recording.

  19. Optical neural computing for associative memories

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Ken Yuh.

    1990-01-01

    Optical techniques for implementing neural computers are presented. In particular, holographic associative memories with feedback are investigated. Characteristics of optical neurons and optical interconnections are discussed. An LCLV is used for simulating a 2-D array of approximately 160,000 optical neurons. Thermoplastic plates are used for providing holographic interconnections among these neurons. The problem of degenerate readout in holographic interconnections and the method of sampling grids to solve this problem are presented. Two optical neural networks for associative memories are implemented and demonstrated. The first one is an optical implementation of the Hopfield network. It performs the function of auto-association that recognizes 2-D images from a distorted or partially blocked input. The trade-off between distortion tolerance and discrimination capability against new images is discussed. The second optical loop is a 2-layer network with feedback. It performs the function of hetero-association, which locks the recognized input and its associated image as a stable state in the loop. In both optical loops, it is shown that the neural gain and the similarity between the input and the stored images are the main factors that determine the dynamics of the network. Neural network models for the optical loops are presented. Equations of motion for describing the dynamical behavior of the systems are derived. The reciprocal vector basis corresponding to stored images is derived. A geometrical method is then introduced which allows us to inspect the convergence property of the system. It is also shown that the main factors that determine the system dynamics are the neural gain and the initial conditions. Photorefractive holography for optical interconnections and sampling grids for volume holographic interconnections are presented.

  20. Implementation of artificial neural networks with optics

    Science.gov (United States)

    Yu, Francis T. S.

    1999-04-01

    Optical implementation of artificial neural nets (ANNs) with electronically addressable liquid crystal televisions (LCTVs) are presented. The major advantages of the proposed ANNs must be the low cost and the flexibility to operate. To test the performance, several artificial neural net models have been implemented in the LCTV ANNs. These models include the Hopfield, Interpattern Association, Hetero-association, and Unsupervised ANNs. System design considerations and experimental demonstrates are provided.

  1. Spatial Information in Large-scale Neural Recordings

    Directory of Open Access Journals (Sweden)

    Thaddeus R. Cybulski

    2015-01-01

    Full Text Available To record from a given neuron, a recording technology must be able to separate the activity of that neuron from the activity of its neighbors. Here, we develop a Fisher information based framework to determine the conditions under which this is feasible for a given technology. This framework combines measurable point spread functions with measurable noise distributions to produce theoretical bounds on the precision with which a recording technology can localize neural activities. If there is suffi□cient information to uniquely localize neural activities, then a technology will, from an information theoretic perspective, be able to record from these neurons. We (1 describe this framework, and (2 demonstrate its application in model experiments. This method generalizes to many recording devices that resolve objects in space and should be useful in the design of next generation scalable neural recording systems.

  2. Stimulation and recording electrodes for neural prostheses

    CERN Document Server

    Pour Aryan, Naser; Rothermel, Albrecht

    2015-01-01

    This book provides readers with basic principles of the electrochemistry of the electrodes used in modern, implantable neural prostheses. The authors discuss the boundaries and conditions in which the electrodes continue to function properly for long time spans, which are required when designing neural stimulator devices for long-term in vivo applications. Two kinds of electrode materials, titanium nitride and iridium are discussed extensively, both qualitatively and quantitatively. The influence of the counter electrode on the safety margins and electrode lifetime in a two electrode system is explained. Electrode modeling is handled in a final chapter.

  3. Mark formation model for optical rewritable recording

    NARCIS (Netherlands)

    Brusche, J.H.

    2007-01-01

    Optically rewritable discs contain one or more so-called recording stacks. These stacks consist of various grooved layers. At least one of these layers contains a so-called phase-change material. In the recording layer, amorphous regions are formed on a crystalline background by means of high power

  4. Detection of neural activity using phase-sensitive optical low-coherence reflectometry

    Science.gov (United States)

    Akkin, Taner; Davã©, Digant P.; Milner, Thomas E.; Rylander, H. Grady, III

    2004-05-01

    We demonstrate non-contact sub-nanometer optical measurement of neural surface displacement associated with action potential propagation. Experimental results are recorded from nerve bundles dissected from crayfish walking leg using a phase-sensitive optical low coherence reflectometer. No exogenous chemicals or reflection coatings are applied. Transient neural surface displacement is less than 1 nm in amplitude, 1 ms in duration and is coincident with action potential arrival to the optical measurement site. Because the technique uses back-reflected light, noninvasive detection of various neuropathies may be possible.

  5. A lightweight feedback-controlled microdrive for chronic neural recordings

    Science.gov (United States)

    Jovalekic, A.; Cavé-Lopez, S.; Canopoli, A.; Ondracek, J. M.; Nager, A.; Vyssotski, A. L.; Hahnloser, R. H. R.

    2017-04-01

    Objective. Chronic neural recordings have provided many insights into the relationship between neural activity and behavior. We set out to develop a miniaturized motorized microdrive that allows precise electrode positioning despite possibly unreliable motors. Approach. We designed a feedback-based motor control mechanism. It contains an integrated position readout from an array of magnets and a Hall sensor. Main results. Our extremely lightweight (feedback-based microdrive control requires little extra size and weight, suggesting that such control can be incorporated into more complex multi-electrode designs.

  6. Mark formation modeling in optical rewritable recording

    NARCIS (Netherlands)

    Brusche, J.H.; Segal, A.; Vuik, C.; Urbach, H.P.

    2006-01-01

    In optical rewritable recording media, such as the Blu-ray Disc, amorphous marks are formed on a crystalline background of a phase-change layer, by means of short, high power laser pulses. In order to improve this data storage concept, it is of great importance to understand the mark formation

  7. Mark formation modeling in optical rewritable recording

    NARCIS (Netherlands)

    Brusche, J.H.; Segal, A.; Vuik, C.; Urbach, H.P.

    2006-01-01

    In optical rewritable recording media, such as the Blu-ray Disc, amorphous marks are formed on a crystalline background of a phase-change layer, by means of short, high power laser pulses. In order to improve this data storage concept, it is of great importance to understand the mark formation proce

  8. EDITORIAL: Special issue on optical neural engineering: advances in optical stimulation technology Special issue on optical neural engineering: advances in optical stimulation technology

    Science.gov (United States)

    Shoham, Shy; Deisseroth, Karl

    2010-08-01

    Neural engineering, itself an 'emerging interdisciplinary research area' [1] has undergone a sea change over the past few years with the emergence of exciting new optical technologies for monitoring, stimulating, inhibiting and, more generally, modulating neural activity. To a large extent, this change is driven by the realization of the promise and complementary strengths that emerging photo-stimulation tools offer to add to the neural engineer's toolbox, which has been almost exclusively based on electrical stimulation technologies. Notably, photo-stimulation is non-contact, can in some cases be genetically targeted to specific cell populations, can achieve high spatial specificity (cellular or even sub-cellular) in two or three dimensions, and opens up the possibility of large-scale spatial-temporal patterned stimulation. It also offers a seamless solution to the problem of cross-talk generated by simultaneous electrical stimulation and recording. As in other biomedical optics phenomena [2], photo-stimulation includes multiple possible modes of interaction between light and the target neurons, including a variety of photo-physical and photo-bio-chemical effects with various intrinsic components or exogenous 'sensitizers' which can be loaded into the tissue or genetically expressed. Early isolated reports of neural excitation with light date back to the late 19th century [3] and to Arvanitaki and Chalazonitis' work five decades ago [4]; however, the mechanism by which these and other direct photo-stimulation, inhibition and modulation events [5-7] took place is yet unclear, as is their short- and long-term safety profile. Photo-chemical photolysis of covalently 'caged' neurotransmitters [8, 9] has been widely used in cellular neuroscience research for three decades, including for exciting or inhibiting neural activity, and for mapping neural circuits. Technological developments now allow neurotransmitters to be uncaged with exquisite spatial specificity (down to

  9. Establishing a fiber-optic-based optical neural interface.

    Science.gov (United States)

    Adamantidis, Antoine R; Zhang, Feng; de Lecea, Luis; Deisseroth, Karl

    2014-08-01

    Selective expression of opsins in genetically defined neurons makes it possible to control a subset of neurons without affecting nearby cells and processes in the intact brain, but light must still be delivered to the target brain structure. Light scattering limits the delivery of light from the surface of the brain. For this reason, we have developed a fiber-optic-based optical neural interface (ONI), which allows optical access to any brain structure in freely moving mammals. The ONI system is constructed by modifying the small animal cannula system from PlasticsOne. The system for bilateral stimulation consists of a bilateral cannula guide that has been stereotactically implanted over the target brain region, a screw cap for securing the optical fiber to the animal's head, a fiber guard modified from the internal cannula adapter, and a bare fiber whose length is customized based on the depth of the target region. For unilateral stimulation, a single-fiber system can be constructed using unilateral cannula parts from PlasticsOne. We describe here the preparation of the bilateral ONI system and its use in optical stimulation of the mouse or rat brain. Delivery of opsin-expressing virus and implantation of the ONI may be conducted in the same surgical session; alternatively, with a transgenic animal no opsin virus is delivered during the surgery. Similar procedures are useful for deep or superficial injections (even for neocortical targets, although in some cases surface light-emitting diodes or cortex-apposed fibers can be used for the most superficial cortical targets).

  10. Micro-Reaction Chamber Electrodes for Neural Stimulation and Recording

    OpenAIRE

    Shanmugasundaram, Balaji; Gluckman, Bruce J.

    2011-01-01

    Biocompatible electrodes with smaller geometric area are preferred to improve the selectivity of the neural recording and stimulation applications. We introduce the concept of a micro-reaction chamber (µRC) in which a volume within the electrode back plane is used to confine and sequester the electrochemical reactions used for charge passage. The µRC electrode design helps decrease impedance and improves the charge storage capacity without altering the geometry of the active site. Here we dem...

  11. Multilevel read-only optical recording methods

    Institute of Scientific and Technical Information of China (English)

    Song Jie; Xu Duan-Yi; Qi Guo-Sheng; Hu Hua; Zhang Qi-Cheng; Xiong Jian-Ping

    2006-01-01

    The advantages of read-only storage is the predominance of optical recording relative to magnetic and other rewritable methods. Multilevel (ML) read-only technology has been a trend to improve the data capacity and transfer rate. Based on the principle and coding method of ML, this paper demonstrates some ML read-only recording methods, of which a new ML read-only recording is developed. This recording method integrates amplitude modulation achieved by the reaction mechanism of physics and chemistry of photoresist with the run-length-limited technology. The discs can be achieved using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs.

  12. Artificial earthquake record generation using cascade neural network

    Directory of Open Access Journals (Sweden)

    Bani-Hani Khaldoon A.

    2017-01-01

    Full Text Available This paper presents the results of using artificial neural networks (ANN in an inverse mapping problem for earthquake accelerograms generation. This study comprises of two parts: 1-D site response analysis; performed for Dubai Emirate at UAE, where eight earthquakes records are selected and spectral matching are performed to match Dubai response spectrum using SeismoMatch software. Site classification of Dubai soil is being considered for two classes C and D based on shear wave velocity of soil profiles. Amplifications factors are estimated to quantify Dubai soil effect. Dubai’s design response spectra are developed for site classes C & D according to International Buildings Code (IBC -2012. In the second part, ANN is employed to solve inverse mapping problem to generate time history earthquake record. Thirty earthquakes records and their design response spectrum with 5% damping are used to train two cascade forward backward neural networks (ANN1, ANN2. ANN1 is trained to map the design response spectrum to time history and ANN2 is trained to map time history records to the design response spectrum. Generalized time history earthquake records are generated using ANN1 for Dubai’s site classes C and D, and ANN2 is used to evaluate the performance of ANN1.

  13. An implantable neural probe with monolithically integrated dielectric waveguide and recording electrodes for optogenetics applications

    Science.gov (United States)

    Wu, Fan; Stark, Eran; Im, Maesoon; Cho, Il-Joo; Yoon, Eui-Sung; Buzsáki, György; Wise, Kensall D.; Yoon, Euisik

    2013-10-01

    Objective. Optogenetics promises exciting neuroscience research by offering optical stimulation of neurons with unprecedented temporal resolution, cell-type specificity and the ability to excite as well as to silence neurons. This work provides the technical solution to deliver light to local neurons and record neural potentials, facilitating local circuit analysis and bridging the gap between optogenetics and neurophysiology research. Approach. We have designed and obtained the first in vivo validation of a neural probe with monolithically integrated electrodes and waveguide. High spatial precision enables optical excitation of targeted neurons with minimal power and recording of single-units in dense cortical and subcortical regions. Main results. The total coupling and transmission loss through the dielectric waveguide at 473 nm was 10.5 ± 1.9 dB, corresponding to an average output intensity of 9400 mW mm-2 when coupled to a 7 mW optical fiber. Spontaneous field potentials and spiking activities of multiple Channelrhodopsin-2 expressing neurons were recorded in the hippocampus CA1 region of an anesthetized rat. Blue light stimulation at intensity of 51 mW mm-2 induced robust spiking activities in the physiologically identified local populations. Significance. This minimally invasive, complete monolithic integration provides unmatched spatial precision and scalability for future optogenetics studies at deep brain regions with high neuronal density.

  14. A digitally assisted, signal folding neural recording amplifier.

    Science.gov (United States)

    Chen, Yi; Basu, Arindam; Liu, Lei; Zou, Xiaodan; Rajkumar, Ramamoorthy; Dawe, Gavin Stewart; Je, Minkyu

    2014-08-01

    A novel signal folding and reconstruction scheme for neural recording applications that exploits the 1/f(n) characteristics of neural signals is described in this paper. The amplified output is 'folded' into a predefined range of voltages by using comparison and reset circuits along with the core amplifier. After this output signal is digitized and transmitted, a reconstruction algorithm can be applied in the digital domain to recover the amplified signal from the folded waveform. This scheme enables the use of an analog-to-digital convertor with less number of bits for the same effective dynamic range. It also reduces the transmission data rate of the recording chip. Both of these features allow power and area savings at the system level. Other advantages of the proposed topology are increased reliability due to the removal of pseudo-resistors, lower harmonic distortion and low-voltage operation. An analysis of the reconstruction error introduced by this scheme is presented along with a behavioral model to provide a quick estimate of the post reconstruction dynamic range. Measurement results from two different core amplifier designs in 65 nm and 180 nm CMOS processes are presented to prove the generality of the proposed scheme in the neural recording applications. Operating from a 1 V power supply, the amplifier in 180 nm CMOS has a gain of 54.2 dB, bandwidth of 5.7 kHz, input referred noise of 3.8 μVrms and power dissipation of 2.52 μW leading to a NEF of 3.1 in spike band. It exhibits a dynamic range of 66 dB and maximum SNDR of 43 dB in LFP band. It also reduces system level power (by reducing the number of bits in the ADC by 2) as well as data rate to 80% of a conventional design. In vivo measurements validate the ability of this amplifier to simultaneously record spike and LFP signals.

  15. EEG in the classroom: Synchronised neural recordings during video presentation

    Science.gov (United States)

    Poulsen, Andreas Trier; Kamronn, Simon; Dmochowski, Jacek; Parra, Lucas C.; Hansen, Lars Kai

    2017-03-01

    We performed simultaneous recordings of electroencephalography (EEG) from multiple students in a classroom, and measured the inter-subject correlation (ISC) of activity evoked by a common video stimulus. The neural reliability, as quantified by ISC, has been linked to engagement and attentional modulation in earlier studies that used high-grade equipment in laboratory settings. Here we reproduce many of the results from these studies using portable low-cost equipment, focusing on the robustness of using ISC for subjects experiencing naturalistic stimuli. The present data shows that stimulus-evoked neural responses, known to be modulated by attention, can be tracked for groups of students with synchronized EEG acquisition. This is a step towards real-time inference of engagement in the classroom.

  16. EEG in the classroom: Synchronised neural recordings during video presentation

    Science.gov (United States)

    Poulsen, Andreas Trier; Kamronn, Simon; Dmochowski, Jacek; Parra, Lucas C.; Hansen, Lars Kai

    2017-01-01

    We performed simultaneous recordings of electroencephalography (EEG) from multiple students in a classroom, and measured the inter-subject correlation (ISC) of activity evoked by a common video stimulus. The neural reliability, as quantified by ISC, has been linked to engagement and attentional modulation in earlier studies that used high-grade equipment in laboratory settings. Here we reproduce many of the results from these studies using portable low-cost equipment, focusing on the robustness of using ISC for subjects experiencing naturalistic stimuli. The present data shows that stimulus-evoked neural responses, known to be modulated by attention, can be tracked for groups of students with synchronized EEG acquisition. This is a step towards real-time inference of engagement in the classroom. PMID:28266588

  17. Wireless Neural Recording With Single Low-Power Integrated Circuit

    Science.gov (United States)

    Harrison, Reid R.; Kier, Ryan J.; Chestek, Cynthia A.; Gilja, Vikash; Nuyujukian, Paul; Ryu, Stephen; Greger, Bradley; Solzbacher, Florian; Shenoy, Krishna V.

    2010-01-01

    We present benchtop and in vivo experimental results from an integrated circuit designed for wireless implantable neural recording applications. The chip, which was fabricated in a commercially available 0.6-μm 2P3M BiCMOS process, contains 100 amplifiers, a 10-bit analog-to-digital converter (ADC), 100 threshold-based spike detectors, and a 902–928 MHz frequency-shift-keying (FSK) transmitter. Neural signals from a selected amplifier are sampled by the ADC at 15.7 kSps and telemetered over the FSK wireless data link. Power, clock, and command signals are sent to the chip wirelessly over a 2.765-MHz inductive (coil-to-coil) link. The chip is capable of operating with only two off-chip components: a power/command receiving coil and a 100-nF capacitor. PMID:19497825

  18. Wireless neural recording with single low-power integrated circuit.

    Science.gov (United States)

    Harrison, Reid R; Kier, Ryan J; Chestek, Cynthia A; Gilja, Vikash; Nuyujukian, Paul; Ryu, Stephen; Greger, Bradley; Solzbacher, Florian; Shenoy, Krishna V

    2009-08-01

    We present benchtop and in vivo experimental results from an integrated circuit designed for wireless implantable neural recording applications. The chip, which was fabricated in a commercially available 0.6- mum 2P3M BiCMOS process, contains 100 amplifiers, a 10-bit analog-to-digital converter (ADC), 100 threshold-based spike detectors, and a 902-928 MHz frequency-shift-keying (FSK) transmitter. Neural signals from a selected amplifier are sampled by the ADC at 15.7 kSps and telemetered over the FSK wireless data link. Power, clock, and command signals are sent to the chip wirelessly over a 2.765-MHz inductive (coil-to-coil) link. The chip is capable of operating with only two off-chip components: a power/command receiving coil and a 100-nF capacitor.

  19. Artificial Neural Network Model for Optical Fiber Direction Coupler Design

    Institute of Scientific and Technical Information of China (English)

    李九生; 鲍振武

    2004-01-01

    A new approach to the design of the optical fiber direction coupler by using neural network is proposed. To train the artificial neural network,the coupling length is defined as the input sample, and the coupling ratio is defined as the output sample. Compared with the numerical value calculation of the theoretical formula, the error of the neural network model output is 1% less.Then, through the model, to design a broadband or a single wavelength optical fiber direction coupler becomes easy. The method is proved to be reliable, accurate and time-saving. So it is promising in the field of both investigation and application.

  20. Dual inductive link coil design for a neural recording system.

    Science.gov (United States)

    Rush, Alexander; Troyk, Philip R

    2011-01-01

    This paper reports an approach to the physical design of the coils used in a dual inductive link to provide two-way wireless communication and power for a neural recording system. The design approach makes use of an analytic model of the link performance in terms of the physical parameters of the link, which allows physical parameters to be iterated on a computer rather than on the bench to find the optimal design within the physical restrictions imposed. In particular, this approach was used to choose the optimal implant data coil sizing to maximize the difference between the contributions of the constructive and destructive paths of the reverse telemetry signal.

  1. EEG in the classroom: Synchronised neural recordings during video presentation

    DEFF Research Database (Denmark)

    Poulsen, Andreas Trier; Kamronn, Simon Due; Dmochowski, Jacek

    2017-01-01

    modulation in earlier studies that used high-grade equipment in laboratory settings. Here we reproduce many of the results from these studies using portable low-cost equipment, focusing on the robustness of using ISC for subjects experiencing naturalistic stimuli. The present data shows that stimulus......We performed simultaneous recordings of electroencephalography (EEG) from multiple students in a classroom, and measured the inter-subject correlation (ISC) of activity evoked by a common video stimulus. The neural reliability, as quantified by ISC, has been linked to engagement and attentional...

  2. Optical Recording of Neuronal Circuit Dynamics

    OpenAIRE

    Wolf, Alexander

    2007-01-01

    This work deals with the optical recording of cerebellar circuit dynamics from acute brain slices of the cerebellar surface. This preparation preserves the functional connectivity of the cerebellar cortex. It was used to investigate the function of Kv3 potassium channels in the cerebellar granule cell axon. Double knockout mice lacking both Kv3.1 and Kv3.3 potassium channels display severe motor deficits, while mice lacking only Kv3.1 or Kv3.3 do not. Since granule cells express both Kv3.1 an...

  3. Optical implementation of the Hopfield neural network with matrix gratings

    Science.gov (United States)

    Yeh, Sheng L.; Lo, Rong C.; Shi, Cha Y.

    2004-02-01

    We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.

  4. Reconciling power laws in microscopic and macroscopic neural recordings

    CERN Document Server

    Pettersen, Klas H; Tetzlaff, Tom; Einevoll, Gaute T

    2013-01-01

    Power laws, characterized by quantities following 1/x^\\alpha{} distributions, are commonly reported when observing nature or society, and the question of their origin has for a long time intrigued physicists. Power laws have also been observed in neural recordings, both at the macroscopic and microscopic levels: at the macroscopic level, the power spectral density (PSD) of the electroencephalogram (EEG) has been seen to follow 1/f^\\alpha{} distributions; at the microscopic level similar power laws have been observed in single-neuron recordings of the neuronal soma potential and soma current, yet with different values of the power-law exponent \\alpha. In this theoretical study we find that these observed macroscopic and microscopic power laws may, despite the widely different spatial scales and different exponents, have the same source. By a combination of simulation on a biophysical detailed, pyramidal neuron model and analytical investigations of a simplified ball and stick neuron, we find that the transfer ...

  5. Electrodeposited iridium oxide for neural stimulation and recording electrodes.

    Science.gov (United States)

    Meyer, R D; Cogan, S F; Nguyen, T H; Rauh, R D

    2001-03-01

    Iridium oxide films formed by electrodeposition onto noniridium metal substrates are compared with activated iridium oxide films (AIROFs) as a low impedance, high charge capacity coating for neural stimulation and recording electrodes. The electrodeposited iridium oxide films (EIROFs) were deposited on Au, Pt, PtIr, and 316 LVM stainless steel substrates from a solution of IrCl4, oxalic acid, and K2CO3. A deposition protocol involving 50 potential sweeps at 50 mV/s between limits of 0.0 V and 0.55 V (versus Ag AgCl) followed by potential pulsing between the same limits produced adherent films with a charge storage capacity of >25 mC/cm2. Characterization by cyclic voltammetry and impedance spectroscopy revealed no differences in the electrochemical behavior of EIROF on non-Ir substrates and AIROF. The mechanical stability of the oxides was evaluated by ultrasonication in distilled water followed by dehydration and rehydration. Stability under charge injection was evaluated using 200 micros, 5.9 A/cm2 (1.2 mC/cm2) cathodal pulses. Loss of iridium oxide charge capacity was comparable for AIROFs and the EIROFs, ranging from 1% to 8% of the capacity immediately after activation or deposition. The EIROFs were deposited and evaluated on silicon microprobe electrodes and on metallized polyimide electrodes being developed for neural recording and stimulation applications.

  6. Neural networks within multi-core optic fibers.

    Science.gov (United States)

    Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

    2016-07-07

    Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks.

  7. Neural networks within multi-core optic fibers

    Science.gov (United States)

    Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

    2016-07-01

    Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks.

  8. Poly (3, 4-ethylenedioxythiophene)-ionic liquid coating improves neural recording and stimulation functionality of MEAs

    OpenAIRE

    Du, Zhanhong Jeff; Luo, Xiliang; Weaver, Cassandra; Cui, Xinyan Tracy

    2015-01-01

    In vivo multi-electrode arrays (MEAs) can sense electrical signals from a small set of neurons or modulate neural activity through micro-stimulation. Electrode's geometric surface area (GSA) and impedance are important for both unit recording and neural stimulation. Smaller GSA is preferred due to enhanced selectivity of neural signal, but it tends to increase electrode impedance. Higher impedance leads to increased electrical noise and signal loss in single unit neural recording. It also yie...

  9. Neural network post-processing of grayscale optical correlator

    Science.gov (United States)

    Lu, Thomas T; Hughlett, Casey L.; Zhoua, Hanying; Chao, Tien-Hsin; Hanan, Jay C.

    2005-01-01

    In this paper we present the use of a radial basis function neural network (RBFNN) as a post-processor to assist the optical correlator to identify the objects and to reject false alarms. Image plane features near the correlation peaks are extracted and fed to the neural network for analysis. The approach is capable of handling large number of object variations and filter sets. Preliminary experimental results are presented and the performance is analyzed.

  10. Incorporating an optical waveguide into a neural interface

    Science.gov (United States)

    Tolosa, Vanessa; Delima, Terri L.; Felix, Sarah H.; Pannu, Satinderpall S.; Shah, Kedar G.; Sheth, Heeral; Tooker, Angela C.

    2016-11-08

    An optical waveguide integrated into a multielectrode array (MEA) neural interface includes a device body, at least one electrode in the device body, at least one electrically conducting lead coupled to the at least one electrode, at least one optical channel in the device body, and waveguide material in the at least one optical channel. The fabrication of a neural interface device includes the steps of providing a device body, providing at least one electrode in the device body, providing at least one electrically conducting lead coupled to the at least one electrode, providing at least one optical channel in the device body, and providing a waveguide material in the at least one optical channel.

  11. Optical forensics for tracing counterfeit recorded media

    Science.gov (United States)

    Smith, Patrick J.; O'Doherty, Phelim; Luna, Carlos; McCarthy, Sean

    2004-12-01

    We describe an optical forensic method for tracing a CD back to the pressing machine in which it was created, and present a system we have developed which maintains a library of the 'fingerprints' of such machines and can compare sample CDs against this library. In principle, any security feature that is deliberately created can be copied by a counterfeiter. In our forensic method we concentrate on features that arise spontaneously in the manufacturing process. Such features act as a signature or 'fingerprint'. In the case of CDs we show how the moulding process leaves an imprint of an unpolished part of the 'mirror plate' on the CD surface. Using machine vision and pattern-matching, we demonstrate the use of the system to acquire a positive match of a sample against a pre-recorded library entry created using a different CD from the same mould.

  12. A Low Noise Amplifier for Neural Spike Recording Interfaces

    Directory of Open Access Journals (Sweden)

    Jesus Ruiz-Amaya

    2015-09-01

    Full Text Available This paper presents a Low Noise Amplifier (LNA for neural spike recording applications. The proposed topology, based on a capacitive feedback network using a two-stage OTA, efficiently solves the triple trade-off between power, area and noise. Additionally, this work introduces a novel transistor-level synthesis methodology for LNAs tailored for the minimization of their noise efficiency factor under area and noise constraints. The proposed LNA has been implemented in a 130 nm CMOS technology and occupies 0.053 mm-sq. Experimental results show that the LNA offers a noise efficiency factor of 2.16 and an input referred noise of 3.8 μVrms for 1.2 V power supply. It provides a gain of 46 dB over a nominal bandwidth of 192 Hz–7.4 kHz and consumes 1.92 μW. The performance of the proposed LNA has been validated through in vivo experiments with animal models.

  13. A Low Noise Amplifier for Neural Spike Recording Interfaces

    Science.gov (United States)

    Ruiz-Amaya, Jesus; Rodriguez-Perez, Alberto; Delgado-Restituto, Manuel

    2015-01-01

    This paper presents a Low Noise Amplifier (LNA) for neural spike recording applications. The proposed topology, based on a capacitive feedback network using a two-stage OTA, efficiently solves the triple trade-off between power, area and noise. Additionally, this work introduces a novel transistor-level synthesis methodology for LNAs tailored for the minimization of their noise efficiency factor under area and noise constraints. The proposed LNA has been implemented in a 130 nm CMOS technology and occupies 0.053 mm-sq. Experimental results show that the LNA offers a noise efficiency factor of 2.16 and an input referred noise of 3.8 μVrms for 1.2 V power supply. It provides a gain of 46 dB over a nominal bandwidth of 192 Hz–7.4 kHz and consumes 1.92 μW. The performance of the proposed LNA has been validated through in vivo experiments with animal models. PMID:26437411

  14. Analysis of optical neural stimulation effects on neural networks affected by neurodegenerative diseases

    Science.gov (United States)

    Zverev, M.; Fanjul-Vélez, F.; Salas-García, I.; Ortega-Quijano, N.; Arce-Diego, J. L.

    2016-03-01

    The number of people in risk of developing a neurodegenerative disease increases as the life expectancy grows due to medical advances. Multiple techniques have been developed to improve patient's condition, from pharmacological to invasive electrodes approaches, but no definite cure has yet been discovered. In this work Optical Neural Stimulation (ONS) has been studied. ONS stimulates noninvasively the outer regions of the brain, mainly the neocortex. The relationship between the stimulation parameters and the therapeutic response is not totally clear. In order to find optimal ONS parameters to treat a particular neurodegenerative disease, mathematical modeling is necessary. Neural networks models have been employed to study the neural spiking activity change induced by ONS. Healthy and pathological neocortical networks have been considered to study the required stimulation to restore the normal activity. The network consisted of a group of interconnected neurons, which were assigned 2D spatial coordinates. The optical stimulation spatial profile was assumed to be Gaussian. The stimulation effects were modeled as synaptic current increases in the affected neurons, proportional to the stimulation fluence. Pathological networks were defined as the healthy ones with some neurons being inactivated, which presented no synaptic conductance. Neurons' electrical activity was also studied in the frequency domain, focusing specially on the changes of the spectral bands corresponding to brain waves. The complete model could be used to determine the optimal ONS parameters in order to achieve the specific neural spiking patterns or the required local neural activity increase to treat particular neurodegenerative pathologies.

  15. Compact 4-D Optical Neural Network Architecture

    Science.gov (United States)

    1990-04-25

    again separated, with each being reimaged onto the cooled CCD detector arrays. I D Array I IImage CiD Array Figure 35. Details of the optical elements...P. Thijssen, R. Van Den Berg and S. Volker, Chemical Physics Letters, 120 (1985) 503. 39. A. R. Gutierrez , J. Friedrich, D. Haarer and H. Wolfrum...Silbey, "Reversible and Irreversible Line Broadening of Photo- chemical Holes in Amorphous Solids," Chem. Phys. Lett. 95 (1983) 119. Gutierrez , A. R., J

  16. Functional recordings from awake, behaving rodents through a microchannel based regenerative neural interface

    Science.gov (United States)

    Gore, Russell K.; Choi, Yoonsu; Bellamkonda, Ravi; English, Arthur

    2015-02-01

    Objective. Neural interface technologies could provide controlling connections between the nervous system and external technologies, such as limb prosthetics. The recording of efferent, motor potentials is a critical requirement for a peripheral neural interface, as these signals represent the user-generated neural output intended to drive external devices. Our objective was to evaluate structural and functional neural regeneration through a microchannel neural interface and to characterize potentials recorded from electrodes placed within the microchannels in awake and behaving animals. Approach. Female rats were implanted with muscle EMG electrodes and, following unilateral sciatic nerve transection, the cut nerve was repaired either across a microchannel neural interface or with end-to-end surgical repair. During a 13 week recovery period, direct muscle responses to nerve stimulation proximal to the transection were monitored weekly. In two rats repaired with the neural interface, four wire electrodes were embedded in the microchannels and recordings were obtained within microchannels during proximal stimulation experiments and treadmill locomotion. Main results. In these proof-of-principle experiments, we found that axons from cut nerves were capable of functional reinnervation of distal muscle targets, whether regenerating through a microchannel device or after direct end-to-end repair. Discrete stimulation-evoked and volitional potentials were recorded within interface microchannels in a small group of awake and behaving animals and their firing patterns correlated directly with intramuscular recordings during locomotion. Of 38 potentials extracted, 19 were identified as motor axons reinnervating tibialis anterior or soleus muscles using spike triggered averaging. Significance. These results are evidence for motor axon regeneration through microchannels and are the first report of in vivo recordings from regenerated motor axons within microchannels in a small

  17. An Inductively-Powered Wireless Neural Recording System with a Charge Sampling Analog Front-End

    OpenAIRE

    Lee, Seung Bae; Lee, Byunghun; Kiani, Mehdi; Mahmoudi, Babak; Gross, Robert; Ghovanloo, Maysam

    2015-01-01

    An inductively-powered wireless integrated neural recording system (WINeR-7) is presented for wireless and battery less neural recording from freely-behaving animal subjects inside a wirelessly-powered standard homecage. The WINeR-7 system employs a novel wide-swing dual slope charge sampling (DSCS) analog front-end (AFE) architecture, which performs amplification, filtering, sampling, and analog-to-time conversion (ATC) with minimal interference and small amount of power. The output of the D...

  18. Polarization holographic optical recording of a new photochromic diarylethene

    Science.gov (United States)

    Pu, Shouzhi; Miao, Wenjuan; Chen, Anyin; Cui, Shiqiang

    2008-12-01

    A new symmetrical photochromic diarylethene, 1,2-bis[2-methyl-5-(3-methoxylphenyl)-3-thienyl]perfluorocyclopentene (1a), was synthesized, and its photochromic properties were investigated. The compound exhibited good photochromism both in solution and in PMMA film with alternating irradiation by UV/VIS light, and the maxima absorption of its closed-ring isomer 1b are 582 and 599 nm, respectively. Using diarylethene 1b/PMMA film as recording medium and a He-Ne laser (633 nm) for recording and readout, four types of polarization and angular multiplexing holographic optical recording were performed perfectly. For different types of polarization recording including parallel linear polarization recording, parallel circular polarization recording, orthogonal linear polarization recording and orthogonal circular polarization recording,have been accomplished successfully. The results demonstrated that the orthogonal circular polarization recording is the best method for polarization holographic optical recording when this compound was used as recording material. With angular multiplexing recording technology, two high contrast holograms were recorded in the same place on the film with the dimension of 0.78 μm2.

  19. System for recording bivariate intensity distribution of optical radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vil' danov, R.R.; Deryugin, I.A.; Gladyshev, D.A.; Mirzaeu, A.T.

    1986-02-01

    This paper describes a system for recording the space-energy characteristics of optical radiation based on an MF-6 photodetector matrix and an AI-4096-3M multivariate pulse analyzer. The system can record optical images with from 2 to 64 quantization levels with visual monitoring of input data in the form of a space distribution in axonometric projection. The recording time for a complete image is from 11 to 700 msec. The system has been used to determine and monitor the crosssectional intensity distribution of laser beams as a function of radiation mode.

  20. Reciprocal inhibitory connections within a neural network for rotational optic-flow processing

    Directory of Open Access Journals (Sweden)

    Juergen Haag

    2007-10-01

    Full Text Available Neurons in the visual system of the blowfly have large receptive fields that are selective for specific optic flow fields. Here, we studied the neural mechanisms underlying flow-field selectivity in proximal Vertical System (VS-cells, a particular subset of tangential cells in the fly. These cells have local preferred directions that are distributed such as to match the flow field occurring during a rotation of the fly. However, the neural circuitry leading to this selectivity is not fully understood. Through dual intracellular recordings from proximal VS cells and other tangential cells, we characterized the specific wiring between VS cells themselves and between proximal VS cells and horizontal sensitive tangential cells. We discovered a spiking neuron (Vi involved in this circuitry that has not been described before. This neuron turned out to be connected to proximal VS cells via gap junctions and, in addition, it was found to be inhibitory onto VS1.

  1. Neural Network-Based Multimode Fiber-Optic Information Transmission

    Science.gov (United States)

    Marusarz, Ronald K.; Sayeh, Mohammad R.

    2001-01-01

    A new technique for transmitting information through multimode fiber-optic cables is presented. This technique sends parallel channels through the fiber-optic cable, thereby greatly improving the data transmission rate compared with that of the current technology, which uses serial data transmission through single-mode fiber. An artificial neural network is employed to decipher the transmitted information from the received speckle pattern. Several different preprocessing algorithms are developed, tested, and evaluated. These algorithms employ average region intensity, distributed individual pixel intensity, and maximum mean-square-difference optimal group selection methods. The effect of modal dispersion on the data rate is analyzed. An increased data transmission rate by a factor of 37 over that of single-mode fibers is realized. When implementing our technique, we can increase the channel capacity of a typical multimode fiber by a factor of 6.

  2. Optical proximity correction using a multilayer perceptron neural network

    Science.gov (United States)

    Luo, Rui

    2013-07-01

    Optical proximity correction (OPC) is one of the resolution enhancement techniques (RETs) in optical lithography, where the mask pattern is modified to improve the output pattern fidelity. Algorithms are needed to generate the modified mask pattern automatically and efficiently. In this paper, a multilayer perceptron (MLP) neural network (NN) is used to synthesize the mask pattern. We employ the pixel-based approach in this work. The MLP takes the pixel values of the desired output wafer pattern as input, and outputs the optimal mask pixel values. The MLP is trained with the backpropagation algorithm, with a training set retrieved from the desired output pattern, and the optimal mask pattern obtained by the model-based method. After training, the MLP is able to generate the optimal mask pattern non-iteratively with good pattern fidelity.

  3. Neural imaging in songbirds using fiber optic fluorescence microscopy

    Science.gov (United States)

    Nooshabadi, Fatemeh; Hearn, Gentry; Lints, Thierry; Maitland, Kristen C.

    2012-02-01

    The song control system of juvenile songbirds is an important model for studying the developmental acquisition and generation of complex learned vocal motor sequences, two processes that are fundamental to human speech and language. To understand the neural mechanisms underlying song production, it is critical to characterize the activity of identified neurons in the song control system when the bird is singing. Neural imaging in unrestrained singing birds, although technically challenging, will advance our understanding of neural ensemble coding mechanisms in this system. We are exploring the use of a fiber optic microscope for functional imaging in the brain of behaving and singing birds in order to better understand the contribution of a key brain nucleus (high vocal center nucleus; HVC) to temporal aspects of song motor control. We have constructed a fluorescence microscope with LED illumination, a fiber bundle for transmission of fluorescence excitation and emission light, a ~2x GRIN lens, and a CCD for image acquisition. The system has 2 μm resolution, 375 μm field of view, 200 μm working distance, and 1 mm outer diameter. As an initial characterization of this setup, neurons in HVC were imaged using the fiber optic microscope after injection of quantum dots or fluorescent retrograde tracers into different song nuclei. A Lucid Vivascope confocal microscope was used to confirm the imaging results. Long-term imaging of the activity of these neurons in juvenile birds during singing may lead us to a better understanding of the central motor codes for song and the central mechanism by which auditory experience modifies song motor commands to enable vocal learning and imitation.

  4. Quantum-dot based nanothermometry in optical plasmonic recording media

    Energy Technology Data Exchange (ETDEWEB)

    Maestro, Laura Martinez [Fluorescence Imaging Group, Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Zhang, Qiming; Li, Xiangping; Gu, Min [Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Jaque, Daniel [Fluorescence Imaging Group, Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Autónoma de Madrid, Madrid 28049 (Spain)

    2014-11-03

    We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media.

  5. Enumerative Encoding of TMTR Codes for Optical Recording Channel

    Directory of Open Access Journals (Sweden)

    Tsai Hui-Feng

    2010-01-01

    Full Text Available We propose a new time-varying maximum transition run (TMTR code for DVD recording systems, which has a rate higher than the EFMPlus code and a lower power spectral density (PSD at low frequencies. An enumeration method for constructing the new TMTR code is presented. Computer simulations indicate that the proposed TMTR code outperforms the EFMPlus code in error performance when applied to partial response optical recording channels.

  6. A low-power 32-channel digitally programmable neural recording integrated circuit.

    Science.gov (United States)

    Wattanapanitch, W; Sarpeshkar, R

    2011-12-01

    We report the design of an ultra-low-power 32-channel neural-recording integrated circuit (chip) in a 0.18 μ m CMOS technology. The chip consists of eight neural recording modules where each module contains four neural amplifiers, an analog multiplexer, an A/D converter, and a serial programming interface. Each amplifier can be programmed to record either spikes or LFPs with a programmable gain from 49-66 dB. To minimize the total power consumption, an adaptive-biasing scheme is utilized to adjust each amplifier's input-referred noise to suit the background noise at the recording site. The amplifier's input-referred noise can be adjusted from 11.2 μVrms (total power of 5.4 μW) down to 5.4 μVrms (total power of 20 μW) in the spike-recording setting. The ADC in each recording module digitizes the a.c. signal input to each amplifier at 8-bit precision with a sampling rate of 31.25 kS/s per channel, with an average power consumption of 483 nW per channel, and, because of a.c. coupling, allows d.c. operation over a wide dynamic range. It achieves an ENOB of 7.65, resulting in a net efficiency of 77 fJ/State, making it one of the most energy-efficient designs for neural recording applications. The presented chip was successfully tested in an in vivo wireless recording experiment from a behaving primate with an average power dissipation per channel of 10.1 μ W. The neural amplifier and the ADC occupy areas of 0.03 mm(2) and 0.02 mm(2) respectively, making our design simultaneously area efficient and power efficient, thus enabling scaling to high channel-count systems.

  7. Optical Imaging of Neuronal Activity and Visualization of Fine Neural Structures in Non-Desheathed Nervous Systems

    Science.gov (United States)

    Stein, Wolfgang

    2014-01-01

    Locating circuit neurons and recording from them with single-cell resolution is a prerequisite for studying neural circuits. Determining neuron location can be challenging even in small nervous systems because neurons are densely packed, found in different layers, and are often covered by ganglion and nerve sheaths that impede access for recording electrodes and neuronal markers. We revisited the voltage-sensitive dye RH795 for its ability to stain and record neurons through the ganglion sheath. Bath-application of RH795 stained neuronal membranes in cricket, earthworm and crab ganglia without removing the ganglion sheath, revealing neuron cell body locations in different ganglion layers. Using the pyloric and gastric mill central pattern generating neurons in the stomatogastric ganglion (STG) of the crab, Cancer borealis, we found that RH795 permeated the ganglion without major residue in the sheath and brightly stained somatic, axonal and dendritic membranes. Visibility improved significantly in comparison to unstained ganglia, allowing the identification of somata location and number of most STG neurons. RH795 also stained axons and varicosities in non-desheathed nerves, and it revealed the location of sensory cell bodies in peripheral nerves. Importantly, the spike activity of the sensory neuron AGR, which influences the STG motor patterns, remained unaffected by RH795, while desheathing caused significant changes in AGR activity. With respect to recording neural activity, RH795 allowed us to optically record membrane potential changes of sub-sheath neuronal membranes without impairing sensory activity. The signal-to-noise ratio was comparable with that previously observed in desheathed preparations and sufficiently high to identify neurons in single-sweep recordings and synaptic events after spike-triggered averaging. In conclusion, RH795 enabled staining and optical recording of neurons through the ganglion sheath and is therefore both a good anatomical

  8. Optical imaging of neuronal activity and visualization of fine neural structures in non-desheathed nervous systems.

    Directory of Open Access Journals (Sweden)

    Christopher John Goldsmith

    Full Text Available Locating circuit neurons and recording from them with single-cell resolution is a prerequisite for studying neural circuits. Determining neuron location can be challenging even in small nervous systems because neurons are densely packed, found in different layers, and are often covered by ganglion and nerve sheaths that impede access for recording electrodes and neuronal markers. We revisited the voltage-sensitive dye RH795 for its ability to stain and record neurons through the ganglion sheath. Bath-application of RH795 stained neuronal membranes in cricket, earthworm and crab ganglia without removing the ganglion sheath, revealing neuron cell body locations in different ganglion layers. Using the pyloric and gastric mill central pattern generating neurons in the stomatogastric ganglion (STG of the crab, Cancer borealis, we found that RH795 permeated the ganglion without major residue in the sheath and brightly stained somatic, axonal and dendritic membranes. Visibility improved significantly in comparison to unstained ganglia, allowing the identification of somata location and number of most STG neurons. RH795 also stained axons and varicosities in non-desheathed nerves, and it revealed the location of sensory cell bodies in peripheral nerves. Importantly, the spike activity of the sensory neuron AGR, which influences the STG motor patterns, remained unaffected by RH795, while desheathing caused significant changes in AGR activity. With respect to recording neural activity, RH795 allowed us to optically record membrane potential changes of sub-sheath neuronal membranes without impairing sensory activity. The signal-to-noise ratio was comparable with that previously observed in desheathed preparations and sufficiently high to identify neurons in single-sweep recordings and synaptic events after spike-triggered averaging. In conclusion, RH795 enabled staining and optical recording of neurons through the ganglion sheath and is therefore both a

  9. Neural signal processing and closed-loop control algorithm design for an implanted neural recording and stimulation system.

    Science.gov (United States)

    Hamilton, Lei; McConley, Marc; Angermueller, Kai; Goldberg, David; Corba, Massimiliano; Kim, Louis; Moran, James; Parks, Philip D; Sang Chin; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    A fully autonomous intracranial device is built to continually record neural activities in different parts of the brain, process these sampled signals, decode features that correlate to behaviors and neuropsychiatric states, and use these features to deliver brain stimulation in a closed-loop fashion. In this paper, we describe the sampling and stimulation aspects of such a device. We first describe the signal processing algorithms of two unsupervised spike sorting methods. Next, we describe the LFP time-frequency analysis and feature derivation from the two spike sorting methods. Spike sorting includes a novel approach to constructing a dictionary learning algorithm in a Compressed Sensing (CS) framework. We present a joint prediction scheme to determine the class of neural spikes in the dictionary learning framework; and, the second approach is a modified OSort algorithm which is implemented in a distributed system optimized for power efficiency. Furthermore, sorted spikes and time-frequency analysis of LFP signals can be used to generate derived features (including cross-frequency coupling, spike-field coupling). We then show how these derived features can be used in the design and development of novel decode and closed-loop control algorithms that are optimized to apply deep brain stimulation based on a patient's neuropsychiatric state. For the control algorithm, we define the state vector as representative of a patient's impulsivity, avoidance, inhibition, etc. Controller parameters are optimized to apply stimulation based on the state vector's current state as well as its historical values. The overall algorithm and software design for our implantable neural recording and stimulation system uses an innovative, adaptable, and reprogrammable architecture that enables advancement of the state-of-the-art in closed-loop neural control while also meeting the challenges of system power constraints and concurrent development with ongoing scientific research designed

  10. Accelerated optical holographic recording using bis-DNO

    DEFF Research Database (Denmark)

    Rasmussen, Palle H.; Ramanujam, P.S.; Hvilsted, Søren

    1999-01-01

    The design, synthesis and optical holographic recording properties of bis-DNO are reported. Bis-DNO is composed of two identical azobenzene oligoornithine segments (DNO) connected via a dipeptide linker. The two segments were assembled in a parallel fashion at the two amino groups of the dipeptide...

  11. Neural networks for the optical recognition of defects in cloth

    Science.gov (United States)

    Hoffer, Lois M.; Francini, Franco; Tiribilli, Bruno; Longobardi, Giuseppe

    1996-11-01

    A fast system to reveal the presence and type of fabric defects during the weaving process is developed. Since the fabric is similar to a 2D grid, its defects are clearly observed in the changes in its optical Fourier transform (OFT), which appears stationary while the fabric is moving across the loom. Previous work, based on the statistical parameters of the OFT, showed that the presence of faults can be detected when only global changes in the images are considered. We show that by selecting a small subset of pixels from the image as input to a neural network, fabric defects can not only be detected but also successfully identified. A knowledge-based system could conceivably be constructed to use this information to resolve problems with the loom in real time, without the need for operator intervention.

  12. A multi-channel fully differential programmable integrated circuit for neural recording application

    Science.gov (United States)

    Yun, Gui; Xu, Zhang; Yuan, Wang; Ming, Liu; Weihua, Pei; Kai, Liang; Suibiao, Huang; Bin, Li; Hongda, Chen

    2013-10-01

    A multi-channel, fully differential programmable chip for neural recording application is presented. The integrated circuit incorporates eight neural recording amplifiers with tunable bandwidth and gain, eight 4th-order Bessel switch capacitor filters, an 8-to-1 analog time-division multiplexer, a fully differential successive approximation register analog-to-digital converter (SAR ADC), and a serial peripheral interface for communication. The neural recording amplifier presents a programmable gain from 53 dB to 68 dB, a tunable low cut-off frequency from 0.1 Hz to 300 Hz, and 3.77 μVrms input-referred noise over a 5 kHz bandwidth. The SAR ADC digitizes signals at maximum sampling rate of 20 kS/s per channel and achieves an ENOB of 7.4. The integrated circuit is designed and fabricated in 0.18-μm CMOS mix-signal process. We successfully performed a multi-channel in-vivo recording experiment from a rat cortex using the neural recording chip.

  13. Evaluating a genetically encoded optical sensor of neural activity using electrophysiology in intact adult fruit flies

    Directory of Open Access Journals (Sweden)

    Gilles Laurent

    2007-11-01

    Full Text Available Genetically encoded optical indicators hold the promise of enabling non-invasive monitoring of activity in identified neurons in behaving organisms. However, the interpretation of images of brain activity produced using such sensors is not straightforward. Several recent studies of sensory coding used G-CaMP 1.3-a calcium sensor-as an indicator of neural activity; some of these studies characterized the imaged neurons as having narrow tuning curves, a conclusion not always supported by parallel electrophysiological studies. To better understand the possible cause of these conflicting results, we performed simultaneous in vivo 2-photon imaging and electrophysiological recording of G-CaMP 1.3 expressing neurons in the antennal lobe (AL of intact fruitflies. We find that G-CaMP has a relatively high threshold, that its signal often fails to capture spiking response kinetics, and that it can miss even high instantaneous rates of activity if those are not sustained. While G-CaMP can be misleading, it is clearly useful for the identification of promising neural targets: when electrical activity is well above the sensor's detection threshold, its signal is fairly well correlated with mean firing rate and G-CaMP does not appear to alter significantly the responses of neurons that express it. The methods we present should enable any genetically encoded sensor, activator, or silencer to be evaluated in an intact neural circuit in vivo in Drosophila.

  14. Model validation of untethered, ultrasonic neural dust motes for cortical recording.

    Science.gov (United States)

    Seo, Dongjin; Carmena, Jose M; Rabaey, Jan M; Maharbiz, Michel M; Alon, Elad

    2015-04-15

    A major hurdle in brain-machine interfaces (BMI) is the lack of an implantable neural interface system that remains viable for a substantial fraction of the user's lifetime. Recently, sub-mm implantable, wireless electromagnetic (EM) neural interfaces have been demonstrated in an effort to extend system longevity. However, EM systems do not scale down in size well due to the severe inefficiency of coupling radio-waves at those scales within tissue. This paper explores fundamental system design trade-offs as well as size, power, and bandwidth scaling limits of neural recording systems built from low-power electronics coupled with ultrasonic power delivery and backscatter communication. Such systems will require two fundamental technology innovations: (1) 10-100 μm scale, free-floating, independent sensor nodes, or neural dust, that detect and report local extracellular electrophysiological data via ultrasonic backscattering and (2) a sub-cranial ultrasonic interrogator that establishes power and communication links with the neural dust. We provide experimental verification that the predicted scaling effects follow theory; (127 μm)(3) neural dust motes immersed in water 3 cm from the interrogator couple with 0.002064% power transfer efficiency and 0.04246 ppm backscatter, resulting in a maximum received power of ∼0.5 μW with ∼1 nW of change in backscatter power with neural activity. The high efficiency of ultrasonic transmission can enable the scaling of the sensing nodes down to 10s of micrometer. We conclude with a brief discussion of the application of neural dust for both central and peripheral nervous system recordings, and perspectives on future research directions.

  15. Simultaneous measurement of neural spike recordings and multi-photon calcium imaging in neuroblastoma cells.

    Science.gov (United States)

    Kim, Suhwan; Jung, Unsang; Baek, Juyeong; Kang, Shinwon; Kim, Jeehyun

    2012-11-08

    This paper proposes the design and implementation of a micro-electrode array (MEA) for neuroblastoma cell culturing. It also explains the implementation of a multi-photon microscope (MPM) customized for neuroblastoma cell excitation and imaging under ambient light. Electrical signal and fluorescence images were simultaneously acquired from the neuroblastoma cells on the MEA. MPM calcium images of the cultured neuroblastoma cell on the MEA are presented and also the neural activity was acquired through the MEA recording. A calcium green-1 (CG-1) dextran conjugate of 10,000 D molecular weight was used in this experiment for calcium imaging. This study also evaluated the calcium oscillations and neural spike recording of neuroblastoma cells in an epileptic condition. Based on our observation of neural spikes in neuroblastoma cells with our proposed imaging modality, we report that neuroblastoma cells can be an important model for epileptic activity studies.

  16. A Bayesian regularized artificial neural network for adaptive optics forecasting

    Science.gov (United States)

    Sun, Zhi; Chen, Ying; Li, Xinyang; Qin, Xiaolin; Wang, Huiyong

    2017-01-01

    Real-time adaptive optics is a technology for enhancing the resolution of ground-based optical telescopes and overcoming the disturbance of atmospheric turbulence. The performance of the system is limited by delay errors induced by the servo system and photoelectrons noise of wavefront sensor. In order to cut these delay errors, this paper proposes a novel model to forecast the future control voltages of the deformable mirror. The predictive model is constructed by a multi-layered back propagation network with Bayesian regularization (BRBP). For the purpose of parallel computation and less disturbance, we adopt a number of sub-BP neural networks to substitute the whole network. The Bayesian regularized network assigns a probability to the network weights, allowing the network to automatically and optimally penalize excessively complex models. The simulation results show that the BRBP introduces smaller mean absolute percentage error (MAPE) and mean square errors (MSE) than other typical algorithms. Meanwhile, real data analysis results show that the BRBP model has strong generalization capability and parallelism.

  17. Review: Human Intracortical recording and neural decoding for brain-computer interfaces.

    Science.gov (United States)

    Brandman, David M; Cash, Sydney S; Hochberg, Leigh R

    2017-03-02

    Brain Computer Interfaces (BCIs) use neural information recorded from the brain for voluntary control of external devices. The development of BCI systems has largely focused on improving functional independence for individuals with severe motor impairments, including providing tools for communication and mobility. In this review, we describe recent advances in intracortical BCI technology and provide potential directions for further research.

  18. Optical path of infrared neural stimulation in the guinea pig and cat cochlea

    Science.gov (United States)

    Rajguru, Suhrud M.; Hwang, Margaret; Moreno, Laura E.; Matic, Agnella I.; Stock, Stuart R.; Richter, Claus-Peter

    2011-03-01

    It has been demonstrated previously that infrared neural stimulation (INS) can be used to stimulate spiral ganglion cells in the cochlea. With INS, neural stimulation can be achieved without direct contact of the radiation source and the tissue and is spatially well resolved. The presence of fluids or bone between the target structure and the radiation source may lead to absorption or scattering of the radiation and limit the efficacy of INS. To develop INS based cochlear implants, it is critical to determine the beam path of the radiation in the cochlea. In the present study, we utilized noninvasive X-ray microtomography (microCT) to visualize the orientation and location of the optical fiber within the guinea pig and cat cochlea. Overall, the results indicated that the optical fiber was directed towards the spiral ganglion cells in the cochlea and not the nerve fibers in the center of the modiolus. The fiber was approximately 300 μm away from the target structures. In future studies, results from the microCT will be correlated with physiology obtained from recordings in the midbrain.

  19. Multilevel optical data recording methods on phase-change media

    Institute of Scientific and Technical Information of China (English)

    肖家曦; 齐国生; 佘鹏; 刘嵘; 徐端颐

    2003-01-01

    Multilevel data storage (ML) is a new method in the optical storage field, which is also a trend for improving the capability of future optical discs. This article introduces several ML methods based on phase-change media including pit depth modulation (PDM) and mark radial width modulation (MRWM). In addition, some disadvantages and advantages concerning the principle of these methods will be discussed. Finally, a new ML method will be advanced, through which the levels in one recording pit will be increased evidently.

  20. Optical voice recorder by off-axis digital holography.

    Science.gov (United States)

    Matoba, Osamu; Inokuchi, Hiroki; Nitta, Kouichi; Awatsuji, Yasuhiro

    2014-11-15

    An optical voice recorder capable of recording and reproducing propagating sound waves by using off-axis digital holography, as well as quantitative visualization, is presented. Propagating sound waves temporally modulate the phase distribution of an impinging light wave via refractive index changes. This temporally modulated phase distribution is recorded in the form of digital holograms by a high-speed image sensor. After inverse propagation using Fresnel diffraction of a series of the recorded holograms, the temporal phase profile of the reconstructed object wave at each three-dimensional position can be used to reproduce the original sound wave. Experimental results using a tuning fork vibrating at 440 Hz and a human voice are presented to show the feasibility of the proposed method.

  1. Logarithmic r-θ mapping for hybrid optical neural network filter for multiple objects recognition within cluttered scenes

    Science.gov (United States)

    Kypraios, Ioannis; Young, Rupert C. D.; Chatwin, Chris R.; Birch, Phil M.

    2009-04-01

    θThe window unit in the design of the complex logarithmic r-θ mapping for hybrid optical neural network filter can allow multiple objects of the same class to be detected within the input image. Additionally, the architecture of the neural network unit of the complex logarithmic r-θ mapping for hybrid optical neural network filter becomes attractive for accommodating the recognition of multiple objects of different classes within the input image by modifying the output layer of the unit. We test the overall filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. Logarithmic r-θ mapping for hybrid optical neural network filter is shown to exhibit with a single pass over the input data simultaneously in-plane rotation, out-of-plane rotation, scale, log r-θ map translation and shift invariance, and good clutter tolerance by recognizing correctly the different objects within the cluttered scenes. We record in our results additional extracted information from the cluttered scenes about the objects' relative position, scale and in-plane rotation.

  2. Parallel optical evaluation of double-exposure records in optical metrology.

    Science.gov (United States)

    Arnold, W; Hinsch, K D

    1989-02-15

    The evaluation of double-exposure records in optical metrology (speckle photography or particle image velocimetry) is simplified by using two-step optical processing that is performed on many interrogation areas simultaneously by a 2-D array of narrow focused light beams. A first application of this procedure to the original record, if dimensioned properly, produces an array of small nonoverlapping Young's fringe systems. The photographic record of these patterns is subjected to the same operation once more, each beam illuminating precisely one pattern. The resulting output is an array of autocorrelation functions that are a direct representation of the displacement field since the spacing of respective side peaks gives the displacement. A single whole-field interrogation of the array of fringe systems produces an optical representation of accumulated displacement values thus rendering the statistics of the displacement field. The required matrix of light beams is generated by holographic optical elements.

  3. A Micromachined SiO2/Silicon Probe for Neural Signal Recordings

    Institute of Scientific and Technical Information of China (English)

    SUI Xiao-Hong; PEI Wei-Hua; ZHANG Ruo-Xin; LU Lin; CHEN Hong-Da

    2006-01-01

    @@ The development of an implantable five channel microelectrode array is presented for neural signal recordings.The detailed fabrication process is outlined with four masks used. The SEM images show that the probe shank is 1.2 mm long, 100 μm wide and 30 μm thick with the recording sites spaced 200 μm apart for good signal isolation.The plot of the single recording site impedance versus frequency is shown by test in vitro and the impedance declines with the increasing frequency. Experiment in vivo using this probe is under way.

  4. High Speed PAM -8 Optical Interconnects with Digital Equalization based on Neural Network

    DEFF Research Database (Denmark)

    Gaiarin, Simone; Pang, Xiaodan; Ozolins, Oskars

    2016-01-01

    We experimentally evaluate a high-speed optical interconnection link with neural network equalization. Enhanced equalization performances are shown comparing to standard linear FFE for an EML-based 32 GBd PAM-8 signal after 4-km SMF transmission.......We experimentally evaluate a high-speed optical interconnection link with neural network equalization. Enhanced equalization performances are shown comparing to standard linear FFE for an EML-based 32 GBd PAM-8 signal after 4-km SMF transmission....

  5. High Speed PAM -8 Optical Interconnects with Digital Equalization based on Neural Network

    DEFF Research Database (Denmark)

    Gaiarin, Simone; Pang, Xiaodan; Ozolins, Oskars

    2016-01-01

    We experimentally evaluate a high-speed optical interconnection link with neural network equalization. Enhanced equalization performances are shown comparing to standard linear FFE for an EML-based 32 GBd PAM-8 signal after 4-km SMF transmission.......We experimentally evaluate a high-speed optical interconnection link with neural network equalization. Enhanced equalization performances are shown comparing to standard linear FFE for an EML-based 32 GBd PAM-8 signal after 4-km SMF transmission....

  6. A multichannel integrated circuit for electrical recording of neural activity, with independent channel programmability.

    Science.gov (United States)

    Mora Lopez, Carolina; Prodanov, Dimiter; Braeken, Dries; Gligorijevic, Ivan; Eberle, Wolfgang; Bartic, Carmen; Puers, Robert; Gielen, Georges

    2012-04-01

    Since a few decades, micro-fabricated neural probes are being used, together with microelectronic interfaces, to get more insight in the activity of neuronal networks. The need for higher temporal and spatial recording resolutions imposes new challenges on the design of integrated neural interfaces with respect to power consumption, data handling and versatility. In this paper, we present an integrated acquisition system for in vitro and in vivo recording of neural activity. The ASIC consists of 16 low-noise, fully-differential input channels with independent programmability of its amplification (from 100 to 6000 V/V) and filtering (1-6000 Hz range) capabilities. Each channel is AC-coupled and implements a fourth-order band-pass filter in order to steeply attenuate out-of-band noise and DC input offsets. The system achieves an input-referred noise density of 37 nV/√Hz, a NEF of 5.1, a CMRR > 60 dB, a THD < 1% and a sampling rate of 30 kS/s per channel, while consuming a maximum of 70 μA per channel from a single 3.3 V. The ASIC was implemented in a 0.35 μm CMOS technology and has a total area of 5.6 × 4.5 mm². The recording system was successfully validated in in vitro and in vivo experiments, achieving simultaneous multichannel recordings of cell activity with satisfactory signal-to-noise ratios.

  7. TECHNICAL NOTE: The development of a PZT-based microdrive for neural signal recording

    Science.gov (United States)

    Park, Sangkyu; Yoon, Euisung; Lee, Sukchan; Shin, Hee-sup; Park, Hyunjun; Kim, Byungkyu; Kim, Daesoo; Park, Jongoh; Park, Sukho

    2008-04-01

    A hand-controlled microdrive has been used to obtain neural signals from rodents such as rats and mice. However, it places severe physical stress on the rodents during its manipulation, and this stress leads to alertness in the mice and low efficiency in obtaining neural signals from the mice. To overcome this issue, we developed a novel microdrive, which allows one to adjust the electrodes by a piezoelectric device (PZT) with high precision. Its mass is light enough to install on the mouse's head. The proposed microdrive has three H-type PZT actuators and their guiding structure. The operation principle of the microdrive is based on the well known inchworm mechanism. When the three PZT actuators are synchronized, linear motion of the electrode is produced along the guiding structure. The electrodes used for the recording of the neural signals from neuron cells were fixed at one of the PZT actuators. Our proposed microdrive has an accuracy of about 400 nm and a long stroke of about 5 mm. In response to formalin-induced pain, single unit activities are robustly measured at the thalamus with electrodes whose vertical depth is adjusted by the microdrive under urethane anesthesia. In addition, the microdrive was efficient in detecting neural signals from mice that were moving freely. Thus, the present study suggests that the PZT-based microdrive could be an alternative for the efficient detection of neural signals from mice during behavioral states without any stress to the mice.

  8. Optical implementation of a feature-based neural network with application to automatic target recognition

    Science.gov (United States)

    Chao, Tien-Hsin; Stoner, William W.

    1993-01-01

    An optical neural network based on the neocognitron paradigm is introduced. A novel aspect of the architecture design is shift-invariant multichannel Fourier optical correlation within each processing layer. Multilayer processing is achieved by feeding back the ouput of the feature correlator interatively to the input spatial light modulator and by updating the Fourier filters. By training the neural net with characteristic features extracted from the target images, successful pattern recognition with intraclass fault tolerance and interclass discrimination is achieved. A detailed system description is provided. Experimental demonstrations of a two-layer neural network for space-object discrimination is also presented.

  9. Neural recording front-end IC using action potential detection and analog buffer with digital delay for data compression.

    Science.gov (United States)

    Liu, Lei; Yao, Lei; Zou, Xiaodan; Goh, Wang Ling; Je, Minkyu

    2013-01-01

    This paper presents a neural recording analog front-end IC intended for simultaneous neural recording with action potential (AP) detection for data compression in wireless multichannel neural implants. The proposed neural recording front-end IC detects the neural spikes and sends only the preserved AP information for wireless transmission in order to reduce the overall power consumption of the neural implant. The IC consists of a low-noise neural amplifier, an AP detection circuit and an analog buffer with digital delay. The neural amplifier makes use of a current-reuse technique to maximize the transconductance efficiency for attaining a good noise efficiency factor. The AP detection circuit uses an adaptive threshold voltage to generate an enable signal for the subsequent functional blocks. The analog buffer with digital delay is employed using a finite impulse response (FIR) filter which preserves the AP waveform before the enable signal as well as provides low-pass filtering. The neural recording front-end IC has been designed using standard CMOS 0.18-µm technology occupying a core area of 220 µm by 820 µm.

  10. Image density property of optical information recording microcapsule material

    Science.gov (United States)

    Lai, Weidong; Li, Xiaowei; Li, Xinzheng; Fu, Guangsheng

    2009-05-01

    The microcapsules can act as novel optical functional material in which the optical recording substance such as color-forming substance, photoinitiator and prepolymer are encapsulated. In this paper, the microcapsules with average particle diameter of 300nm are prepared with interfacial polymerization method. The optical responding character of the microcapsule is analyzed based on IR spectra and image density technique. Results show that the microcapsule material encapsulated prepolymer TMPTA and photoinitiator Irgacure-ITX, TPO has thermal phase-change at 140°C, at which the penetrability of the microcapsule has the highest efficiency. With the increase of exposure time, the reduction in absorption intensities of the prepolymer TMPTA are observed at 1635cm-1 of C=C stretching and 898cm-1 of C-H stretching on the C=C molecular bond. Such a result can be ascribed to the double bond cleavage process of the prepolymer TMPTA is initiated by the optical-exposed photoinitiator, and superpolymer network is formed. The image density contrast between the unexposed and exposed microcapsule is enhanced with exposure time increased.

  11. Recurrent Neural Networks for Polyphonic Sound Event Detection in Real Life Recordings

    OpenAIRE

    Parascandolo, Giambattista; Huttunen, Heikki; Virtanen, Tuomas

    2016-01-01

    In this paper we present an approach to polyphonic sound event detection in real life recordings based on bi-directional long short term memory (BLSTM) recurrent neural networks (RNNs). A single multilabel BLSTM RNN is trained to map acoustic features of a mixture signal consisting of sounds from multiple classes, to binary activity indicators of each event class. Our method is tested on a large database of real-life recordings, with 61 classes (e.g. music, car, speech) from 10 different ever...

  12. Design techniques and analysis of high-resolution neural recording systems targeting epilepsy focus localization.

    Science.gov (United States)

    Shoaran, Mahsa; Pollo, Claudio; Leblebici, Yusuf; Schmid, Alexandre

    2012-01-01

    The design of a high-density neural recording system targeting epilepsy monitoring is presented. Circuit challenges and techniques are discussed to optimize the amplifier topology and the included OTA. A new platform supporting active recording devices targeting wireless and high-resolution focus localization in epilepsy diagnosis is also proposed. The post-layout simulation results of an amplifier dedicated to this application are presented. The amplifier is designed in a UMC 0.18µm CMOS technology, has an NEF of 2.19 and occupies a silicon area of 0.038 mm(2), while consuming 5.8 µW from a 1.8-V supply.

  13. An implantable wireless neural interface for recording cortical circuit dynamics in moving primates

    Science.gov (United States)

    Borton, David A.; Yin, Ming; Aceros, Juan; Nurmikko, Arto

    2013-04-01

    Objective. Neural interface technology suitable for clinical translation has the potential to significantly impact the lives of amputees, spinal cord injury victims and those living with severe neuromotor disease. Such systems must be chronically safe, durable and effective. Approach. We have designed and implemented a neural interface microsystem, housed in a compact, subcutaneous and hermetically sealed titanium enclosure. The implanted device interfaces the brain with a 510k-approved, 100-element silicon-based microelectrode array via a custom hermetic feedthrough design. Full spectrum neural signals were amplified (0.1 Hz to 7.8 kHz, 200× gain) and multiplexed by a custom application specific integrated circuit, digitized and then packaged for transmission. The neural data (24 Mbps) were transmitted by a wireless data link carried on a frequency-shift-key-modulated signal at 3.2 and 3.8 GHz to a receiver 1 m away by design as a point-to-point communication link for human clinical use. The system was powered by an embedded medical grade rechargeable Li-ion battery for 7 h continuous operation between recharge via an inductive transcutaneous wireless power link at 2 MHz. Main results. Device verification and early validation were performed in both swine and non-human primate freely-moving animal models and showed that the wireless implant was electrically stable, effective in capturing and delivering broadband neural data, and safe for over one year of testing. In addition, we have used the multichannel data from these mobile animal models to demonstrate the ability to decode neural population dynamics associated with motor activity. Significance. We have developed an implanted wireless broadband neural recording device evaluated in non-human primate and swine. The use of this new implantable neural interface technology can provide insight into how to advance human neuroprostheses beyond the present early clinical trials. Further, such tools enable mobile

  14. Observation of Amorphous Recording Marks Using Reflection-Mode Near-Field Scanning Optical Microscope Supported by Optical Interference Method

    Science.gov (United States)

    Sakai, Masaru; Mononobe, Shuji; Yusu, Keiichiro; Tadokoro, Toshiyasu; Saiki, Toshiharu

    2005-09-01

    A signal enhancing technique for a reflection-mode near-field scanning optical microscope (NSOM) is proposed. Optical interference between the signal light, from an aperture at the tip of a tapered optical fiber, and the reflected light, from a metallic coating around the aperture, enhances the signal intensity. We used a rewritable high-definition digital versatile disc (HD DVD) with dual recording layers as a sample medium, and demonstrated observation of amorphous recording marks on the semitransparent (the first) recording layer. In spite of low optical contrast between the crystal region and the amorphous region on this layer, we successfully observed recording marks with good contrast.

  15. Neural organization and visual processing in the anterior optic tubercle of the honeybee brain.

    Science.gov (United States)

    Mota, Theo; Yamagata, Nobuhiro; Giurfa, Martin; Gronenberg, Wulfila; Sandoz, Jean-Christophe

    2011-08-10

    The honeybee Apis mellifera represents a valuable model for studying the neural segregation and integration of visual information. Vision in honeybees has been extensively studied at the behavioral level and, to a lesser degree, at the physiological level using intracellular electrophysiological recordings of single neurons. However, our knowledge of visual processing in honeybees is still limited by the lack of functional studies of visual processing at the circuit level. Here we contribute to filling this gap by providing a neuroanatomical and neurophysiological characterization at the circuit level of a practically unstudied visual area of the bee brain, the anterior optic tubercle (AOTu). First, we analyzed the internal organization and neuronal connections of the AOTu. Second, we established a novel protocol for performing optophysiological recordings of visual circuit activity in the honeybee brain and studied the responses of AOTu interneurons during stimulation of distinct eye regions. Our neuroanatomical data show an intricate compartmentalization and connectivity of the AOTu, revealing a dorsoventral segregation of the visual input to the AOTu. Light stimuli presented in different parts of the visual field (dorsal, lateral, or ventral) induce distinct patterns of activation in AOTu output interneurons, retaining to some extent the dorsoventral input segregation revealed by our neuroanatomical data. In particular, activity patterns evoked by dorsal and ventral eye stimulation are clearly segregated into distinct AOTu subunits. Our results therefore suggest an involvement of the AOTu in the processing of dorsoventrally segregated visual information in the honeybee brain.

  16. Holographic optical elements recorded in silver halide sensitized gelatin emulsions. Part I. Transmission holographic optical elements.

    Science.gov (United States)

    Kim, J M; Choi, B S; Kim, S I; Kim, J M; Bjelkhagen, H I; Phillips, N J

    2001-02-10

    Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOE's). The drawback of DCG is its low sensitivity and limited spectral response. Silver halide materials can be processed in such a way that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-high-resolution silver halide emulsions. An optimized processing technique for transmission HOE's recorded in these materials is introduced. Diffraction efficiencies over 90% can be obtained for transmissive diffraction gratings. Understanding the importance of the selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOE's.

  17. Decision-Directed Correction for Bloom in Optical Recording Channels

    Science.gov (United States)

    Gopalaswamy, Srinivasan; Kee, Ng See; Farhang-Boroujeny, B.

    2000-02-01

    A threshold adaptation scheme is proposed in a non-Viterbi simple detector for d=2 minimum run-length-constraint coded optical recording schemes, to increase robustness to bloom. The detector has a simple structure comprising of a threshold detector, post processing error correction, and decision directed threshold adaptation. The equalization target is a free symmetric 7-tap target and the detection exploits the d=2 constraint in the input sequence. The detector is evaluated for digital versatile disk (DVD) specifications and compared with other threshold-based detectors as well as Viterbi detectors following targets of length up to 5. Performance improvement of over 1.5 dB is observed with the proposed feature for bloom larger than 15% of the channel bit period.

  18. The Relationship Between Flying Height Variation of the Flying Optical Head and Statistical Recording Density in Near—field Optical Recording

    Institute of Scientific and Technical Information of China (English)

    PEIXiandeng,; ZHANGXiaoga; HUANGHao

    2003-01-01

    This paper models the head-disk cou-pling in waveguide probe near-field recording, and derives the relationship curve between full width at half maxi-mum (FWHM) of static light distribution as well as static recording density and near-field coupling distance by com-puter simulation. Then after defining the FWHM of sta-tistical light distribution and statistical recording density,we discuss the relationship between flying height variation of the flying optical head and statistical recording density in near-field optical recording.

  19. Training-free compressed sensing for wireless neural recording using analysis model and group weighted [Formula: see text]-minimization.

    Science.gov (United States)

    Sun, Biao; Zhao, Wenfeng; Zhu, Xinshan

    2017-06-01

    Data compression is crucial for resource-constrained wireless neural recording applications with limited data bandwidth, and compressed sensing (CS) theory has successfully demonstrated its potential in neural recording applications. In this paper, an analytical, training-free CS recovery method, termed group weighted analysis [Formula: see text]-minimization (GWALM), is proposed for wireless neural recording. The GWALM method consists of three parts: (1) the analysis model is adopted to enforce sparsity of the neural signals, therefore overcoming the drawbacks of conventional synthesis models and enhancing the recovery performance. (2) A multi-fractional-order difference matrix is constructed as the analysis operator, thus avoiding the dictionary learning procedure and reducing the need for previously acquired data and computational complexities. (3) By exploiting the statistical properties of the analysis coefficients, a group weighting approach is developed to enhance the performance of analysis [Formula: see text]-minimization. Experimental results on synthetic and real datasets reveal that the proposed approach outperforms state-of-the-art CS-based methods in terms of both spike recovery quality and classification accuracy. Energy and area efficiency of the GWALM make it an ideal candidate for resource-constrained, large scale wireless neural recording applications. The training-free feature of the GWALM further improves its robustness to spike shape variation, thus making it more practical for long term wireless neural recording.

  20. Reorganization of neural systems mediating peripheral visual selective attention in the deaf: An optical imaging study.

    Science.gov (United States)

    Seymour, Jenessa L; Low, Kathy A; Maclin, Edward L; Chiarelli, Antonio M; Mathewson, Kyle E; Fabiani, Monica; Gratton, Gabriele; Dye, Matthew W G

    2017-01-01

    Theories of brain plasticity propose that, in the absence of input from the preferred sensory modality, some specialized brain areas may be recruited when processing information from other modalities, which may result in improved performance. The Useful Field of View task has previously been used to demonstrate that early deafness positively impacts peripheral visual attention. The current study sought to determine the neural changes associated with those deafness-related enhancements in visual performance. Based on previous findings, we hypothesized that recruitment of posterior portions of Brodmann area 22, a brain region most commonly associated with auditory processing, would be correlated with peripheral selective attention as measured using the Useful Field of View task. We report data from severe to profoundly deaf adults and normal-hearing controls who performed the Useful Field of View task while cortical activity was recorded using the event-related optical signal. Behavioral performance, obtained in a separate session, showed that deaf subjects had lower thresholds (i.e., better performance) on the Useful Field of View task. The event-related optical data indicated greater activity for the deaf adults than for the normal-hearing controls during the task in the posterior portion of Brodmann area 22 in the right hemisphere. Furthermore, the behavioral thresholds correlated significantly with this neural activity. This work provides further support for the hypothesis that cross-modal plasticity in deaf individuals appears in higher-order auditory cortices, whereas no similar evidence was obtained for primary auditory areas. It is also the only neuroimaging study to date that has linked deaf-related changes in the right temporal lobe to visual task performance outside of the imaging environment. The event-related optical signal is a valuable technique for studying cross-modal plasticity in deaf humans. The non-invasive and relatively quiet characteristics of

  1. Neural signal recording using microelectrode arrays fabricated on liquid crystal polymer material

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choong Jae; Oh, Seung Jae; Song, Jong Keun; Kim, Sung June

    2004-01-05

    Microelectrode arrays have been developed for simultaneous multi-channel recordings from nervous systems, typically using silicon substrates. However, it has been known that it is difficult to meet the biocompatibility and durability requirements using silicon and other dielectric materials (SiO{sub 2}, Si{sub 3}N{sub 4}), due to environmental moisture and ions. Additional disadvantage of silicon being the rigid material makes it hard to apply these materials in chronic recording situations. Liquid Crystal Polymer (LCP) was recently introduced as a candidate material for electronic packaging purposes. The material acts as efficient barrier against ions and moisture, a desirable feature for a substrate material of microelectrode arrays. In this paper, we report on the neural recording performed using the LCP-based microelectrode arrays. The cell adhesion on the new material was compared very favorably with that using silicon, SiO{sub 2}, or polyimide material. The microelectrode arrays were patterned with Ti (500 Angst)/Au (3500 Angst) on the LCP film and were employed in both stimulation and recording from rat sciatic nerve. The electrical characteristic of the recorded signal was as good as those using other substrate materials, proving this material as an excellent candidate for next generation microelectrode arrays.

  2. Application of artificial neural networks for versatile preprocessing of electrocardiogram recordings.

    Science.gov (United States)

    Mateo, J; Rieta, J J

    2012-02-01

    The electrocardiogram (ECG) is the most widely used method for diagnosis of heart diseases, where a good quality of recordings allows the proper interpretation and identification of physiological and pathological phenomena. However, ECG recordings often have interference from noises including thermal, muscle, baseline and powerline noises. These signals severely limit ECG recording utility and, hence, have to be removed. To deal with this problem, the present paper proposes an artificial neural network (ANN) as a filter to remove all kinds of noise in just one step. The method is based on a growing ANN which optimizes both the number of nodes in the hidden layer and the coefficient matrices, which are optimized by means of the Widrow-Hoff delta algorithm. The ANN has been trained with a database comprising all kinds of noise, both from synthesized and real ECG recordings, in order to handle any noise signal present in the ECG. The proposed system improves results yielded by conventional techniques of ECG filtering, such as FIR-based systems, adaptive filtering and wavelet filtering. Therefore, the algorithm could serve as an effective framework to substantially reduce noise in ECG recordings. In addition, the resulting ECG signal distortion is notably more reduced in comparison with conventional methodologies. In summary, the current contribution introduces a new method which is able to suppress all ECG interference signals in only one step with low ECG distortion and a high noise reduction.

  3. A wireless recording system that utilizes Bluetooth technology to transmit neural activity in freely moving animals.

    Science.gov (United States)

    Hampson, Robert E; Collins, Vernell; Deadwyler, Sam A

    2009-09-15

    A new wireless transceiver is described for recording individual neuron firing from behaving rats utilizing Bluetooth transmission technology and a processor onboard for discrimination of neuronal waveforms and associated time stamps. This universal brain activity transmitter (UBAT) is attached to rodents via a backpack and amplifier headstage and can transmit 16 channels of captured neuronal firing data via a Bluetooth transceiver chip over very large and unconstrained distances. The onboard microprocessor of the UBAT allows flexible online control over waveform isolation criteria via transceiver instruction and the two-way communication capacity allows for closed-loop applications between neural events and behavioral or physiological processes which can be modified by transceiver instructions. A detailed description of the multiplexer processing of channel data as well as examples of neuronal recordings in different behavioral testing contexts is provided to demonstrate the capacity for robust transmission within almost any laboratory environment. A major advantage of the UBAT is the long transmission range and lack of object-based line of sight interference afforded by Bluetooth technology, allowing flexible recording capabilities within multiple experimental paradigms without interruption. Continuous recordings over very large distance separations from the monitor station are demonstrated providing experimenters with recording advantages not previously available with other telemetry devices.

  4. An auto-calibrated neural spike recording channel with feature extraction capabilities

    Science.gov (United States)

    Rodríguez-Pérez, Alberto; Ruiz-Amaya, Jesús; Delgado-Restituto, Manuel; Rodríguez-Vázquez, Ángel

    2011-05-01

    This paper presents a power efficient architecture for a neural spike recording channel. The channel offers a selfcalibration operation mode and can be used both for signal tracking (to raw digitize the acquired neural waveform) and feature extraction (to build a PWL approximation of the spikes in order to reduce data bandwidth on the RF-link). The neural threshold voltage is adaptively calculated during the spike detection period using basic digital operations. The neural input signal is amplified and filtered using a LNA, reconfigurable Band-Pass Filter, followed by a fully reconfigurable 8-bit ADC. The key element is the ADC architecture. It is a binary search data converter with a SCimplementation. Due to its architecture, it can be programmed to work either as a PGA, S&H or ADC. In order to allow power saving, inactive blocks are powered off depending on the selected operation mode, ADC sampling frequency is reconfigured and bias current is dynamically adapted during the conversion. Due to the ADC low input capacitance, the power consumption of the input LNA can be decreased and the overall power consumption of the channel is low. The prototype was implemented using a CMOS 0.13um standard process, and it occupies 400um x 400um. Simulations from extracted layout show very promising results. The power consumption of the complete channel for the signal tracking operations is 2.8uW, and is increased to 3.0uW when the feature extraction operation is performed, one of the lowest reported.

  5. Assessing artificial neural networks and statistical methods for infilling missing soil moisture records

    Science.gov (United States)

    Dumedah, Gift; Walker, Jeffrey P.; Chik, Li

    2014-07-01

    Soil moisture information is critically important for water management operations including flood forecasting, drought monitoring, and groundwater recharge estimation. While an accurate and continuous record of soil moisture is required for these applications, the available soil moisture data, in practice, is typically fraught with missing values. There are a wide range of methods available to infilling hydrologic variables, but a thorough inter-comparison between statistical methods and artificial neural networks has not been made. This study examines 5 statistical methods including monthly averages, weighted Pearson correlation coefficient, a method based on temporal stability of soil moisture, and a weighted merging of the three methods, together with a method based on the concept of rough sets. Additionally, 9 artificial neural networks are examined, broadly categorized into feedforward, dynamic, and radial basis networks. These 14 infilling methods were used to estimate missing soil moisture records and subsequently validated against known values for 13 soil moisture monitoring stations for three different soil layer depths in the Yanco region in southeast Australia. The evaluation results show that the top three highest performing methods are the nonlinear autoregressive neural network, rough sets method, and monthly replacement. A high estimation accuracy (root mean square error (RMSE) of about 0.03 m/m) was found in the nonlinear autoregressive network, due to its regression based dynamic network which allows feedback connections through discrete-time estimation. An equally high accuracy (0.05 m/m RMSE) in the rough sets procedure illustrates the important role of temporal persistence of soil moisture, with the capability to account for different soil moisture conditions.

  6. Long-term neural recordings using MEMS based moveable microelectrodes in the brain

    Directory of Open Access Journals (Sweden)

    Nathan Jackson

    2010-06-01

    Full Text Available One of the critical requirements of the emerging class of neural prosthetic devices is to maintain good quality neural recordings over long time periods. We report here a novel (Micro-ElectroMechanical Systems based technology that can move microelectrodes in the event of deterioration in neural signal to sample a new set of neurons. Microscale electro-thermal actuators are used to controllably move microelectrodes post-implantation in steps of approximately 9 µm. In this study, a total of 12 moveable microelectrode chips were individually implanted in adult rats. Two of the 12 moveable microelectrode chips were not moved over a period of 3 weeks and were treated as control experiments. During the first three weeks of implantation, moving the microelectrodes led to an improvement in the average SNR from 14.61 ± 5.21 dB before movement to 18.13 ± 4.99 dB after movement across all microelectrodes and all days. However, the average RMS values of noise amplitudes were similar at 2.98 ± 1.22 µV and 3.01 ± 1.16 µV before and after microelectrode movement. Beyond three weeks, the primary observed failure mode was biological rejection of the PMMA (dental cement based skull mount resulting in the device loosening and eventually falling from the skull. Additionally, the average SNR for functioning devices beyond three weeks was 11.88 ± 2.02 dB before microelectrode movement and was significantly different (p<0.01 from the average SNR of 13.34 ± 0.919 dB after movement. The results of this study demonstrate that MEMS based technologies can move microelectrodes in rodent brains in long-term experiments resulting in improvements in signal quality. Further improvements in packaging and surgical techniques will potentially enable movable microelectrodes to record cortical neuronal activity in chronic experiments.

  7. SEMICONDUCTOR INTEGRATED CIRCUITS: Low power CMOS preamplifier for neural recording applications

    Science.gov (United States)

    Xu, Zhang; Weihua, Pei; Beiju, Huang; Hongda, Chen

    2010-04-01

    A fully-differential bandpass CMOS (complementary metal oxide semiconductor) preamplifier for extracellular neural recording is presented. The capacitive-coupled and capacitive-feedback topology is adopted. The preamplifier has a midband gain of 20.4 dB and a DC gain of 0. The -3 dB upper cut-off frequency of the preamplifier is 6.7 kHz. The lower cut-off frequency can be adjusted for amplifying the field or action potentials located in different bands. It has an input-referred noise of 8.2 μVrms integrated from 0.15 Hz to 6.7 kHz for recording the local field potentials and the mixed neural spikes with a power dissipation of 23.1 μW from a 3.3 V supply. A bandgap reference circuitry is also designed for providing the biasing voltage and current. The 0.22 mm2 prototype chip, including the preamplifier and its biasing circuitry, is fabricated in the 0.35-μm N-well CMOS 2P4M process.

  8. Application of BP neural networks in non-linearity correction of optical tweezers

    Institute of Scientific and Technical Information of China (English)

    Ziqiang WANG; Yinmei LI; Liren LOU; Henghua WEI; Zhong WANG

    2008-01-01

    The back-propagation (BP) neural network is proposed to correct nonlinearity and optimize the force measurement and calibration of an optical tweezer sys-tem. Considering the low convergence rate of the BP algo-rithm, the Levenberg-Marquardt (LM) algorithm is used to improve the BP network. The proposed method is experimentally studied for force calibration in a typical optical tweezer system using hydromechanics. The result shows that with the nonlinear correction using BP net-works, the range of force measurement of an optical tweezer system is enlarged by 30% and the precision is also improved compared with the polynomial fitting method. It is demonstrated that nonlinear correction by the neural network method effectively improves the per-formance of optical tweezers without adding or changing the measuring system.

  9. Adaptive neural network in a hybrid optical/electronic architecture using lateral inhibition.

    Science.gov (United States)

    Groot, P J; Noll, R J

    1989-09-15

    We report the optical implementation of a neural network based on a nearest matched filter algorithm and extensive lateral inhibition. Extremely rapid learning is demonstrated in pattern recognition and autonomous control applications, without introducing processing artifacts such as spurious states and ambiguous solutions. The optical implementation is achieved with a reconfigurable, bipolar mask-type crossbar switch based on an inexpensive liquid crystal spatial light modulator.

  10. Single neural code for blur in subjects with different interocular optical blur orientation.

    Science.gov (United States)

    Radhakrishnan, Aiswaryah; Sawides, Lucie; Dorronsoro, Carlos; Peli, Eli; Marcos, Susana

    2015-01-01

    The ability of the visual system to compensate for differences in blur orientation between eyes is not well understood. We measured the orientation of the internal blur code in both eyes of the same subject monocularly by presenting pairs of images blurred with real ocular point spread functions (PSFs) of similar blur magnitude but varying in orientations. Subjects assigned a level of confidence to their selection of the best perceived image in each pair. Using a classification-images-inspired paradigm and applying a reverse correlation technique, a classification map was obtained from the weighted averages of the PSFs, representing the internal blur code. Positive and negative neural PSFs were obtained from the classification map, representing the neural blur for best and worse perceived blur, respectively. The neural PSF was found to be highly correlated in both eyes, even for eyes with different ocular PSF orientations (rPos = 0.95; rNeg = 0.99; p neural PSF was closer to the orientation of the ocular PSF of the eye with the better optical quality (average difference was ∼10°), while the orientation of the positive and negative neural PSFs tended to be orthogonal. These results suggest a single internal code for blur with orientation driven by the orientation of the optical blur of the eye with better optical quality.

  11. 无线光刺激与神经传感系统%Wireless neural sensing system integrated optical stimulation

    Institute of Scientific and Technical Information of China (English)

    袁明军; 岳森; 张云鹏; 赵晓东; 王守岩

    2016-01-01

    Neuromodulation based on optogenetics is developed toward closed-loop control,a wireless light stimulation and neural sensing system is developed for requirements of free moving of test animal which has functions of larger range of optical stimulation,synchronous record,wireless programmable,which contains light stimulation-electric record neural interface,a stimulating and sensing module,a wireless transceiver module and upper PC software. The device can adjust light stimulation frequency,amplitude,duty ratio wirelessly and in real-time and synchronously acquire neural signal. The animal experiment shows that 30 Hz light stimulation at motor cortex movement of the mice is obviously enhanced,and EEG signal provoked by stimulation is recorded simultaneously. The system provides a multifunction neural regulation platform for optogenetics,which is beneficial to long schedule research for neural circuit and neural disease.%光遗传神经调控正在向闭环技术发展,针对实验动物可自由活动的需求,研发具有大范围光刺激、神经信号同步记录、无线程控等功能的无线光刺激与神经传感系统。该系统包括光刺激—电记录神经接口、刺激传感模块、无线收发模块以及上位机软件。可无线实时调节光刺激频率、幅度和占空比等参数,并同步采集神经信号。给予小鼠刺激运动皮层30Hz光刺激,小鼠运动明显增强,同时记录到刺激诱发的脑电信号。系统为光遗传技术提供多功能神经调控平台,有助于神经环路和神经疾病的长时程研究。

  12. Computational Analysis of Optical Neural Network Models to Weather Forecasting

    OpenAIRE

    A. C. Subhajini; V. Joseph Raj

    2010-01-01

    Neural networks have been in use in numerous meteorological applications including weather forecasting. They are found to be more powerful than any traditional expert system in the classification of meteorological patterns, in performing pattern classification tasks as they learn from examples without explicitly stating the rules and being non linear they solve complex problems more than linear techniques. A weather forecasting problem - rain fall estimation has been experimented using differ...

  13. An Inductively-Powered Wireless Neural Recording System with a Charge Sampling Analog Front-End.

    Science.gov (United States)

    Lee, Seung Bae; Lee, Byunghun; Kiani, Mehdi; Mahmoudi, Babak; Gross, Robert; Ghovanloo, Maysam

    2016-01-15

    An inductively-powered wireless integrated neural recording system (WINeR-7) is presented for wireless and battery less neural recording from freely-behaving animal subjects inside a wirelessly-powered standard homecage. The WINeR-7 system employs a novel wide-swing dual slope charge sampling (DSCS) analog front-end (AFE) architecture, which performs amplification, filtering, sampling, and analog-to-time conversion (ATC) with minimal interference and small amount of power. The output of the DSCS-AFE produces a pseudo-digital pulse width modulated (PWM) signal. A circular shift register (CSR) time division multiplexes (TDM) the PWM pulses to create a TDM-PWM signal, which is fed into an on-chip 915 MHz transmitter (Tx). The AFE and Tx are supplied at 1.8 V and 4.2 V, respectively, by a power management block, which includes a high efficiency active rectifier and automatic resonance tuning (ART), operating at 13.56 MHz. The 8-ch system-on-a-chip (SoC) was fabricated in a 0.35-μm CMOS process, occupying 5.0 × 2.5 mm(2) and consumed 51.4 mW. For each channel, the sampling rate is 21.48 kHz and the power consumption is 19.3 μW. In vivo experiments were conducted on freely behaving rats in an energized homecage by continuously delivering 51.4 mW to the WINeR-7 system in a closed-loop fashion and recording local field potentials (LFP).

  14. Optical implementation of neural learning algorithms based on cross-gain modulation in a semiconductor optical amplifier

    Science.gov (United States)

    Li, Qiang; Wang, Zhi; Le, Yansi; Sun, Chonghui; Song, Xiaojia; Wu, Chongqing

    2016-10-01

    Neuromorphic engineering has a wide range of applications in the fields of machine learning, pattern recognition, adaptive control, etc. Photonics, characterized by its high speed, wide bandwidth, low power consumption and massive parallelism, is an ideal way to realize ultrafast spiking neural networks (SNNs). Synaptic plasticity is believed to be critical for learning, memory and development in neural circuits. Experimental results have shown that changes of synapse are highly dependent on the relative timing of pre- and postsynaptic spikes. Synaptic plasticity in which presynaptic spikes preceding postsynaptic spikes results in strengthening, while the opposite timing results in weakening is called antisymmetric spike-timing-dependent plasticity (STDP) learning rule. And synaptic plasticity has the opposite effect under the same conditions is called antisymmetric anti-STDP learning rule. We proposed and experimentally demonstrated an optical implementation of neural learning algorithms, which can achieve both of antisymmetric STDP and anti-STDP learning rule, based on the cross-gain modulation (XGM) within a single semiconductor optical amplifier (SOA). The weight and height of the potentitation and depression window can be controlled by adjusting the injection current of the SOA, to mimic the biological antisymmetric STDP and anti-STDP learning rule more realistically. As the injection current increases, the width of depression and potentitation window decreases and height increases, due to the decreasing of recovery time and increasing of gain under a stronger injection current. Based on the demonstrated optical STDP circuit, ultrafast learning in optical SNNs can be realized.

  15. Neural Network for Image-to-Image Control of Optical Tweezers

    Science.gov (United States)

    Decker, Arthur J.; Anderson, Robert C.; Weiland, Kenneth E.; Wrbanek, Susan Y.

    2004-01-01

    A method is discussed for using neural networks to control optical tweezers. Neural-net outputs are combined with scaling and tiling to generate 480 by 480-pixel control patterns for a spatial light modulator (SLM). The SLM can be combined in various ways with a microscope to create movable tweezers traps with controllable profiles. The neural nets are intended to respond to scattered light from carbon and silicon carbide nanotube sensors. The nanotube sensors are to be held by the traps for manipulation and calibration. Scaling and tiling allow the 100 by 100-pixel maximum resolution of the neural-net software to be applied in stages to exploit the full 480 by 480-pixel resolution of the SLM. One of these stages is intended to create sensitive null detectors for detecting variations in the scattered light from the nanotube sensors.

  16. Optogenetics in Silicon: A Neural Processor for Predicting Optically Active Neural Networks.

    Science.gov (United States)

    Luo, Junwen; Nikolic, Konstantin; Evans, Benjamin D; Dong, Na; Sun, Xiaohan; Andras, Peter; Yakovlev, Alex; Degenaar, Patrick

    2016-08-17

    We present a reconfigurable neural processor for real-time simulation and prediction of opto-neural behaviour. We combined a detailed Hodgkin-Huxley CA3 neuron integrated with a four-state Channelrhodopsin-2 (ChR2) model into reconfigurable silicon hardware. Our architecture consists of a Field Programmable Gated Array (FPGA) with a custom-built computing data-path, a separate data management system and a memory approach based router. Advancements over previous work include the incorporation of short and long-term calcium and light-dependent ion channels in reconfigurable hardware. Also, the developed processor is computationally efficient, requiring only 0.03 ms processing time per sub-frame for a single neuron and 9.7 ms for a fully connected network of 500 neurons with a given FPGA frequency of 56.7 MHz. It can therefore be utilized for exploration of closed loop processing and tuning of biologically realistic optogenetic circuitry.

  17. Optogenetics in Silicon: A Neural Processor for Predicting Optically Active Neural Networks.

    Science.gov (United States)

    Junwen Luo; Nikolic, Konstantin; Evans, Benjamin D; Na Dong; Xiaohan Sun; Andras, Peter; Yakovlev, Alex; Degenaar, Patrick

    2017-02-01

    We present a reconfigurable neural processor for real-time simulation and prediction of opto-neural behaviour. We combined a detailed Hodgkin-Huxley CA3 neuron integrated with a four-state Channelrhodopsin-2 (ChR2) model into reconfigurable silicon hardware. Our architecture consists of a Field Programmable Gated Array (FPGA) with a custom-built computing data-path, a separate data management system and a memory approach based router. Advancements over previous work include the incorporation of short and long-term calcium and light-dependent ion channels in reconfigurable hardware. Also, the developed processor is computationally efficient, requiring only 0.03 ms processing time per sub-frame for a single neuron and 9.7 ms for a fully connected network of 500 neurons with a given FPGA frequency of 56.7 MHz. It can therefore be utilized for exploration of closed loop processing and tuning of biologically realistic optogenetic circuitry.

  18. Holographic optical elements recorded in silver halide sensitized gelatin emulsions. Part 2. Reflection holographic optical elements.

    Science.gov (United States)

    Kim, Jong Man; Choi, Byung So; Choi, Yoon Sun; Kim, Jong Min; Bjelkhagen, Hans I; Phillips, Nicholas J

    2002-03-10

    Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOEs). The drawback of DCG is its low energetic sensitivity and limited spectral response. Silver halide materials can be processed in such away that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-fine-grain silver halide (AgHal) emulsions. In particular, high spatial-frequency fringes associated with HOEs of the reflection type are difficult to construct when SHSG processing methods are employed. Therefore an optimized processing technique for reflection HOEs recorded in the new AgHal materials is introduced. Diffraction efficiencies over 90% can be obtained repeatably for reflection diffraction gratings. Understanding the importance of a selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOEs, also including high-quality display holograms of the reflection type in both monochrome and full color.

  19. Estimating the directed information to infer causal relationships in ensemble neural spike train recordings.

    Science.gov (United States)

    Quinn, Christopher J; Coleman, Todd P; Kiyavash, Negar; Hatsopoulos, Nicholas G

    2011-02-01

    Advances in recording technologies have given neuroscience researchers access to large amounts of data, in particular, simultaneous, individual recordings of large groups of neurons in different parts of the brain. A variety of quantitative techniques have been utilized to analyze the spiking activities of the neurons to elucidate the functional connectivity of the recorded neurons. In the past, researchers have used correlative measures. More recently, to better capture the dynamic, complex relationships present in the data, neuroscientists have employed causal measures-most of which are variants of Granger causality-with limited success. This paper motivates the directed information, an information and control theoretic concept, as a modality-independent embodiment of Granger's original notion of causality. Key properties include: (a) it is nonzero if and only if one process causally influences another, and (b) its specific value can be interpreted as the strength of a causal relationship. We next describe how the causally conditioned directed information between two processes given knowledge of others provides a network version of causality: it is nonzero if and only if, in the presence of the present and past of other processes, one process causally influences another. This notion is shown to be able to differentiate between true direct causal influences, common inputs, and cascade effects in more two processes. We next describe a procedure to estimate the directed information on neural spike trains using point process generalized linear models, maximum likelihood estimation and information-theoretic model order selection. We demonstrate that on a simulated network of neurons, it (a) correctly identifies all pairwise causal relationships and (b) correctly identifies network causal relationships. This procedure is then used to analyze ensemble spike train recordings in primary motor cortex of an awake monkey while performing target reaching tasks, uncovering

  20. Linear-phase delay filters for ultra-low-power signal processing in neural recording implants.

    Science.gov (United States)

    Gosselin, Benoit; Sawan, Mohamad; Kerherve, Eric

    2010-06-01

    We present the design and implementation of linear-phase delay filters for ultra-low-power signal processing in neural recording implants. We use these filters as low-distortion delay elements along with an automatic biopotential detector to perform integral waveform extraction and efficient power management. The presented delay elements are realized employing continuous-time OTA-C filters featuring 9th-order equiripple transfer functions with constant group delay. Such analog delay enables processing neural waveforms with reduced overhead compared to a digital delay since it does not requires sampling and digitization. It uses an allpass transfer function for achieving wider constant-delay bandwidth than all-pole does. Two filters realizations are compared for implementing the delay element: the Cascaded structure and the Inverse follow-the-leader feedback filter. Their respective strengths and drawbacks are assessed by modeling parasitics and non-idealities of OTAs, and by transistor-level simulations. A budget of 200 nA is used in both filters. Experimental measurements with the chosen filter topology are presented and discussed.

  1. Optimization neural net for multiple-target data association: real-time optical lab results

    Science.gov (United States)

    Yee, Mark L.; Casasent, David P.

    1991-08-01

    The Hopfield neural network was first used for optimization in solving the famous Traveling Salesman Problem. A similar approach has been applied to the solution of another problem, namely, data association for multiple targets. Simulation data are presented which demonstrate the network''s ability to successfully determine the optimum data association solutions, with target noise present. Simulations also indicate the ability to solve the problem on a low accuracy (analog optical) processor. Optical implementation issues are discussed, and an optical architecture is presented with laboratory results.

  2. Sputtered iridium oxide films (SIROFs) for low-impedance neural stimulation and recording electrodes.

    Science.gov (United States)

    Cogan, S F; Plante, T D; Ehrlich, J

    2004-01-01

    Iridium oxide films formed by electrochemical activation of iridium metal (AIROF) or by electrochemical deposition (EIROF) are being evaluated as low-impedance charge-injection coatings for neural stimulation and recording. Iridium oxide may also be deposited by reactive sputtering from iridium metal in an oxidizing plasma. The characterization of sputtered iridium oxide films (SIROFs) as coatings for nerve electrodes is reported. SIROFs were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and potential transient measurements during charge-injection. The surface morphology of the SIROF transitions from smooth to highly nodular with increasing film thickness from 80 nm to 4600 nm. Charge-injection capacities exceed 0.75 mC/cm(2) with 0.75 ms current pulses in thicker films. The SIROF was deposited on both planar and non-planar substrates and photolithographically patterned by lift-off.

  3. Microelectrode Recording of Tissue Neural Oscillations for a Bionic Olfactory Biosensor

    Institute of Scientific and Technical Information of China (English)

    Qingjun Liu; Fenni Zhang; Ning Hu; Hua Wang; Kuen Jimmy Hsia; Ping Wang

    2012-01-01

    In olfactory research,neural oscillations exhibit excellent temporal regularity,which are functional and necessary at the physiological and cognitive levels.In this paper,we employed a bionic tissue biosensor which treats intact epithelium as sensing element to record the olfactory oscillations extracellularly.After being stimulated by odorant of butanedione,the olfactory receptor neurons generated different kinds of oscillations,which can be described as pulse firing oscillation,transient firing oscillation,superposed firing oscillation,and sustained firing oscillation,according to their temporal appearances respectively.With a time-frequency analysis of sonogram,the oscillations also demonstrated different frequency properties,such as δ,θ,α,β and γ oscillations.The results suggest that the bionic biosensor cooperated with sonogram analysis can well improve the investigation of olfactory oscillations,and provide a novel model for artificial olfaction sensor design.

  4. Electronic performance of a dual inductive link for a wireless neural recording implant.

    Science.gov (United States)

    Rush, Alexander; Troyk, R

    2011-01-01

    This paper reports a dual inductive link to provide two-way wireless communication and power for a neural recording system. Particular emphasis is placed on explaining the challenges associated with two inductive links operating in the same space and possible solutions. This system uses a class E converter to sustain a large AC current in an external coil for transcutaneous energy transfer to an implant coil. A telemetry circuit generates a reverse-telemetry carrier frequency using an Integer-N PLL to support multiple outward data channels. Interference from the class E converter fundamental and harmonics is rejected using a differential coil configuration. An approach to filtering harmonic interference from the external power coil is also presented.

  5. Characterization of neural entrainment to speech with and without slow spectral energy fluctuations in laminar recordings in monkey A1.

    Science.gov (United States)

    Zoefel, Benedikt; Costa-Faidella, Jordi; Lakatos, Peter; Schroeder, Charles E; VanRullen, Rufin

    2017-04-15

    Neural entrainment, the alignment between neural oscillations and rhythmic stimulation, is omnipresent in current theories of speech processing - nevertheless, the underlying neural mechanisms are still largely unknown. Here, we hypothesized that laminar recordings in non-human primates provide us with important insight into these mechanisms, in particular with respect to processing in cortical layers. We presented one monkey with human everyday speech sounds and recorded neural (as current-source density, CSD) oscillations in primary auditory cortex (A1). We observed that the high-excitability phase of neural oscillations was only aligned with those spectral components of speech the recording site was tuned to; the opposite, low-excitability phase was aligned with other spectral components. As low- and high-frequency components in speech alternate, this finding might reflect a particularly efficient way of stimulus processing that includes the preparation of the relevant neuronal populations to the upcoming input. Moreover, presenting speech/noise sounds without systematic fluctuations in amplitude and spectral content and their time-reversed versions, we found significant entrainment in all conditions and cortical layers. When compared with everyday speech, the entrainment in the speech/noise conditions was characterized by a change in the phase relation between neural signal and stimulus and the low-frequency neural phase was dominantly coupled to activity in a lower gamma-band. These results show that neural entrainment in response to speech without slow fluctuations in spectral energy includes a process with specific characteristics that is presumably preserved across species. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination.

    Science.gov (United States)

    You, Yuyi; Gupta, Vivek K; Chitranshi, Nitin; Reedman, Brittany; Klistorner, Alexander; Graham, Stuart L

    2015-07-29

    The visual evoked potential (VEP) recording is widely used in clinical practice to assess the severity of optic neuritis in its acute phase, and to monitor the disease course in the follow-up period. Changes in the VEP parameters closely correlate with pathological damage in the optic nerve. This protocol provides a detailed description about the rodent model of optic nerve microinjection, in which a partial demyelination lesion is produced in the optic nerve. VEP recording techniques are also discussed. Using skull implanted electrodes, we are able to acquire reproducible intra-session and between-session VEP traces. VEPs can be recorded on individual animals over a period of time to assess the functional changes in the optic nerve longitudinally. The optic nerve demyelination model, in conjunction with the VEP recording protocol, provides a tool to investigate the disease processes associated with demyelination and remyelination, and can potentially be employed to evaluate the effects of new remyelinating drugs or neuroprotective therapies.

  7. Classification of remotely sensed data using OCR-inspired neural network techniques. [Optical Character Recognition

    Science.gov (United States)

    Kiang, Richard K.

    1992-01-01

    Neural networks have been applied to classifications of remotely sensed data with some success. To improve the performance of this approach, an examination was made of how neural networks are applied to the optical character recognition (OCR) of handwritten digits and letters. A three-layer, feedforward network, along with techniques adopted from OCR, was used to classify Landsat-4 Thematic Mapper data. Good results were obtained. To overcome the difficulties that are characteristic of remote sensing applications and to attain significant improvements in classification accuracy, a special network architecture may be required.

  8. Recent developments in wireless recording from the nervous system with ultrasonic neural dust (Conference Presentation)

    Science.gov (United States)

    Maharbiz, Michel M.

    2017-05-01

    The emerging field of bioelectronic medicine seeks methods for deciphering and modulating electrophysiological activity in the body to attain therapeutic effects at target organs. Current approaches to interfacing with peripheral nerves and muscles rely heavily on wires, creating problems for chronic use, while emerging wireless approaches lack the size scalability necessary to interrogate small-diameter nerves. Furthermore, conventional electrode-based technologies lack the capability to record from nerves with high spatial resolution or to record independently from many discrete sites within a nerve bundle. We recently demonstrated (Seo et al., arXiV, 2013; Seo et al., Neuron, 2016) "neural dust," a wireless and scalable ultrasonic backscatter system for powering and communicating with implanted bioelectronics. There, we showed that ultrasound is effective at delivering power to mm-scale devices in tissue; likewise, passive, battery-less communication using backscatter enabled high-fidelity transmission of electromyogram (EMG) and electroneurogram (ENG) signals from anesthetized rats. In this talk, I will review recent developments from my group and collaborators in this area.

  9. A regenerative microchannel neural interface for recording from and stimulating peripheral axons in vivo

    Science.gov (United States)

    FitzGerald, James J.; Lago, Natalia; Benmerah, Samia; Serra, Jordi; Watling, Christopher P.; Cameron, Ruth E.; Tarte, Edward; Lacour, Stéphanie P.; McMahon, Stephen B.; Fawcett, James W.

    2012-02-01

    Neural interfaces are implanted devices that couple the nervous system to electronic circuitry. They are intended for long term use to control assistive technologies such as muscle stimulators or prosthetics that compensate for loss of function due to injury. Here we present a novel design of interface for peripheral nerves. Recording from axons is complicated by the small size of extracellular potentials and the concentration of current flow at nodes of Ranvier. Confining axons to microchannels of ˜100 µm diameter produces amplified potentials that are independent of node position. After implantation of microchannel arrays into rat sciatic nerve, axons regenerated through the channels forming ‘mini-fascicles’, each typically containing ˜100 myelinated fibres and one or more blood vessels. Regenerated motor axons reconnected to distal muscles, as demonstrated by the recovery of an electromyogram and partial prevention of muscle atrophy. Efferent motor potentials and afferent signals evoked by muscle stretch or cutaneous stimulation were easily recorded from the mini-fascicles and were in the range of 35-170 µV. Individual motor units in distal musculature were activated from channels using stimulus currents in the microampere range. Microchannel interfaces are a potential solution for applications such as prosthetic limb control or enhancing recovery after nerve injury.

  10. Chronic multichannel neural recordings from soft regenerative microchannel electrodes during gait.

    Science.gov (United States)

    Musick, Katherine M; Rigosa, Jacopo; Narasimhan, Shreya; Wurth, Sophie; Capogrosso, Marco; Chew, Daniel J; Fawcett, James W; Micera, Silvestro; Lacour, Stéphanie P

    2015-09-24

    Reliably interfacing a nerve with an electrode array is one of the approaches to restore motor and sensory functions after an injury to the peripheral nerve. Accomplishing this with current technologies is challenging as the electrode-neuron interface often degrades over time, and surrounding myoelectric signals contaminate the neuro-signals in awake, moving animals. The purpose of this study was to evaluate the potential of microchannel electrode implants to monitor over time and in freely moving animals, neural activity from regenerating nerves. We designed and fabricated implants with silicone rubber and elastic thin-film metallization. Each implant carries an eight-by-twelve matrix of parallel microchannels (of 120 × 110 μm(2) cross-section and 4 mm length) and gold thin-film electrodes embedded in the floor of ten of the microchannels. After sterilization, the soft, multi-lumen electrode implant is sutured between the stumps of the sciatic nerve. Over a period of three months and in four rats, the microchannel electrodes recorded spike activity from the regenerating sciatic nerve. Histology indicates mini-nerves formed of axons and supporting cells regenerate robustly in the implants. Analysis of the recorded spikes and gait kinematics over the ten-week period suggests firing patterns collected with the microchannel electrode implant can be associated with different phases of gait.

  11. Chronic multichannel neural recordings from soft regenerative microchannel electrodes during gait

    Science.gov (United States)

    Musick, Katherine M.; Rigosa, Jacopo; Narasimhan, Shreya; Wurth, Sophie; Capogrosso, Marco; Chew, Daniel J.; Fawcett, James W.; Micera, Silvestro; Lacour, Stéphanie P.

    2015-09-01

    Reliably interfacing a nerve with an electrode array is one of the approaches to restore motor and sensory functions after an injury to the peripheral nerve. Accomplishing this with current technologies is challenging as the electrode-neuron interface often degrades over time, and surrounding myoelectric signals contaminate the neuro-signals in awake, moving animals. The purpose of this study was to evaluate the potential of microchannel electrode implants to monitor over time and in freely moving animals, neural activity from regenerating nerves. We designed and fabricated implants with silicone rubber and elastic thin-film metallization. Each implant carries an eight-by-twelve matrix of parallel microchannels (of 120 × 110 μm2 cross-section and 4 mm length) and gold thin-film electrodes embedded in the floor of ten of the microchannels. After sterilization, the soft, multi-lumen electrode implant is sutured between the stumps of the sciatic nerve. Over a period of three months and in four rats, the microchannel electrodes recorded spike activity from the regenerating sciatic nerve. Histology indicates mini-nerves formed of axons and supporting cells regenerate robustly in the implants. Analysis of the recorded spikes and gait kinematics over the ten-week period suggests firing patterns collected with the microchannel electrode implant can be associated with different phases of gait.

  12. Ultra-sharp metal and nanotube-based probes for applications in scanning microscopy and neural recording.

    Science.gov (United States)

    Borzenets, I V; Yoon, I; Prior, M M; Donald, B R; Mooney, R D; Finkelstein, G

    2012-04-01

    This paper discusses several methods for manufacturing ultra-sharp probes, with applications geared toward, but not limited to, scanning microscopy (STM, AFM) and intra-cellular recordings of neural signals. We present recipes for making tungsten, platinum/iridium alloy, and nanotube fibril tips. Electrical isolation methods using Parylene-C or PMMA are described.

  13. Energy efficient low-noise neural recording amplifier with enhanced noise efficiency factor.

    Science.gov (United States)

    Majidzadeh, V; Schmid, A; Leblebici, Y

    2011-06-01

    This paper presents a neural recording amplifier array suitable for large-scale integration with multielectrode arrays in very low-power microelectronic cortical implants. The proposed amplifier is one of the most energy-efficient structures reported to date, which theoretically achieves an effective noise efficiency factor (NEF) smaller than the limit that can be achieved by any existing amplifier topology, which utilizes a differential pair input stage. The proposed architecture, which is referred to as a partial operational transconductance amplifier sharing architecture, results in a significant reduction of power dissipation as well as silicon area, in addition to the very low NEF. The effect of mismatch on crosstalk between channels and the tradeoff between noise and crosstalk are theoretically analyzed. Moreover, a mathematical model of the nonlinearity of the amplifier is derived, and its accuracy is confirmed by simulations and measurements. For an array of four neural amplifiers, measurement results show a midband gain of 39.4 dB and a -3-dB bandwidth ranging from 10 Hz to 7.2 kHz. The input-referred noise integrated from 10 Hz to 100 kHz is measured at 3.5 μVrms and the power consumption is 7.92 μW from a 1.8-V supply, which corresponds to NEF = 3.35. The worst-case crosstalk and common-mode rejection ratio within the desired bandwidth are - 43.5 dB and 70.1 dB, respectively, and the active silicon area of each amplifier is 256 μm × 256 μm in 0.18-μm complementary metal-oxide semiconductor technology.

  14. Research on fault location technology based on BP neural network in DWDM optical network

    Institute of Scientific and Technical Information of China (English)

    LIAO Xiao-min; ZHANG Yin-fa; YANG Shi-ping; LIN Chu-shan

    2008-01-01

    BP neural network is introduced to the fault location field of DWDM optical network in this paper. The alarm characteris-tics of the optical network equipments are discussed, and alarm vector and fault vector diagrams are generated by analyzingsome typical instances. A 17×14×18 BP neural network structure is constructed and trained by using MATLAB. Bycomparing the training performances, the best training algorithm of fault location among the three training algorithms ischosen. Numerical simulation results indicate that the sum squared error (SSE) of fault location is less than 0.01, and theprocessing time is less than 100 ms. This method not only well deals with the missing alarms or false alarms, but alsoimproves the fault location accuracy and real-time ability.

  15. Sheehan's Syndrome with Edema in Optical Neural Sheaths: A Case Report

    Directory of Open Access Journals (Sweden)

    Mehtap Evran

    2013-04-01

    Full Text Available Sheehan syndrome is partial or complete hypophyseal insufficiency due to hypophyseal necrosis secondary to postpartum hemorrhage and hypovolemia. Clinical findings are cessation of lactation, secondary amenorrhea, loss of libido and hypophyseal reserve loss. Treatment is hormone replacement. Forty-four years old women admitted with somnolence, malaise, edema and blurred vision. Physical examination revealed edema and hypotension. She had massive bleeding during her birth 11 years old ago; therefore she had received blood transfusion and could not breast-feed then. She had amenorrhea when she admitted. She was diagnosed to be Sheehan syndrome while glucocorticoid and levothyroxine replacement was started. Hypophyseal and orbital magnetic resonance imaging revealed empty sella and edema in bilateral optical neural sheaths respectively. Empty sella may cause edema in optical neural sheaths by increasing pressure in subarachnoidal space. We present this case to point out this coincidence. [Cukurova Med J 2013; 38(2.000: 299-304

  16. Wide-field optical mapping of neural activity and brain haemodynamics: considerations and novel approaches

    Science.gov (United States)

    Ma, Ying; Shaik, Mohammed A.; Kozberg, Mariel G.; Thibodeaux, David N.; Zhao, Hanzhi T.; Yu, Hang

    2016-01-01

    Although modern techniques such as two-photon microscopy can now provide cellular-level three-dimensional imaging of the intact living brain, the speed and fields of view of these techniques remain limited. Conversely, two-dimensional wide-field optical mapping (WFOM), a simpler technique that uses a camera to observe large areas of the exposed cortex under visible light, can detect changes in both neural activity and haemodynamics at very high speeds. Although WFOM may not provide single-neuron or capillary-level resolution, it is an attractive and accessible approach to imaging large areas of the brain in awake, behaving mammals at speeds fast enough to observe widespread neural firing events, as well as their dynamic coupling to haemodynamics. Although such wide-field optical imaging techniques have a long history, the advent of genetically encoded fluorophores that can report neural activity with high sensitivity, as well as modern technologies such as light emitting diodes and sensitive and high-speed digital cameras have driven renewed interest in WFOM. To facilitate the wider adoption and standardization of WFOM approaches for neuroscience and neurovascular coupling research, we provide here an overview of the basic principles of WFOM, considerations for implementation of wide-field fluorescence imaging of neural activity, spectroscopic analysis and interpretation of results. This article is part of the themed issue ‘Interpreting BOLD: a dialogue between cognitive and cellular neuroscience’. PMID:27574312

  17. A low-power configurable neural recording system for epileptic seizure detection.

    Science.gov (United States)

    Qian, Chengliang; Shi, Jess; Parramon, Jordi; Sánchez-Sinencio, Edgar

    2013-08-01

    This paper describes a low-power configurable neural recording system capable of capturing and digitizing both neural action-potential (AP) and fast-ripple (FR) signals. It demonstrates the functionality of epileptic seizure detection through FR recording. This system features a fixed-gain, variable-bandwidth (BW) front-end circuit and a sigma-delta ADC with scalable bandwidth and power consumption. The ADC employs a 2nd-order single-bit sigma-delta modulator (SDM) followed by a low-power decimation filter. Direct impulse-response implementation of a sinc(3) filter and 8-cycle data pipelining in an IIR filter are proposed for the decimation filter design to improve the power and area efficiency. In measurements, the front end exhibits 39.6-dB DC gain, 0.8 Hz to 5.2 kHz of BW, 5.86- μVrms input-referred noise, and 2.4- μW power consumption in AP mode, while showing 38.5-dB DC gain, 250 to 486 Hz of BW, 2.48- μVrms noise, and 4.5- μW power consumption in FR mode. The noise efficiency factor (NEF) is 2.93 and 7.6 for the AP and FR modes, respectively. At 77-dB dynamic range (DR), the ADC has a peak SNR and SNDR of 75.9 dB and 67 dB, respectively, while consuming 2.75-mW power in AP mode. It achieves 78-dB DR, 76.2-dB peak SNR, 73.2-dB peak SNDR, and 588- μW power consumption in FR mode. Both analog and digital power supply voltages are 2.8 V. The chip is fabricated in a standard 0.6- μm CMOS process. The die size is 11.25 mm(2).

  18. Design of pitch conversion component for formation of multibeam optical recording head.

    Science.gov (United States)

    Sasaki, Kentaro; Kawamura, Norikazu; Tokumaru, Haruki

    2008-04-10

    We describe a design of a planar lightwave circuit for parallel information processing using visible light. The circuit serves as a pitch conversion component (PCC) that can align multiple beams close together and easily composes a compact optical system that can project optical spots at a narrow pitch on a certain small plane. From the viewpoint of its application to optical recording, a PCC is designed to have over 50 waveguides according to the fabrication of waveguides for a blue-violet beam. It is analytically confirmed that a PCC contributes to the formation of a multibeam optical recording head with numerous beams.

  19. Eigenanalysis of a neural network for optic flow processing

    Science.gov (United States)

    Weber, F.; Eichner, H.; Cuntz, H.; Borst, A.

    2008-01-01

    Flies gain information about self-motion during free flight by processing images of the environment moving across their retina. The visual course control center in the brain of the blowfly contains, among others, a population of ten neurons, the so-called vertical system (VS) cells that are mainly sensitive to downward motion. VS cells are assumed to encode information about rotational optic flow induced by self-motion (Krapp and Hengstenberg 1996 Nature 384 463-6). Recent evidence supports a connectivity scheme between the VS cells where neurons with neighboring receptive fields are connected to each other by electrical synapses at the axonal terminals, whereas the boundary neurons in the network are reciprocally coupled via inhibitory synapses (Haag and Borst 2004 Nat. Neurosci. 7 628-34 Farrow et al 2005 J. Neurosci. 25 3985-93 Cuntz et al 2007 Proc. Natl Acad. Sci. USA). Here, we investigate the functional properties of the VS network and its connectivity scheme by reducing a biophysically realistic network to a simplified model, where each cell is represented by a dendritic and axonal compartment only. Eigenanalysis of this model reveals that the whole population of VS cells projects the synaptic input provided from local motion detectors on to its behaviorally relevant components. The two major eigenvectors consist of a horizontal and a slanted line representing the distribution of vertical motion components across the fly's azimuth. They are, thus, ideally suited for reliably encoding translational and rotational whole-field optic flow induced by respective flight maneuvers. The dimensionality reduction compensates for the contrast and texture dependence of the local motion detectors of the correlation-type, which becomes particularly pronounced when confronted with natural images and their highly inhomogeneous contrast distribution.

  20. Flexible, Polarization-Diverse UWB Antennas for Implantable Neural Recording Systems.

    Science.gov (United States)

    Bahrami, Hadi; Mirbozorgi, S Abdollah; Ameli, Reza; Rusch, Leslie A; Gosselin, Benoit

    2016-02-01

    Implanted antennas for implant-to-air data communications must be composed of material compatible with biological tissues. We design single and dual-polarization antennas for wireless ultra-wideband neural recording systems using an inhomogeneous multi-layer model of the human head. Antennas made from flexible materials are more easily adapted to implantation; we investigate both flexible and rigid materials and examine performance trade-offs. The proposed antennas are designed to operate in a frequency range of 2-11 GHz (having S11 below -10 dB) covering both the 2.45 GHz (ISM) band and the 3.1-10.6 GHz UWB band. Measurements confirm simulation results showing flexible antennas have little performance degradation due to bending effects (in terms of impedance matching). Our miniaturized flexible antennas are 12 mm×12 mm and 10 mm×9 mm for single- and dual-polarizations, respectively. Finally, a comparison is made of four implantable antennas covering the 2-11 GHz range: 1) rigid, single polarization, 2) rigid, dual polarization, 3) flexible, single polarization and 4) flexible, dual polarization. In all cases a rigid antenna is used outside the body, with an appropriate polarization. Several advantages were confirmed for dual polarization antennas: 1) smaller size, 2) lower sensitivity to angular misalignments, and 3) higher fidelity.

  1. A wireless power interface for rechargeable battery operated neural recording implants.

    Science.gov (United States)

    Li, Pengfei; Principe, Jose C; Bashirullah, Rizwan

    2006-01-01

    This paper describes an integrated analog front-end for wireless powering and recharging of miniature Li-ion batteries used in implantable neural recording microsystems. DC signal extraction from a wireless carrier is accomplished using Schottky barrier contact diodes with lower forward voltage drop for improved efficiency. The battery charger employs a new control loop that relaxes comparator resolution requirements, provides simultaneous operation of constant-current and constant-voltage loops, and eliminates the external current sense resistor from the charging path. The accuracy of the end-of-charge detection is primarily determined by the voltage drop across matched resistors and current-sources and the offset voltage of the sense comparator. Experimental results in 0.6 mum bulk CMOS technology indicate that +/- 1.3% (or +/-20 microA) end-of-charge accuracy can be obtained under worst-case conditions for a comparator offset voltage of +/-5mV. The circuits occupy 1.735 mm(2) with a power dissipation of 8.4 mW when delivering a load current of 1.5 mA at 4.1 V (or 6.15 mW) for an efficiency of 73%

  2. Implantable Loop Recorder: Diagnostic Yield And Possible Therapeutic Effect In Patients With Neurally Mediated Reflex Syncope.

    Science.gov (United States)

    M, Unterhuber; W, Rauhe; P, Sgobino; F, Pescoller; M, Manfrin; M, Tomaino

    2016-01-01

    Through a retrospective study concerning the experience of our center in patients affected by Neurally Mediated reflex Syncope (NMS) we wanted to verify not only the diagnostic yield of the Implantable Loop Recorder (ILR) but its possible placebo therapeutic effect. In the context of patients affected by a severe clinical presentation of NMS identified through a careful clinical evaluation, we selected those who followed a diagnostic iter using the ILR. We analysed 84 patients (39 male and 45 female, mean age 71 years), during the period 2009-2013. 34 patients (40.5%) had no recurrences after a mean follow-up (FU) of 35 months, among these 17 concluded a FU of 4 years. 50 patients (59.5%) had recurrences and a specific diagnosis after an average period of 7 months. We found an important number of patients who showed a disappearance of syncope during an observation period of 2-3 and 4 years. At first glance this results could be explained considering the possible placebo therapeutic effect of ILR.

  3. Soft implantable microelectrodes for future medicine: prosthetics, neural signal recording and neuromodulation.

    Science.gov (United States)

    Lee, Joong Hoon; Kim, Hanseop; Kim, Jeong Hun; Lee, Sang-Hoon

    2016-03-21

    Implantable devices have provided various potential diagnostic options and therapeutic methods in diverse medical fields. A variety of hard-material-based implantable electrodes have been developed. However, several limitations for their chronic implantation remain, including mechanical mismatches at the interface between the electrode and the soft tissue, and biocompatibility. Soft-material-based implantable devices are suitable candidates for complementing the limitations of hard electrodes. Advances in microtechnology and materials science have largely solved many challenges, such as optimization of shape, minimization of infection, enhancement of biocompatibility and integration with components for diverse functions. Significant strides have also been made in mechanical matching of electrodes to soft tissue. In this review, we provide an overview of recent advances in soft-material-based implantable electrodes for medical applications, categorized according to their implantation site and material composition. We then review specific applications in three categories: neuroprosthetics, neural signal recording, and neuromodulation. Finally, we describe various strategies for the future development and application of implantable, soft-material-based devices.

  4. Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio

    2011-01-01

    A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

  5. Artificial neural networks based estimation of optical parameters by diffuse reflectance imaging under in vitro conditions

    Directory of Open Access Journals (Sweden)

    Mahmut Ozan Gökkan

    2017-01-01

    Full Text Available Optical parameters (properties of tissue-mimicking phantoms are determined through noninvasive optical imaging. Objective of this study is to decompose obtained diffuse reflectance into these optical properties such as absorption and scattering coefficients. To do so, transmission spectroscopy is firstly used to measure the coefficients via an experimental setup. Next, the optical properties of each characterized phantom are input for Monte Carlo (MC simulations to get diffuse reflectance. Also, a surface image for each single phantom with its known optical properties is obliquely captured due to reflectance-based geometrical setup using CMOS camera that is positioned at 5∘ angle to the phantoms. For the illumination of light, a laser light source at 633nm wavelength is preferred, because optical properties of different components in a biological tissue on that wavelength are nonoverlapped. During in vitro measurements, we prepared 30 different mixture samples adding clinoleic intravenous lipid emulsion (CILE and evans blue (EB dye into a distilled water. Finally, all obtained diffuse reflectance values are used to estimate the optical coefficients by artificial neural networks (ANNs in inverse modeling. For a biological tissue it is found that the simulated and measured values in our results are in good agreement.

  6. In vivo monitoring of glial scar proliferation on chronically implanted neural electrodes by fiber optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Yijing eXie

    2014-08-01

    Full Text Available In neural prosthetics and stereotactic neurosurgery, intracortical electrodes are often utilized for delivering therapeutic electrical pulses, and recording neural electrophysiological signals. Unfortunately, neuroinflammation impairs the neuron-electrode-interface by developing a compact glial encapsulation around the implants in long term. At present, analyzing this immune reaction is only feasible with post-mortem histology; currently no means for specific in vivo monitoring exist and most applicable imaging modalities can not provide information in deep brain regions. Optical coherence tomography (OCT is a well established imaging modality for in vivo studies, providing cellular resolution and up to 1.2 mm imaging depth in brain tissue. A fiber based spectral domain OCT was shown to be capable of minimally invasive brain imaging. In the present study, we propose to use a fiber based spectral domain OCT to monitor the progression of the tissue's immune response through scar encapsulation progress in a rat animal model. A fine fiber catheter was implanted in rat brain together with a flexible polyimide microelectrode in sight both of which used as a foreign body to induce the brain tissue immune reaction. OCT signals were collected from animals up to 12 weeks after implantation and thus gliotic scarring in vivo monitored for that time. Preliminary data showed a significant enhancement of the OCT backscattering signal during the first three weeks after implantation, and increased attenuation factor of the sampled tissue due to the glial scar formation.

  7. Magneto-optical recording media - CoNi/Pt and Co/Pt multilayers

    NARCIS (Netherlands)

    Meng, Q.; Meng, Q.

    1996-01-01

    Concluding Remarks 5.1. General Statement As described in Chapter 1, magneto-optical recording disks have been used in the audio (MiniDisc) and PC as removable disks with high data capacity. Recently, MO disks have been in the competition with the phase-change type of optical disks. Up to now, the

  8. Magneto-optical recording media - CoNi/Pt and Co/Pt multilayers

    NARCIS (Netherlands)

    Meng, Q.

    1996-01-01

    Concluding Remarks 5.1. General Statement As described in Chapter 1, magneto-optical recording disks have been used in the audio (MiniDisc) and PC as removable disks with high data capacity. Recently, MO disks have been in the competition with the phase-change type of optical disks. Up to now,

  9. A Neural Network Approach to Infer Optical Depth of Thick Ice Clouds at Night

    Science.gov (United States)

    Minnis, P.; Hong, G.; Sun-Mack, S.; Chen, Yan; Smith, W. L., Jr.

    2016-01-01

    One of the roadblocks to continuously monitoring cloud properties is the tendency of clouds to become optically black at cloud optical depths (COD) of 6 or less. This constraint dramatically reduces the quantitative information content at night. A recent study found that because of their diffuse nature, ice clouds remain optically gray, to some extent, up to COD of 100 at certain wavelengths. Taking advantage of this weak dependency and the availability of COD retrievals from CloudSat, an artificial neural network algorithm was developed to estimate COD values up to 70 from common satellite imager infrared channels. The method was trained using matched 2007 CloudSat and Aqua MODIS data and is tested using similar data from 2008. The results show a significant improvement over the use of default values at night with high correlation. This paper summarizes the results and suggests paths for future improvement.

  10. An externally head-mounted wireless neural recording device for laboratory animal research and possible human clinical use.

    Science.gov (United States)

    Yin, Ming; Li, Hao; Bull, Christopher; Borton, David A; Aceros, Juan; Larson, Lawrence; Nurmikko, Arto V

    2013-01-01

    In this paper we present a new type of head-mounted wireless neural recording device in a highly compact package, dedicated for untethered laboratory animal research and designed for future mobile human clinical use. The device, which takes its input from an array of intracortical microelectrode arrays (MEA) has ninety-seven broadband parallel neural recording channels and was integrated on to two custom designed printed circuit boards. These house several low power, custom integrated circuits, including a preamplifier ASIC, a controller ASIC, plus two SAR ADCs, a 3-axis accelerometer, a 48MHz clock source, and a Manchester encoder. Another ultralow power RF chip supports an OOK transmitter with the center frequency tunable from 3GHz to 4GHz, mounted on a separate low loss dielectric board together with a 3V LDO, with output fed to a UWB chip antenna. The IC boards were interconnected and packaged in a polyether ether ketone (PEEK) enclosure which is compatible with both animal and human use (e.g. sterilizable). The entire system consumes 17mA from a 1.2Ahr 3.6V Li-SOCl2 1/2AA battery, which operates the device for more than 2 days. The overall system includes a custom RF receiver electronics which are designed to directly interface with any number of commercial (or custom) neural signal processors for multi-channel broadband neural recording. Bench-top measurements and in vivo testing of the device in rhesus macaques are presented to demonstrate the performance of the wireless neural interface.

  11. Mapping the spatiotemporal dynamics of calcium signaling in cellular neural networks using optical flow

    CERN Document Server

    Buibas, Marius; Nizar, Krystal; Silva, Gabriel A

    2009-01-01

    An optical flow gradient algorithm was applied to spontaneously forming networks of neurons and glia in culture imaged by fluorescence optical microscopy in order to map functional calcium signaling with single pixel resolution. Optical flow estimates the direction and speed of motion of objects in an image between subsequent frames in a recorded digital sequence of images (i.e. a movie). Computed vector field outputs by the algorithm were able to track the spatiotemporal dynamics of calcium signaling patterns. We begin by briefly reviewing the mathematics of the optical flow algorithm, describe how to solve for the displacement vectors, and how to measure their reliability. We then compare computed flow vectors with manually estimated vectors for the progression of a calcium signal recorded from representative astrocyte cultures. Finally, we applied the algorithm to preparations of primary astrocytes and hippocampal neurons and to the rMC-1 Muller glial cell line in order to illustrate the capability of the ...

  12. A CMOS frontend chip for implantable neural recording with wide voltage supply range

    Science.gov (United States)

    Jialin, Liu; Xu, Zhang; Xiaohui, Hu; Yatao, Guo; Peng, Li; Ming, Liu; Bin, Li; Hongda, Chen

    2015-10-01

    A design for a CMOS frontend integrated circuit (chip) for neural signal acquisition working at wide voltage supply range is presented in this paper. The chip consists of a preamplifier, a serial instrumental amplifier (IA) and a cyclic analog-to-digital converter (CADC). The capacitive-coupled and capacitive-feedback topology combined with MOS-bipolar pseudo-resistor element is adopted in the preamplifier to create a -3 dB upper cut-off frequency less than 1 Hz without using a ponderous discrete device. A dual-amplifier instrumental amplifier is used to provide a low output impedance interface for ADC as well as to boost the gain. The preamplifier and the serial instrumental amplifier together provide a midband gain of 45.8 dB and have an input-referred noise of 6.7 μVrms integrated from 1 Hz to 5 kHz. The ADC digitizes the amplified signal at 12-bits precision with a highest sampling rate of 130 kS/s. The measured effective number of bits (ENOB) of the ADC is 8.7 bits. The entire circuit draws 165 to 216 μA current from the supply voltage varied from 1.34 to 3.3 V. The prototype chip is fabricated in the 0.18-μm CMOS process and occupies an area of 1.23 mm2 (including pads). In-vitro recording was successfully carried out by the proposed frontend chip. Project supported by the National Natural Science Foundation of China (Nos. 61474107, 61372060, 61335010, 61275200, 61178051) and the Key Program of the Chinese Academy of Sciences (No. KJZD-EW-L11-01).

  13. Ultrafast chirped optical waveform recorder using a time microscope

    Science.gov (United States)

    Bennett, Corey Vincent

    2015-04-21

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  14. A CMOS IC-based multisite measuring system for stimulation and recording in neural preparations in vitro

    OpenAIRE

    Tateno, Takashi; Nishikawa, Jun

    2014-01-01

    In this report, we describe the system integration of a complementary metal oxide semiconductor (CMOS) integrated circuit (IC) chip, capable of both stimulation and recording of neurons or neural tissues, to investigate electrical signal propagation within cellular networks in vitro. The overall system consisted of three major subunits: a 5.0 × 5.0 mm CMOS IC chip, a reconfigurable logic device (field-programmable gate array, FPGA), and a PC. To test the system, microelectrode arrays (MEAs) w...

  15. A CMOS IC–based multisite measuring system for stimulation and recording in neural preparations in vitro

    OpenAIRE

    Takashi eTateno; Jun eNishikawa

    2014-01-01

    In this report, we describe the system integration of a complementary metal oxide semiconductor (CMOS) integrated circuit (IC) chip, capable of both stimulation and recording of neurons or neural tissues, to investigate electrical signal propagation within cellular networks in vitro. The overall system consisted of three major subunits: a 5.0 mm × 5.0 mm CMOS IC chip, a reconfigurable logic device (field-programmable gate array, FPGA), and a PC. To test the system, microelectrode arrays (MEAs...

  16. Engrafted human induced pluripotent stem cell-derived anterior specified neural progenitors protect the rat crushed optic nerve.

    Directory of Open Access Journals (Sweden)

    Leila Satarian

    Full Text Available BACKGROUND: Degeneration of retinal ganglion cells (RGCs is a common occurrence in several eye diseases. This study examined the functional improvement and protection of host RGCs in addition to the survival, integration and neuronal differentiation capabilities of anterior specified neural progenitors (NPs following intravitreal transplantation. METHODOLOGY/PRINCIPAL FINDINGS: NPs were produced under defined conditions from human induced pluripotent stem cells (hiPSCs and transplanted into rats whose optic nerves have been crushed (ONC. hiPSCs were induced to differentiate into anterior specified NPs by the use of Noggin and retinoic acid. The hiPSC-NPs were labeled by green fluorescent protein or a fluorescent tracer 1,1' -dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI and injected two days after induction of ONC in hooded rats. Functional analysis according to visual evoked potential recordings showed significant amplitude recovery in animals transplanted with hiPSC-NPs. Retrograde labeling by an intra-collicular DiI injection showed significantly higher numbers of RGCs and spared axons in ONC rats treated with hiPSC-NPs or their conditioned medium (CM. The analysis of CM of hiPSC-NPs showed the secretion of ciliary neurotrophic factor, basic fibroblast growth factor, and insulin-like growth factor. Optic nerve of cell transplanted groups also had increased GAP43 immunoreactivity and myelin staining by FluoroMyelin™ which imply for protection of axons and myelin. At 60 days post-transplantation hiPSC-NPs were integrated into the ganglion cell layer of the retina and expressed neuronal markers. CONCLUSIONS/SIGNIFICANCE: The transplantation of anterior specified NPs may improve optic nerve injury through neuroprotection and differentiation into neuronal lineages. These NPs possibly provide a promising new therapeutic approach for traumatic optic nerve injuries and loss of RGCs caused by other diseases.

  17. Detecting single DNA molecule interactions with optical microcavities (Presentation Recording)

    Science.gov (United States)

    Vollmer, Frank

    2015-09-01

    Detecting molecules and their interactions lies at the heart of all biosensor devices, which have important applications in health, environmental monitoring and biomedicine. Achieving biosensing capability at the single molecule level is, moreover, a particularly important goal since single molecule biosensors would not only operate at the ultimate detection limit by resolving individual molecular interactions, but they could also monitor biomolecular properties which are otherwise obscured in ensemble measurements. For example, a single molecule biosensor could resolve the fleeting interaction kinetics between a molecule and its receptor, with immediate applications in clinical diagnostics. We have now developed a label-free biosensing platform that is capable of monitoring single DNA molecules and their interaction kinetics[1], hence achieving an unprecedented sensitivity in the optical domain, Figure 1. We resolve the specific contacts between complementary oligonucleotides, thereby detecting DNA strands with less than 2.4 kDa molecular weight. Furthermore we can discern strands with single nucleotide mismatches by monitoring their interaction kinetics. Our device utilizes small glass microspheres as optical transducers[1,2, 3], which are capable of increasing the number of interactions between a light beam and analyte molecules. A prism is used to couple the light beam into the microsphere. Ourr biosensing approach resolves the specific interaction kinetics between single DNA fragments. The optical transducer is assembled in a simple three-step protocol, and consists of a gold nanorod attached to a glass microsphere, where the surface of the nanorod is further modified with oligonucleotide receptors. The interaction kinetics of an oligonucleotide receptor with DNA fragments in the surrounding aqueous solution is monitored at the single molecule level[1]. The light remains confined inside the sphere where it is guided by total internal reflections along a

  18. High-performance genetically targetable optical neural silencing by light-driven proton pumps.

    Science.gov (United States)

    Chow, Brian Y; Han, Xue; Dobry, Allison S; Qian, Xiaofeng; Chuong, Amy S; Li, Mingjie; Henninger, Michael A; Belfort, Gabriel M; Lin, Yingxi; Monahan, Patrick E; Boyden, Edward S

    2010-01-07

    The ability to silence the activity of genetically specified neurons in a temporally precise fashion would provide the opportunity to investigate the causal role of specific cell classes in neural computations, behaviours and pathologies. Here we show that members of the class of light-driven outward proton pumps can mediate powerful, safe, multiple-colour silencing of neural activity. The gene archaerhodopsin-3 (Arch) from Halorubrum sodomense enables near-100% silencing of neurons in the awake brain when virally expressed in the mouse cortex and illuminated with yellow light. Arch mediates currents of several hundred picoamps at low light powers, and supports neural silencing currents approaching 900 pA at light powers easily achievable in vivo. Furthermore, Arch spontaneously recovers from light-dependent inactivation, unlike light-driven chloride pumps that enter long-lasting inactive states in response to light. These properties of Arch are appropriate to mediate the optical silencing of significant brain volumes over behaviourally relevant timescales. Arch function in neurons is well tolerated because pH excursions created by Arch illumination are minimized by self-limiting mechanisms to levels comparable to those mediated by channelrhodopsins or natural spike firing. To highlight how proton pump ecological and genomic diversity may support new innovation, we show that the blue-green light-drivable proton pump from the fungus Leptosphaeria maculans (Mac) can, when expressed in neurons, enable neural silencing by blue light, thus enabling alongside other developed reagents the potential for independent silencing of two neural populations by blue versus red light. Light-driven proton pumps thus represent a high-performance and extremely versatile class of 'optogenetic' voltage and ion modulator, which will broadly enable new neuroscientific, biological, neurological and psychiatric investigations.

  19. Three-dimensional structure of CA1 pyramidal cells in rat hippocampus——Optical recording of LSM and computer simulation of fractal structure

    Institute of Scientific and Technical Information of China (English)

    冯春华; 刘力; 刘守忠; 宁红; 孙海坚; 郭爱克

    1995-01-01

    The optical recording of three-dimensional(3-D)reconstruction of CA1 pyramidal cells wasderived from the studies on the CA1 region of the hippocampus in adult male Wistar rats.The recordingwas produced by the Confocal Laser Scan Microscope(LSM-10).The attemption was to outline themorphological neural network of CA1 pyramidal cells organization,following the trail of axo-dendritic connec-tions in 3-D spatial distributions among neurons.The fractal structure of neurons with their dendritic andaxonal trees using fractal algorithm was noticed,and 2—18 simulated cells were obtained using PC-486 comput-er.The simulational cells are similar in morphology to the natural CA1 hippocampal pyramidal cells.There-fore,the exploitation of an advanced neurohistological research technique combining optical recording of theLSM-10 and computer simulation of fractal structure can provide the quantitative fractal structural basis forchaosic dynamics of brain.

  20. Plasma-etched nanostructures for optical applications (Presentation Recording)

    Science.gov (United States)

    Schulz, Ulrike; Rickelt, Friedrich; Munzert, Peter; Kaiser, Norbert

    2015-08-01

    A basic requirement for many optical applications is the reduction of Fresnel-reflections. Besides of interference coatings, nanostructures with sub-wavelength size as known from the eye of the night-flying moth can provide antireflective (AR) properties. The basic principle is to mix a material with air on a sub-wavelength scale to decrease the effective refractive index. To realize AR nanostructures on polymers, the self-organized formation of stochastically arranged antireflective structures using a low-pressure plasma etching process was studied. An advanced procedure involves the use of additional deposition of a thin oxide layer prior etching. A broad range of different structure morphologies exhibiting antireflective properties can be generated on almost all types of polymeric materials. For applications on glass, organic films are used as a transfer medium. Organic layers as thin film materials were evaluated to identify compounds suitable for forming nanostructures by plasma etching. The vapor deposition and etching of organic layers on glass offers a new possibility to achieve antireflective properties in a broad spectral range and for a wide range of light incidence.

  1. Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography.

    Science.gov (United States)

    Wang, Shang; Garcia, Monica D; Lopez, Andrew L; Overbeek, Paul A; Larin, Kirill V; Larina, Irina V

    2017-01-01

    Neural tube closure is a critical feature of central nervous system morphogenesis during embryonic development. Failure of this process leads to neural tube defects, one of the most common forms of human congenital defects. Although molecular and genetic studies in model organisms have provided insights into the genes and proteins that are required for normal neural tube development, complications associated with live imaging of neural tube closure in mammals limit efficient morphological analyses. Here, we report the use of optical coherence tomography (OCT) for dynamic imaging and quantitative assessment of cranial neural tube closure in live mouse embryos in culture. Through time-lapse imaging, we captured two neural tube closure mechanisms in different cranial regions, zipper-like closure of the hindbrain region and button-like closure of the midbrain region. We also used OCT imaging for phenotypic characterization of a neural tube defect in a mouse mutant. These results suggest that the described approach is a useful tool for live dynamic analysis of normal neural tube closure and neural tube defects in the mouse model.

  2. BP artificial neural network based wave front correction for sensor-less free space optics communication

    Science.gov (United States)

    Li, Zhaokun; Zhao, Xiaohui

    2017-02-01

    The sensor-less adaptive optics (AO) is one of the most promising methods to compensate strong wave front disturbance in free space optics communication (FSO). The back propagation (BP) artificial neural network is applied for the sensor-less AO system to design a distortion correction scheme in this study. This method only needs one or a few online measurements to correct the wave front distortion compared with other model-based approaches, by which the real-time capacity of the system is enhanced and the Strehl Ratio (SR) is largely improved. Necessary comparisons in numerical simulation with other model-based and model-free correction methods proposed in Refs. [6,8,9,10] are given to show the validity and advantage of the proposed method.

  3. Performances of Neural Networks and LDPC Decoders for OFDM High Speed Transmission in Optical Fiber

    Directory of Open Access Journals (Sweden)

    Sanou Serge Roland 1, 2 * , Zougmoré François 1 , Kébré Marcel 1 , Koalaga Zacharie 1 , Doumounia Ali

    2013-09-01

    Full Text Available This paper presents a comparison of the performances of coded OFDM (Orthogonal Frequency Division Multiplexing for optical broadband transmission using Random Neural Network (RNN, a variant of RNN, Soft Decision Decoding (SDD and LDPC channel decoding techniques. The performance evaluation is based firstly on the Error Vector Magnitude (EVM to assess the effects of imperfections in the optical channel, and secondly on the estimated Bit Error Rate (BER based on OSNR. The simulations are performed at a rate of 10Gb/s over 1000 km using VPI software cosimulation environment. The results show that the error correcting codes, particularly LDPC codes, are well suited and efficient for broadband.These codes provide satisfactory solutions for OFDM, reducing the effects of chromatic dispersion (CD, polarization mode dispersion (PMD, Intersymbol Interference(ISI and non-linearities.

  4. An integrated interface for peripheral neural system recording and stimulation: system design, electrical tests and in-vivo results.

    Science.gov (United States)

    Carboni, Caterina; Bisoni, Lorenzo; Carta, Nicola; Puddu, Roberto; Raspopovic, Stanisa; Navarro, Xavier; Raffo, Luigi; Barbaro, Massimo

    2016-04-01

    The prototype of an electronic bi-directional interface between the Peripheral Nervous System (PNS) and a neuro-controlled hand prosthesis is presented. The system is composed of 2 integrated circuits: a standard CMOS device for neural recording and a HVCMOS device for neural stimulation. The integrated circuits have been realized in 2 different 0.35μ m CMOS processes available from ams. The complete system incorporates 8 channels each including the analog front-end, the A/D conversion, based on a sigma delta architecture and a programmable stimulation module implemented as a 5-bit current DAC; two voltage boosters supply the output stimulation stage with a programmable voltage scalable up to 17V. Successful in-vivo experiments with rats having a TIME electrode implanted in the sciatic nerve were carried out, showing the capability of recording neural signals in the tens of microvolts, with a global noise of 7μ V r m s , and to selectively elicit the tibial and plantar muscles using different active sites of the electrode.

  5. Optical recording of neuronal activity with a genetically-encoded calcium indicator in anesthetized and freely moving mice

    Directory of Open Access Journals (Sweden)

    Henry Lütcke

    2010-04-01

    Full Text Available Fluorescent calcium (Ca2+ indicator proteins (FCIPs are promising tools for functional imaging of cellular activity in living animals. However, they have still not reached their full potential for in vivo imaging of neuronal activity due to limitations in expression levels, dynamic range, and sensitivity for reporting action potentials. Here, we report that viral expression of the ratiometric Ca2+ sensor yellow cameleon 3.60 (YC3.60 in pyramidal neurons of mouse barrel cortex enables in vivo measurement of neuronal activity with high dynamic range and sensitivity across multiple spatial scales. By combining juxtacellular recordings and two-photon imaging in vitro and in vivo, we demonstrate that YC3.60 can resolve single action potential (AP-evoked Ca2+ transients and reliably reports bursts of APs with negligible saturation. Spontaneous and whisker-evoked Ca2+ transients were detected in individual apical dendrites and somata as well as in local neuronal populations. Moreover, bulk measurements using wide-field imaging or fiber-optics revealed sensory-evoked YC3.60 signals in large areas of the barrel field. Fiber-optic recordings in particular enabled measurements in awake, freely moving mice and revealed complex Ca2+ dynamics, possibly reflecting different behavior-related brain states. Viral expression of YC3.60 - in combination with various optical techniques - thus opens a multitude of opportunities for functional studies of the neural basis of animal behavior, from dendrites to the levels of local and large-scale neuronal populations.

  6. A CMOS IC-based multisite measuring system for stimulation and recording in neural preparations in vitro.

    Science.gov (United States)

    Tateno, Takashi; Nishikawa, Jun

    2014-01-01

    In this report, we describe the system integration of a complementary metal oxide semiconductor (CMOS) integrated circuit (IC) chip, capable of both stimulation and recording of neurons or neural tissues, to investigate electrical signal propagation within cellular networks in vitro. The overall system consisted of three major subunits: a 5.0 × 5.0 mm CMOS IC chip, a reconfigurable logic device (field-programmable gate array, FPGA), and a PC. To test the system, microelectrode arrays (MEAs) were used to extracellularly measure the activity of cultured rat cortical neurons and mouse cortical slices. The MEA had 64 bidirectional (stimulation and recording) electrodes. In addition, the CMOS IC chip was equipped with dedicated analog filters, amplification stages, and a stimulation buffer. Signals from the electrodes were sampled at 15.6 kHz with 16-bit resolution. The measured input-referred circuitry noise was 10.1 μ V root mean square (10 Hz to 100 kHz), which allowed reliable detection of neural signals ranging from several millivolts down to approximately 33 μ Vpp. Experiments were performed involving the stimulation of neurons with several spatiotemporal patterns and the recording of the triggered activity. An advantage over current MEAs, as demonstrated by our experiments, includes the ability to stimulate (voltage stimulation, 5-bit resolution) spatiotemporal patterns in arbitrary subsets of electrodes. Furthermore, the fast stimulation reset mechanism allowed us to record neuronal signals from a stimulating electrode around 3 ms after stimulation. We demonstrate that the system can be directly applied to, for example, auditory neural prostheses in conjunction with an acoustic sensor and a sound processing system.

  7. A CMOS IC–based multisite measuring system for stimulation and recording in neural preparations in vitro

    Directory of Open Access Journals (Sweden)

    Takashi eTateno

    2014-10-01

    Full Text Available In this report, we describe the system integration of a complementary metal oxide semiconductor (CMOS integrated circuit (IC chip, capable of both stimulation and recording of neurons or neural tissues, to investigate electrical signal propagation within cellular networks in vitro. The overall system consisted of three major subunits: a 5.0 mm × 5.0 mm CMOS IC chip, a reconfigurable logic device (field-programmable gate array, FPGA, and a PC. To test the system, microelectrode arrays (MEAs were used to extracellularly measure the activity of cultured rat cortical neurons and mouse cortical slices. The MEA had 64 bidirectional (stimulation and recording electrodes. In addition, the CMOS IC chip was equipped with dedicated analog filters, amplification stages, and a stimulation buffer. Signals from the electrodes were sampled at 15.6 kHz with 16-bit resolution. The measured input-referred circuitry noise was 10.1 μV root mean square (10 Hz to 100 kHz, which allowed reliable detection of neural signals ranging from several millivolts down to approximately 33 μVpp. Experiments were performed involving the stimulation of neurons with several spatiotemporal patterns and the recording of the triggered activity. An advantage over current MEAs, as demonstrated by our experiments, includes the ability to stimulate (voltage stimulation, 5-bit resolution spatiotemporal patterns in arbitrary subsets of electrodes. Furthermore, the fast stimulation reset mechanism allowed us to record neuronal signals from a stimulating electrode around 3 ms after stimulation. We demonstrate that the system can be directly applied to, for example, auditory neural prostheses in conjunction with an acoustic sensor and a sound processing system.

  8. Nanoscale live cell optical imaging of the dynamics of intracellular microvesicles in neural cells.

    Science.gov (United States)

    Lee, Sohee; Heo, Chaejeong; Suh, Minah; Lee, Young Hee

    2013-11-01

    Recent advances in biotechnology and imaging technology have provided great opportunities to investigate cellular dynamics. Conventional imaging methods such as transmission electron microscopy, scanning electron microscopy, and atomic force microscopy are powerful techniques for cellular imaging, even at the nanoscale level. However, these techniques have limitations applications in live cell imaging because of the experimental preparation required, namely cell fixation, and the innately small field of view. In this study, we developed a nanoscale optical imaging (NOI) system that combines a conventional optical microscope with a high resolution dark-field condenser (Cytoviva, Inc.) and halogen illuminator. The NOI system's maximum resolution for live cell imaging is around 100 nm. We utilized NOI to investigate the dynamics of intracellular microvesicles of neural cells without immunocytological analysis. In particular, we studied direct, active random, and moderate random dynamic motions of intracellular microvesicles and visualized lysosomal vesicle changes after treatment of cells with a lysosomal inhibitor (NH4Cl). Our results indicate that the NOI system is a feasible, high-resolution optical imaging system for live small organelles that does not require complicated optics or immunocytological staining processes.

  9. Far-field head-media optical interaction in heat-assisted magnetic recording

    CERN Document Server

    Yang, Ruoxi; Klemmer, Timothy; Olson, Heidi; Zhang, Deming; Perry, Tyler; Yin, Huaqing; Hipwell, Roger; Thiele, Jan-Ulrich; Tang, Huan; Seigler, Mike

    2015-01-01

    We have used a plane-wave expansion method to theoretically study the far-field head-media optical interaction in HAMR. For the ASTC media stack specifically, we notice the outstanding sensitivity related to interlayer's optical thickness for media reflection and magnetic layer's light absorption. With 10-nm interlayer thickness change, the recording layer absorption can be changed by more than 25%. The 2-D results are found to correlate well with full 3-D model and magnetic recording tests on flyable disc with different interlayer thickness.

  10. Fixed weight Hopfield Neural Network based on optical implementation of all-optical MZI-XNOR logic gate

    Science.gov (United States)

    Nugamesh Mutter, Kussay; Mat Jafri, Mohd Zubir; Abdul Aziz, Azlan

    2010-05-01

    Many researches are conducted to improve Hopfield Neural Network (HNN) performance especially for speed and memory capacity in different approaches. However, there is still a significant scope of developing HNN using Optical Logic Gates. We propose here a new model of HNN based on all-optical XNOR logic gates for real time color image recognition. Firstly, we improved HNN toward optimum learning and converging operations. We considered each unipolar image as a set of small blocks of 3-pixels as vectors for HNN. This enables to save large number of images in the net with best reaching into global minima, and because there are only eight fixed states of weights so that only single iteration performed to construct a vector with stable state at minimum energy. HNN is useless in dealing with data not in bipolar representation. Therefore, HNN failed to work with color images. In RGB bands each represents different values of brightness, for d-bit RGB image it is simply consists of d-layers of unipolar. Each layer is as a single unipolar image for HNN. In addition, the weight matrices with stability of unity at the diagonal perform clear converging in comparison with no self-connecting architecture. Synchronously, each matrix-matrix multiplication operation would run optically in the second part, since we propose an array of all-optical XOR gates, which uses Mach-Zehnder Interferometer (MZI) for neurons setup and a controlling system to distribute timely signals with inverting to achieve XNOR function. The primary operation and simulation of the proposal HNN is demonstrated.

  11. Manipulation of orthogonal neural systems together in electrophysiological recordings: the MONSTER approach to simultaneous assessment of multiple neurocognitive dimensions.

    Science.gov (United States)

    Kappenman, Emily S; Luck, Steven J

    2012-01-01

    Event-related potentials (ERPs) are a powerful tool in understanding and evaluating cognitive, affective, motor, and sensory processing in both healthy and pathological samples. A typical ERP recording session takes considerable time but is designed to isolate only 1-2 components. Although this is appropriate for most basic science purposes, it is an inefficient approach for measuring the broad set of neurocognitive functions that may be disrupted in a neurological or psychiatric disease. The present study provides a framework for more efficiently evaluating multiple neural processes in a single experimental paradigm through the manipulation of functionally orthogonal dimensions. We describe the general MONSTER (Manipulation of Orthogonal Neural Systems Together in Electrophysiological Recordings) approach and explain how it can be adapted to investigate a variety of neurocognitive domains, ERP components, and neural processes of interest. We also demonstrate how this approach can be used to assess group differences by providing data from an implementation of the MONSTER approach in younger (18-30 y of age) and older (65-85 y of age) adult samples. This specific implementation of the MONSTER framework assesses 4 separate neural processes in the visual domain: (1) early sensory processing, using the C1 wave; (2) shifts of covert attention, with the N2pc component; (3) categorization, with the P3 component; and (4) self-monitoring, with the error-related negativity. Although the MONSTER approach is primarily described in the context of ERP experiments, it could also be adapted easily for use with functional magnetic resonance imaging.

  12. Optical and Thermal Properties of Nickel-Azo Dyes for Digital Versatile Disc-Recordable

    Institute of Scientific and Technical Information of China (English)

    魏斌; 吴谊群; 顾冬红; 干福熹

    2003-01-01

    We investigate the absorption spectra, optical constants and thermal decomposition as well as red-light (650 nm)static recording properties of three novel nickel-azo dye filrns based on 4-methylthiazole, benzothiazole and 6-methylbenzothiazole. Particularly, we obtain the nickel-azo complex film based on 4-methylthiazole, peaking at 562nm and 613nm, with higher refractive index (n = 2.46) and lower extinction coefficient (k = 0.18) at the wavelength 650nm and a sharp threshold of thermal decomposition at 330℃. The results of the static optical recording test of this dye film indicate that high reflectivity contrast of 51% can be observed at a laser writing power of 5.9mW and pulse width of 350ns. These results imply that the nickel-azo complex based on 4-methylthiazole is a promising candidate for a recording medium of digital versatile disc-recordable.

  13. Classifying Algorithm Based on a Fuzzy Neural network for the control of a Network Attached Optical Jukebox

    Institute of Scientific and Technical Information of China (English)

    LIU Xuan; JIA Hui-bo; CHENG Ming

    2006-01-01

    A new analytical method for improving the performance of a network attached optical jukebox is presented by means of artificial neural networks. Through analyzing operation (request) process in this system,the mathematics model and algorithm are built for this storage system,and then a classified method based on artificial neural networks for this system is proposed. Simulation results testified the feasibility and validity of the proposed method that it could overcome the drawbacks of the frequent I/O operation and provide an effective way for using the Network Attached Optical Jukebox.

  14. Could bright γ-ray burst optical transients have been recorded historically?

    Institute of Scientific and Technical Information of China (English)

    Richard G. Strom; Fu-Yuan Zhao; Cheng-Min Zhang

    2012-01-01

    The brightest optical flash from a γ-ray burst (GRB) was,briefly,a nakedeye object.Several other GRBs have produced optical transients only slightly fainter.We argue that,based upon the recently accumulated data from hundreds of GRB transients,many such optical events should have been visible to the unaided eye in the course of human history.The most likely repositories of such observations are historical records from the Orient,and we have located and discuss a number of candidates.We also consider the value of such observations,should any very likely ones be uncovered,to modern astrophysics.

  15. Classification of antibiotics by neural network analysis of optical resonance data of whispering gallery modes in dielectric microspheres

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schweiger, Gustav; Ostendorf, Andreas

    2012-04-01

    A novel emerging technique for the label-free analysis of nanoparticles and biomolecules in liquid fluids using optical micro cavity resonance of whispering-gallery-type modes is being developed.A scheme based on polymer microspheres fixed by adhesive on the evanescence wave coupling element has been used. We demonstrated that the only spectral shift can't be used for identification of biological agents by developed approach. So neural network classifier for biological agents and micro/nano particles classification has been developed. The developed technique is the following. While tuning the laser wavelength images were recorded as avi-file. All sequences were broken into single frames and the location of the resonance was allocated in each frame. The image was filtered for noise reduction and integrated over two coordinates for evaluation of integrated energy of a measured signal. As input data normalized resonance shift of whispering-gallery modes and the relative efficiency of whispering-gallery modes excitation were used. Other parameters such as polarization of excited light, "center of gravity" of a resonance spectra etc. are also tested as input data for probabilistic neural network. After network designing and training we estimated the accuracy of classification. The classification of antibiotics such as penicillin and cephasolin have been performed with the accuracy of not less 97 %. Developed techniques can be used for lab-on-chip sensor based diagnostic tools as for identification of different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells and for dynamics of a delivery of medicines to bodies.

  16. Microstructures and Recording Mechanism of Mo/Si Bilayer Applied for Write-Once Blue Laser Optical Recording

    Directory of Open Access Journals (Sweden)

    Sin-Liang Ou

    2014-01-01

    Full Text Available Mo/Si bilayer thin films were grown by magnetron sputtering and applied to write-once blu-ray disc (BD-R. The microstructures and optical storage properties of Mo/Si bilayer were investigated. From the temperature dependence of reflectivity measurement, it was revealed that a phase change occurred in the range of 255–425°C. Transmission electron microscopy analysis showed that the as-deposited film possessed Mo polycrystalline phase. The hexagonal MoSi2 and cubic Mo3Si phases appeared after annealing at 300 and 450°C, respectively. By measuring the optical reflectivity at a wavelength of 405 nm, the optical contrast of Mo/Si bilayer between as-deposited and 450°C-annealed states was evaluated to 25.8%. The optimum jitter value of 6.8% was obtained at 10.65 mW for 4× recording speed. The dynamic tests show that the Mo/Si bilayer has high potential in BD-R applications.

  17. Synthesis and application for optical recording of a new diarylethene having a benzene unit

    Energy Technology Data Exchange (ETDEWEB)

    Yan Peijian; Pu Shouzhi; Liu Weijun; Liu Gang, E-mail: pushouzhi@tsinghua.org.cn [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China)

    2011-02-01

    A novel photochromic diarylethene was synthesized and its photochromism, fluorescence properties have been investigated. This compound exhibited good photochromism and functioned as a fluorescence switch upon alternating irradiation with UV and visible light both in solution and in PMMA film. When diarylethene was used as recording medium, the results demonstrated that the diarylethene compound had attractive properties for high density optical storage.

  18. Active galactic nuclei synapses: X-ray versus optical classifications using artificial neural networks

    CERN Document Server

    Gonzalez-Martin, O; Acosta-Pulido, J A; Masegosa, J; Papadakis, I E; Rodriguez-Espinosa, J M; Marquez, I; Hernandez-Garcia, L

    2014-01-01

    (Abridged) Many classes of active galactic nuclei (AGN) have been defined entirely throughout optical wavelengths while the X-ray spectra have been very useful to investigate their inner regions. However, optical and X-ray results show many discrepancies that have not been fully understood yet. The aim of this paper is to study the "synapses" between the X-ray and optical classifications. For the first time, the new EFLUXER task allowed us to analyse broad band X-ray spectra of emission line nuclei (ELN) without any prior spectral fitting using artificial neural networks (ANNs). Our sample comprises 162 XMM-Newton/pn spectra of 90 local ELN in the Palomar sample. It includes starbursts (SB), transition objects (T2), LINERs (L1.8 and L2), and Seyferts (S1, S1.8, and S2). The ANNs are 90% efficient at classifying the trained classes S1, S1.8, and SB. The S1 and S1.8 classes show a wide range of S1- and S1.8-like components. We suggest that this is related to a large degree of obscuration at X-rays. The S1, S1.8...

  19. Regulation of spindle orientation and neural stem cell fate in the Drosophila optic lobe

    Directory of Open Access Journals (Sweden)

    Brand Andrea H

    2007-01-01

    Full Text Available Abstract Background The choice of a stem cell to divide symmetrically or asymmetrically has profound consequences for development and disease. Unregulated symmetric division promotes tumor formation, whereas inappropriate asymmetric division affects organ morphogenesis. Despite its importance, little is known about how spindle positioning is regulated. In some tissues cell fate appears to dictate the type of cell division, whereas in other tissues it is thought that stochastic variation in spindle position dictates subsequent sibling cell fate. Results Here we investigate the relationship between neural progenitor identity and spindle positioning in the Drosophila optic lobe. We use molecular markers and live imaging to show that there are two populations of progenitors in the optic lobe: symmetrically dividing neuroepithelial cells and asymmetrically dividing neuroblasts. We use genetically marked single cell clones to show that neuroepithelial cells give rise to neuroblasts. To determine if a change in spindle orientation can trigger a neuroepithelial to neuroblast transition, we force neuroepithelial cells to divide along their apical/basal axis by misexpressing Inscuteable. We find that this does not induce neuroblasts, nor does it promote premature neuronal differentiation. Conclusion We show that symmetrically dividing neuroepithelial cells give rise to asymmetrically dividing neuroblasts in the optic lobe, and that regulation of spindle orientation and division symmetry is a consequence of cell type specification, rather than a mechanism for generating cell type diversity.

  20. Optical bandgap modeling of thermal annealed ZnO:Ga thin films using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Eun; Moon, Pyung; Yun, Ilgu [School of Electrical and Electronic Engineering, Yonsei University, 262 Seongsanno, Seodaemoon-gu, Seoul 120-749 (Korea); Kim, Sungyeon; Myoung, Jae-Min [Department of Materials Science and Engineering, Yonsei University, 262 Seongsanno, Seodaemoon-gu, Seoul 120-749 (Korea); Jang, Hyeon Woo; Bang, Jungsik [LG Chem, Ltd., Research Park, 104-1 Moonji-Dong, Yuseng-Gu, Daejeon 305-380 (Korea)

    2010-07-15

    In this paper, the thermal annealing process modeling for the optical bandgap of ZnO:Ga thin films for transparent conductive oxide was presented using neural network (NNets) based on error backpropagation (BPNN) algorithm and multilayer perceptron (MLP). The thermal annealing process of ZnO:Ga thin films were analyzed by general factorial experimental design. The annealing temperature and film thickness were considered as input factors. To model the nonlinear annealing process, 6 experiments were trained by BPNN which has 2-4-1 structures and 2 additional samples were experimented to verify the predicted models. The output response model on optical bandgap and carrier concentration of ZnO:Ga thin films trained by BPNN was represented by surface plot of response surface model. Based on the modeling results, NNets can provide sufficient correspondence between the predicted output values and the measured. The optical bandgap variation of ZnO:Ga thin films by annealing is due to increased carrier concentration and explained by Burstein-Moss effect. The thermal annealing process is nonlinear and complex but the output response can be predicted by the NNets model. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  1. Nanofabrication at 1nm resolution by quantum optical lithography (Presentation Recording)

    Science.gov (United States)

    Pavel, Eugen

    2015-08-01

    A major problem in the optical lithography was the diffraction limit. Here, we report and demonstrate a lithography method, Quantum Optical Lithography [1,2], able to attain 1 nm resolution by optical means using new materials (fluorescent photosensitive glass-ceramics and QMC-5 resist). The performance is several times better than that described for any optical or Electron Beam Lithography (EBL) methods. In Fig. 1 we present TEM images of 1 nm lines recorded at 9.6 m/s. a) b) Fig. 1 TEM images of: a) multiple 1 nm lines written in a fluorescent photosensitive glass-ceramics sample; b) single 1 nm line written in QMC-5 resist. References [1] E. Pavel, S. Jinga, B.S. Vasile, A. Dinescu, V. Marinescu, R. Trusca and N. Tosa, "Quantum Optical Lithography from 1 nm resolution to pattern transfer on silicon wafer", Optics and Laser Technology, 60 (2014) 80-84. [2] E. Pavel, S. Jinga, E. Andronescu, B.S. Vasile, G. Kada, A. Sasahara, N. Tosa, A. Matei, M. Dinescu, A. Dinescu and O.R. Vasile, "2 nm Quantum Optical Lithography", Optics Communications,291 (2013) 259-263

  2. The influence of oxygen and nitrogen doping on GeSbTe phase-change optical recording media properties

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrov, D.; Shieh, H.-P.D

    2004-03-15

    Nitrogen and oxygen doped and co-doped GeSbTe (GST) films for phase-change optical recording are investigated. It is found that the crystallization temperature increased as well as the crystalline microstructure refined by doping. The carrier-to-noise ratio (CNR) and erasability of phase-change optical disks are improved being up to 52 and 35 dB, respectively, by using an appropriate nitrogen doping or co-doping concentration in the recording layer. Optical disks with co-doped recording layer are found to be superior in the recording characteristics then the single doped recording layer disks.

  3. Seismic Design Value Evaluation Based on Checking Records and Site Geological Conditions Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Tienfuan Kerh

    2013-01-01

    Full Text Available This study proposes an improved computational neural network model that uses three seismic parameters (i.e., local magnitude, epicentral distance, and epicenter depth and two geological conditions (i.e., shear wave velocity and standard penetration test value as the inputs for predicting peak ground acceleration—the key element for evaluating earthquake response. Initial comparison results show that a neural network model with three neurons in the hidden layer can achieve relatively better performance based on the evaluation index of correlation coefficient or mean square error. This study further develops a new weight-based neural network model for estimating peak ground acceleration at unchecked sites. Four locations identified to have higher estimated peak ground accelerations than that of the seismic design value in the 24 subdivision zones are investigated in Taiwan. Finally, this study develops a new equation for the relationship of horizontal peak ground acceleration and focal distance by the curve fitting method. This equation represents seismic characteristics in Taiwan region more reliably and reasonably. The results of this study provide an insight into this type of nonlinear problem, and the proposed method may be applicable to other areas of interest around the world.

  4. Determination of Electron Optical Properties for Aperture Zoom Lenses Using an Artificial Neural Network Method.

    Science.gov (United States)

    Isik, Nimet

    2016-04-01

    Multi-element electrostatic aperture lens systems are widely used to control electron or charged particle beams in many scientific instruments. By means of applied voltages, these lens systems can be operated for different purposes. In this context, numerous methods have been performed to calculate focal properties of these lenses. In this study, an artificial neural network (ANN) classification method is utilized to determine the focused/unfocused charged particle beam in the image point as a function of lens voltages for multi-element electrostatic aperture lenses. A data set for training and testing of ANN is taken from the SIMION 8.1 simulation program, which is a well known and proven accuracy program in charged particle optics. Mean squared error results of this study indicate that the ANN classification method provides notable performance characteristics for electrostatic aperture zoom lenses.

  5. Optical dissection of neural circuits responsible for Drosophila larval locomotion with halorhodopsin.

    Directory of Open Access Journals (Sweden)

    Kengo Inada

    Full Text Available Halorhodopsin (NpHR, a light-driven microbial chloride pump, enables silencing of neuronal function with superb temporal and spatial resolution. Here, we generated a transgenic line of Drosophila that drives expression of NpHR under control of the Gal4/UAS system. Then, we used it to dissect the functional properties of neural circuits that regulate larval peristalsis, a continuous wave of muscular contraction from posterior to anterior segments. We first demonstrate the effectiveness of NpHR by showing that global and continuous NpHR-mediated optical inhibition of motor neurons or sensory feedback neurons induce the same behavioral responses in crawling larvae to those elicited when the function of these neurons are inhibited by Shibire(ts, namely complete paralyses or slowed locomotion, respectively. We then applied transient and/or focused light stimuli to inhibit the activity of motor neurons in a more temporally and spatially restricted manner and studied the effects of the optical inhibition on peristalsis. When a brief light stimulus (1-10 sec was applied to a crawling larva, the wave of muscular contraction stopped transiently but resumed from the halted position when the light was turned off. Similarly, when a focused light stimulus was applied to inhibit motor neurons in one or a few segments which were about to be activated in a dissected larva undergoing fictive locomotion, the propagation of muscular constriction paused during the light stimulus but resumed from the halted position when the inhibition (>5 sec was removed. These results suggest that (1 Firing of motor neurons at the forefront of the wave is required for the wave to proceed to more anterior segments, and (2 The information about the phase of the wave, namely which segment is active at a given time, can be memorized in the neural circuits for several seconds.

  6. Evaluation of a fiber-optic technique for recording intramuscular pressure in the human leg.

    Science.gov (United States)

    Nilsson, Andreas; Zhang, Qiuxia; Styf, Jorma

    2016-10-01

    To evaluate a forward-sensing fiber-optic pressure technique for recording of intramuscular pressure (IMP) in the human leg and investigate factors that may influence IMP measurements used in diagnosing compartment syndromes. IMP in the tibialis anterior muscle was recorded simultaneously by a fiber-optic technique and needle-injection technique in 12 legs of 7 healthy subjects. Both measurement catheters were placed in parallel with the muscle fibers to the same depth, as verified by sonography. IMP recordings were performed at rest before, during and after applying a model of abnormally elevated IMP (simulated compartment syndrome). IMP was elevated by venous obstruction induced by a thigh tourniquet of a casted leg. IMP was also measured during injections of 0.1 ml of saline into the muscle through the catheters. IMP at baseline was 5.1 (SD = 2.6) mmHg measured with the fiber-optic technique and 7.1 (SD = 2.5) mmHg with the needle-injection technique (p syndrome. IMP increased significantly following injection of 0.1 ml of saline, measured by both techniques. It remained increased 1 min after injection. The fiber-optic technique was able to record pulse-synchronous IMP oscillations. The fiber-optic technique may be used for IMP measurements in a muscle with both normal and abnormally elevated IMP. It has good dynamic properties allowing for measurement of IMP oscillations. Saline injection used with needle-injection systems to ensure catheter patency compromises IMP readings at least one minute after injection.

  7. Polymer Optical Fiber Sensor and the Prediction of Sensor Response Utilizing Artificial Neural Networks

    Science.gov (United States)

    Haroglu, Derya

    characteristics: reproducibility, accuracy, selectivity, aging, and resolution. Artificial neural network (ANN), a mathematical model formed by mimicking the human nervous system, was used to predict the sensor response. Qwiknet (version 2.23) software was used to develop ANNs and according to the results of Qwiknet the prediction performances for training and testing data sets were 75%, and 83.33% respectively. In this dissertation, Chapter 1 describes the worldwide plastic optical fiber (POF) and fiber optic sensor markets, and the existing textile structures used in fiber optic sensing design particularly for the applications of biomedical and structural health monitoring (SHM). Chapter 2 provides a literature review in detail on polymer optical fibers, fiber optic sensors, and occupancy sensing in the passenger seats of automobiles. Chapter 3 includes the research objectives. Chapter 4 presents the response of POF to tensile loading, bending, and cyclic tensile loading with discussion parts. Chapter 5 includes an e-mail based survey to prioritize customer needs in a Quality Function Deployment (QFD) format utilizing Analytic Hierarchy Process (AHP) and survey results. Chapter 6 describes the POF sensor design and the behavior of it under pressure. Chapter 7 provides a data analysis based on the experimental results of Chapter 6. Chapter 8 presents the summary of this study and recommendations for future work.

  8. An implantable two axis micromanipulator made with a 3D printer for recording neural activity in free-swimming fish.

    Science.gov (United States)

    Rogers, Loranzie S; Van Wert, Jacey C; Mensinger, Allen F

    2017-08-15

    Chronically implanted electrodes allow monitoring neural activity from free moving animals. While a wide variety of implanted headstages, microdrives and electrodes exist for terrestrial animals, few have been developed for use with aquatic animals. A two axis micromanipulator was fabricated with a Formlabs 3D printer for implanting electrodes into free-swimming oyster toadfish (Opsanus tau). The five piece manipulator consisted of a base, body, electrode holder, manual screw drive and locking nut. The manipulator measured approximately 25×20×30mm (l×w×h) and weighed 5.28g after hand assembly. Microwire electrodes were inserted successfully with the manipulator to record high fidelity signals from the anterior lateral line nerve of the toadfish. The micromanipulator allowed the chronically implanted electrodes to be repositioned numerous times to record from multiple sites and extended successful recording time in the toadfish by several days. Three dimensional printing allowed an inexpensive (<$US 5 material), two axis micromanipulator to be printed relatively rapidly (<2h) to successfully record from multiple sites in the anterior lateral line nerve of free-swimming toadfish. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Design and performance of magnetic heads for magneto-optic recording with magnetic field modulation

    Science.gov (United States)

    Ruigrok, J. J. M.; Greidanus, F. J. A. M.; Godlieb, W. F.; Spruit, J. H. M.

    1988-04-01

    In magneto-optic recording, the most direct way to overwrite stored information is to switch the magnetization in a laser-heated region of the magneto-optic layer by means of an alternating magnetic field generated by a magnetic head. The heat dissipation in the head and the necessary voltage and current amplitude associated with fast switching, the desired high field, and a large head-to-medium distance make high demands upon the head design and the current source, respectively. Design criteria and numerical and experimental results for some circularly symmetric head configurations are presented.

  10. An optogenetics- and imaging-assisted simultaneous multiple patch-clamp recording system for decoding complex neural circuits.

    Science.gov (United States)

    Wang, Guangfu; Wyskiel, Daniel R; Yang, Weiguo; Wang, Yiqing; Milbern, Lana C; Lalanne, Txomin; Jiang, Xiaolong; Shen, Ying; Sun, Qian-Quan; Zhu, J Julius

    2015-03-01

    Deciphering neuronal circuitry is central to understanding brain function and dysfunction, yet it remains a daunting task. To facilitate the dissection of neuronal circuits, a process requiring functional analysis of synaptic connections and morphological identification of interconnected neurons, we present here a method for stable simultaneous octuple patch-clamp recordings. This method allows physiological analysis of synaptic interconnections among 4-8 simultaneously recorded neurons and/or 10-30 sequentially recorded neurons, and it allows anatomical identification of >85% of recorded interneurons and >99% of recorded principal neurons. We describe how to apply the method to rodent tissue slices; however, it can be used on other model organisms. We also describe the latest refinements and optimizations of mechanics, electronics, optics and software programs that are central to the realization of a combined single- and two-photon microscopy-based, optogenetics- and imaging-assisted, stable, simultaneous quadruple-viguple patch-clamp recording system. Setting up the system, from the beginning of instrument assembly and software installation to full operation, can be completed in 3-4 d.

  11. Multichannel decision feedback equalizer for high track density in optical recording

    Science.gov (United States)

    Gopalaswamy, Srinivasan; Kumar, B. V. K.

    1996-08-01

    A possible approach to high track density in optical recording is to reduce the track widths and eliminate the spacing between consecutive tracks. Parallel readback of several tracks and combined equalization of the multitrack readback signals is a viable approach toward reducing the deteriorating effects of interference in such a high-track- density system. Multichannel readback using laser diode arrays has been reported in optical recording. An additional advantage of multitrack readback is a high data rate. A novel multichannel decision feedback equalizer to reduce interference both within and across the tracks using 2D feedback is presented. Simulation results shows good improvement in error-rate performance by using multichannel decision feedback equalization. By this readback method, tracks can be brought closer, thus increasing the areal density.

  12. Stability Comparison of Recordable Optical Discs—A Study of Error Rates in Harsh Conditions

    Science.gov (United States)

    Slattery, Oliver; Lu, Richang; Zheng, Jian; Byers, Fred; Tang, Xiao

    2004-01-01

    The reliability and longevity of any storage medium is a key issue for archivists and preservationists as well as for the creators of important information. This is particularly true in the case of digital media such as DVD and CD where a sufficient number of errors may render the disc unreadable. This paper describes an initial stability study of commercially available recordable DVD and CD media using accelerated aging tests under conditions of increased temperature and humidity. The effect of prolonged exposure to direct light is also investigated and shown to have an effect on the error rates of the media. Initial results show that high quality optical media have very stable characteristics and may be suitable for long-term storage applications. However, results also indicate that significant differences exist in the stability of recordable optical media from different manufacturers. PMID:27366630

  13. Solvent-free optical recording of structural colours on pre-imprinted photocrosslinkable nanostructures

    Science.gov (United States)

    Jiang, Hao; Rezaei, Mohamad; Abdolahi, Mahssa; Kaminska, Bozena

    2017-09-01

    Optical digital information storage media, despite their ever-increasing storage capacity and data transfer rate, are vulnerable to the potential risk of turning inaccessible. For this reason, long-term eye-readable full-colour optical archival storage is in high demand for preserving valuable information from cultural, intellectual, and scholarly resources. However, the concurrent requirements in recording colours inexpensively and precisely, and preserving colours for the very long term (for at least 100 years), have not yet been met by existing storage techniques. Structural colours hold the promise to overcome such challenges. However, there is still the lack of an inexpensive, rapid, reliable, and solvent-free optical patterning technique for recording structural colours. In this paper, we introduce an enabling technique based on optical and thermal patterning of nanoimprinted SU-8 nanocone arrays. Using photocrosslinking and thermoplastic flow of SU-8, diffractive structural colours of nanocone arrays are recorded using ultra-violet (UV) exposure followed by the thermal development and reshaping of nanocones. Different thermal treatment procedures in reshaping nanocones are investigated and compared, and two-step progressive baking is found to allow the controllable reshaping of nanocones. The height of the nanocones and brightness of diffractive colours are modulated by varying the UV exposure dose to enable grey-scale patterning. An example of recorded full-colour image through half-tone patterning is also demonstrated. The presented technique requires only low-power continuous-wave UV light and is very promising to be adopted for professional and consumer archival storage applications.

  14. Laser Setup for Volume Diffractive Optical Elements Recording in Photo-Thermo-Refractive Glass

    Science.gov (United States)

    2016-04-14

    ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 UV laser , third harmonic generation, hologram recording...of uniformity of VBGs across the aperture that is a key for large aperture pulse compressors used in high power ultrashort pulse lasers . ? A new...the College of Optics and Photonics, University of Central Florida. 4304 Scorpius Str. Orlando, FL 32816 6. Key words: UV laser , third harmonic

  15. Electroconductive polymer-coated silk fiber electrodes for neural recording and stimulation in vivo

    Science.gov (United States)

    Watanabe, Satoshi; Takahashi, Hideyuki; Torimitsu, Keiichi

    2017-03-01

    We fabricated a silk-based low-impedance flexible electrode by coating a silk thread with the electroconductive polymer poly(3,4-ethylenedioxythiophene) doped with p-toluenesulfonate (PEDOT:pTS). This electrode had a lower impedance (about 1.8 kΩ/cm) than the silk electrode coated with PEDOT doped with poly(styrene sulfonate) (PEDOT:PSS) (about 1.3 MΩ/cm) reported previously. Using this electrode, a novel gamma-band oscillatory activity was recorded in the electrocorticogram from the embryonic chick brain with a high signal-to-noise ratio. Electrical stimulation was also possible with the silk electrode. We also fabricated an all-silk electrode array and recorded synchronized gamma oscillations. These results demonstrate that the silk electrode can be used for electrophysiological recording and local stimulation in vivo. The silk electrode has the potential to be used for diagnostic and therapeutic purposes and as a brain–machine interface.

  16. Chemically deposited Sb{sub 2}S{sub 3} thin films for optical recording

    Energy Technology Data Exchange (ETDEWEB)

    Shaji, S; Arato, A; Castillo, G Alan; Palma, M I Mendivil; Roy, T K Das; Krishnan, B [Facultad de IngenierIa Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P- 66450 (Mexico); O' Brien, J J; Liu, J, E-mail: bkrishnan@fime.uanl.m [Center for Nanoscience and Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One Univ. Blvd., St. Louis, MO - 63121 (United States)

    2010-02-24

    Laser induced changes in the properties of Sb{sub 2}S{sub 3} thin films prepared by chemical bath deposition are described in this paper. Sb{sub 2}S{sub 3} thin films of thickness 550 nm were deposited from a solution containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3} at 27 {sup 0}C for 5 h. These thin films were irradiated by a 532 nm continuous wave laser beam under different conditions at ambient atmosphere. X-ray diffraction analysis showed amorphous to polycrystalline transformation due to laser exposure of these thin films. Morphology and composition of these films were described. Optical properties of these films before and after laser irradiation were analysed. The optical band gap of the material was decreased due to laser induced crystallization. The results obtained confirm that there is further scope for developing this material as an optical recording media.

  17. Single-intensity-recording optical encryption technique based on phase retrieval algorithm and QR code

    Science.gov (United States)

    Wang, Zhi-peng; Zhang, Shuai; Liu, Hong-zhao; Qin, Yi

    2014-12-01

    Based on phase retrieval algorithm and QR code, a new optical encryption technology that only needs to record one intensity distribution is proposed. In this encryption process, firstly, the QR code is generated from the information to be encrypted; and then the generated QR code is placed in the input plane of 4-f system to have a double random phase encryption. For only one intensity distribution in the output plane is recorded as the ciphertext, the encryption process is greatly simplified. In the decryption process, the corresponding QR code is retrieved using phase retrieval algorithm. A priori information about QR code is used as support constraint in the input plane, which helps solve the stagnation problem. The original information can be recovered without distortion by scanning the QR code. The encryption process can be implemented either optically or digitally, and the decryption process uses digital method. In addition, the security of the proposed optical encryption technology is analyzed. Theoretical analysis and computer simulations show that this optical encryption system is invulnerable to various attacks, and suitable for harsh transmission conditions.

  18. A CMOS power-efficient low-noise current-mode front-end amplifier for neural signal recording.

    Science.gov (United States)

    Wu, Chung-Yu; Chen, Wei-Ming; Kuo, Liang-Ting

    2013-04-01

    In this paper, a new current-mode front-end amplifier (CMFEA) for neural signal recording systems is proposed. In the proposed CMFEA, a current-mode preamplifier with an active feedback loop operated at very low frequency is designed as the first gain stage to bypass any dc offset current generated by the electrode-tissue interface and to achieve a low high-pass cutoff frequency below 0.5 Hz. No reset signal or ultra-large pseudo resistor is required. The current-mode preamplifier has low dc operation current to enhance low-noise performance and decrease power consumption. A programmable current gain stage is adopted to provide adjustable gain for adaptive signal scaling. A following current-mode filter is designed to adjust the low-pass cutoff frequency for different neural signals. The proposed CMFEA is designed and fabricated in 0.18-μm CMOS technology and the area of the core circuit is 0.076 mm(2). The measured high-pass cutoff frequency is as low as 0.3 Hz and the low-pass cutoff frequency is adjustable from 1 kHz to 10 kHz. The measured maximum current gain is 55.9 dB. The measured input-referred current noise density is 153 fA /√Hz , and the power consumption is 13 μW at 1-V power supply. The fabricated CMFEA has been successfully applied to the animal test for recording the seizure ECoG of Long-Evan rats.

  19. Characterization of volume holographic optical elements recorded in Bayfol HX photopolymer for solar photovoltaic applications.

    Science.gov (United States)

    Marín-Sáez, Julia; Atencia, Jesús; Chemisana, Daniel; Collados, María-Victoria

    2016-03-21

    Volume Holographic Optical Elements (HOEs) present interesting characteristics for photovoltaic applications as they can select spectrum for concentrating the target bandwidth and avoiding non-desired wavelengths, which can cause the decrease of the performance on the cell, for instance by overheating it. Volume HOEs have been recorded on Bayfol HX photopolymer to test the suitability of this material for solar concentrating photovoltaic systems. The HOEs were recorded at 532 nm and provided a dynamic range, reaching close to 100% efficiency at 800 nm. The diffracted spectrum had a FWHM of 230 nm when illuminating at Bragg angle. These characteristics prove HOEs recorded on Bayfol HX photopolymer are suitable for concentrating solar light onto photovoltaic cells sensitive to that wavelength range.

  20. Application of artificial neural networks for conformity analysis of fuel performed with an optical fiber sensor

    Science.gov (United States)

    Possetti, Gustavo Rafael Collere; Coradin, Francelli Klemba; Côcco, Lílian Cristina; Yamamoto, Carlos Itsuo; de Arruda, Lucia Valéria Ramos; Falate, Rosane; Muller, Marcia; Fabris, José Luís

    2008-04-01

    The liquid fuel quality control is an important issue that brings benefits for the State, for the consumers and for the environment. The conformity analysis, in special for gasoline, demands a rigorous sampling technique among gas stations and other economic agencies, followed by a series of standard physicochemical tests. Such procedures are commonly expensive and time demanding and, moreover, a specialist is often required to carry out the tasks. Such drawbacks make the development of alternative analysis tools an important research field. The fuel refractive index is an additional parameter to help the fuel conformity analysis, besides the prospective optical fiber sensors, which operate like transducers with singular properties. When this parameter is correlated with the sample density, it becomes possible to determine conformity zones that cannot be analytically defined. This work presents an application of artificial neural networks based on Radial Basis Function to determine these zones. A set of 45 gasoline samples, collected in several gas stations and previously analyzed according to the rules of Agência Nacional do Petróleo, Gás Natural e Biocombustíveis, a Brazilian regulatory agency, constituted the database to build two neural networks. The input variables of first network are the samples refractive indices, measured with an Abbe refractometer, and the density of the samples measured with a digital densimeter. For the second network the input variables included, besides the samples densities, the wavelength response of a long-period grating to the samples refractive indices. The used grating was written in an optical fiber using the point-to-point technique by submitting the fiber to consecutive electrical arcs from a splice machine. The output variables of both Radial Basis Function Networks are represented by the conformity status of each sample, according to report of tests carried out following the American Society for Testing and Materials

  1. HermesD: A High-Rate Long-Range Wireless Transmission System for Simultaneous Multichannel Neural Recording Applications.

    Science.gov (United States)

    Miranda, Henrique; Gilja, Vikash; Chestek, Cindy A; Shenoy, Krishna V; Meng, Teresa H

    2010-06-01

    HermesD is a high-rate, low-power wireless transmission system to aid research in neural prosthetic systems for motor disabilities and basic motor neuroscience. It is the third generation of our "Hermes systems" aimed at recording and transmitting neural activity from brain-implanted electrode arrays. This system supports the simultaneous transmission of 32 channels of broadband data sampled at 30 ks/s, 12 b/sample, using frequency-shift keying modulation on a carrier frequency adjustable from 3.7 to 4.1 GHz, with a link range extending over 20 m. The channel rate is 24 Mb/s and the bit stream includes synchronization and error detection mechanisms. The power consumption, approximately 142 mW, is low enough to allow the system to operate continuously for 33 h, using two 3.6-V/1200-mAh Li-SOCl2 batteries. The transmitter was designed using off-the-shelf components and is assembled in a stack of three 28 mm ? 28-mm boards that fit in a 38 mm ? 38 mm ? 51-mm aluminum enclosure, a significant size reduction over the initial version of HermesD. A 7-dBi circularly polarized patch antenna is used as the transmitter antenna, while on the receiver side, a 13-dBi circular horn antenna is employed. The advantages of using circularly polarized waves are analyzed and confirmed by indoor measurements. The receiver is a stand-alone device composed of several submodules and is interfaced to a computer for data acquisition and processing. It is based on the superheterodyne architecture and includes automatic frequency control that keeps it optimally tuned to the transmitter frequency. The HermesD communications performance is shown through bit-error rate measurements and eye-diagram plots. The sensitivity of the receiver is -83 dBm for a bit-error probability of 10(-9). Experimental recordings from a rhesus monkey conducting multiple tasks show a signal quality comparable to commercial acquisition systems, both in the low-frequency (local field potentials) and upper-frequency bands

  2. Strategies for High-Performance Resource-Efficient Compression of Neural Spike Recordings

    OpenAIRE

    Palmi Thor Thorbergsson; Martin Garwicz; Jens Schouenborg; Johansson, Anders J

    2014-01-01

    Brain-machine interfaces (BMIs) based on extracellular recordings with microelectrodes provide means of observing the activities of neurons that orchestrate fundamental brain function, and are therefore powerful tools for exploring the function of the brain. Due to physical restrictions and risks for post-surgical complications, wired BMIs are not suitable for long-term studies in freely behaving animals. Wireless BMIs ideally solve these problems, but they call for low-complexity techniques ...

  3. A frequency shaping neural recorder with 3 pF input capacitance and 11 plus 4.5 bits dynamic range.

    Science.gov (United States)

    Xu, Jian; Wu, Tong; Liu, Wentai; Yang, Zhi

    2014-08-01

    This paper presents a frequency-shaping (FS) neural recording architecture and its implementation in a 0.13 μ m CMOS process. Compared with its conventional counterpart, the proposed architecture inherently rejects electrode offset, increases input impedance 5-10 fold, compresses neural data dynamic range (DR) by 4.5-bit, simultaneously records local field potentials (LFPs) and extracellular spikes, and is more suitable for long-term recording experiments. Measured at a 40 kHz sampling clock and ± 0.6 V supply, the recorder consumes 50 μW/ch, of which 22 μW per FS amplifier, 24 μ W per buffer, 4 μ W per 11-bit successive approximation register analog-to-digital converter (SAR ADC). The input-referred noise for LFPs and extracellular spikes are 13 μ Vrms and 7 μVrms, respectively, which are sufficient to achieve high-fidelity full-spectrum neural data. In addition, the designed recorder has a 3 pF input capacitance and allows " 11+4.5"-bit neural data DR without system saturation, where the extra 4.5-bit owes to the FS technique. Its figure-of-merit (FOM) based on data DR reaches 36.0 fJ/conversion-step.

  4. Modal demultiplexing properties of tapered and nanostructured optical fibers for in vivo optogenetic control of neural activity.

    Science.gov (United States)

    Pisanello, Marco; Della Patria, Andrea; Sileo, Leonardo; Sabatini, Bernardo L; De Vittorio, Massimo; Pisanello, Ferruccio

    2015-10-01

    Optogenetic approaches to manipulate neural activity have revolutionized the ability of neuroscientists to uncover the functional connectivity underlying brain function. At the same time, the increasing complexity of in vivo optogenetic experiments has increased the demand for new techniques to precisely deliver light into the brain, in particular to illuminate selected portions of the neural tissue. Tapered and nanopatterned gold-coated optical fibers were recently proposed as minimally invasive multipoint light delivery devices, allowing for site-selective optogenetic stimulation in the mammalian brain [Pisanello , Neuron82, 1245 (2014)]. Here we demonstrate that the working principle behind these devices is based on the mode-selective photonic properties of the fiber taper. Using analytical and ray tracing models we model the finite conductance of the metal coating, and show that single or multiple optical windows located at specific taper sections can outcouple only specific subsets of guided modes injected into the fiber.

  5. Development of an optical character recognition pipeline for handwritten form fields from an electronic health record.

    Science.gov (United States)

    Rasmussen, Luke V; Peissig, Peggy L; McCarty, Catherine A; Starren, Justin

    2012-06-01

    Although the penetration of electronic health records is increasing rapidly, much of the historical medical record is only available in handwritten notes and forms, which require labor-intensive, human chart abstraction for some clinical research. The few previous studies on automated extraction of data from these handwritten notes have focused on monolithic, custom-developed recognition systems or third-party systems that require proprietary forms. We present an optical character recognition processing pipeline, which leverages the capabilities of existing third-party optical character recognition engines, and provides the flexibility offered by a modular custom-developed system. The system was configured and run on a selected set of form fields extracted from a corpus of handwritten ophthalmology forms. The processing pipeline allowed multiple configurations to be run, with the optimal configuration consisting of the Nuance and LEADTOOLS engines running in parallel with a positive predictive value of 94.6% and a sensitivity of 13.5%. While limitations exist, preliminary experience from this project yielded insights on the generalizability and applicability of integrating multiple, inexpensive general-purpose third-party optical character recognition engines in a modular pipeline.

  6. Illusions in the spatial sense of the eye: geometrical-optical illusions and the neural representation of space.

    Science.gov (United States)

    Westheimer, Gerald

    2008-09-01

    Differences between the geometrical properties of simple configurations and their visual percept are called geometrical-optical illusions. They can be differentiated from illusions in the brightness or color domains, from ambiguous figures and impossible objects, from trompe l'oeil and perspective drawing with perfectly valid views, and from illusory contours. They were discovered independently by several scientists in a short time span in the 1850's. The clear distinction between object and visual space that they imply allows the question to be raised whether the transformation between the two spaces can be productively investigated in terms of differential geometry and metrical properties. Perceptual insight and psychophysical research prepares the ground for investigation of the neural representation of space but, because visual attributes are processed separately in parallel, one looks in vain for a neural map that is isomorphic with object space or even with individual forms it contains. Geometrical-optical illusions help reveal parsing rules for sensory signals by showing how conflicts are resolved when there is mismatch in the output of the processing modules for various primitives as a perceptual pattern's unitary structure is assembled. They point to a hierarchical ordering of spatial primitives: cardinal directions and explicit contours predominate over oblique orientation and implicit contours (Poggendorff illusion); rectilinearity yields to continuity (Hering illusion), point position and line length to contour orientation (Ponzo). Hence the geometrical-optical illusions show promise as analytical tools in unraveling neural processing in vision.

  7. Optical recording of calcium currents during impulse conduction in cardiac tissue.

    Science.gov (United States)

    Jousset, Florian; Rohr, Stephan

    2015-04-01

    We explore the feasibility of obtaining a spatially resolved picture of [Formula: see text] inward currents ([Formula: see text]) in multicellular cardiac tissue by differentiating optically recorded [Formula: see text] transients that accompany propagating action potentials. Patterned growth strands of neonatal rat ventricular cardiomyocytes were stained with the [Formula: see text] indicators Fluo-4 or Fluo-4FF. Preparations were stimulated at 1 Hz, and [Formula: see text] transients were recorded with high spatiotemporal resolution ([Formula: see text], 2 kHz analog bandwidth) with a photodiode array. Signals were differentiated after appropriate digital filtering. Differentiation of [Formula: see text] transients resulted in optically recorded calcium currents (ORCCs) that carried the temporal and pharmacological signatures of L-type [Formula: see text] inward currents: the time to peak amounted to [Formula: see text] (Fluo-4FF) and [Formula: see text] (Fluo-4), full-width at half-maximum was [Formula: see text], and ORCCs were completely suppressed by [Formula: see text][Formula: see text]. Also, and as reported before from patch-clamp studies, caffeine reversibly depressed the amplitude of ORCCs. The results demonstrate that the differentiation of [Formula: see text] transients can be used to obtain a spatially resolved picture of the initial phase of [Formula: see text] in cardiac tissue and to assess relative changes of activation/fast inactivation of [Formula: see text] following pharmacological interventions.

  8. Feature extraction for magnetic domain images of magneto-optical recording films using gradient feature segmentation

    Science.gov (United States)

    Quanqing, Zhu; Xinsai, Wang; Xuecheng, Zou; Haihua, Li; Xiaofei, Yang

    2002-07-01

    In this paper, we present a method to realize feature extraction on low contrast magnetic domain images of magneto-optical recording films. The method is based on the following three steps: first, Lee-filtering method is adopted to realize pre-filtering and noise reduction; this is followed by gradient feature segmentation, which separates the object area from the background area; finally the common linking method is adopted and the characteristic parameters of magnetic domain are calculated. We describe these steps with particular emphasis on the gradient feature segmentation. The results show that this method has advantages over other traditional ones for feature extraction of low contrast images.

  9. Decision feedback equalization with multichannel readback in high-density optical recording

    Science.gov (United States)

    Gopalaswamy, Srinivasan; Vijaya Kumar, Bhagavatula

    1995-12-01

    Multi-channel readback using array heads has been reported in optical recording. A method to reduce both interference along and across the tracks using multi-channel readback is presented. In this method, the non-linear multi-channel decision feedback equalization is used to remove both forms of interference. Simulation results show good improvement (in performance) by using the multi-channel equalization. By this readback method, tracks can be brought closer, thus increasing the areal density. Another advantage of this method is the high data rate possible.

  10. Land/groove optical recording with GeTe/Sb2Te3 superlattice-like structure

    Institute of Scientific and Technical Information of China (English)

    Wei Qiang(墙威); Luping Shi; Towchong Chong; Yang Cao(曹阳)

    2004-01-01

    A superlattice-like (SLL) structure was applied to phase-change optical recording. The recording layer consisting of alternating thin layers of two different phase-change materials, GeTe and Sb2Tes, were grown by magnetron sputtering on polycarbonate substrates. Land/groove optical recording was adopted to suppress crosstalk and obtain a large track density. Dynamic properties of the SLL disc were investigated with the shortest 1T pulse duration of 8 ns. Clear eye pattern was observed after 10000 direct overwrite cycles. Erasability above 20 dB was achieved at a constant linear velocity of 19 m/s. Carrier-noise ratio (CNR) kept above 46 dB when the recording frequency reaches 21 MHz. The SLL phase change optical disc demonstrates a better recording performance than the Ge1Sb2Te4 and Ge1Sb4Te7 discs in terms of CNR, erasability, and overwrite jitter.

  11. Silicon-substrate microelectrode arrays for parallel recording of neural activity in peripheral and cranial nerves.

    Science.gov (United States)

    Kovacs, G T; Storment, C W; Halks-Miller, M; Belczynski, C R; Della Santina, C C; Lewis, E R; Maluf, N I

    1994-06-01

    A new process for the fabrication of regeneration microelectrode arrays for peripheral and cranial nerve applications is presented. This type of array is implanted between the severed ends of nerves, the axons of which regenerate through via holes in the silicon and are thereafter held fixed with respect to the microelectrodes. The process described is designed for compatibility with industry-standard CMOS or BiCMOS processes (it does not involve high-temperature process steps nor heavily-doped etch-stop layers), and provides a thin membrane for the via holes, surrounded by a thick silicon supporting rim. Many basic questions remain regarding the optimum via hole and microelectrode geometries in terms of both biological and electrical performance of the implants, and therefore passive versions were fabricated as tools for addressing these issues in on-going work. Versions of the devices were implanted in the rat peroneal nerve and in the frog auditory nerve. In both cases, regeneration was verified histologically and it was observed that the regenerated nerves had reorganized into microfascicles containing both myelinated and unmyelinated axons and corresponding to the grid pattern of the via holes. These microelectrode arrays were shown to allow the recording of action potential signals in both the peripheral and cranial nerve setting, from several microelectrodes in parallel.

  12. Neural networks underlying parietal lobe seizures: a quantified study from intracerebral recordings.

    Science.gov (United States)

    Bartolomei, Fabrice; Gavaret, Martine; Hewett, Russell; Valton, Luc; Aubert, Sandrine; Régis, Jean; Wendling, Fabrice; Chauvel, Patrick

    2011-02-01

    In this study we have quantified the "epileptogenicity" of several brain regions in seizures originating in the posterior parietal cortex in 17 patients investigated by intracerebral recordings using stereotactic EEG (SEEG). Epileptogenicity of brain structures was quantified according to the "epileptogenicity index" (EI), a way to quantify rapid discharges at seizure onset. Seven patients had maximal epileptogenicity in the superior parietal lobule-BA area 7 (Gr1), 2 patients in the superior parietal lobule-area 5 (Gr2), 4 patients in inferior parietal lobule (Gr3) and 4 in the opercular region (Gr4). A large majority of patients (15/17 (88%)) reported to have at least one aura during the course of their disease. Somato-sensory manifestations were reported in the four groups. Vestibular disturbance was observed mainly in seizures from the superior parietal lobule (Gr1 and 2). Ipsilateral version was the most frequent objective manifestation (64%). Hyperkinetic behaviour (motor agitation) was found to be frequent, observed in 4/17 cases (23%) and observed in seizures from inferior parietal regions. In conclusion, the electrophysiological organization and the clinical manifestations of PLS are various and complex. The subjective manifestations are frequent and often suggestive, therefore must be actively sought. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Strategies for high-performance resource-efficient compression of neural spike recordings.

    Science.gov (United States)

    Thorbergsson, Palmi Thor; Garwicz, Martin; Schouenborg, Jens; Johansson, Anders J

    2014-01-01

    Brain-machine interfaces (BMIs) based on extracellular recordings with microelectrodes provide means of observing the activities of neurons that orchestrate fundamental brain function, and are therefore powerful tools for exploring the function of the brain. Due to physical restrictions and risks for post-surgical complications, wired BMIs are not suitable for long-term studies in freely behaving animals. Wireless BMIs ideally solve these problems, but they call for low-complexity techniques for data compression that ensure maximum utilization of the wireless link and energy resources, as well as minimum heat dissipation in the surrounding tissues. In this paper, we analyze the performances of various system architectures that involve spike detection, spike alignment and spike compression. Performance is analyzed in terms of spike reconstruction and spike sorting performance after wireless transmission of the compressed spike waveforms. Compression is performed with transform coding, using five different compression bases, one of which we pay special attention to. That basis is a fixed basis derived, by singular value decomposition, from a large assembly of experimentally obtained spike waveforms, and therefore represents a generic basis specially suitable for compressing spike waveforms. Our results show that a compression factor of 99.8%, compared to transmitting the raw acquired data, can be achieved using the fixed generic compression basis without compromising performance in spike reconstruction and spike sorting. Besides illustrating the relative performances of various system architectures and compression bases, our findings show that compression of spikes with a fixed generic compression basis derived from spike data provides better performance than compression with downsampling or the Haar basis, given that no optimization procedures are implemented for compression coefficients, and the performance is similar to that obtained when the optimal SVD based

  14. Strategies for high-performance resource-efficient compression of neural spike recordings.

    Directory of Open Access Journals (Sweden)

    Palmi Thor Thorbergsson

    Full Text Available Brain-machine interfaces (BMIs based on extracellular recordings with microelectrodes provide means of observing the activities of neurons that orchestrate fundamental brain function, and are therefore powerful tools for exploring the function of the brain. Due to physical restrictions and risks for post-surgical complications, wired BMIs are not suitable for long-term studies in freely behaving animals. Wireless BMIs ideally solve these problems, but they call for low-complexity techniques for data compression that ensure maximum utilization of the wireless link and energy resources, as well as minimum heat dissipation in the surrounding tissues. In this paper, we analyze the performances of various system architectures that involve spike detection, spike alignment and spike compression. Performance is analyzed in terms of spike reconstruction and spike sorting performance after wireless transmission of the compressed spike waveforms. Compression is performed with transform coding, using five different compression bases, one of which we pay special attention to. That basis is a fixed basis derived, by singular value decomposition, from a large assembly of experimentally obtained spike waveforms, and therefore represents a generic basis specially suitable for compressing spike waveforms. Our results show that a compression factor of 99.8%, compared to transmitting the raw acquired data, can be achieved using the fixed generic compression basis without compromising performance in spike reconstruction and spike sorting. Besides illustrating the relative performances of various system architectures and compression bases, our findings show that compression of spikes with a fixed generic compression basis derived from spike data provides better performance than compression with downsampling or the Haar basis, given that no optimization procedures are implemented for compression coefficients, and the performance is similar to that obtained when the

  15. Design and measurements of 64-channel ASIC for neural signal recording.

    Science.gov (United States)

    Kmon, P; Zoladz, M; Grybos, P; Szczygiel, R

    2009-01-01

    This paper presents the design and measurements of a low noise multi-channel front-end electronics for recording extra-cellular neuronal signals using microelectrode arrays. The integrated circuit contains 64 readout channels and was fabricated in CMOS 0.18 microm technology. A single readout channel is built of an AC coupling circuit at the input, a low noise preamplifier, a band-pass filter and a second amplifier. In order to reduce the number of output lines, the 64 analog signals from readout channels are multiplexed to a single output by an analog multiplexer. The chip is optimized for low noise and matching performance with the possibility of cut-off frequencies tuning. The low cut-off frequency can be tuned in the 1 Hz-60 Hz range and the high cut-off frequency can be tuned in the 3.5 kHz-15 kHz range. For the nominal gain setting at 44 dB and power dissipation per single channel of 220 microW the equivalent input noise is in the range from 6 microV-11 microV rms depending on the band-pass filter settings. The chip has good uniformity concerning the spread of its electrical parameters from channel to channel. The spread of gain calculated as standard deviation to mean value is about 4.4% and the spread of the low cut-off frequency is on the same level. The chip occupies 5x2.3 mm(2) of silicon area.

  16. Detection of micro gap weld joint by using magneto-optical imaging and Kalman filtering compensated with RBF neural network

    Science.gov (United States)

    Gao, Xiangdong; Chen, Yuquan; You, Deyong; Xiao, Zhenlin; Chen, Xiaohui

    2017-02-01

    An approach for seam tracking of micro gap weld whose width is less than 0.1 mm based on magneto optical (MO) imaging technique during butt-joint laser welding of steel plates is investigated. Kalman filtering(KF) technology with radial basis function(RBF) neural network for weld detection by an MO sensor was applied to track the weld center position. Because the laser welding system process noises and the MO sensor measurement noises were colored noises, the estimation accuracy of traditional KF for seam tracking was degraded by the system model with extreme nonlinearities and could not be solved by the linear state-space model. Also, the statistics characteristics of noises could not be accurately obtained in actual welding. Thus, a RBF neural network was applied to the KF technique to compensate for the weld tracking errors. The neural network can restrain divergence filter and improve the system robustness. In comparison of traditional KF algorithm, the RBF with KF was not only more effectively in improving the weld tracking accuracy but also reduced noise disturbance. Experimental results showed that magneto optical imaging technique could be applied to detect micro gap weld accurately, which provides a novel approach for micro gap seam tracking.

  17. Experiments on the data recording of optical waveguide multilayer storage devices

    Science.gov (United States)

    Liang, Zhongcheng; Ding, Dongyan; Xie, Haiyan; Gu, Minfen; Chen, Jiabi; Zhuang, Songlin

    2005-12-01

    The basic principles of optical waveguide multilayer storage (WMS) device include recording data in the form of waveguide defects, reading data by collecting the scatter light from the waveguide defects, and restraining the cross talk between layers by taking the benefit of the waveguide structure. In this paper, we give some experimental results obtained by three different approaches of data recording. They are laser direct writing, photolithography and hot embossing. In the first method, a laser beam is focused on the top of a polymer film. The thermal effect alters the medium property locally at the focus point, which acts as the defect in the waveguide structure. The second method resorts to the processes of photolithography to record pits on the photoresist layer. The process of hot embossing is similar to the fabrication of CD-ROM, however, the data pits deeper than the wavelength are embossed on the polymer surface to increase the scattering efficiency. WMS devices based on different data writing methods are presented and the data scattering patterns are observed. The comparison between the different data writing approaches is made and discussed as well.

  18. A Wireless and Batteryless Microsystem with Implantable Grid Electrode/3-Dimensional Probe Array for ECoG and Extracellular Neural Recording in Rats

    Directory of Open Access Journals (Sweden)

    Chih-Wei Chang

    2013-04-01

    Full Text Available This paper presents the design and implementation of an integrated wireless microsystem platform that provides the possibility to support versatile implantable neural sensing devices in free laboratory rats. Inductive coupled coils with low dropout regulator design allows true long-term recording without limitation of battery capacity. A 16-channel analog front end chip located on the headstage is designed for high channel account neural signal conditioning with low current consumption and noise. Two types of implantable electrodes including grid electrode and 3D probe array are also presented for brain surface recording and 3D biopotential acquisition in the implanted target volume of tissue. The overall system consumes less than 20 mA with small form factor, 3.9 × 3.9 cm2 mainboard and 1.8 × 3.4 cm2 headstage, is packaged into a backpack for rats. Practical in vivo recordings including auditory response, brain resection tissue and PZT-induced seizures recording demonstrate the correct function of the proposed microsystem. Presented achievements addressed the aforementioned properties by combining MEMS neural sensors, low-power circuit designs and commercial chips into system-level integration.

  19. On the Pulsewidth Analysis in the Presence of PMD and PDL in Optical Fibers Using Neural Network Algorithm

    Directory of Open Access Journals (Sweden)

    A. Sivasubramanian

    2007-01-01

    Full Text Available In long haul networks, the random birefringence induced in the optical fiber leads to a considerable Polarization Mode Dispersion (PMD. Polarization Dependent Loss (PDL mainly occurs in optical components and depends on the state of polarization of optical signals. The presence of PMD and PDL causes pulsewidth narrowing and the pulsewidth reduction depends on states of polarization at which the input light launched and also the input pulsewidth. A system comprising of a PDL element sandwiched between two PMD elements was considered. This system was characterized using neural network approach. Back propagation algorithm was applied to train the network with four input vectors namely PMD, PDL, input pulsewidth and the angle describing the input states of polarization and one output vector indicating effective squared pulsewidth difference. On analysis, it was found that the pulsewidth reduction was higher for a PMD of 30ps, a PDL of 3.5 and input pulsewidth of 100ps at various (Linear and Circular input states of polarization with the angle describing the input state of polarization to be |π/4|. Similarly, for a given value of PMD, PDL, input pulsewidth and a specific pulsewidth reduction, the input state of polarization at which the light was to be launched can also be determined using neural network approach.

  20. Neural maps of interaural time and intensity differences in the optic tectum of the barn owl.

    Science.gov (United States)

    Olsen, J F; Knudsen, E I; Esterly, S D

    1989-07-01

    This report describes the binaural basis of the auditory space map in the optic tectum of the barn owl (Tyto alba). Single units were recorded extracellularly in ketamine-anesthetized birds. Unit tuning for interaural differences in timing and intensity of wideband noise was measured using digitally synthesized sound presented through earphones. Spatial receptive fields of the same units were measured with a free field sound source. Auditory units in the optic tectum are sharply tuned for both the azimuth and the elevation of a free field sound source. To determine the binaural cues that could be responsible for this spatial tuning, we measured in the ear canals the amplitude and phase spectra produced by a free field noise source and calculated from these measurements the interaural differences in time and intensity associated with each of 178 locations throughout the frontal hemisphere. For all frequencies, interaural time differences (ITDs) varied systematically and most strongly with source azimuth. The pattern of variation of interaural intensity differences (IIDs) depended on frequency. For low frequencies (below 4 kHz) IID varied primarily with source azimuth, whereas for high frequencies (above 5 kHz) IID varied primarily with source elevation. Tectal units were tuned for interaural differences in both time and intensity of dichotic stimuli. Changing either parameter away from the best value for the unit decreased the unit's response. The tuning of units to either parameter was sharp: the width of ITD tuning curves, measured at 50% of the maximum response with IID held constant (50% tuning width), ranged from 18 to 82 microsecs. The 50% tuning widths of IID tuning curves, measured with ITD held constant, ranged from 8 to 37 dB. For most units, tuning for ITD was largely independent of IID, and vice versa. A few units exhibited systematic shifts of the best ITD with changes in IID (or shifts of the best IID with changes in ITD); for these units, a change in

  1. Integrating artificial neural network and classical methods for unsupervised classification of optical remote sensing data

    Science.gov (United States)

    Tahir, Ahmed AK

    2012-12-01

    A novel system named unsupervised multiple classifier system (UMCS) for unsupervised classification of optical remote sensing data is presented. The system is based on integrating two or more individual classifiers. A new dynamic selection-based method is developed for integrating the decisions of the individual classifiers. It is based on competition distance arranged in a table named class-distance map (CDM) associated to each individual classifier. These maps are derived from the class-to-class-distance measures which represent the distances between each class and the remaining classes for each individual classifier. Three individual classifiers are used for the development of the system, K-means and K-medians clustering of the classical approach and Kohonen network of the artificial neural network approach. The system is applied to ETM + images of an area North to Mosul dam in northern part of Iraq. To show the significance of increasing the number of individual classifiers, the application covered three modes, UMCS@, UMCS#, and UMCS*. In UMCS@, K-means and Kohonen are used as individual classifiers. In UMCS#, K-medians and Kohonen are used as individual classifiers. In UMCS*, K-means, K-medians and Kohonen are used as individual classifiers. The performance of the system for the three modes is evaluated by comparing the outputs of individual classifiers to the outputs of UMCSs using test data extracted by visual interpretation of color composite images. The evaluation has shown that the performance of the system with all three modes outrages the performance of the individual classifiers. However, the improvement in the class and average accuracy for UMCS* was significant compared to the improvements made by UMCS@, and UMCS#. For UMCS*, the accuracy of all classes were improved over the accuracy achieved by each of the individual classifiers and the average improvements reached (4.27, 3.70, and 6.41%) over the average accuracy achieved by K-means, K-medians and

  2. Reconstruction of long-term aerosol optical depth series with sunshine duration records

    Science.gov (United States)

    Sanchez-Romero, A.; Sanchez-Lorenzo, A.; González, J. A.; Calbó, J.

    2016-02-01

    We report the suitability of sunshine duration (SD) records as a proxy for the reconstruction of atmospheric aerosol content, for which little information exists, especially prior to the 1980s. Specifically, we have treated cloudless summer days in 16 stations throughout Spain. For almost all sites we find statistically significant relationships between aerosol optical depth (AOD) and daily SD. The correlation coefficient presents a mean value of -0.72, and slope values of the linear regressions are within the range [-0.11, -0.36]. The relationships are used to generate AOD series back to the 1960s (to the 1920s for Madrid). These reconstructed series show an increase in AOD from the mid-1960s to the 1980s, followed by a decrease until the present, in agreement with changes in anthropogenic aerosol emissions and with opposite trends of solar irradiance. The method can be used to reconstruct AOD from the late nineteenth century at many stations worldwide.

  3. Optical recording-guided pacing to create functional line of block during ventricular fibrillation

    Science.gov (United States)

    Ravi, Krishna; Nihei, Motoki; Willmer, Anjuli; Hayashi, Hideki; Lin, Shien-Fong

    2006-03-01

    Low-energy defibrillation is very desirable in cardiac rhythm management. We previously reported that ventricular fibrillation (VF) can be synchronized with a novel synchronized pacing technique (SyncP) using low-energy pacing pulses. This study sought to create a line of block during VF using SyncP. SyncP was performed in six isolated rabbit hearts during VF using optical recording to control the delivery of pacing pulses in real time. Four pacing electrodes with interelectrode distances of 5 mm were configured in a line along and across the myocardial fiber direction. The electrodes were controlled independently (independent mode) or fired together (simultaneous mode). Significant wavefront synchronization was observed along the electrode line as indicated by a decrease in variance. With the independent SyncP protocol, the decrease in the variance was 19.3 and 13.7% (Pventricular defibrillation.

  4. Thermal Analysis of Heat-Assisted Magnetic Recording Optical Head with Laser Diode on Slider

    Science.gov (United States)

    Xu, Baoxi; Chia, Cheow Wee; Zhang, Qide; Teck Toh, Yeow; An, Chengwu; Vienne, Guillaume

    2011-09-01

    For the optical head used in heat-assisted magnetic recording (HAMR), mounting a laser diode chip on the slider offers a more integrated, compact, and stable design. However, the heat generated by the laser diode will cause the head temperature to increase, which may decrease the laser output power and change the slider flying status. In this paper, the thermal analysis of the HAMR head including the laser diode and a transducer is conducted. The effects of the laser diode power, the power absorbed by the transducer, boundary thermal resistance between the laser diode chip and the slider substrate, and slider fly speed and fly height on the laser temperature increase, the transducer temperature increase, and the air-bearing surface temperature distribution are studied. The deformation of the air-bearing surface caused by its temperature change is also analyzed.

  5. Aerosol optical depth retrievals at the Izaña Atmospheric Observatory from 1941 to 2013 by using artificial neural networks

    Science.gov (United States)

    García, R. D.; García, O. E.; Cuevas, E.; Cachorro, V. E.; Barreto, A.; Guirado-Fuentes, C.; Kouremeti, N.; Bustos, J. J.; Romero-Campos, P. M.; de Frutos, A. M.

    2016-01-01

    This paper presents the reconstruction of a 73-year time series of the aerosol optical depth (AOD) at 500 nm at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (Canary Islands, Spain). For this purpose, we have combined AOD estimates from artificial neural networks (ANNs) from 1941 to 2001 and AOD measurements directly obtained with a Precision Filter Radiometer (PFR) between 2003 and 2013. The analysis is limited to summer months (July-August-September), when the largest aerosol load is observed at IZO (Saharan mineral dust particles). The ANN AOD time series has been comprehensively validated against coincident AOD measurements performed with a solar spectrometer Mark-I (1984-2009) and AERONET (AErosol RObotic NETwork) CIMEL photometers (2004-2009) at IZO, obtaining a rather good agreement on a daily basis: Pearson coefficient, R, of 0.97 between AERONET and ANN AOD, and 0.93 between Mark-I and ANN AOD estimates. In addition, we have analysed the long-term consistency between ANN AOD time series and long-term meteorological records identifying Saharan mineral dust events at IZO (synoptical observations and local wind records). Both analyses provide consistent results, with correlations > 85 %. Therefore, we can conclude that the reconstructed AOD time series captures well the AOD variations and dust-laden Saharan air mass outbreaks on short-term and long-term timescales and, thus, it is suitable to be used in climate analysis.

  6. Refractometry of melanocyte cell nuclei using optical scatter images recorded by digital Fourier microscopy.

    Science.gov (United States)

    Seet, Katrina Y T; Nieminen, Timo A; Zvyagin, Andrei V

    2009-01-01

    The cell nucleus is the dominant optical scatterer in the cell. Neoplastic cells are characterized by cell nucleus polymorphism and polychromism-i.e., the nuclei exhibits an increase in the distribution of both size and refractive index. The relative size parameter, and its distribution, is proportional to the product of the nucleus size and its relative refractive index and is a useful discriminant between normal and abnormal (cancerous) cells. We demonstrate a recently introduced holographic technique, digital Fourier microscopy (DFM), to provide a sensitive measure of this relative size parameter. Fourier holograms were recorded and optical scatter of individual scatterers were extracted and modeled with Mie theory to determine the relative size parameter. The relative size parameter of individual melanocyte cell nuclei were found to be 16.5+/-0.2, which gives a cell nucleus refractive index of 1.38+/-0.01 and is in good agreement with previously reported data. The relative size parameters of individual malignant melanocyte cell nuclei are expected to be greater than 16.5.

  7. Assessment of 10 Year Record of Aerosol Optical Depth from OMI UV Observations

    Science.gov (United States)

    Ahn, Changwoo; Torres, Omar; Jethva, Hiren

    2014-01-01

    The Ozone Monitoring Instrument (OMI) onboard the EOS-Aura satellite provides information on aerosol optical properties by making use of the large sensitivity to aerosol absorption in the near-ultraviolet (UV) spectral region. Another important advantage of using near UV observations for aerosol characterization is the low surface albedo of all terrestrial surfaces in this spectral region that reduces retrieval errors associated with land surface reflectance characterization. In spite of the 13 × 24 square kilometers coarse sensor footprint, the OMI near UV aerosol algorithm (OMAERUV) retrieves aerosol optical depth (AOD) and single-scattering albedo under cloud-free conditions from radiance measurements at 354 and 388 nanometers. We present validation results of OMI AOD against space and time collocated Aerosol Robotic Network measured AOD values over multiple stations representing major aerosol episodes and regimes. OMAERUV's performance is also evaluated with respect to those of the Aqua-MODIS Deep Blue and Terra-MISR AOD algorithms over arid and semi-arid regions in Northern Africa. The outcome of the evaluation analysis indicates that in spite of the "row anomaly" problem, affecting the sensor since mid-2007, the long-term aerosol record shows remarkable sensor stability.

  8. A multi-channel low-power system-on-chip for single-unit recording and narrowband wireless transmission of neural signal.

    Science.gov (United States)

    Bonfanti, A; Ceravolo, M; Zambra, G; Gusmeroli, R; Spinelli, A S; Lacaita, A L; Angotzi, G N; Baranauskas, G; Fadiga, L

    2010-01-01

    This paper reports a multi-channel neural recording system-on-chip (SoC) with digital data compression and wireless telemetry. The circuit consists of a 16 amplifiers, an analog time division multiplexer, an 8-bit SAR AD converter, a digital signal processor (DSP) and a wireless narrowband 400-MHz binary FSK transmitter. Even though only 16 amplifiers are present in our current die version, the whole system is designed to work with 64 channels demonstrating the feasibility of a digital processing and narrowband wireless transmission of 64 neural recording channels. A digital data compression, based on the detection of action potentials and storage of correspondent waveforms, allows the use of a 1.25-Mbit/s binary FSK wireless transmission. This moderate bit-rate and a low frequency deviation, Manchester-coded modulation are crucial for exploiting a narrowband wireless link and an efficient embeddable antenna. The chip is realized in a 0.35- εm CMOS process with a power consumption of 105 εW per channel (269 εW per channel with an extended transmission range of 4 m) and an area of 3.1 × 2.7 mm(2). The transmitted signal is captured by a digital TV tuner and demodulated by a wideband phase-locked loop (PLL), and then sent to a PC via an FPGA module. The system has been tested for electrical specifications and its functionality verified in in-vivo neural recording experiments.

  9. Synthesis, photochromism and holographic optical recording of a novel diarylethene bearing a pyrrole unit

    Science.gov (United States)

    Liu, Gang; Liu, Ming; Pu, Shouzhi; Fan, Congbin

    2011-02-01

    A unsymmetrical photochromic diarylethene, 1-[2-methyl-5-(3-fluorophenyl)-3-thienyl]-2 -(2-cyano-1,5-dimethyl-4-pyrryl)hexafluorocyclopentene (1o), was synthesized. The photoconversion ratios from open-ring to closed-ring isomers at photostationary state under UV irradiation in hexane solution was measured by HPLC, and the properties, including photochromism and fluorescence properties were also investigated systematically. The results showed that this compound had good thermal stability and exhibited reversible photochromism, changing from colorless to blue after irradiation with UV light both in solution and in PMMA amorphous film. The open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 427 nm in hexane solution (5×10-5 mol/L) when excited at 340 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light and its closed-ring isomer showed almost no fluorescence. Using diarylethene 1 as recording medium, polarization holographic optical recording was carried out successfully.

  10. Synthesis, photochromism and holographic optical recording of a novel diarylethene bearing a pyrrole unit

    Energy Technology Data Exchange (ETDEWEB)

    Liu Gang; Liu Ming; Pu Shouzhi; Fan Congbin, E-mail: pushouzhi@tsinghua.org.cn [Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013 (China)

    2011-02-01

    A unsymmetrical photochromic diarylethene, 1-[2-methyl-5-(3-fluorophenyl)-3-thienyl]-2 -(2-cyano-1,5-dimethyl-4-pyrryl)hexafluorocyclopentene (1o), was synthesized. The photoconversion ratios from open-ring to closed-ring isomers at photostationary state under UV irradiation in hexane solution was measured by HPLC, and the properties, including photochromism and fluorescence properties were also investigated systematically. The results showed that this compound had good thermal stability and exhibited reversible photochromism, changing from colorless to blue after irradiation with UV light both in solution and in PMMA amorphous film. The open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 427 nm in hexane solution (5x10{sup -5} mol/L) when excited at 340 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light and its closed-ring isomer showed almost no fluorescence. Using diarylethene 1 as recording medium, polarization holographic optical recording was carried out successfully.

  11. Negative hemodynamic response without neuronal inhibition investigated by combining optical imaging and electrophysiological recording.

    Science.gov (United States)

    Ma, Zengguang; Cao, Pengjia; Sun, Pengcheng; Lu, Zhuofan; Li, Liming; Chen, Yao; Chai, Xinyu

    2017-01-10

    Understanding the mechanisms underlying negative hemodynamic responses is critical for the interpretation of functional brain imaging signals. Negative imaging signals have been found in the visual, somatosensory and motor cortices in functional magnetic resonance imaging (fMRI) and intrinsic signal optical imaging (ISOI) studies. However, the origin of negative imaging signals is still controversial. The present study investigated the visual cortical responses to peripheral grating stimuli using multi-wavelength ISOI and electrophysiological recording. We found an increased cerebral blood volume (CBV) in the stimulus-induced regions and a decreased CBV in the adjacent regions in the visual cortex. Nevertheless, there was no significant change in blood oxygenation in the negative CBV regions. Furthermore, by combining the planar and laminar electrophysiological recordings, we did not observe significantly decreased neuronal activity in the negative CBV regions. Our results suggest that the negative hemodynamic response does not necessarily originate in decreased neuronal activity. Therefore, caution should be taken when interpreting a negative hemodynamic response as neuronal inhibition.

  12. Multiple-color optical activation, silencing, and desynchronization of neural activity, with single-spike temporal resolution.

    Directory of Open Access Journals (Sweden)

    Xue Han

    Full Text Available The quest to determine how precise neural activity patterns mediate computation, behavior, and pathology would be greatly aided by a set of tools for reliably activating and inactivating genetically targeted neurons, in a temporally precise and rapidly reversible fashion. Having earlier adapted a light-activated cation channel, channelrhodopsin-2 (ChR2, for allowing neurons to be stimulated by blue light, we searched for a complementary tool that would enable optical neuronal inhibition, driven by light of a second color. Here we report that targeting the codon-optimized form of the light-driven chloride pump halorhodopsin from the archaebacterium Natronomas pharaonis (hereafter abbreviated Halo to genetically-specified neurons enables them to be silenced reliably, and reversibly, by millisecond-timescale pulses of yellow light. We show that trains of yellow and blue light pulses can drive high-fidelity sequences of hyperpolarizations and depolarizations in neurons simultaneously expressing yellow light-driven Halo and blue light-driven ChR2, allowing for the first time manipulations of neural synchrony without perturbation of other parameters such as spiking rates. The Halo/ChR2 system thus constitutes a powerful toolbox for multichannel photoinhibition and photostimulation of virally or transgenically targeted neural circuits without need for exogenous chemicals, enabling systematic analysis and engineering of the brain, and quantitative bioengineering of excitable cells.

  13. Improving Recording Density of All-Optical Magnetic Storage by Using High-Pass Angular Spectrum Filters

    Institute of Scientific and Technical Information of China (English)

    ZHUANG You-Yi; ZHANG Yao-Ju

    2009-01-01

    A new design is presented to improve the magnetic recording density in all-optical magnetic storage.By using the high numerical lens with a high-pass angular spectrum filter, circularly polarized laser pulses are focused into the magneto-optic film with the perpendicular anisotropy.Magnetization of the film is induced by the inverse Faraday effect.As the obstructed angle of the filter increases the magnetic recording density increases evidently.The magnetization intensity and the sidelobe effect are also discussed.

  14. In Vivo Neural Recording and Electrochemical Performance of Microelectrode Arrays Modified by Rough-Surfaced AuPt Alloy Nanoparticles with Nanoporosity

    Directory of Open Access Journals (Sweden)

    Zongya Zhao

    2016-11-01

    Full Text Available In order to reduce the impedance and improve in vivo neural recording performance of our developed Michigan type silicon electrodes, rough-surfaced AuPt alloy nanoparticles with nanoporosity were deposited on gold microelectrode sites through electro-co-deposition of Au-Pt-Cu alloy nanoparticles, followed by chemical dealloying Cu. The AuPt alloy nanoparticles modified gold microelectrode sites were characterized by scanning electron microscopy (SEM, electrochemical impedance spectroscopy (EIS, cyclic voltammetry (CV and in vivo neural recording experiment. The SEM images showed that the prepared AuPt alloy nanoparticles exhibited cauliflower-like shapes and possessed very rough surfaces with many different sizes of pores. Average impedance of rough-surfaced AuPt alloy nanoparticles modified sites was 0.23 MΩ at 1 kHz, which was only 4.7% of that of bare gold microelectrode sites (4.9 MΩ, and corresponding in vitro background noise in the range of 1 Hz to 7500 Hz decreased to 7.5 μ V rms from 34.1 μ V rms at bare gold microelectrode sites. Spontaneous spike signal recording was used to evaluate in vivo neural recording performance of modified microelectrode sites, and results showed that rough-surfaced AuPt alloy nanoparticles modified microelectrode sites exhibited higher average spike signal-to-noise ratio (SNR of 4.8 in lateral globus pallidus (GPe due to lower background noise compared to control microelectrodes. Electro-co-deposition of Au-Pt-Cu alloy nanoparticles combined with chemical dealloying Cu was a convenient way for increasing the effective surface area of microelectrode sites, which could reduce electrode impedance and improve the quality of in vivo spike signal recording.

  15. Decoding of digital magnetic recording with longitudinal magnetization of a tape from a magneto-optical image of stray fields

    Science.gov (United States)

    Lisovskii, F. V.; Mansvetova, E. G.

    2017-05-01

    For digital magnetic recording of encoded information with longitudinal magnetization of the tape, the connection between the domain structure of a storage medium and magneto-optical image of its stray fields obtained using a magnetic film with a perpendicular anisotropy and a large Faraday rotation has been studied. For two-frequency binary code without returning to zero, an algorithm is developed, that allows uniquely decoding of the information recorded on the tape based on analysis of an image of stray fields.

  16. Circuit-breakers: optical technologies for probing neural signals and systems.

    Science.gov (United States)

    Zhang, Feng; Aravanis, Alexander M; Adamantidis, Antoine; de Lecea, Luis; Deisseroth, Karl

    2007-08-01

    Neuropsychiatric disorders, which arise from a combination of genetic, epigenetic and environmental influences, epitomize the challenges faced in understanding the mammalian brain. Elucidation and treatment of these diseases will benefit from understanding how specific brain cell types are interconnected and signal in neural circuits. Newly developed neuroengineering tools based on two microbial opsins, channelrhodopsin-2 (ChR2) and halorhodopsin (NpHR), enable the investigation of neural circuit function with cell-type-specific, temporally accurate and reversible neuromodulation. These tools could lead to the development of precise neuromodulation technologies for animal models of disease and clinical neuropsychiatry.

  17. Coupling of a CMOS Optical Sensor to a Micromachined Deformable Mirror with an Adaline Neural Method

    NARCIS (Netherlands)

    De Lima Monteiro, D.W.; Ferreira, A.I.; Teixeira, F.B.; Melo, J.G.M.; Vdovin, G.V.

    2006-01-01

    We report on the preliminary results of an Adaline neural method for the coupling of a custom CMOS wavefront sensor to a micromachined adaptive mirror. The algorithm does not rely on a fixed basis matrix -as opposed to traditional methods-, offers excellent immunity to round-off errors and admits re

  18. Coupling of a CMOS Optical Sensor to a Micromachined Deformable Mirror with an Adaline Neural Method

    NARCIS (Netherlands)

    De Lima Monteiro, D.W.; Ferreira, A.I.; Teixeira, F.B.; Melo, J.G.M.; Vdovin, G.V.

    2006-01-01

    We report on the preliminary results of an Adaline neural method for the coupling of a custom CMOS wavefront sensor to a micromachined adaptive mirror. The algorithm does not rely on a fixed basis matrix -as opposed to traditional methods-, offers excellent immunity to round-off errors and admits re

  19. Reconstruction of mechanically recorded sound from an edison cylinder using three dimensional non-contact optical surface metrology

    Energy Technology Data Exchange (ETDEWEB)

    Fadeyev, V.; Haber, C.; Maul, C.; McBride, J.W.; Golden, M.

    2004-04-20

    Audio information stored in the undulations of grooves in a medium such as a phonograph disc record or cylinder may be reconstructed, without contact, by measuring the groove shape using precision optical metrology methods and digital image processing. The viability of this approach was recently demonstrated on a 78 rpm shellac disc using two dimensional image acquisition and analysis methods. The present work reports the first three dimensional reconstruction of mechanically recorded sound. The source material, a celluloid cylinder, was scanned using color coded confocal microscopy techniques and resulted in a faithful playback of the recorded information.

  20. Optical memory system based on incoherent recorder and coherent reader of multiplexed computer generated one-dimensional Fourier transform holograms

    Science.gov (United States)

    Odinokov, Sergey; Zlokazov, Evgenii; Donchenko, Sergey; Verenikina, Nina

    2017-09-01

    The present article highlights the development results of archive memory holographic system based on application of computer generated Fourier holograms. The proposed idea allows realization of holographic principles of digital data record using simple and compact optical devices. Special interest is paid to synthesis and multiplexed record of one-dimensional Fourier transform holograms. The principal schemes of constructed prototypes of incoherent data recorder and coherent data reader are described in the present paper. The results of experimental implementation of the constructed devices are presented.

  1. Data-driven model comparing the effects of glial scarring and interface interactions on chronic neural recordings in non-human primates

    Science.gov (United States)

    Malaga, Karlo A.; Schroeder, Karen E.; Patel, Paras R.; Irwin, Zachary T.; Thompson, David E.; Bentley, J. Nicole; Lempka, Scott F.; Chestek, Cynthia A.; Patil, Parag G.

    2016-02-01

    Objective. We characterized electrode stability over twelve weeks of impedance and neural recording data from four chronically-implanted Utah arrays in two rhesus macaques, and investigated the effects of glial scarring and interface interactions at the electrode recording site on signal quality using a computational model. Approach. A finite-element model of a Utah array microelectrode in neural tissue was coupled with a multi-compartmental model of a neuron to quantify the effects of encapsulation thickness, encapsulation resistivity, and interface resistivity on electrode impedance and waveform amplitude. The coupled model was then reconciled with the in vivo data. Histology was obtained seventeen weeks post-implantation to measure gliosis. Main results. From week 1-3, mean impedance and amplitude increased at rates of 115.8 kΩ/week and 23.1 μV/week, respectively. This initial ramp up in impedance and amplitude was observed across all arrays, and is consistent with biofouling (increasing interface resistivity) and edema clearing (increasing tissue resistivity), respectively, in the model. Beyond week 3, the trends leveled out. Histology showed that thin scars formed around the electrodes. In the model, scarring could not match the in vivo data. However, a thin interface layer at the electrode tip could. Despite having a large effect on impedance, interface resistivity did not have a noticeable effect on amplitude. Significance. This study suggests that scarring does not cause an electrical problem with regard to signal quality since it does not appear to be the main contributor to increasing impedance or significantly affect amplitude unless it displaces neurons. This, in turn, suggests that neural signals can be obtained reliably despite scarring as long as the recording site has sufficiently low impedance after accumulating a thin layer of biofouling. Therefore, advancements in microelectrode technology may be expedited by focusing on improvements to the

  2. NOAA Climate Data Record (CDR) of AVHRR Daily and Monthly Aerosol Optical Thickness over Global Oceans, Version 2.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) of Aerosol Optical Thickness (AOT) is derived from data taken over global oceans from the PATMOS-x AVHRR level-2b channel 1 (0.63...

  3. Problems of large neurodynamics system modeling: optical synergetics and neural networks

    Science.gov (United States)

    Vorontsov, Mikhail A.

    1991-04-01

    The possibilities of modeling developed neuronetwork dynamics are investigated by nonlinear coherent optical systems with a 2-D feedback. A comparative analysis of neuron-like systems of various physical nature has been made. The results of experimental investigations of nonlinear optical system dynamics with nonlocal connections are discussed.

  4. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes.

    Science.gov (United States)

    Galeazzi, Juan M; Navajas, Joaquín; Mender, Bedeho M W; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M

    2016-01-01

    Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw. A camera mounted on the head captured images of the hand and jigsaw, while eye movements were recorded using an eye-tracking device. This combination of data allowed us to reconstruct the retinal images seen as humans undertook the jigsaw task. These retinal images were then fed into the neural network model during self-organization of its synaptic connectivity using a biologically plausible trace learning rule. A trace learning mechanism encourages neurons in the model to learn to respond to input images that tend to occur in close temporal proximity. In the data recorded from human subjects, we found that the participant's gaze often shifted through a sequence of locations around a fixed spatial configuration of the hand and one of the jigsaw pieces. In this case, trace learning should bind these retinal images together onto the same subset of output neurons. The simulation results consequently confirmed that some cells learned to respond selectively to the hand and a jigsaw piece in a fixed spatial configuration across different retinal views.

  5. Lab-on-a-brain: Implantable micro-optical fluidic devices for neural cell analysis in vivo

    Science.gov (United States)

    Takehara, Hiroaki; Nagaoka, Akira; Noguchi, Jun; Akagi, Takanori; Kasai, Haruo; Ichiki, Takanori

    2014-10-01

    The high-resolution imaging of neural cells in vivo has brought about great progress in neuroscience research. Here, we report a novel experimental platform, where the intact brain of a living mouse can be studied with the aid of a surgically implanted micro-optical fluidic device; acting as an interface between neurons and the outer world. The newly developed device provides the functions required for the long-term and high-resolution observation of the fine structures of neurons by two-photon laser scanning microscopy and the microfluidic delivery of chemicals or drugs directly into the brain. A proof-of-concept experiment of single-synapse stimulation by two-photon uncaging of caged glutamate and observation of dendritic spine shrinkage over subsequent days demonstrated a promising use for the present technology.

  6. Effects of multi-context information recorded at different regions in holographic polymer-dispersed liquid crystal on optical reconfiguration

    Science.gov (United States)

    Ogiwara, Akifumi; Watanabe, Minoru

    2016-08-01

    A holographic polymer-dispersed liquid crystal (HPDLC) memory to record multi-context information for an optically reconfigurable gate array is formed by constructing a laser illumination system to implement successive laser exposures at different small regions in a glass cell filled with LC composites. The context pattern arrangements for circuit information are designed in a 3 × 3 in.2 photomask by electron beam lithography, and they are recorded as laser interference patterns at nine regions separated in an HPDLC sample by a laser interferometer composed of movable pinhole and photomask plates placed on motorized stages. The multi-context information reconstructed from the different regions in the HPDLC is written to a photodiode array in a gate-array VLSI by switching only the position of laser irradiation using the displacement of the pinhole plate under the control of a personal computer (PC). The effects of multi-context information recorded at different regions in the HPDLC on optical reconfiguration are discussed in terms of the optical system composed of ORGA VLSI and HPDLC memory. The internal structures in the HPDLC memory formed by multi-context recording are investigated by scanning electron microscopy (SEM) observation, and the configurations composed of LC and polymer phases are revealed at various regions in the HPDLC memory.

  7. Effects of deprivation of oxygen or glucose on the neural activity in the guinea pig hippocampal slice--intracellular recording study of pyramidal neurons.

    Science.gov (United States)

    Takata, T; Okada, Y

    1995-06-12

    The block of synaptic transmission and neural activity during deprivation of oxygen or glucose has been simply attributed to the lack of energy due to the disorder of energy production. To clarify the interrelation between neural activity and energy metabolism during hypoxia or glucose deprivation, we studied the changes in ATP levels and electrical events of pyramidal neurons in the CA3 region and [Ca2+]i mobilization of the dendritic and cellular region of CA3 area, using guinea pig hippocampal slices. The studies of field potentials and intracellular recording from the pyramidal cell of CA3 area during hypoxia or glucose deprivation revealed that the cessation of synaptic activity and the depolarization of resting potential occurred earlier than during glucose deprivation while the increase of [Ca2+]i was slow during hypoxia but rapid during glucose deprivation although the ATP level of CA3 area was maintained at its original level for 20 min during both conditions. When glucose was replaced by lactate, ATP concentration was not reduced but the electrical activity decayed and [Ca2+]i increased with the similar time course as observed during lack of glucose, only. These results suggest that different mechanisms underlie the block of synaptic transmission in the CA3 pyramidal neurons during hypoxia and glucose deprivation and that lactate cannot substitute for glucose in the maintenance of neural activity.

  8. Write-once optical disk system measuring 300 mm using high-density, pit-edge recording.

    Science.gov (United States)

    Maeda, T; Saito, A; Sugiyama, H; Arai, S; Shigematsu, K

    1995-08-01

    To meet the requirement for a second-generation digital optical disk with a larger capacity and a higher speed, the new 300-mm, write-once optical disk system described here uses pit-edge recording and the modified-constant-angular-velocity method [Maeda et al., Trans. IEICE E74, 951 (1991)]. New techniques that can use these methods together and are suitable for interchangeability-data composition and independent detection of the leading and trailing edges-have resulted in the most reliable data-storage system ever produced, we believe. The concept of this system, the characteristics of the new techniques, and the optimization of system performance are described.

  9. Integration of silicon-based neural probes and micro-drive arrays for chronic recording of large populations of neurons in behaving animals

    Science.gov (United States)

    Michon, Frédéric; Aarts, Arno; Holzhammer, Tobias; Ruther, Patrick; Borghs, Gustaaf; McNaughton, Bruce; Kloosterman, Fabian

    2016-08-01

    Objective. Understanding how neuronal assemblies underlie cognitive function is a fundamental question in system neuroscience. It poses the technical challenge to monitor the activity of populations of neurons, potentially widely separated, in relation to behaviour. In this paper, we present a new system which aims at simultaneously recording from a large population of neurons from multiple separated brain regions in freely behaving animals. Approach. The concept of the new device is to combine the benefits of two existing electrophysiological techniques, i.e. the flexibility and modularity of micro-drive arrays and the high sampling ability of electrode-dense silicon probes. Main results. Newly engineered long bendable silicon probes were integrated into a micro-drive array. The resulting device can carry up to 16 independently movable silicon probes, each carrying 16 recording sites. Populations of neurons were recorded simultaneously in multiple cortical and/or hippocampal sites in two freely behaving implanted rats. Significance. Current approaches to monitor neuronal activity either allow to flexibly record from multiple widely separated brain regions (micro-drive arrays) but with a limited sampling density or to provide denser sampling at the expense of a flexible placement in multiple brain regions (neural probes). By combining these two approaches and their benefits, we present an alternative solution for flexible and simultaneous recordings from widely distributed populations of neurons in freely behaving rats.

  10. Adaptive, optical, radial basis function neural network for handwritten digit recognition

    Science.gov (United States)

    Foor, Wesley E.; Neifeld, Mark A.

    1995-11-01

    An adaptive, optical, radial basis function classifier for handwritten digit recognition is experimentally demonstrated. We describe a spatially multiplexed system that incorporates an on-line adaptation of weights and basis function widths to provide robustness to optical system imperfections and system noise. The optical system computes the Euclidean distances between a 100-dimensional input vector and 198 stored reference patterns in parallel by using dual vector-matrix multipliers and a contrast-reversing spatial light modulator. Software is used to emulate an electronic chip that performs the on-line learning of the weights and basis function widths. An experimental recognition rate of 92.7% correct out of 300 testing samples is achieved with the adaptive training, versus 31.0% correct for nonadaptive training. We compare the experimental results with a detailed computer model of the system in order to analyze the influence of various noise sources on the system performance.

  11. Combined use of high-definition and volumetric optical coherence tomography for the segmentation of neural canal opening in cases of optic nerve edema

    Science.gov (United States)

    Wang, Jui-Kai; Kardon, Randy H.; Garvin, Mona K.

    2015-03-01

    In cases of optic-nerve-head edema, the presence of the swelling reduces the visibility of the underlying neural canal opening (NCO) within spectral-domain optical coherence tomography (SD-OCT) volumes. Consequently, traditional SD-OCT-based NCO segmentation methods often overestimate the size of the NCO. The visibility of the NCO can be improved using high-definition 2D raster scans, but such scans do not provide 3D contextual image information. In this work, we present a semi-automated approach for the segmentation of the NCO in cases of optic disc edema by combining image information from volumetric and high-definition raster SD-OCT image sequences. In particular, for each subject, five high-definition OCT B-scans and the OCT volume are first separately segmented, and then the five high-definition B-scans are automatically registered to the OCT volume. Next, six NCO points are placed (manually, in this work) in the central three high-definition OCT B-scans (two points for each central B-scans) and are automatically transferred into the OCT volume. Utilizing a combination of these mapped points and the 3D image information from the volumetric scans, a graph-based approach is used to identify the complete NCO on the OCT en-face image. The segmented NCO points using the new approach were significantly closer to expert-marked points than the segmented NCO points using a traditional approach (root mean square differences in pixels: 5.34 vs. 21.71, p < 0.001).

  12. Local domains of motor cortical activity revealed by fiber-optic calcium recordings in behaving nonhuman primates

    Science.gov (United States)

    Adelsberger, Helmuth; Zainos, Antonio; Alvarez, Manuel; Romo, Ranulfo; Konnerth, Arthur

    2014-01-01

    Brain mapping experiments involving electrical microstimulation indicate that the primary motor cortex (M1) directly regulates muscle contraction and thereby controls specific movements. Possibly, M1 contains a small circuit “map” of the body that is formed by discrete local networks that code for specific movements. Alternatively, movements may be controlled by distributed, larger-scale overlapping circuits. Because of technical limitations, it remained unclear how movement-determining circuits are organized in M1. Here we introduce a method that allows the functional mapping of small local neuronal circuits in awake behaving nonhuman primates. For this purpose, we combined optic-fiber–based calcium recordings of neuronal activity and cortical microstimulation. The method requires targeted bulk loading of synthetic calcium indicators (e.g., OGB-1 AM) for the staining of neuronal microdomains. The tip of a thin (200 µm) optical fiber can detect the coherent activity of a small cluster of neurons, but is insensitive to the asynchronous activity of individual cells. By combining such optical recordings with microstimulation at two well-separated sites of M1, we demonstrate that local cortical activity was tightly associated with distinct and stereotypical simple movements. Increasing stimulation intensity increased both the amplitude of the movements and the level of neuronal activity. Importantly, the activity remained local, without invading the recording domain of the second optical fiber. Furthermore, there was clear response specificity at the two recording sites in a trained behavioral task. Thus, the results provide support for movement control in M1 by local neuronal clusters that are organized in discrete cortical domains. PMID:24344287

  13. Neural-Net Based Optical NDE Method for Structural Health Monitoring

    Science.gov (United States)

    Decker, Arthur J.; Weiland, Kenneth E.

    2003-01-01

    This paper answers some performance and calibration questions about a non-destructive-evaluation (NDE) procedure that uses artificial neural networks to detect structural damage or other changes from sub-sampled characteristic patterns. The method shows increasing sensitivity as the number of sub-samples increases from 108 to 6912. The sensitivity of this robust NDE method is not affected by noisy excitations of the first vibration mode. A calibration procedure is proposed and demonstrated where the output of a trained net can be correlated with the outputs of the point sensors used for vibration testing. The calibration procedure is based on controlled changes of fastener torques. A heterodyne interferometer is used as a displacement sensor for a demonstration of the challenges to be handled in using standard point sensors for calibration.

  14. Determination of Optical Properties of Turbid Media from Spatially Resolved Diffuse Reflectance by Neural Network

    Institute of Scientific and Technical Information of China (English)

    REN Hongwu; FANG Zujie

    2000-01-01

    A backpropagation (BP) network is applied to the inversion of spatially resolved diffuse reflectance from turbid media and then to determine its optical properties. A standard BP network may be trapped to the local minimum. A BP network with variable momentum and variable leaning rate can reduce this effect. After being trained, this network will produce reduced scattering coefficients and absorption coefficients when the spatially resolved diffuse reflectance are fed to its input.

  15. Marinesco-Sjogren Syndrome With Sensori Neural Deafness And Primary Optic Atrophy

    Directory of Open Access Journals (Sweden)

    Aleem M A

    1999-01-01

    Full Text Available Marinesco-Sjogren syndrome (MSS is a rare genetically determined disorder characterised by bilateral cataract, cerebellar ataxia and mental deficiency. The pattern of inheritance is autosomal recessive but it may be variable. In MSS association of hyperlactacidaemia and hypopyruvicaemia, a defective oxidative phosphorylation in mitochondria, is supposed. We are reporting three patients of MSS along with sensorineural deafness and optic atrophy from a single Indian family.

  16. Microexplosion Recording in Spin-Coated Polymer Films Including ZnO Nanoparticles for Three-Dimensional Optical Memory

    Science.gov (United States)

    Shiono, Teruhiro; Yamamoto, Hiroaki; Nishino, Seiji

    2004-07-01

    As a microexplosion recording material, we propose polymer films including ZnO nanoparticles (ZnO polyester composite) for write-once multilayered recording media. These media with the ZnO composite material can be fabricated by a spin-coating method and can be read at the violet wavelength of 0.405 μm. By the electromagnetic analysis of diffraction loss, we clarified the pit design and the optical performance for void formation recording. From the results of experiments performed using three kinds of mode-locked pulsed lasers (pulse widths of 150 fs, 16 ps and 6 ns), with a clear reflection microscope image of submicrometer pits, the microexplosion sensitivity was confirmed to be greatly improved by 14, 38 and 50 times, respectively.

  17. Optical implementation of a single-layer finite impulse response neural network

    Science.gov (United States)

    Silveira, Paulo E. X.; Pati, G. S.; Wagner, Kelvin H.

    2000-05-01

    This paper demonstrates a space integrating optical implementation of a single-layer FIRNN. A scrolling spatial light modulator is used for representing the spatio-temporal input plane, while the weights are implemented by the adaptive grating formation in a photorefractive crystal. Differential heterodyning is used for low-noise bipolar output detection and an active stabilization technique using a lock-in amplifier and a piezo-electric actuator is adopted for long term interferometric stability. Simulations and initial experimental results for adaptive sonar broadband beamforming are presented.

  18. Generalized regression neural network trained preprocessing of frequency domain correlation filter for improved face recognition and its optical implementation

    Science.gov (United States)

    Banerjee, Pradipta K.; Datta, Asit K.

    2013-02-01

    The paper proposes an improved strategy for face recognition using correlation filter under varying lighting conditions and occlusion where spatial domain preprocessing is carried out by two convolution kernels. The first convolution kernel is a contour kernel for emphasizing high frequency components of face image and the other kernel is a smoothing kernel used for minimization of noise those may arise due to preprocessing. The convolution kernels are obtained by training a generalized regression neural network using enhanced face features. Face features are enhanced by conventional principal component analysis. The proposed method reduces the false acceptance rate and false rejection rate in comparison to other standard correlation filtering techniques. Moreover, the processing is fast when compared to the existing illumination normalization techniques. A scheme of hardware implementation of all optical correlation technique is also suggested based on single spatial light modulator in a beam folding architecture. Two benchmark databases YaleB and PIE are used for performance verification of the proposed scheme and the improved results are obtained for both illumination variations and occlusions in test face images.

  19. Synthesis and optical storage properties of a thiophene-based holographic recording

    DEFF Research Database (Denmark)

    Matharu, Avtar; Jeeva, S.; Huddleston, P.R.;

    2007-01-01

    The results of the fabrication and optical data storage characteristics of a novel azothiophene polyester 9 for potential holographic storage are reported. The polyester is derived from an azothiophene diol 1 and diphenyl phthalate 8 via in vacuo melt transesterification. Inclusion of a 5-methoxy-2......-thienyl moiety generates a trans pi-pi* transition centered close to 405 nm. An investigation of the optical data storage characteristics of a solution cast film of azopolyester with a thickness of 65 mm is summarised. The optical anisotropy induced by a 532 nm frequency doubled YAG laser and probed...... at a wavelength of 633 nm outside the absorption band with a polarimeter reveals a very high induced anisotropy of 7 rad ( laser intensity, 250 mW cm(-2)). The calculated birefringence of the film is 0.02 per micron. Maximum anisotropy is reached after approximately 70 s of irradiation. The induced anisotropy...

  20. Optical recording in functional polymer nanocomposites by multi-beam interference holography

    Science.gov (United States)

    Zhuk, Dmitrij; Burunkova, Julia; Kalabin, Viacheslav; Csarnovics, Istvan; Kokenyesi, Sandor

    2017-05-01

    Our investigations relate to the development of new polymer nanocomposite materials and technologies for fabrication of photonic elements like gratings, integrated elements, photonic crystals. The goal of the present work was the development and application of the multi-beam interference method for one step, direct formation of 1-, 2- or even 3D photonic structures in functional acrylate nanocomposites, which contain SiO2 and Au nanoparticles and which are sensitized to blue and green laser illumination. The presence of gold nanoparticles and possibility to excite plasmonic effects can essentially influence the polymerization processes and the spatial redistribution of nanoparticles in the nanocomposite during the recording. This way surface and volume phase reliefs can be recorded. It is essential, that no additional treatments of the material after the recording are necessary and the elements possess high transparency, are stable after some relaxation time. New functionalities can be provided to the recorded structures if luminescent materials are added to such materials.

  1. Connectorization of fibre Bragg grating sensors recorded in microstructured polymer optical fibre

    DEFF Research Database (Denmark)

    Abang, A.; Saez-Rodriguez, D.; Nielsen, Kristian

    2013-01-01

    We describe te production and characterization of FC/PC connectorised fibre Bragg grating sensors in polymer fibre. Sensors were recorded in few-moded and single mode microstructured fibre composed of poly (methyl methacrylate).......We describe te production and characterization of FC/PC connectorised fibre Bragg grating sensors in polymer fibre. Sensors were recorded in few-moded and single mode microstructured fibre composed of poly (methyl methacrylate)....

  2. Open Ephys electroencephalography (Open Ephys  +  EEG): a modular, low-cost, open-source solution to human neural recording

    Science.gov (United States)

    Black, Christopher; Voigts, Jakob; Agrawal, Uday; Ladow, Max; Santoyo, Juan; Moore, Christopher; Jones, Stephanie

    2017-06-01

    Objective. Electroencephalography (EEG) offers a unique opportunity to study human neural activity non-invasively with millisecond resolution using minimal equipment in or outside of a lab setting. EEG can be combined with a number of techniques for closed-loop experiments, where external devices are driven by specific neural signals. However, reliable, commercially available EEG systems are expensive, often making them impractical for individual use and research development. Moreover, by design, a majority of these systems cannot be easily altered to the specification needed by the end user. We focused on mitigating these issues by implementing open-source tools to develop a new EEG platform to drive down research costs and promote collaboration and innovation. Approach. Here, we present methods to expand the open-source electrophysiology system, Open Ephys (www.openephys.org), to include human EEG recordings. We describe the equipment and protocol necessary to interface various EEG caps with the Open Ephys acquisition board, and detail methods for processing data. We present applications of Open Ephys  +  EEG as a research tool and discuss how this innovative EEG technology lays a framework for improved closed-loop paradigms and novel brain-computer interface experiments. Main results. The Open Ephys  +  EEG system can record reliable human EEG data, as well as human EMG data. A side-by-side comparison of eyes closed 8-14 Hz activity between the Open Ephys  +  EEG system and the Brainvision ActiCHamp EEG system showed similar average power and signal to noise. Significance. Open Ephys  +  EEG enables users to acquire high-quality human EEG data comparable to that of commercially available systems, while maintaining the price point and extensibility inherent to open-source systems.

  3. Open Ephys electroencephalography (Open Ephys  +  EEG): a modular, low-cost, open-source solution to human neural recording.

    Science.gov (United States)

    Black, Christopher; Voigts, Jakob; Agrawal, Uday; Ladow, Max; Santoyo, Juan; Moore, Christopher; Jones, Stephanie

    2017-06-01

    Electroencephalography (EEG) offers a unique opportunity to study human neural activity non-invasively with millisecond resolution using minimal equipment in or outside of a lab setting. EEG can be combined with a number of techniques for closed-loop experiments, where external devices are driven by specific neural signals. However, reliable, commercially available EEG systems are expensive, often making them impractical for individual use and research development. Moreover, by design, a majority of these systems cannot be easily altered to the specification needed by the end user. We focused on mitigating these issues by implementing open-source tools to develop a new EEG platform to drive down research costs and promote collaboration and innovation. Here, we present methods to expand the open-source electrophysiology system, Open Ephys (www.openephys.org), to include human EEG recordings. We describe the equipment and protocol necessary to interface various EEG caps with the Open Ephys acquisition board, and detail methods for processing data. We present applications of Open Ephys  +  EEG as a research tool and discuss how this innovative EEG technology lays a framework for improved closed-loop paradigms and novel brain-computer interface experiments. The Open Ephys  +  EEG system can record reliable human EEG data, as well as human EMG data. A side-by-side comparison of eyes closed 8-14 Hz activity between the Open Ephys  +  EEG system and the Brainvision ActiCHamp EEG system showed similar average power and signal to noise. Open Ephys  +  EEG enables users to acquire high-quality human EEG data comparable to that of commercially available systems, while maintaining the price point and extensibility inherent to open-source systems.

  4. Thomson develops new optical reader, digital switching system: Gigadisc reader recorder

    Science.gov (United States)

    Levy, D.

    1984-01-01

    A digital optical disk, newly developed by Thomson of France, is announced. The disk, which has a greatly enhanced data storage capacity, is capable of capturing a leading position in information processing and business communications systems by overtaking the share of the market now held by the flexible magnetic disk. A marketing strategy is presented.

  5. Hydrologic Record Extension of Water-Level Data in the Everglades Depth Estimation Network (EDEN) Using Artificial Neural Network Models, 2000-2006

    Science.gov (United States)

    Conrads, Paul A.; Roehl, Edwin A.

    2007-01-01

    The Everglades Depth Estimation Network (EDEN) is an integrated network of real-time water-level gaging stations, ground-elevation models, and water-surface models designed to provide scientists, engineers, and water-resource managers with current (2000-present) water-depth information for the entire freshwater portion of the greater Everglades. The U.S. Geological Survey Greater Everglades Priority Ecosystem Science provides support for EDEN and the goal of providing quality assured monitoring data for the U.S. Army Corps of Engineers Comprehensive Everglades Restoration Plan. To increase the accuracy of the water-surface models, 25 real-time water-level gaging stations were added to the network of 253 established water-level gaging stations. To incorporate the data from the newly added stations to the 7-year EDEN database in the greater Everglades, the short-term water-level records (generally less than 1 year) needed to be simulated back in time (hindcasted) to be concurrent with data from the established gaging stations in the database. A three-step modeling approach using artificial neural network models was used to estimate the water levels at the new stations. The artificial neural network models used static variables that represent the gaging station location and percent vegetation in addition to dynamic variables that represent water-level data from the established EDEN gaging stations. The final step of the modeling approach was to simulate the computed error of the initial estimate to increase the accuracy of the final water-level estimate. The three-step modeling approach for estimating water levels at the new EDEN gaging stations produced satisfactory results. The coefficients of determination (R2) for 21 of the 25 estimates were greater than 0.95, and all of the estimates (25 of 25) were greater than 0.82. The model estimates showed good agreement with the measured data. For some new EDEN stations with limited measured data, the record extension

  6. Optical recording of stable holographic grating in a low Tg statistical copolymer covalently functionalized with an azo-dye

    Science.gov (United States)

    Cambiasso, Javier; Garate, Hernan; D'Accorso, Norma; Ledesma, Silvia; Goyanes, Silvia

    2015-11-01

    A novel photoaddressable copolymer with low glass transition temperature was synthesised and its optical properties were studied. The photoresponsive material was obtained from chemical modification of a poly(styrene-co-acrylic acid) copolymer. A holographic polarization grating was recorded in the material and was monitored by measuring its diffraction efficiency. It is shown that the holographic grating stored in the material is highly stable in time, despite the fact that the polymer glass transition temperature is near room temperature. This stability is a consequence of electrostatic interactions between the azo-groups and the carboxylic substituent group of the main polymer chain.

  7. A novel bio-mimicking, planar nano-edge microelectrode enables enhanced long-term neural recording

    Science.gov (United States)

    Wijdenes, Pierre; Ali, Hasan; Armstrong, Ryden; Zaidi, Wali; Dalton, Colin; Syed, Naweed I.

    2016-01-01

    Our inability to accurately monitor individual neurons and their synaptic activity precludes fundamental understanding of brain function under normal and various pathological conditions. However, recent breakthroughs in micro- and nano-scale fabrication processes have advanced the development of neuro-electronic hybrid technology. Among such devices are three-dimensional and planar electrodes, offering the advantages of either high fidelity or longer-term recordings respectively. Here, we present the next generation of planar microelectrode arrays with “nano-edges” that enable long-term (≥1 month) and high fidelity recordings at a resolution 15 times higher than traditional planar electrodes. This novel technology enables better understanding of brain function and offers a tremendous opportunity towards the development of future bionic hybrids and drug discovery devices. PMID:27731326

  8. A novel bio-mimicking, planar nano-edge microelectrode enables enhanced long-term neural recording

    Science.gov (United States)

    Wijdenes, Pierre; Ali, Hasan; Armstrong, Ryden; Zaidi, Wali; Dalton, Colin; Syed, Naweed I.

    2016-10-01

    Our inability to accurately monitor individual neurons and their synaptic activity precludes fundamental understanding of brain function under normal and various pathological conditions. However, recent breakthroughs in micro- and nano-scale fabrication processes have advanced the development of neuro-electronic hybrid technology. Among such devices are three-dimensional and planar electrodes, offering the advantages of either high fidelity or longer-term recordings respectively. Here, we present the next generation of planar microelectrode arrays with “nano-edges” that enable long-term (≥1 month) and high fidelity recordings at a resolution 15 times higher than traditional planar electrodes. This novel technology enables better understanding of brain function and offers a tremendous opportunity towards the development of future bionic hybrids and drug discovery devices.

  9. Neural Activity Elicited by a Cognitive Task can be Detected in Single-Trials with Simultaneous Intracerebral EEG-fMRI Recordings.

    Science.gov (United States)

    Saignavongs, Mani; Ciumas, Carolina; Petton, Mathilde; Bouet, Romain; Boulogne, Sébastien; Rheims, Sylvain; Carmichael, David W; Lachaux, Jean-Philippe; Ryvlin, Philippe

    2017-02-01

    Recent studies have shown that it is feasible to record simultaneously intracerebral EEG (icEEG) and functional magnetic resonance imaging (fMRI) in patients with epilepsy. While it has mainly been used to explore the hemodynamic changes associated with epileptic spikes, this approach could also provide new insight into human cognition. However, the first step is to ensure that cognitive EEG components, that have lower amplitudes than epileptic spikes, can be appropriately detected under fMRI. We compared the high frequency activities (HFA, 50-150[Formula: see text]Hz) elicited by a reading task in icEEG-only and subsequent icEEG-fMRI in the same patients ([Formula: see text]), implanted with depth electrodes. Comparable responses were obtained, with 71% of the recording sites that responded during the icEEG-only session also responding during the icEEG-fMRI session. For all the remaining sites, nearby clusters (distant of 7[Formula: see text]mm or less) also demonstrated significant HFA increase during the icEEG-fMRI session. Significant HFA increases were also observable at the single-trial level in icEEG-fMRI recordings. Our results show that low-amplitude icEEG signal components such as cognitive-induced HFAs can be reliably recorded with simultaneous fMRI. This paves the way for the use of icEEG-fMRI to address various fundamental and clinical issues, notably the identification of the neural correlates of the BOLD signal.

  10. Restocking the optical designers' toolbox for next-generation wearable displays (Presentation Recording)

    Science.gov (United States)

    Kress, Bernard C.

    2015-09-01

    Three years ago, industry and consumers learned that there was more to Head Mounted Displays (HMDs) than the long-lasting but steady market for defense or the market for gadget video player headsets: the first versions of Smart Glasses were introduced to the public. Since then, most major consumer electronics companies unveiled their own versions of Connected Glasses, Smart Glasses or Smart Eyewear, AR (Augmented Reality) and VR (Virtual Reality) headsets. This rush resulted in the build-up of a formidable zoo of optical technologies, each claiming to be best suited for the task on hand. Today, the question is not so much anymore "will the Smart Glass market happen?" but rather "which optical technologies will be best fitted for the various declinations of the existing wearable display market," one of the main declination being the Smart Glasses market.

  11. Optical nanoscopy to reveal structural and functional properties of liver cells (Presentation Recording)

    Science.gov (United States)

    McCourt, Peter; Huser, Thomas R.; Sørensen, Karen K.; Øie, Cristina I.; Mönkemöller, Viola; Ahluwalia, Balpreet S.

    2015-08-01

    The advent of optical nanoscopy has provided an opportunity to study fundamental properties of nanoscale biological functions, such as liver sinusoidal endothelial cells (LSEC) and their fenestrations. The fenestrations are nano-pores (50-200 nm) on the LSEC plasma membrane that allow free passage of molecules through cells. The fenestrated LSEC also hase a voracious appetite for waste molecules, viruses and nanoparticles. LSEC daily remove huge amounts of waste, nanoparticles and virus from the blood. Pharmaceuticals also need to pass through these fenestrations to be activated (e.g. cholesterol reducing statins) or detoxified by hepatocytes. And, when we age, our LSEC fenestrations become smaller and fewer. Today, we study these cells and structures using either conventional light microscopy on living cells, or high-resolution (but static) methods such as transmission and scanning electron microscopy on fixed (i.e. dead) tissue. Such methods, while very powerful, yield no real time information about the uptake of virus or nanoparticles, nor any information about fenestration dynamics. Therefore, to study LS-SEC, we are now using optical nanoscopy methods, and developing our own, to map their functions in 4 dimensions. Attaining this goal will shed new light on the cell biology of the liver and how it keeps us alive. This paper describes the challenges of studying LS-SEC with light microscopy, as well as current and potential solutions to this challenge using optical nanoscopy.

  12. Searching for learning-dependent changes in the antennal lobe: simultaneous recording of neural activity and aversive olfactory learning in honeybees

    Directory of Open Access Journals (Sweden)

    Edith Roussel

    2010-09-01

    Full Text Available Plasticity in the honeybee brain has been studied using the appetitive olfactory conditioning of the proboscis extension reflex, in which a bee learns the association between an odor and a sucrose reward. In this framework, coupling behavioral measurements of proboscis extension and invasive recordings of neural activity has been difficult because proboscis movements usually introduce brain movements that affect physiological preparations. Here we took advantage of a new conditioning protocol, the aversive olfactory conditioning of the sting extension reflex, which does not generate this problem. We achieved the first simultaneous recordings of conditioned sting extension responses and calcium imaging of antennal lobe activity, thus revealing on-line processing of olfactory information during conditioning trials. Based on behavioral output we distinguished learners and non-learners and analyzed possible learning-dependent changes in antennal lobe activity. We did not find differences between glomerular responses to the CS+ and the CS- in learners. Unexpectedly, we found that during conditioning trials non-learners exhibited a progressive decrease in physiological responses to odors, irrespective of their valence. This effect could neither be attributed to a fitness problem nor to abnormal dye bleaching. We discuss the absence of learning-induced changes in the antennal lobe of learners and the decrease in calcium responses found in non-learners. Further studies will have to extend the search for functional plasticity related to aversive learning to other brain areas and to look on a broader range of temporal scales

  13. A 13µW 87dB dynamic range implantable ΔΣ modulator for full-spectrum neural recording.

    Science.gov (United States)

    Xu, Jian; Islam, Md Kafiul; Wang, Shuo; Yang, Zhi

    2013-01-01

    Experiment analysis on in-vivo data sequences suggests a wide system dynamic range (DR) is required to simultaneously record local field potentials (LFPs), extra-cellular spikes, and artifacts/interferences. In this paper, we present a 13 µW 87 dB DR ΔΣ modulator for full-spectrum neural recording. To achieve a wide DR and low power consumption, a fully-differential topology is used with multi-bit (MB) quantization scheme and switched-opamp (SO) technique. By adopting a novel fully-clocked scheme, a power-efficient current-mirror SO is developed with 50% power saving, which doubles the figure-of-merit (FOM) over its counterpart. A new static power-less multi-bit quantizer with 96% power and 69% area reduction is also introduced. Besides, instead of metal-insulator-metal (MIM) capacitor, three high-density MOS capacitor (MOSCAP) structures are employed to reduce circuit area. Measurement results show a peak signal-to-noise and distortion ratio (SNDR) of 85 dB with 10 kHz bandwidth at 1.0 V supply, corresponding to an FOM of 45 fJ/conv.-step. which is implemented in a 0.18 µm CMOS.

  14. OCT detection of neural activity in American cockroach nervous system

    Science.gov (United States)

    Gorczyńska, Iwona; Wyszkowska, Joanna; Bukowska, Danuta; Ruminski, Daniel; Karnowski, Karol; Stankiewicz, Maria; Wojtkowski, Maciej

    2013-03-01

    We show results of a project which focuses on detection of activity in neural tissue with Optical Coherence Tomography (OCT) methods. Experiments were performed in neural cords dissected from the American cockroach (Periplaneta americana L.). Functional OCT imaging was performed with ultrahigh resolution spectral / Fourier domain OCT system (axial resolution 2.5 μm). Electrical stimulation (voltage pulses) was applied to the sensory cercal nerve of the neural cord. Optical detection of functional activation of the sample was performed in the connective between the terminal abdominal ganglion and the fifth abdominal ganglion. Functional OCT data were collected over time with the OCT beam illuminating selected single point in the connectives (i.e. OCT M-scans were acquired). Phase changes of the OCT signal were analyzed to visualize occurrence of activation in the neural cord. Electrophysiology recordings (microelectrode method) were also performed as a reference method to demonstrate electrical response of the sample to stimulation.

  15. Improving optical fiber current sensor accuracy using artificial neural networks to compensate temperature and minor non-ideal effects

    Science.gov (United States)

    Zimmermann, Antonio C.; Besen, Marcio; Encinas, Leonardo S.; Nicolodi, Rosane

    2011-05-01

    This article presents a practical signal processing methodology, based on Artificial Neural Networks - ANN, to process the measurement signals of typical Fiber Optic Current Sensors - FOCS, achieving higher accuracy from temperature and non-linearity compensation. The proposed idea resolve FOCS primary problems, mainly when it is difficult to determine all errors sources present in the physical phenomenon or the measurement equation becomes too nonlinear to be applied in a wide measurement range. The great benefit of ANN is to get a transfer function for the measurement system taking in account all unknowns, even those from unwanted and unknowing effects, providing a compensated output after the ANN training session. Then, the ANN training is treated like a black box, based on experimental data, where the transfer function of the measurement system, its unknowns and non-idealities are processed and compensated at once, given a fast and robust alternative to the FOCS theoretical method. A real FOCS system was built and the signals acquired from the photo-detectors are processed by the Faraday's Laws formulas and the ANN method, giving measurement results for both signal processing strategies. The coil temperature measurements are also included in the ANN signal processing. To compare these results, a current measuring instrument standard is used together with a metrological calibration procedure. Preliminary results from a variable temperature experiment shows the higher accuracy, better them 0.2% of maximum error, of the ANN methodology, resulting in a quick and robust method to hands with FOCS difficulties on of non-idealities compensation.

  16. Co/Pt and Co/Pd multilayers as a new class of magneto-optical recording materials

    Science.gov (United States)

    Zeper, W. B.; Greidanus, Franciscus J. A. M.; van Kesteren, H. W.; Jacobs, Ben A. J.; Spruit, J. H. M.; Carcia, Peter F.

    1990-08-01

    In this paper we give an overview of the magnetic and magneto-optical properties of Co/Pt and, to a less extent, Co/Pd multilayers as optimized for magneto-optical storage applications. The Co layers should be very thin, i.e. about 4 A , and the Pt layers about 10-20 A to achieve a 100 % remanent layer with perpendicular magnetic anisotropy and high coercivity (80-100 kA/m). Furthermore, the hysteresis loop becomes rectangular for total film thicknesses below about 20 nm. We measured the optical properties as a function of the wavelength of the light and calculated the figure of merit at three wavelengths (820, 633 and 410 nm) for various disk structures. Optimal figures of merit are obtained for film thicknesses below 20 nm, i.e. thicknesses that are optimum for the magnetic properties. The figure of merit at A. = 820 am for Co/Pt is comparable to that of GdTbFe and increases towards shorter wavelengths which favor higher-density recording. We discuss the recording performance using Lorentz images of the written domain patterns. Very regularly shaped domains can be written at normal writing conditions, i.e. at a laser power of 5-10 mW and fields of 25 kA/m. The highest carrier-to-noise ratio measured for Co/Pt is 51 dB (375 kHz carrier, 1.4 m/s, 10 kHz bandwidth). Aging experiments in dry oxygen-nitrogen atmosphere showed that Co/Pt multilayers are chemically stable up to 1 50 °C . Finally, no change in carrier-to-noise ratio is observed for Co/Pt multilayers with a Curie temperature below 300 °C after 2x104 write/read/erase cycles.

  17. Depth Profile of Optically Recorded Patterns in Light-Sensitive Liquid Crystal Elastomers

    CERN Document Server

    Gregorc, Marko; Domenici, Valentina; Ambrožič, Gabriela; Drevenšek-Olenik, Irena; Fally, Martin; Čopič, Martin

    2011-01-01

    We investigated nonlinear absorption and photobleaching processes in a liquid crystal elastomer (LCE) doped with light-sensitive azobenzene moiety. A conventional one-dimensional holographic grating was recorded in the material with the use of two crossed UV laser beams and the angular dependence of the diffraction efficiency in the vicinity of the Bragg peak was analyzed. These measurements gave information on the depth to which trans to cis isomerisation had progressed into the sample as a function of the UV irradiation time. Using a numerical model that takes into account the propagation of writing beams and rate equations for the local concentration of the absorbing trans conformer, we computed the expected spatial distribution of the trans and cis conformers and the shape of the corresponding Bragg diffraction peak for different irradiation doses. Due to residual absorption of the cis conformers the depth of the recording progresses logarithmically with time and is limited by the thermal relaxation from ...

  18. Application of non-invasive optical monitoring methodologies to follow and record painting cleaning processes

    Science.gov (United States)

    Fontana, R.; Dal Fovo, A.; Striova, J.; Pezzati, L.; Pampaloni, E.; Raffaelli, M.; Barucci, M.

    2015-11-01

    The cleaning of painted artworks, i.e. the critical operation whereby materials are selectively removed from a painted surface by partial thinning or complete elimination of varnish, is one of the most debated conservation operations, being an irreversible process, which may result in chromatic and morphological variations in the painted surface. Due to ageing, the upper layer is subject to darkening and yellowing because of blanching and fading from ultraviolet exposure, dust deposition, and overpainted layers due, for instance, to restoration interventions. This degradation can either alter the original appearance of painting polychromy or cause mechanical failure of the finishes. To address these adverse conditions, a process of examination and analysis is critical to the definition and interpretation of the varnish layer. When investigating the ageing process of old paintings, it is of great importance to obtain insight into the painting technique as practiced in the past, and the first step in gaining this knowledge is, to a large extent, based on the study of the varnish film. An effective control of the process and objective evaluation of its outcome requires therefore instrumental/analytical support. The present study illustrates the successful application of non-invasive optical techniques—such as colorimetry, multispectral reflectography, laser scanning micro-profilometry, and optical coherence tomography—to the monitoring of an Italian fourteenth-century painting cleaning process. Results presented here confirm that optical techniques play a pivotal role in artwork diagnostics, especially with regard to conservation operations, while also indicating their validity when applied to the monitoring of the cleaning process.

  19. DREXONTM Optical Memory Media For Laser Recording And Archival Data Storage

    Science.gov (United States)

    Drexler, J.

    1981-06-01

    The objective of this paper is to present the concept, description, and characteristics of a new class of direct-read-after-write (DRAW) reflective laser recording material which has been given the tradename DREXONTM. Information is recorded by thermal melting of the media surface. The material consists of an organic film containing dispersed metal particles which have such a high volume concentration that the surface has a mirrorlike appearance. However, the particles do not touch one another; and, therefore, the surface is electrically nonconductive. When recording, the laser-beam energy is absorbed by the metal particles, which rise in temperature and cause melting of the organic film at temperatures in the range of 200°C. This melting creates spots of low reflectivity in a field of high reflectivity. The metal particles do not melt since their melting temperature is much highter than that of the underlying organic film. It is possible that one version of the media could achieve archival life of a hundred years. This version comprises three ingredients, all of which have rated archival lives of hundreds of years: (1) cross-linked, photographic-quality gelatin, (2) filamentary silver crystals, and (3) spheroidal silver crystals. This archival version of the media is produced from special, fine-grained silver-halide emulsions.

  20. Development and characterization of thermally stable electro-optic polymers and devices (Presentation Recording)

    Science.gov (United States)

    Otomo, Akira; Aoki, Isao; Yamada, Chiyumi; Yamada, Toshiki

    2015-10-01

    Electro-optic (EO) polymers are key materials for next generation optical communications not only in wide area network but also in local area and storage area network because EO polymer modulator can be operated at fast speed more than 100 GHz with low energy consumption and can be miniaturized in combination with silicon photonics. In practical applications, thermal stability is one of the important issues to be considered for developing EO polymers. Since EO activity of the polymer is proportional to dipole orientation factor of the EO moieties, electric field assisted poling around glass transition temperature (Tg) of the polymer is necessary. However, the poled order of the molecules relaxes gradually at finite temperature, and then EO activity decreases after long period of time. We have successfully developed thermally stable EO polymers that have high-Tg up to 180 °C. They show excellent thermal stability with the Telcordia thermal test. Thermal stability is also characterized by thermally stimulated depolarization current (TSDC) measurement. Analyzing the TSDC, we can estimate the activation energy and relaxation time of polarization at any temperature. We will discuss thermal stability of the high-Tg EO polymers and devices.

  1. Dust aerosol, clouds, and the atmospheric optical depth record over 5 Mars years of the Mars Exploration Rover mission

    CERN Document Server

    Lemmon, Mark T; Bell, James F; Smith, Michael D; Cantor, Bruce A; Smith, Peter H

    2014-01-01

    Dust aerosol plays a fundamental role in the behavior and evolution of the Martian atmosphere. The first five Mars years of Mars Exploration Rover data provide an unprecedented record of the dust load at two sites. This record is useful for characterization of the atmosphere at the sites and as ground truth for orbital observations. Atmospheric extinction optical depths have been derived from solar images after calibration and correction for time-varying dust that has accumulated on the camera windows. The record includes local, regional, and globally extensive dust storms. Comparison with contemporaneous thermal infrared data suggests significant variation in the size of the dust aerosols, with a 1 {\\mu}m effective radius during northern summer and a 2 {\\mu}m effective radius at the onset of a dust lifting event. The solar longitude (LS) 20-136{\\deg} period is also characterized by the presence of cirriform clouds at the Opportunity site, especially near LS=50 and 115{\\deg}. In addition to water ice clouds, ...

  2. Dust Aerosol, Clouds, and the Atmospheric Optical Depth Record over 5 Mars Years of the Mars Exploration Rover Mission

    Science.gov (United States)

    Lemmon, Mark T.; Wolff, Michael J.; Bell, James F., III; Smith, Michael D.; Cantor, Bruce A.; Smith, Peter H.

    2014-01-01

    Dust aerosol plays a fundamental role in the behavior and evolution of the Martian atmosphere. The first five Mars years of Mars Exploration Rover data provide an unprecedented record of the dust load at two sites. This record is useful for characterization of the atmosphere at the sites and as ground truth for orbital observations. Atmospheric extinction optical depths have been derived from solar images after calibration and correction for time-varying dust that has accumulated on the camera windows. The record includes local, regional, and globally extensive dust storms. Comparison with contemporaneous thermal infrared data suggests significant variation in the size of the dust aerosols, with a 1 micrometer effective radius during northern summer and a 2 micrometer effective radius at the onset of a dust lifting event. The solar longitude (L (sub s)) 20-136 degrees period is also characterized by the presence of cirriform clouds at the Opportunity site, especially near LS = 50 and 115 degrees. In addition to water ice clouds, a water ice haze may also be present, and carbon dioxide clouds may be present early in the season. Variations in dust opacity are important to the energy balance of each site, and work with seasonal variations in insolation to control dust devil frequency at the Spirit site.

  3. Point-process analysis of neural spiking activity of muscle spindles recorded from thin-film longitudinal intrafascicular electrodes.

    Science.gov (United States)

    Citi, Luca; Djilas, Milan; Azevedo-Coste, Christine; Yoshida, Ken; Brown, Emery N; Barbieri, Riccardo

    2011-01-01

    Recordings from thin-film Longitudinal Intra-Fascicular Electrodes (tfLIFE) together with a wavelet-based de-noising and a correlation-based spike sorting algorithm, give access to firing patterns of muscle spindle afferents. In this study we use a point process probability structure to assess mechanical stimulus-response characteristics of muscle spindle spike trains. We assume that the stimulus intensity is primarily a linear combination of the spontaneous firing rate, the muscle extension, and the stretch velocity. By using the ability of the point process framework to provide an objective goodness of fit analysis, we were able to distinguish two classes of spike clusters with different statistical structure. We found that spike clusters with higher SNR have a temporal structure that can be fitted by an inverse Gaussian distribution while lower SNR clusters follow a Poisson-like distribution. The point process algorithm is further able to provide the instantaneous intensity function associated with the stimulus-response model with the best goodness of fit. This important result is a first step towards a point process decoding algorithm to estimate the muscle length and possibly provide closed loop Functional Electrical Stimulation (FES) systems with natural sensory feedback information.

  4. Highly Stable Glassy Carbon Interfaces for Long-Term Neural Stimulation and Low-Noise Recording of Brain Activity

    Science.gov (United States)

    Vomero, Maria; Castagnola, Elisa; Ciarpella, Francesca; Maggiolini, Emma; Goshi, Noah; Zucchini, Elena; Carli, Stefano; Fadiga, Luciano; Kassegne, Sam; Ricci, Davide

    2017-01-01

    We report on the superior electrochemical properties, in-vivo performance and long term stability under electrical stimulation of a new electrode material fabricated from lithographically patterned glassy carbon. For a direct comparison with conventional metal electrodes, similar ultra-flexible, micro-electrocorticography (μ-ECoG) arrays with platinum (Pt) or glassy carbon (GC) electrodes were manufactured. The GC microelectrodes have more than 70% wider electrochemical window and 70% higher CTC (charge transfer capacity) than Pt microelectrodes of similar geometry. Moreover, we demonstrate that the GC microelectrodes can withstand at least 5 million pulses at 0.45 mC/cm2 charge density with less than 7.5% impedance change, while the Pt microelectrodes delaminated after 1 million pulses. Additionally, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was selectively electrodeposited on both sets of devices to specifically reduce their impedances for smaller diameters (<60 μm). We observed that PEDOT-PSS adhered significantly better to GC than Pt, and allowed drastic reduction of electrode size while maintaining same amount of delivered current. The electrode arrays biocompatibility was demonstrated through in-vitro cell viability experiments, while acute in vivo characterization was performed in rats and showed that GC microelectrode arrays recorded somatosensory evoked potentials (SEP) with an almost twice SNR (signal-to-noise ratio) when compared to the Pt ones.

  5. Highly Stable Glassy Carbon Interfaces for Long-Term Neural Stimulation and Low-Noise Recording of Brain Activity

    Science.gov (United States)

    Vomero, Maria; Castagnola, Elisa; Ciarpella, Francesca; Maggiolini, Emma; Goshi, Noah; Zucchini, Elena; Carli, Stefano; Fadiga, Luciano; Kassegne, Sam; Ricci, Davide

    2017-01-01

    We report on the superior electrochemical properties, in-vivo performance and long term stability under electrical stimulation of a new electrode material fabricated from lithographically patterned glassy carbon. For a direct comparison with conventional metal electrodes, similar ultra-flexible, micro-electrocorticography (μ-ECoG) arrays with platinum (Pt) or glassy carbon (GC) electrodes were manufactured. The GC microelectrodes have more than 70% wider electrochemical window and 70% higher CTC (charge transfer capacity) than Pt microelectrodes of similar geometry. Moreover, we demonstrate that the GC microelectrodes can withstand at least 5 million pulses at 0.45 mC/cm2 charge density with less than 7.5% impedance change, while the Pt microelectrodes delaminated after 1 million pulses. Additionally, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was selectively electrodeposited on both sets of devices to specifically reduce their impedances for smaller diameters (<60 μm). We observed that PEDOT-PSS adhered significantly better to GC than Pt, and allowed drastic reduction of electrode size while maintaining same amount of delivered current. The electrode arrays biocompatibility was demonstrated through in-vitro cell viability experiments, while acute in vivo characterization was performed in rats and showed that GC microelectrode arrays recorded somatosensory evoked potentials (SEP) with an almost twice SNR (signal-to-noise ratio) when compared to the Pt ones. PMID:28084398

  6. A nonlinear training set superposition filter derived by neural network training methods for implementation in a shift-invariant optical correlator

    Science.gov (United States)

    Kypraios, Ioannis; Young, Rupert C. D.; Birch, Philip M.; Chatwin, Christopher R.

    2003-08-01

    The various types of synthetic discriminant function (sdf) filter result in a weighted linear superposition of the training set images. Neural network training procedures result in a non-linear superposition of the training set images or, effectively, a feature extraction process, which leads to better interpolation properties than achievable with the sdf filter. However, generally, shift invariance is lost since a data dependant non-linear weighting function is incorporated in the input data window. As a compromise, we train a non-linear superposition filter via neural network methods with the constraint of a linear input to allow for shift invariance. The filter can then be used in a frequency domain based optical correlator. Simulation results are presented that demonstrate the improved training set interpolation achieved by the non-linear filter as compared to a linear superposition filter.

  7. Ultrafast chirped optical waveform recording using referenced heterodyning and a time microscope

    Science.gov (United States)

    Bennett, Corey Vincent

    2010-06-15

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  8. Ultrafast chirped optical waveform recorder using referenced heterodyning and a time microscope

    Science.gov (United States)

    Bennett, Corey Vincent [Livermore, CA

    2011-11-22

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  9. Effects of higher order aberrations on beam shape in an optical recording system

    Science.gov (United States)

    Wang, Mark S.; Milster, Tom D.

    1992-01-01

    An unexpected irradiance pattern in the detector plane of an optical data storage system was observed. Through wavefront measurement and scalar diffraction modeling, it was discovered that the energy redistribution is due to residual third-order and fifth-order spherical aberration of the objective lens and cover-plate assembly. The amount of residual aberration is small, and the beam focused on the disk would be considered diffraction limited by several criteria. Since the detector is not in the focal plane, even this small amount of aberration has a significant effect on the energy distribution. We show that the energy redistribution can adversely affect focus error signals, which are responsible for maintaining sub-micron spot diameters on the spinning disk.

  10. RECORDING AND MODELLING OF MONUMENTS' INTERIOR SPACE USING RANGE AND OPTICAL SENSORS

    Directory of Open Access Journals (Sweden)

    C. Georgiadis

    2016-06-01

    Full Text Available Three dimensional modelling of artefacts and building interiors is a highly active research field in our days. Several techniques are being utilized to perform such a task, spanning from traditional surveying techniques and photogrammetry to structured light scanners, laser scanners and so on. New technological advancements in both hardware and software create new recording techniques, tools and approaches. In this paper we present a new recording and modelling approach based on the SwissRanger SR4000 range camera coupled with a Canon 400D dSLR camera. The hardware component of our approach consists of a fixed base, which encloses the range and SLR cameras. The two sensors are fully calibrated and registered to each other thus we were able to produce colorized point clouds acquired from the range camera. In this paper we present the initial design and calibration of the system along with experimental data regarding the accuracy of the proposed approach. We are also providing results regarding the modelling of interior spaces and artefacts accompanied with accuracy tests from other modelling approaches based on photogrammetry and laser scanning.

  11. Recording and Modelling of MONUMENTS' Interior Space Using Range and Optical Sensors

    Science.gov (United States)

    Georgiadis, Charalampos; Patias, Petros; Tsioukas, Vasilios

    2016-06-01

    Three dimensional modelling of artefacts and building interiors is a highly active research field in our days. Several techniques are being utilized to perform such a task, spanning from traditional surveying techniques and photogrammetry to structured light scanners, laser scanners and so on. New technological advancements in both hardware and software create new recording techniques, tools and approaches. In this paper we present a new recording and modelling approach based on the SwissRanger SR4000 range camera coupled with a Canon 400D dSLR camera. The hardware component of our approach consists of a fixed base, which encloses the range and SLR cameras. The two sensors are fully calibrated and registered to each other thus we were able to produce colorized point clouds acquired from the range camera. In this paper we present the initial design and calibration of the system along with experimental data regarding the accuracy of the proposed approach. We are also providing results regarding the modelling of interior spaces and artefacts accompanied with accuracy tests from other modelling approaches based on photogrammetry and laser scanning.

  12. Brain machine interfaces combining microelectrode arrays with nanostructured optical biochemical sensors

    Science.gov (United States)

    Hajj-Hassan, Mohamad; Gonzalez, Timothy; Ghafer-Zadeh, Ebrahim; Chodavarapu, Vamsy; Musallam, Sam; Andrews, Mark

    2009-02-01

    Neural microelectrodes are an important component of neural prosthetic systems which assist paralyzed patients by allowing them to operate computers or robots using their neural activity. These microelectrodes are also used in clinical settings to localize the locus of seizure initiation in epilepsy or to stimulate sub-cortical structures in patients with Parkinson's disease. In neural prosthetic systems, implanted microelectrodes record the electrical potential generated by specific thoughts and relay the signals to algorithms trained to interpret these thoughts. In this paper, we describe novel elongated multi-site neural electrodes that can record electrical signals and specific neural biomarkers and that can reach depths greater than 8mm in the sulcus of non-human primates (monkeys). We hypothesize that additional signals recorded by the multimodal probes will increase the information yield when compared to standard probes that record just electropotentials. We describe integration of optical biochemical sensors with neural microelectrodes. The sensors are made using sol-gel derived xerogel thin films that encapsulate specific biomarker responsive luminophores in their nanostructured pores. The desired neural biomarkers are O2, pH, K+, and Na+ ions. As a prototype, we demonstrate direct-write patterning to create oxygen-responsive xerogel waveguide structures on the neural microelectrodes. The recording of neural biomarkers along with electrical activity could help the development of intelligent and more userfriendly neural prosthesis/brain machine interfaces as well as aid in providing answers to complex brain diseases and disorders.

  13. Origin of the Red-Shifted Optical Spectra Recorded for Aza-BODIPY Dyes.

    Science.gov (United States)

    Karlsson, Joshua K G; Harriman, Anthony

    2016-04-28

    The optical properties are compared for two boron dipyrromethene (BODIPY) dyes that differ by virtue of the substituent at the meso-site, namely, aza-N versus C-methine atoms. Both compounds are equipped with aryl rings at the 3- and 5-positions of the dipyrrin backbone, which help to extend the degree of π-delocalization. The aza-BODIPY dye absorbs and fluoresces at much lower energy than does the conventional BODIPY dye, with red shifts of about 100 nm being observed in fluid solution, but with comparable fluorescence yield and lifetime. Hydrogen bonding donors, such as alcohols, attach to the aza-N atom and promote nonradiative decay without affecting the properties of the conventional dye. Triplet formation is ineffective in the absence of a spin-orbit coupler. Quantum chemical calculations indicate that the electronegative aza-N atom lowers the energy of the LUMO while having little effect on the corresponding HOMO energy. The resultant decrease in the HOMO-LUMO energy gap is primarily responsible for the red shift. The HOMO-LUMO energy gap is also affected by the dihedral angle subtended by the aryl rings, but this is insensitive to the geometry around the central 6-membered ring. The aza-N atom, by virtue of restricting spatial overlap between the HOMO and LUMO, decreases the energy gap between excited-singlet and -triplet states.

  14. A 1500 yr record of North Atlantic storm activity based on optically dated relict beach scarps

    Science.gov (United States)

    Buynevich, Ilya V.; Fitzgerald, Duncan M.; Goble, Ronald J.

    2007-06-01

    Understanding of long-term dynamics of intense coastal storms is important for determining the frequency and impact of these events on sandy coasts. We use optically stimulated luminescence (OSL) dates on relict scarps within a prograded barrier sequence to reconstruct the chronology of large-magnitude erosional events in the western Gulf of Maine. OSL dates obtained on quartz-rich sediments immediately overlying relict scarps indicate severe beach erosion and retreat due to erosional events ca. 1550, 390, 290, and 150 cal yr B.P. Our data provide new evidence of increased storm activity (most likely frequency and/or intensity of extratropical storms) during the past 500 yr, which was preceded by a relatively calm period lasting ˜1000 yr. The width of the coastal sequence preserved between successive paleoscarps shows strong correlation with the time interval elapsed between storms. Our findings indicate that diagnostic geophysical and sedimentological signatures of severe erosional events offer new opportunities for assessing the impact and timing of major storms along sandy coasts.

  15. A band-tunable, multichannel amplifier for neural recording with AP/LFP separation and dual-threshold adaptive AP detector.

    Science.gov (United States)

    Wu, Jo-Yu; Tang, Kea-Tiong

    2011-01-01

    This article presents a low-power low-noise neural recording system comprising a set of 4-channel amplifiers and a dual-threshold adaptive action potential detector. The front-end amplifier is optimized for power efficiency, noise, and silicon area. A balanced tunable pseudo-resistor is used to acquire local field potential (LFP) and action potential (AP) separately. The post-layout simulation results show that the system achieved input referred noise 4.7 μVrms and noise efficiency factor (NEF) 2.79 with mid-band gain of 51.9 dB and power consumption of 5.22 μW. The bandwidth is highly tunable in the range of 2.38 Hz-300 Hz for high-pass corner and 248 Hz-12.9 kHz for low-pass corner, which can acquire AP and LPF without out-band noise. The proposed dual-threshold adaptive AP detector can capture action potential precisely from background activity, thus data reduction can be realized by only processing these significant waveforms. The results show that the proposed low-power, low-noise biomedical system is suitable for implantable device applications.

  16. Real-Time Growth Control of Ge-Sb-Te Multilayer Film as Optical Recording Media by In Situ Ellipsometry

    Science.gov (United States)

    An, Sung Hyuck; Kim, Jong Hyouk; Li, Xuezhe; Kim, Sang Jun; Kim, Sang Youl

    2004-09-01

    Using an in situ ellipsometer, we monitored the thin film growth curve of optical recording media in real time. Utilizing the complex refractive indices of Ge2Sb2Te5 and ZnS-SiO2 obtained from the analysis of spectroscopic ellipsometry data, we calculated the growth curves of ellipsometric constants vs thickness. By comparing the calculated growth curve of ellipsometric constants with the measured one, and by analyzing the effect of the density variation of the Ge2Sb2Te5 recording layer on ellipsometric constants, we precisely monitored the growth rate of Ge2Sb2Te5 and ZnS-SiO2 films, respectively, and eventually controlled the whole growth process of a multilayer sample made of Ge2Sb2Te5 and ZnS-SiO2 films. The accurate thickness control using in situ ellipsometry was verified through the analysis of the deposited multilayer sample using an ex situ spectroscopic ellipsometer.

  17. Stochastic thermodynamics with a Brownian particle in an optical trap (Presentation Recording)

    Science.gov (United States)

    Martinez, Ignacio A.; Roldán, Édgar; Dinis, Luis; Mestres, Pau; Parrondo, Juan M. R.; Rica, Raúl A.

    2015-08-01

    Stochastic thermodynamics [1,2] is a recently developed framework to deal with the thermodynamics at the microscope, where thermal fluctuations strongly influence their behaviour. Typical such systems are colloids and biomolecules or cells. These thermal fluctuations do not only lead to Brownian motion, but to a continuous and unavoidable heat exchange between the suspending medium and the particles, leading to a very interesting phenomenology. In order to explore such phenomenology and to test theoretical results obtained from stochastic thermodynamics, we developed an "experimental simulator" of thermodynamic devices in the microscale with an optically trapped bead that is subject to an external noise that mimics a controllable thermal bath. The noise is applied by means of electric fields acting on the charge of the trapped particle. In this talk, I will present some of the results we obtained with this simulator, demonstrating excellent control over the effective temperature of the system and a control parameter. This allows us to perform a variety of equilibrium and non-equilibrium thermodynamic processes [3-5]. In particular, we were able to realize microadiabatic processes, where no heat is exchanged on average between the particle and the medium [6]. This achievement allowed us to implement a Carnot microengine as a concatenation of isothermal and adiabatic processes [7], whose theoretical study is playing a key role in the foundations of stochastic thermodynamics. References [1] K Sekimoto; Lecture Notes in Physics (Springer, Berlin, 2010), Vol. 799. [2] U Seifert; Rep. Prog. Phys. 75 (2012) 126001 [3] IA Martínez, E Roldan, JMR Parrondo, D Petrov; Phys. Rev. E 87 (2013) 032159 [4] É Roldán, IA Martínez, L Dinis, RA Rica; Appl. Phys. Lett. 104 (2014) 234103 [5] P Mestres, IA Martinez, A Ortiz-Ambriz, RA Rica, E Roldan; Phys. Rev. E 90 (2014) 032116 [6] IA Martínez, E Roldan, L Dinis, D Petrov, RA Rica; Phys. Rev. Lett. (2015) In press [7] IA Martinez

  18. Evolution of the C2RCC Neural Network for Sentinel 2 and 3 for the Retrieval of Ocean Colour Products in Normal and Extreme Optically Complex Waters

    Science.gov (United States)

    Brockmann, Carsten; Doerffer, Roland; Peters, Marco; Kerstin, Stelzer; Embacher, Sabine; Ruescas, Ana

    2016-08-01

    Retrieval of water constituents, or its optical properties, requires inversion of the water leaving reflectance spectrum, measured at top of atmosphere by ocean colour satellites. The Case 2 Regional processor, originally developed by Doerffer and Schiller [6], uses a large database of radiative transfer simulations inverted by neural networks as basic technology. Through the CoastColour project major improvements were introduced. It has been amended by a set of additional neural networks performing specific tasks and special neural networks have been trained to cover extreme ranges of scattering and absorption. The processor has been renamed into C2RCC (Case 2 Regional CoastColour) and is applicable to all past and current ocean colour sensors as well as Sentinel 2. It has been validated in various studies and is available through ESA's Sentinel toolbox SNAP. It is also used in the Sentinel 3 OLCI ground segment processor of ESA for the generation of the Case 2 water products, as well as in the processor for the upcoming MERIS 4th reprocessing.

  19. EDITORIAL: Focus on the neural interface Focus on the neural interface

    Science.gov (United States)

    Durand, Dominique M.

    2009-10-01

    they can fail to record reliably neural signals for long periods of time. McConnell et al show that by measuring the impedance of the tissue, one can evaluate the extent of the tissue response to the presence of the electrode. Another problem with the neural interface is the mismatch of the mechanical properties between electrode and tissue. Basinger et al use finite element modeling to analyze this mismatch in retinal prostheses and guide the design of new implantable devices. Electrical stimulation has been the method of choice to activate externally the nervous system. However, Zhang et al show that a novel dual hybrid device integrating electrical and optical stimulation can provide an effective interface for simultaneous recording and stimulation. By interfacing an EMG recording system and a movement detection system, Johnson and Fuglevand develop a model capable of predicting muscle activity during movement that could be important for the development of motor prostheses. Sensory restoration is another unsolved problem in neural prostheses. By developing a novel interface between the dorsal root ganglia and electrodes arrays, Gaunt et al show that it is possible to recruit afferent fibers for sensory substitution. Finally, by interfacing directly with muscles, Jung and colleagues show that stimulation of muscles involved in locomotion following spinal cord damage in rats can provide an effective treatment modality for incomplete spinal cord injury. This series of articles clearly shows that the interface is indeed one of the keys to successful therapeutic neural devices. The next Neural Interfaces Conference will take place in Los Angeles, CA in June 2010 and one can expect to see new developments in neural engineering obtained by focusing on the neural interface.

  20. Optical technologies for computational intelligence

    Science.gov (United States)

    Pavlov, Alexander V.

    2001-11-01

    Optics has a number of deep analogies with main principles of Computational Intelligence. We can see strong analogies between basic optical phenomena, used in Fourier-holography, and mathematical foundations of Fuzzy Set Theory. Also, analogies between optical holography technique and principles of Neural Networks Paradigm can be seen. Progress in new holographic recording media with self-developing property leads to Evolutionary Computations holographic realization. Based on these analogies we review holographic techniques from two points of view: Fuzzy Logic and Fuzzy relations.

  1. In vivo application of an optical segment tracking approach for bone loading regimes recording in humans: a reliability study.

    Science.gov (United States)

    Yang, Peng-Fei; Sanno, Maximilian; Ganse, Bergita; Koy, Timmo; Brüggemann, Gert-Peter; Müller, Lars Peter; Rittweger, Jörn

    2014-08-01

    This paper demonstrates an optical segment tracking (OST) approach for assessing the in vivo bone loading regimes in humans. The relative movement between retro-reflective marker clusters affixed to the tibia cortex by bone screws was tracked and expressed as tibia loading regimes in terms of segment deformation. Stable in vivo fixation of bone screws was tested by assessing the resonance frequency of the screw-marker structure and the relative marker position changes after hopping and jumping. Tibia deformation was recorded during squatting exercises to demonstrate the reliability of the OST approach. Results indicated that the resonance frequencies remain unchanged prior to and after all exercises. The changes of Cardan angle between marker clusters induced by the exercises were rather minor, maximally 0.06°. The reproducibility of the deformation angles during squatting remained small (0.04°/m-0.65°/m). Most importantly, all surgical and testing procedures were well tolerated. The OST method promises to bring more insights of the mechanical loading acting on bone than in the past.

  2. Crystallization studies on phase-change optical recording media by use of a two-dimensional periodic mark array.

    Science.gov (United States)

    Xun, X; Erwin, J K; Bletscher, W; Choi, J; Kallenbach, S; Mansuripur, M

    2001-12-10

    We present the results of crystallization studies in thin-film samples of amorphous and crystalline Ge(x)Sb(y)Te(z). The experiments, conducted at moderately elevated temperatures, are based on measurements of the first-order diffraction efficiency from a two-dimensional periodic array of recorded marks. When the samples are slowly heated above room temperature, changes in the efficiencies of various diffracted orders give information about the on-going crystallization process within the sample. Two different compositions of the GeSbTe alloy are used in these experiments. Measurements on Ge(2)Sb(2.3)Te(5) films show crystallization dominated by nucleation. For the Sb-rich eutectic composition Ge-(SbTe), crystallization is found to be dominated by growth from crystalline boundaries. We also show that crystalline marks written by relatively high-power laser pulses are different in their optical properties from the regions crystallized by slow heating of the sample to moderate temperatures.

  3. 光学相干成像技术对神经及脑的成像%Optical coherence tomography technology for neural and brain imaging

    Institute of Scientific and Technical Information of China (English)

    官光英; 李春晖; 石慧

    2008-01-01

    神经与脑的成像作为最具挑战性的课题之一,得到越来越多的关注.对神经与脑部的成像,能够对神经系统及脑部形态、结构以及功能量化,不仅有助于更加深入地了解脑及神经系统.并且可以提高临床诊疗的效率.光学相干成像技术(OCT)是一种新型的成像技术,已被广泛用于生物与医学领域.光学相干成像技术在对神经及脑的成像研究中,最为人们所关注,其该技术的发展也最为迅速.该技术为解决神经及脑的成像问题提供了新的思路和方法,其发展潜力还有待发掘.概述了光学相干成像技术在神经和脑成像领域的最新技术以及成果,讨论了其在神经和脑成像领域的优缺点以及其未来的发展趋势.%Neural and brain imaging has become one of the most challenging subjects and attracted more attentions. Neural and brain imaging can quantify morphological pattern, structure and function of brain and nerve system, which offers us not only a deeper understanding of brain and nerve system, but also improved effectiveness of clinical diagnosis and treatment of diseases. Optical Coherence Tomography (OCT) is a new imaging technique and has been widely used in areas of biology and medicine. Study on OCT technique applying to neural and brain imaging has drawn special attention and rapid developments have been achieved. The technique provides new ideas and methods to solve problems in neural and brain imaging and its potential needs to be discovered. This article re-views the latest techniques and development in OCT for neural and brain imaging. Advantages and disadvantages of the technique and foreground of the development are discussed.

  4. The potential of computer vision, optical backscattering parameters and artificial neural network modelling in monitoring the shrinkage of sweet potato (Ipomoea batatas L.) during drying.

    Science.gov (United States)

    Onwude, Daniel I; Hashim, Norhashila; Abdan, Khalina; Janius, Rimfiel; Chen, Guangnan

    2017-07-30

    Drying is a method used to preserve agricultural crops. During the drying of products with high moisture content, structural changes in shape, volume, area, density and porosity occur. These changes could affect the final quality of dried product and also the effective design of drying equipment. Therefore, this study investigated a novel approach in monitoring and predicting the shrinkage of sweet potato during drying. Drying experiments were conducted at temperatures of 50-70 °C and samples thicknesses of 2-6 mm. The volume and surface area obtained from camera vision, and the perimeter and illuminated area from backscattered optical images were analysed and used to evaluate the shrinkage of sweet potato during drying. The relationship between dimensionless moisture content and shrinkage of sweet potato in terms of volume, surface area, perimeter and illuminated area was found to be linearly correlated. The results also demonstrated that the shrinkage of sweet potato based on computer vision and backscattered optical parameters is affected by the product thickness, drying temperature and drying time. A multilayer perceptron (MLP) artificial neural network with input layer containing three cells, two hidden layers (18 neurons), and five cells for output layer, was used to develop a model that can monitor, control and predict the shrinkage parameters and moisture content of sweet potato slices under different drying conditions. The developed ANN model satisfactorily predicted the shrinkage and dimensionless moisture content of sweet potato with correlation coefficient greater than 0.95. Combined computer vision, laser light backscattering imaging and artificial neural network can be used as a non-destructive, rapid and easily adaptable technique for in-line monitoring, predicting and controlling the shrinkage and moisture changes of food and agricultural crops during drying. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  5. Satellite Ocean Color Data Merging Using a Bio-optical model: A Path for Earth Science Data Records ?

    Science.gov (United States)

    Maritorena, S.; Siegel, D. A.; Hembise Fanton D'Andon, O.; Mangin, A.; Frew, J.; Nelson, N.

    2009-12-01

    The characteristics and benefits of ocean color merged data sets created using a semi-analytical model and the normalized water-leaving radiance observations from the SeaWiFS, MODIS-AQUA and MERIS ocean color missions are presented. Merged data products are coalesced from multiple mission observations into a single data product with better spatial and temporal coverage than the individual missions. Using the data from SeaWiFS, MODIS-AQUA and MERIS for the 2002-2009 time period, the average daily coverage of a merged product is ~25% of the world ocean which is nearly twice that of any single mission’s observations. The frequency at which a particular area is sampled from space is also greatly improved in merged data as some areas can be sampled as frequently as 64% of the time (in days). The merged data are validated through matchup analyses and by comparing them to the data sets obtained from individual missions. Further, a complete error budget was developed which accounts for uncertainty associated with input water-leaving radiances, the bio-optical model and uncertainty estimates for the output products (i.e. the chlorophyll concentration, the combined dissolved and detrital absorption coefficient and the particulate backscattering coefficient). These merged products and their uncertainties at each pixel were developed within the NASA MEASURES (http://wiki.icess.ucsb.edu/measures/index.php/Main_Page) and ESA GlobColour (http://www.globcolour.info/) projects and are available to the scientific community. The merging approach has many potential benefits for the creation of Earth Science Data Records from satellite ocean color observations.

  6. Reaching record-low β* at the CERN Large Hadron Collider using a novel scheme of collimator settings and optics

    Science.gov (United States)

    Bruce, R.; Bracco, C.; De Maria, R.; Giovannozzi, M.; Mereghetti, A.; Mirarchi, D.; Redaelli, S.; Quaranta, E.; Salvachua, B.

    2017-03-01

    The Large Hadron Collider (LHC) at CERN is built to collide intense proton beams with an unprecedented energy of 7 TeV. The design stored energy per beam of 362 MJ makes the LHC beams highly destructive, so that any beam losses risk to cause quenches of superconducting magnets or damage to accelerator components. Collimators are installed to protect the machine and they define a minimum normalized aperture, below which no other element is allowed. This imposes a limit on the achievable luminosity, since when squeezing β* (the β-function at the collision point) to smaller values for increased luminosity, the β-function in the final focusing system increases. This leads to a smaller normalized aperture that risks to go below the allowed collimation aperture. In the first run of the LHC, this was the main limitation on β*, which was constrained to values above the design specification. In this article, we show through theoretical and experimental studies how tighter collimator openings and a new optics with specific phase-advance constraints allows a β* as small as 40 cm, a factor 2 smaller than β*=80 cm used in 2015 and significantly below the design value β*=55 cm, in spite of a lower beam energy. The proposed configuration with β*=40 cm has been successfully put into operation and has been used throughout 2016 as the LHC baseline. The decrease in β* compared to 2015 has been an essential contribution to reaching and surpassing, in 2016, the LHC design luminosity for the first time, and to accumulating a record-high integrated luminosity of around 40 fb-1 in one year, in spite of using less bunches than in the design.

  7. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  8. Identification and estimation algorithm for stochastic neural system.

    Science.gov (United States)

    Nakao, M; Hara, K; Kimura, M; Sato, R

    1984-01-01

    An algorithm for the estimation of stochastic processes in a neural system is presented. This process is defined here as the continuous stochastic process reflecting the dynamics of the neural system which has some inputs and generates output spike trains. The algorithm proposed here is to identify the system parameters and then estimate the stochastic process called neural system process here. These procedures carried out on the basis of the output spike trains which are supposed to be the data observed in the randomly missing way by the threshold time function in the neural system. The algorithm is constructed with the well-known Kalman filters and realizes the estimation of the neural system process by cooperating with the algorithm for the parameter estimation of the threshold time function presented previously (Nakao et al., 1983). The performance of the algorithm is examined by applying it to the various spike trains simulated by some artificial models and also to the neural spike trains recorded in cat's optic tract fibers. The results in these applications are thought to prove the effectiveness of the algorithm proposed here to some extent. Such attempts, we think, will serve to improve the characterizing and modelling techniques of the stochastic neural systems.

  9. Optical Processing.

    Science.gov (United States)

    1985-12-31

    34perceptron" (F. Rosenblatt, Principles of Neurodynamics ), workers in the neural network field have been seeking to understand how neural networks can perform...Moscow). 13. F. Rosenblatt, Principles of Neurodynamics , (Spartan, 1962). 14. W. Stoner "Incoherent optical processing via spatially offset pupil

  10. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  11. Lhx1 in the proximal region of the optic vesicle permits neural retina development in the chicken

    Directory of Open Access Journals (Sweden)

    Takumi Kawaue

    2012-08-01

    How the eye forms has been one of the fundamental issues in developmental biology. The retinal anlage first appears as the optic vesicle (OV evaginating from the forebrain. Subsequently, its distal portion invaginates to form the two-walled optic cup, which develops into the outer pigmented and inner neurosensory layers of the retina. Recent work has shown that this optic-cup morphogenesis proceeds as a self-organizing activity without any extrinsic molecules. However, intrinsic factors that regulate this process have not been elucidated. Here we show that a LIM-homeobox gene, Lhx1, normally expressed in the proximal region of the nascent OV, induces a second neurosensory retina formation from the outer pigmented retina when overexpressed in the chicken OV. Lhx2, another LIM-homeobox gene supposed to be involved in early OV formation, could not substitute this function of Lhx1, while Lhx5, closely related to Lhx1, could replace it. Conversely, knockdown of Lhx1 expression by RNA interference resulted in the formation of a small or pigmented vesicle. These results suggest that the proximal region demarcated by Lhx1 expression permits OV development, eventually dividing the two retinal domains.

  12. Optical processing

    Science.gov (United States)

    Gustafson, S. C.

    1985-12-01

    The technical contributions were as follows: (1) Optical parallel 2-D neighborhood processor and optical processor assessment technique; (2) High accuracy with moderately accurate components and optical fredkin gate architectures; (3) Integrated optical threshold computing, pipelined polynomial processor, and all optical analog/digital converter; (4) Adaptive optical associative memory model with attention; (5) Effectiveness of parallelism and connectivity in optical computers; (6) Optical systolic array processing using an integrated acoustooptic module; (7) Optical threshold elements and networks, holographic threshold processors, adaptive matched spatial filtering, and coherence theory in optical computing; (8) Time-varying optical processing for sub-pixel targets, optical Kalman filtering, and adaptive matched filtering; (9) Optical degrees of freedom, ultra short optical pulses, number representations, content-addressable-memory processors, and integrated optical Givens rotation devices; (10) Optical J-K flip flop analysis and interfacing for optical computers; (11) Matrix multiplication algorithms and limits of incoherent optical computers; (12) Architecture for machine vision with sensor fusion, pattern recognition functions, and neural net implementations; (13) Optical computing algorithms, architectures, and components; and (14) Dynamic optical interconnections, advantages and architectures.

  13. System impairment compensation in coherent optical communications by using a bio-inspired detector based on artificial neural network and genetic algorithm

    Science.gov (United States)

    Wang, Danshi; Zhang, Min; Li, Ze; Song, Chuang; Fu, Meixia; Li, Jin; Chen, Xue

    2017-09-01

    A bio-inspired detector based on the artificial neural network (ANN) and genetic algorithm is proposed in the context of a coherent optical transmission system. The ANN is designed to mitigate 16-quadrature amplitude modulation system impairments, including linear impairment: Gaussian white noise, laser phase noise, in-phase/quadrature component imbalance, and nonlinear impairment: nonlinear phase. Without prior information or heuristic assumptions, the ANN, functioning as a machine learning algorithm, can learn and capture the characteristics of impairments from observed data. Numerical simulations were performed, and dispersion-shifted, dispersion-managed, and dispersion-unmanaged fiber links were investigated. The launch power dynamic range and maximum transmission distance for the bio-inspired method were 2.7 dBm and 240 km greater, respectively, than those of the maximum likelihood estimation algorithm. Moreover, the linewidth tolerance of the bio-inspired technique was 170 kHz greater than that of the k-means method, demonstrating its usability for digital signal processing in coherent systems.

  14. Hysteresis compensation of the piezoelectric ceramic actuators-based tip/tilt mirror with a neural network method in adaptive optics

    Science.gov (United States)

    Wang, Chongchong; Wang, Yukun; Hu, Lifa; Wang, Shaoxin; Cao, Zhaoliang; Mu, Quanquan; Li, Dayu; Yang, Chengliang; Xuan, Li

    2016-05-01

    The intrinsic hysteresis nonlinearity of the piezo-actuators can severely degrade the positioning accuracy of a tip-tilt mirror (TTM) in an adaptive optics system. This paper focuses on compensating this hysteresis nonlinearity by feed-forward linearization with an inverse hysteresis model. This inverse hysteresis model is based on the classical Presiach model, and the neural network (NN) is used to describe the hysteresis loop. In order to apply it in the real-time adaptive correction, an analytical nonlinear function derived from the NN is introduced to compute the inverse hysteresis model output instead of the time-consuming NN simulation process. Experimental results show that the proposed method effectively linearized the TTM behavior with the static hysteresis nonlinearity of TTM reducing from 15.6% to 1.4%. In addition, the tip-tilt tracking experiments using the integrator with and without hysteresis compensation are conducted. The wavefront tip-tilt aberration rejection ability of the TTM control system is significantly improved with the -3 dB error rejection bandwidth increasing from 46 to 62 Hz.

  15. Estimating nocturnal opaque ice cloud optical depth from MODIS multispectral infrared radiances using a neural network method

    Science.gov (United States)

    Minnis, Patrick; Hong, Gang; Sun-Mack, Szedung; Smith, William L.; Chen, Yan; Miller, Steven D.

    2016-05-01

    Retrieval of ice cloud properties using IR measurements has a distinct advantage over the visible and near-IR techniques by providing consistent monitoring regardless of solar illumination conditions. Historically, the IR bands at 3.7, 6.7, 11.0, and 12.0 µm have been used to infer ice cloud parameters by various methods, but the reliable retrieval of ice cloud optical depth τ is limited to nonopaque cirrus with τ water path in the future. Factors affecting the uncertainties and potential improvements are discussed. With improved techniques for discriminating between opaque and semitransparent ice clouds, the method can ultimately improve cloud property monitoring over the entire diurnal cycle.

  16. NOAA Climate Data Record (CDR) of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN-CDR), Version 1 Revision 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PERSIANN Precipitation Climate Data Record (PERSIANN-CDR) is a daily quasi-global precipitation product for the period of 1982 to 2011. The data covers from 60...

  17. Dual optical recordings for action potentials and calcium handling in induced pluripotent stem cell models of cardiac arrhythmias using genetically encoded fluorescent indicators.

    Science.gov (United States)

    Song, LouJin; Awari, Daniel W; Han, Elizabeth Y; Uche-Anya, Eugenia; Park, Seon-Hye E; Yabe, Yoko A; Chung, Wendy K; Yazawa, Masayuki

    2015-05-01

    Reprogramming of human somatic cells to pluripotency has been used to investigate disease mechanisms and to identify potential therapeutics. However, the methods used for reprogramming, in vitro differentiation, and phenotyping are still complicated, expensive, and time-consuming. To address the limitations, we first optimized a protocol for reprogramming of human fibroblasts and keratinocytes into pluripotency using single lipofection and the episomal vectors in a 24-well plate format. This method allowed us to generate multiple lines of integration-free and feeder-free induced pluripotent stem cells (iPSCs) from seven patients with cardiac diseases and three controls. Second, we differentiated human iPSCs derived from patients with Timothy syndrome into cardiomyocytes using a monolayer differentiation method. We found that Timothy syndrome cardiomyocytes showed slower, irregular contractions and abnormal calcium handling compared with the controls. The results are consistent with previous reports using a retroviral method for reprogramming and an embryoid body-based method for cardiac differentiation. Third, we developed an efficient approach for recording the action potentials and calcium transients simultaneously in control and patient cardiomyocytes using genetically encoded fluorescent indicators, ArcLight and R-GECO1. The dual optical recordings enabled us to observe prolonged action potentials and abnormal calcium handling in Timothy syndrome cardiomyocytes. We confirmed that roscovitine rescued the phenotypes in Timothy syndrome cardiomyocytes and that these findings were consistent with previous studies using conventional electrophysiological recordings and calcium imaging with dyes. The approaches using our optimized methods and dual optical recordings will improve iPSC applicability for disease modeling to investigate mechanisms underlying cardiac arrhythmias and to test potential therapeutics.

  18. Optical and Short-wavelength Recording Properties of Ag8In14Sb55Te23 Phase-change Films

    Institute of Scientific and Technical Information of China (English)

    LI Jinyan; HOU Lisong; GAN Fuxi

    2001-01-01

    The Ag-In-Sb-Te phase-change films were deposited on K9 glass substrates by RF magnetron sputtering technology with an Ag-In-Sb-Te alloy target. The spectral properties and short-wavelength optical storage properties of Ag8In13Sb55Te23 films were studied. X-ray diffraction results have indicated that the crystallization compounds include mainly AgSbTe2 with small amounts of Sb and AgInTe2. A comparatively large absorption has been observed in the visible wavelength range. The optical storage characteristics of Ag8In13Sb55Te23 thin films indicated that larger reflectivity contrast can be obtained at lower writing power and shorter writing pulse width.

  19. A Novel Approach to Obtain GeSbTe-Based High Speed Crystallizing Materials for Phase Change Optical Recording

    Science.gov (United States)

    2001-04-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012318 TITLE: A Novel Approach to Obtain GeSbTe -Based High Speed...UNCLASSIFIED Mat. Res. Soc. Symp. Proc. Vol. 674 © 2001 Materials Research Society A Novel Approach to Obtain GeSbTe -Based High Speed Crystallizing...fast crystallizing materials based on a conventional GeSbTe alloy for rewritable phase change optical data storage. By means of co-sputtering

  20. Chronic neural probe for simultaneous recording of single-unit, multi-unit, and local field potential activity from multiple brain sites

    Science.gov (United States)

    Pothof, F.; Bonini, L.; Lanzilotto, M.; Livi, A.; Fogassi, L.; Orban, G. A.; Paul, O.; Ruther, P.

    2016-08-01

    Objective. Drug resistant focal epilepsy can be treated by resecting the epileptic focus requiring a precise focus localisation using stereoelectroencephalography (SEEG) probes. As commercial SEEG probes offer only a limited spatial resolution, probes of higher channel count and design freedom enabling the incorporation of macro and microelectrodes would help increasing spatial resolution and thus open new perspectives for investigating mechanisms underlying focal epilepsy and its treatment. This work describes a new fabrication process for SEEG probes with materials and dimensions similar to clinical probes enabling recording single neuron activity at high spatial resolution. Approach. Polyimide is used as a biocompatible flexible substrate into which platinum electrodes and leads are integrated with a minimal feature size of 5 μm. The polyimide foils are rolled into the cylindrical probe shape at a diameter of 0.8 mm. The resulting probe features match those of clinically approved devices. Tests in saline solution confirmed the probe stability and functionality. Probes were implanted into the brain of one monkey (Macaca mulatta), trained to perform different motor tasks. Suitable configurations including up to 128 electrode sites allow the recording of task-related neuronal signals. Main results. Probes with 32 and 64 electrode sites were implanted in the posterior parietal cortex. Local field potentials and multi-unit activity were recorded as early as one hour after implantation. Stable single-unit activity was achieved for up to 26 days after implantation of a 64-channel probe. All recorded signals showed modulation during task execution. Significance. With the novel probes it is possible to record stable biologically relevant data over a time span exceeding the usual time needed for epileptic focus localisation in human patients. This is the first time that single units are recorded along cylindrical polyimide probes chronically implanted 22 mm deep into the

  1. A high-speed, reconfigurable, channel- and time-tagged photon arrival recording system for intensity-interferometry and quantum optics experiments

    Science.gov (United States)

    Girish, B. S.; Pandey, Deepak; Ramachandran, Hema

    2017-08-01

    We present a compact, inexpensive multichannel module, APODAS (Avalanche Photodiode Output Data Acquisition System), capable of detecting 0.8 billion photons per second and providing real-time recording on a computer hard-disk, of channel- and time-tagged information of the arrival of upto 0.4 billion photons per second. Built around a Virtex-5 Field Programmable Gate Array (FPGA) unit, APODAS offers a temporal resolution of 5 nanoseconds with zero deadtime in data acquisition, utilising an efficient scheme for time and channel tagging and employing Gigabit ethernet for the transfer of data. Analysis tools have been developed on a Linux platform for multi-fold coincidence studies and time-delayed intensity interferometry. As illustrative examples, the second-order intensity correlation function ( g 2) of light from two commonly used sources in quantum optics —a coherent laser source and a dilute atomic vapour emitting spontaneously, constituting a thermal source— are presented. With easy reconfigurability and with no restriction on the total record length, APODAS can be readily used for studies over various time scales. This is demonstrated by using APODAS to reveal Rabi oscillations on nanosecond time scales in the emission of ultracold atoms, on the one hand, and, on the other hand, to measure the second-order correlation function on the millisecond time scales from tailored light sources. The efficient and versatile performance of APODAS promises its utility in diverse fields, like quantum optics, quantum communication, nuclear physics, astrophysics and biology.

  2. Total ozone column, aerosol optical depth and precipitable water effects on solar erythemal ultraviolet radiation recorded in Malta.

    Science.gov (United States)

    Bilbao, Julia; Román, Roberto; Yousif, Charles; Mateos, David; Miguel, Argimiro

    2013-04-01

    The Universities of Malta and Valladolid (Spain) developed a measurement campaign, which took place in the Institute for Energy Technology in Marsaxlokk (Southern Malta) between May and October 2012, and it was supported by the Spanish government through the Project titled "Measurement campaign about Solar Radiation, Ozone, and Aerosol in the Mediterranean area" (with reference CGL2010-12140-E). This campaign provided the first ground-based measurements in Malta of erythemal radiation and UV index, which indicate the effectiveness of the sun exposure to produce sunburn on human skin. A wide variety of instruments was involved in the campaign, providing a complete atmospheric characterization. Data of erythemal radiation and UV index (from UVB-1 pyranometer), total shortwave radiaton (global and diffuse components from CM-6B pyranometers), and total ozone column, aerosol optical thickness, and precitable water column (from a Microtops-II sunphotometer) were available in the campaign. Ground-based and satellite instruments were used in the analysis, and several intercomparisons were carried out to validate remote sensing data. OMI, GOME, GOME-2, and MODIS instruments, which provide data of ozone, aerosol load and optical properties, were used to this end. The effects on solar radiation, ultraviolet and total shortwave ranges, of total ozone column, aerosol optical thickness and precipitable water column were obtained using radiation measurements at different fixed solar zenith angles. The empirical results shown a determinant role of the solar position, a negligible effect of ozone on total shortwave radiation, and a stronger attenuation provided by aerosol particles in the erythemal radiation. A variety of aerosol types from different sources (desert dust, biomass burning, continental, and maritime) reach Malta, in this campaign several dust events from the Sahara desert occurred and were analyzed establishing the air mass back-trajectories ending at Malta at

  3. An optical comparator for measuring two-dimensional polyacrylamide gel electrophoresis records using an on-line microcomputer.

    Science.gov (United States)

    Spragg, S P; Jones, M I; Hill, B J

    1983-03-01

    A comparator which makes it possible to compare two wet gels or photographic negatives or autoradiograms through a flickering light system has been built. The system consists of two special-purpose projectors which combine the images on a digitizing platform. When the lights are switched On and off out of phase, the positions of the common components remain unchanged, whereas those that are spatially displaced appear to jump from side to side and those present in one image but not the other switch on and off. This produces a flickering image in which differences are readily seen. Commercial camera lenses were used to construct the projectors and the overall specifications for the system are given. The coordinates of both the displaced components, as well as the selected standards from the two images, are digitized and entered automatically into an on-line microcomputer. By using an iterative procedure for collecting records from several superimposable records of the gel, it is possible to compensate for the lack of total reproducibility over the whole gels. These coordinates are then normalized and superimposed on a master map through a television display using a curser to adjust the coordinates. The whole procedure can be repeated for many gels using a common reference gel in the comparator, and the result is a set of normalized coordinates which can be plotted on a single map to provide a final record of the experiments.

  4. Optical trapping of nanoparticles with significantly reduced laser powers by using counter-propagating beams (Presentation Recording)

    Science.gov (United States)

    Zhao, Chenglong; LeBrun, Thomas W.

    2015-08-01

    Gold nanoparticles (GNP) have wide applications ranging from nanoscale heating to cancer therapy and biological sensing. Optical trapping of GNPs as small as 18 nm has been successfully achieved with laser power as high as 855 mW, but such high powers can damage trapped particles (particularly biological systems) as well heat the fluid, thereby destabilizing the trap. In this article, we show that counter propagating beams (CPB) can successfully trap GNP with laser powers reduced by a factor of 50 compared to that with a single beam. The trapping position of a GNP inside a counter-propagating trap can be easily modulated by either changing the relative power or position of the two beams. Furthermore, we find that under our conditions while a single-beam most stably traps a single particle, the counter-propagating beam can more easily trap multiple particles. This (CPB) trap is compatible with the feedback control system we recently demonstrated to increase the trapping lifetimes of nanoparticles by more than an order of magnitude. Thus, we believe that the future development of advanced trapping techniques combining counter-propagating traps together with control systems should significantly extend the capabilities of optical manipulation of nanoparticles for prototyping and testing 3D nanodevices and bio-sensing.

  5. 基于CNN的录音设备判别研究%Recording Equipment Identifying Research Based on Convolution Neural Networks

    Institute of Scientific and Technical Information of China (English)

    高冲红; 丛韫; 郑义; 侍孝一; 童茜雯; 徐欣铖

    2016-01-01

    文章拟解决音频取证中录音设备判别的问题.不同设备采用的压缩算法不同,会导致录音设备录音时附加到音频中的某些参量不同.从压缩算法角度,文章介绍一种基于卷积神经网络(Convolution Neural Networks,CNN)的录音设备的判别研究.首先获得不同比特率的音频,结合改进的梅尔频率倒谱系数算法(Mel Frequency Cepstrum Coefficient,Mel),用以分析录音设备对音频文件的特征参数影响,接着构建卷积神经网络识别模型,并将得到的Mel倒谱参数输入至构建好的神经网络中训练测试,最后识别并统计识别结果.实验结果表明,本研究对手机比特率的识别率达到92%.

  6. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons.

    Science.gov (United States)

    Ma, Ying; Shaik, Mohammed A; Kozberg, Mariel G; Kim, Sharon H; Portes, Jacob P; Timerman, Dmitriy; Hillman, Elizabeth M C

    2016-12-27

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI.

  7. Vertically Aligned Carbon Nanofiber as Nano-Neuron Interface for Monitoring Neural Function

    OpenAIRE

    Yu, Zhe; McKnight, Timothy E.; Ericson, M. Nance; Melechko, Anatoli V.; Simpson, Michael L.; Morrison, Barclay

    2012-01-01

    Neural chips, which are capable of simultaneous, multi-site neural recording and stimulation, have been used to detect and modulate neural activity for almost 30 years. As a neural interface, neural chips provide dynamic functional information for neural decoding and neural control. By improving sensitivity and spatial resolution, nano-scale electrodes may revolutionize neural detection and modulation at cellular and molecular levels as nano-neuron interfaces. We developed a carbon-nanofiber ...

  8. A Wireless Optogenetic Headstage with Multichannel Electrophysiological Recording Capability

    Directory of Open Access Journals (Sweden)

    Gabriel Gagnon-Turcotte

    2015-09-01

    Full Text Available We present a small and lightweight fully wireless optogenetic headstage capable of optical neural stimulation and electrophysiological recording. The headstage is suitable for conducting experiments with small transgenic rodents, and features two implantable fiber-coupled light-emitting diode (LED and two electrophysiological recording channels. This system is powered by a small lithium-ion battery and is entirely built using low-cost commercial off-the-shelf components for better flexibility, reduced development time and lower cost. Light stimulation uses customizable stimulation patterns of varying frequency and duty cycle. The optical power that is sourced from the LED is delivered to target light-sensitive neurons using implantable optical fibers, which provide a measured optical power density of 70 mW/mm2 at the tip. The headstage is using a novel foldable rigid-flex printed circuit board design, which results into a lightweight and compact device. Recording experiments performed in the cerebral cortex of transgenic ChR2 mice under anesthetized conditions show that the proposed headstage can trigger neuronal activity using optical stimulation, while recording microvolt amplitude electrophysiological signals.

  9. Magnetic anisotropy and spin reorientation effects in Gd/Fe and Gd/(FeCo) multilayers for high density magneto-optical recording

    Science.gov (United States)

    Stavrou, E.; Sbiaa, R.; Suzuki, T.; Knappmann, S.; Röll, K.

    2000-05-01

    We have investigated the anisotropy behavior and temperature dependent changes of the magnetic anisotropy in Gd/Fe and Gd/(FeCo) multilayers. The spin reorientation effects are very important for the super resolution readout in new methods for high-density magneto-optical recording. Gd/(Fe, Co) multilayered films are a good alternative to the common Gd(Fe, Co) alloy films, because the magnetic anisotropy and also spin reorientation effects can be comfortably adjusted by varying the interface and volume anisotropy components and the composition using experimental parameters such as the periodicity λ=tGd+tTM [tGd,tTM: the sublayer thicknesses of the Gd and transition metal Fe, FeCo (TM)] and the ratio of the sublayer thicknesses tGd/tTM. We have found the mechanisms for spin reorientation, which are explained qualitatively with a new model.

  10. Flexible parylene-film optical waveguide arrays

    Science.gov (United States)

    Yamagiwa, S.; Ishida, M.; Kawano, T.

    2015-08-01

    Modulation of neuronal activities by light [e.g., laser or light-emitting diode] using optogenetics is a powerful tool for studies on neuronal functions in a brain. Herein, flexible thin-film optical waveguide arrays based on a highly biocompatible material of parylene are reported. Parylene-C and -N thin layers with the different refractive indices form the clad and the core of the waveguide, respectively, and neural recording microelectrodes are integrated to record optical stimuli and electrical recordings simultaneously using the same alignment. Both theoretical and experimental investigations confirm that light intensities of more than 90% can propagate in a bent waveguide with a curvature radius of >5 mm. The proposed flexible thin-film waveguide arrays with microelectrodes can be used for numerous spherical bio-tissues, including brain and spinal cord samples.

  11. Implantable neurotechnologies: a review of integrated circuit neural amplifiers.

    Science.gov (United States)

    Ng, Kian Ann; Greenwald, Elliot; Xu, Yong Ping; Thakor, Nitish V

    2016-01-01

    Neural signal recording is critical in modern day neuroscience research and emerging neural prosthesis programs. Neural recording requires the use of precise, low-noise amplifier systems to acquire and condition the weak neural signals that are transduced through electrode interfaces. Neural amplifiers and amplifier-based systems are available commercially or can be designed in-house and fabricated using integrated circuit (IC) technologies, resulting in very large-scale integration or application-specific integrated circuit solutions. IC-based neural amplifiers are now used to acquire untethered/portable neural recordings, as they meet the requirements of a miniaturized form factor, light weight and low power consumption. Furthermore, such miniaturized and low-power IC neural amplifiers are now being used in emerging implantable neural prosthesis technologies. This review focuses on neural amplifier-based devices and is presented in two interrelated parts. First, neural signal recording is reviewed, and practical challenges are highlighted. Current amplifier designs with increased functionality and performance and without penalties in chip size and power are featured. Second, applications of IC-based neural amplifiers in basic science experiments (e.g., cortical studies using animal models), neural prostheses (e.g., brain/nerve machine interfaces) and treatment of neuronal diseases (e.g., DBS for treatment of epilepsy) are highlighted. The review concludes with future outlooks of this technology and important challenges with regard to neural signal amplification.

  12. Detection of cortical optical changes during seizure activity using optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Ornelas, Danielle; Hasan, Md.; Gonzalez, Oscar; Krishnan, Giri; Szu, Jenny I.; Myers, Timothy; Hirota, Koji; Bazhenov, Maxim; Binder, Devin K.; Park, Boris H.

    2017-02-01

    Electrophysiology has remained the gold standard of neural activity detection but its resolution and high susceptibility to noise and motion artifact limit its efficiency. Imaging techniques, including fMRI, intrinsic optical imaging, and diffuse optical imaging, have been used to detect neural activity, but rely on indirect measurements such as changes in blood flow. Fluorescence-based techniques, including genetically encoded indicators, are powerful techniques, but require introduction of an exogenous fluorophore. A more direct optical imaging technique is optical coherence tomography (OCT), a label-free, high resolution, and minimally invasive imaging technique that can produce depth-resolved cross-sectional and 3D images. In this study, we sought to examine non-vascular depth-dependent optical changes directly related to neural activity. We used an OCT system centered at 1310 nm to search for changes in an ex vivo brain slice preparation and an in vivo model during 4-AP induced seizure onset and propagation with respect to electrical recording. By utilizing Doppler OCT and the depth-dependency of the attenuation coefficient, we demonstrate the ability to locate and remove the optical effects of vasculature within the upper regions of the cortex from in vivo attenuation calculations. The results of this study show a non-vascular decrease in intensity and attenuation in ex vivo and in vivo seizure models, respectively. Regions exhibiting decreased optical changes show significant temporal correlation to regions of increased electrical activity during seizure. This study allows for a thorough and biologically relevant analysis of the optical signature of seizure activity both ex vivo and in vivo using OCT.

  13. Relationships between columnar aerosol optical properties and surface particulate matter observations in north-central Spain from long-term records (2003–2011

    Directory of Open Access Journals (Sweden)

    Y. S. Bennouna

    2014-06-01

    Full Text Available This work examines the relationships between Aerosol Optical Depth (AOD and Particulate Matter (PMX parameters, based on long records (2003–2011 of two nearby sites from the AERONET and EMEP networks in the north-central area of Spain. The climatological annual cycle of PM10 and PM2.5 present a bimodality which might be partly due to desert dust intrusions, a pattern which does not appear in the annual cycle of the AOD. In the case of the AOD, this bimodality is likely to be masked because of the poor sampling of sunphotometer data as compared to PMX (67% of days against 90%, and this fact stresses the necessity of long-term observations. In monthly series, significant interannual variations are observed and most extrema coincide, however the bimodal shape remains relatively stable for PMX. Significant and consistent trends were found for both datasets likely associated to a decrease of desert dust apportionment until 2009. PM10 and AOD daily data are moderately correlated (0.56, a correlation improving for monthly means (0.70. In the case of strong desert dust events day-to-day correlation is not systematic, therefore an extensive analysis on PMX, fine-PM ratio, AOD and associated Ångström exponent (α is carried out.

  14. Simultaneous optical recording in multiple cells by digital holographic microscopy of chloride current associated to activation of the ligand-gated chloride channel GABA(A) receptor.

    Science.gov (United States)

    Jourdain, Pascal; Boss, Daniel; Rappaz, Benjamin; Moratal, Corinne; Hernandez, Maria-Clemencia; Depeursinge, Christian; Magistretti, Pierre Julius; Marquet, Pierre

    2012-01-01

    Chloride channels represent a group of targets for major clinical indications. However, molecular screening for chloride channel modulators has proven to be difficult and time-consuming as approaches essentially rely on the use of fluorescent dyes or invasive patch-clamp techniques which do not lend themselves to the screening of large sets of compounds. To address this problem, we have developed a non-invasive optical method, based on digital holographic microcopy (DHM), allowing monitoring of ion channel activity without using any electrode or fluorescent dye. To illustrate this approach, GABA(A) mediated chloride currents have been monitored with DHM. Practically, we show that DHM can non-invasively provide the quantitative determination of transmembrane chloride fluxes mediated by the activation of chloride channels associated with GABA(A) receptors. Indeed through an original algorithm, chloride currents elicited by application of appropriate agonists of the GABA(A) receptor can be derived from the quantitative phase signal recorded with DHM. Finally, chloride currents can be determined and pharmacologically characterized non-invasively simultaneously on a large cellular sampling by DHM.

  15. Simultaneous optical recording in multiple cells by digital holographic microscopy of chloride current associated to activation of the ligand-gated chloride channel GABA(A receptor.

    Directory of Open Access Journals (Sweden)

    Pascal Jourdain

    Full Text Available Chloride channels represent a group of targets for major clinical indications. However, molecular screening for chloride channel modulators has proven to be difficult and time-consuming as approaches essentially rely on the use of fluorescent dyes or invasive patch-clamp techniques which do not lend themselves to the screening of large sets of compounds. To address this problem, we have developed a non-invasive optical method, based on digital holographic microcopy (DHM, allowing monitoring of ion channel activity without using any electrode or fluorescent dye. To illustrate this approach, GABA(A mediated chloride currents have been monitored with DHM. Practically, we show that DHM can non-invasively provide the quantitative determination of transmembrane chloride fluxes mediated by the activation of chloride channels associated with GABA(A receptors. Indeed through an original algorithm, chloride currents elicited by application of appropriate agonists of the GABA(A receptor can be derived from the quantitative phase signal recorded with DHM. Finally, chloride currents can be determined and pharmacologically characterized non-invasively simultaneously on a large cellular sampling by DHM.

  16. An improved holographic recording medium

    Science.gov (United States)

    Gange, R. A.

    1973-01-01

    Solid, linear chain hydrocarbons with molecular weight ranging from about 300 to 2000 can serve as long-lived recording medium in optical memory system. Suitable recording hydrocarbons include microcrystalline waxes and low molecular weight polymers or ethylene.

  17. Monitoring activity in neural circuits with genetically encoded indicators

    Directory of Open Access Journals (Sweden)

    Gerard Joseph Broussard

    2014-12-01

    Full Text Available Recent developments in genetically encoded indicators of neural activity (GINAs have greatly advanced the field of systems neuroscience. As they are encoded by DNA, GINAs can be targeted to genetically defined cellular populations. Combined with fluorescence microscopy, most notably multi-photon imaging, GINAs allow chronic simultaneous optical recordings from large populations of neurons or glial cells in awake, behaving mammals, particularly rodents. This large-scale recording of neural activity at multiple temporal and spatial scales has greatly advanced our understanding of the dynamics of neural circuitry underlying behavior—a critical first step toward understanding the complexities of brain function, such as sensorimotor integration and learning.Here, we summarize the recent development and applications of the major classes of GINAs. In particular, we take an in-depth look at the design of available GINA families with a particular focus on genetically encoded calcium indicators, sensors probing synaptic activity, and genetically encoded voltage indicators. Using the family of the genetically encoded calcium indicator GCaMP as an example, we review established sensor optimization pipelines. We also discuss practical considerations for end users of GINAs about experimental methods including approaches for gene delivery, imaging system requirements, and data analysis techniques. With the growing toolbox of GINAs and with new microscopy techniques pushing beyond their current limits, the age of light can finally achieve the goal of broad and dense sampling of neuronal activity across time and brain structures to obtain a dynamic picture of brain function.

  18. RF magnetron sputtered (BiDy)3(FeGa)5O12:Bi2O3 composite garnet-oxide materials possessing record magneto-optic quality in the visible spectral region.

    Science.gov (United States)

    Vasiliev, Mikhail; Alam, Mohammad Nur-E; Kotov, Viacheslav A; Alameh, Kamal; Belotelov, Vladimir I; Burkov, Vladimir I; Zvezdin, Anatoly K

    2009-10-26

    Bismuth-substituted iron garnets are considered to be the most promising magneto-optical materials because of their excellent optical transparency and very high magneto-optical figures of merit in the near-infrared spectral region. However, the practical application of garnets in the visible and short-wavelength infrared parts of spectrum is currently limited, due to their very high optical absorption (especially in sputtered films) in these spectral regions. In this paper, we identify the likely source of excess absorption observed in sputtered garnet films in comparison with epitaxial layers and demonstrate (Bi,Dy)(3)(Fe,Ga)(5)O(12): Bi(2)O(3) composites possessing record MO quality in the visible region.

  19. Hologram recording tubes

    Science.gov (United States)

    Rajchman, J. H.

    1973-01-01

    Optical memories allow extremely large numbers of bits to be stored and recalled in a matter of microseconds. Two recording tubes, similar to conventional image-converting tubes, but having a soft-glass surface on which hologram is recorded, do not degrade under repeated hologram read/write cycles.

  20. Multi-layer holographic bifurcative neural network system for real-time adaptive EOS data analysis

    Science.gov (United States)

    Liu, Hua-Kuang; Huang, K. S.; Diep, J.

    1993-01-01

    Optical data processing techniques have the inherent advantage of high data throughout, low weight and low power requirements. These features are particularly desirable for onboard spacecraft in-situ real-time data analysis and data compression applications. the proposed multi-layer optical holographic neural net pattern recognition technique will utilize the nonlinear photorefractive devices for real-time adaptive learning to classify input data content and recognize unexpected features. Information can be stored either in analog or digital form in a nonlinear photofractive device. The recording can be accomplished in time scales ranging from milliseconds to microseconds. When a system consisting of these devices is organized in a multi-layer structure, a feedforward neural net with bifurcating data classification capability is formed. The interdisciplinary research will involve the collaboration with top digital computer architecture experts at the University of Southern California.

  1. Multipoint-emitting optical fibers for spatially addressable in vivo optogenetics.

    Science.gov (United States)

    Pisanello, Ferruccio; Sileo, Leonardo; Oldenburg, Ian A; Pisanello, Marco; Martiradonna, Luigi; Assad, John A; Sabatini, Bernardo L; De Vittorio, Massimo

    2014-06-18

    Optical stimulation and silencing of neural activity is a powerful technique for elucidating the structure and function of neural circuitry. In most in vivo optogenetic experiments, light is delivered into the brain through a single optical fiber. However, this approach limits illumination to a fixed volume of the brain. Here a focused ion beam is used to pattern multiple light windows on a tapered optical fiber. We show that such fibers allow selective and dynamic illumination of different brain regions along the taper. Site selection is achieved by a simple coupling strategy at the fiber input, and the use of a single tapered waveguide minimizes the implant invasiveness. We demonstrate the effectiveness of this approach for multipoint optical stimulation in the mammalian brain in vivo by coupling the fiber to a microelectrode array and performing simultaneous extracellular recording and stimulation at multiple sites in the mouse striatum and cerebral cortex.

  2. Highly Functional TNTs with Superb Photocatalytic, Optical, and Electronic Performance Achieving Record PV Efficiency of 10.1% for 1D-Based DSSCs.

    Science.gov (United States)

    Qadir, Muhammad Bilal; Li, Yuewen; Sahito, Iftikhar Ali; Arbab, Alvira Ayoub; Sun, Kyung Chul; Mengal, Naveed; Memon, Anam Ali; Jeong, Sung Hoon

    2016-09-01

    Different nanostructures of TiO2 play an important role in the photocatalytic and photoelectronic applications. TiO2 nanotubes (TNTs) have received increasing attention for these applications due to their unique physicochemical properties. Focusing on highly functional TNTs (HF-TNTs) for photocatalytic and photoelectronic applications, this study describes the facile hydrothermal synthesis of HF-TNTs by using commercial and cheaper materials for cost-effective manufacturing. To prove the functionality and applicability, these TNTs are used as scattering structure in dye-sensitized solar cells (DSSCs). Photocatalytic, optical, Brunauer-Emmett-Teller (BET), electrochemical impedance spectrum, incident-photon-to-current efficiency, and intensity-modulated photocurrent spectroscopy/intensity-modulated photovoltage spectroscopy characterizations are proving the functionality of HF-TNTs for DSSCs. HF-TNTs show 50% higher photocatalytic degradation rate and also 68% higher dye loading ability than conventional TNTs (C-TNTs). The DSSCs having HF-TNT and its composite-based multifunctional overlayer show effective light absorption, outstanding light scattering, lower interfacial resistance, longer electron lifetime, rapid electron transfer, and improved diffusion length, and consequently, J SC , quantum efficiency, and record photoconversion efficiency of 10.1% using commercial N-719 dye is achieved, for 1D-based DSSCs. These new and highly functional TNTs will be a concrete fundamental background toward the development of more functional applications in fuel cells, dye-sensitized solar cells, Li-ion batteries, photocatalysis process, ion-exchange/adsorption process, and photoelectrochemical devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Neural constructivism or self-organization?

    NARCIS (Netherlands)

    van der Maas, H.L.J.; Molenaar, P.C.M.

    2000-01-01

    Comments on the article by S. R. Quartz et al (see record 1998-00749-001) which discussed the constructivist perspective of interaction between cognition and neural processes during development and consequences for theories of learning. Three arguments are given to show that neural constructivism la

  4. Coherence resonance in bursting neural networks.

    Science.gov (United States)

    Kim, June Hoan; Lee, Ho Jun; Min, Cheol Hong; Lee, Kyoung J

    2015-10-01

    Synchronized neural bursts are one of the most noticeable dynamic features of neural networks, being essential for various phenomena in neuroscience, yet their complex dynamics are not well understood. With extrinsic electrical and optical manipulations on cultured neural networks, we demonstrate that the regularity (or randomness) of burst sequences is in many cases determined by a (few) low-dimensional attractor(s) working under strong neural noise. Moreover, there is an optimal level of noise strength at which the regularity of the interburst interval sequence becomes maximal-a phenomenon of coherence resonance. The experimental observations are successfully reproduced through computer simulations on a well-established neural network model, suggesting that the same phenomena may occur in many in vivo as well as in vitro neural networks.

  5. Applied optics and optical engineering v.9

    CERN Document Server

    Shannon, Robert

    1983-01-01

    Applied Optics and Optical Engineering, Volume IX covers the theories and applications of optics and optical engineering. The book discusses the basic algorithms for optical engineering; diffraction gratings, ruled and holographic; and recording and reading of information on optical disks. The text also describes the perfect point spread function; the multiple aperture telescope diffraction images; and the displays and simulators. Ophthalmic optics, as well as the canonical and real-space coordinates used in the theory of image formation are also encompassed. Optical engineers and students tak

  6. Temporal coupling between stimulus-evoked neural activity and hemodynamic responses from individual cortical columns

    Energy Technology Data Exchange (ETDEWEB)

    Bruyns-Haylett, Michael; Zheng Ying; Berwick, Jason; Jones, Myles [The Centre for Signal Processing in Neuroimaging and Systems Neuroscience (SPINSN), Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TP (United Kingdom)], E-mail: m.jones@sheffield.ac.uk

    2010-04-21

    Using previously published data from the whisker barrel cortex of anesthetized rodents (Berwick et al 2008 J. Neurophysiol. 99 787-98) we investigated whether highly spatially localized stimulus-evoked cortical hemodynamics responses displayed a linear time-invariant (LTI) relationship with neural activity. Presentation of stimuli to individual whiskers of 2 s and 16 s durations produced hemodynamics and neural activity spatially localized to individual cortical columns. Two-dimensional optical imaging spectroscopy (2D-OIS) measured hemoglobin responses, while multi-laminar electrophysiology recorded neural activity. Hemoglobin responses to 2 s stimuli were deconvolved with underlying evoked neural activity to estimate impulse response functions which were then convolved with neural activity evoked by 16 s stimuli to generate predictions of hemodynamic responses. An LTI system more adequately described the temporal neuro-hemodynamics coupling relationship for these spatially localized sensory stimuli than in previous studies that activated the entire whisker cortex. An inability to predict the magnitude of an initial 'peak' in the total and oxy- hemoglobin responses was alleviated when excluding responses influenced by overlying arterial components. However, this did not improve estimation of the hemodynamic responses return to baseline post-stimulus cessation.

  7. Neural Networks

    Directory of Open Access Journals (Sweden)

    Schwindling Jerome

    2010-04-01

    Full Text Available This course presents an overview of the concepts of the neural networks and their aplication in the framework of High energy physics analyses. After a brief introduction on the concept of neural networks, the concept is explained in the frame of neuro-biology, introducing the concept of multi-layer perceptron, learning and their use as data classifer. The concept is then presented in a second part using in more details the mathematical approach focussing on typical use cases faced in particle physics. Finally, the last part presents the best way to use such statistical tools in view of event classifers, putting the emphasis on the setup of the multi-layer perceptron. The full article (15 p. corresponding to this lecture is written in french and is provided in the proceedings of the book SOS 2008.

  8. Records Management

    Data.gov (United States)

    U.S. Environmental Protection Agency — All Federal Agencies are required to prescribe an appropriate records maintenance program so that complete records are filed or otherwise preserved, records can be...

  9. FGF Signaling Transforms Non-neural Ectoderm into Neural Crest

    OpenAIRE

    Yardley, Nathan; García-Castro, Martín I.

    2012-01-01

    The neural crest arises at the border between the neural plate and the adjacent non-neural ectoderm. It has been suggested that both neural and non-neural ectoderm can contribute to the neural crest. Several studies have examined the molecular mechanisms that regulate neural crest induction in neuralized tissues or the neural plate border. Here, using the chick as a model system, we address the molecular mechanisms by which non-neural ectoderm generates neural crest. We report that in respons...

  10. Neural Network Applications

    NARCIS (Netherlands)

    Vonk, E.; Jain, L.C.; Veelenturf, L.P.J.

    1995-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  11. Cross-validation of serial optical coherence scanning and diffusion tensor imaging: a study on neural fiber maps in human medulla oblongata.

    Science.gov (United States)

    Wang, Hui; Zhu, Junfeng; Reuter, Martin; Vinke, Louis N; Yendiki, Anastasia; Boas, David A; Fischl, Bruce; Akkin, Taner

    2014-10-15

    We established a strategy to perform cross-validation of serial optical coherence scanner imaging (SOCS) and diffusion tensor imaging (DTI) on a postmortem human medulla. Following DTI, the sample was serially scanned by SOCS, which integrates a vibratome slicer and a multi-contrast optical coherence tomography rig for large-scale three-dimensional imaging at microscopic resolution. The DTI dataset was registered to the SOCS space. An average correlation coefficient of 0.9 was found between the co-registered fiber maps constructed by fractional anisotropy and retardance contrasts. Pixelwise comparison of fiber orientations demonstrated good agreement between the DTI and SOCS measures. Details of the comparison were studied in regions exhibiting a variety of fiber organizations. DTI estimated the preferential orientation of small fiber tracts; however, it didn't capture their complex patterns as SOCS did. In terms of resolution and imaging depth, SOCS and DTI complement each other, and open new avenues for cross-modality investigations of the brain.

  12. Laser color recording unit

    Science.gov (United States)

    Jung, E.

    1984-05-01

    A color recording unit was designed for output and control of digitized picture data within computer controlled reproduction and picture processing systems. In order to get a color proof picture of high quality similar to a color print, together with reduced time and material consumption, a photographic color film material was exposed pixelwise by modulated laser beams of three wavelengths for red, green and blue light. Components of different manufacturers for lasers, acousto-optic modulators and polygon mirrors were tested, also different recording methods as (continuous tone mode or screened mode and with a drum or flatbed recording principle). Besides the application for the graphic arts - the proof recorder CPR 403 with continuous tone color recording with a drum scanner - such a color hardcopy peripheral unit with large picture formats and high resolution can be used in medicine, communication, and satellite picture processing.

  13. Cracking the Neural Code for Sensory Perception by Combining Statistics, Intervention, and Behavior.

    Science.gov (United States)

    Panzeri, Stefano; Harvey, Christopher D; Piasini, Eugenio; Latham, Peter E; Fellin, Tommaso

    2017-02-08

    The two basic processes underlying perceptual decisions-how neural responses encode stimuli, and how they inform behavioral choices-have mainly been studied separately. Thus, although many spatiotemporal features of neural population activity, or "neural codes," have been shown to carry sensory information, it is often unknown whether the brain uses these features for perception. To address this issue, we propose a new framework centered on redefining the neural code as the neural features that carry sensory information used by the animal to drive appropriate behavior; that is, the features that have an intersection between sensory and choice information. We show how this framework leads to a new statistical analysis of neural activity recorded during behavior that can identify such neural codes, and we discuss how to combine intersection-based analysis of neural recordings with intervention on neural activity to determine definitively whether specific neural activity features are involved in a task.

  14. Abnormality detection in retinal images using ant colony optimization and artificial neural networks - biomed 2010.

    Science.gov (United States)

    Kavitha, Ganesan; Ramakrishnan, Swaminathan

    2010-01-01

    Optic disc and retinal vasculature are important anatomical structures in the retina of the eye and any changes observed in these structures provide vital information on severity of various diseases. Digital retinal images are shown to provide a meaningful way of documenting and assessing some of the key elements inside the eye including the optic nerve and the tiny retinal blood vessels. In this work, an attempt has been made to detect and differentiate abnormalities of the retina using Digital image processing together with Optimization based segmentation and Artificial Neural Network methods. The retinal fundus images were recorded using standard protocols. Ant Colony Optimization is employed to extract the most significant objects namely the optic disc and blood vessel. The features related to these objects are obtained and corresponding indices are also derived. Further, these features are subjected to classification using Radial Basis Function Neural Networks and compared with conventional training algorithms. Results show that the Ant Colony Optimization is efficient in extracting useful information from retinal images. The features derived are effective for classification of normal and abnormal images using Radial basis function networks compared to other methods. As Optic disc and blood vessels are significant markers of abnormality in retinal images, the method proposed appears to be useful for mass screening. In this paper, the objectives of the study, methodology and significant observations are presented.

  15. Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo

    Science.gov (United States)

    Hirai, Yasuharu; Nishino, Eri

    2015-01-01

    Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices. PMID:25761950

  16. Validation and reconstruction of FY-3B/MWRI soil moisture using an artificial neural network based on reconstructed MODIS optical products over the Tibetan Plateau

    Science.gov (United States)

    Cui, Yaokui; Long, Di; Hong, Yang; Zeng, Chao; Zhou, Jie; Han, Zhongying; Liu, Ronghua; Wan, Wei

    2016-12-01

    Soil moisture is a key variable in the exchange of water and energy between the land surface and the atmosphere, especially over the Tibetan Plateau (TP) which is climatically and hydrologically sensitive as the Earth's 'third pole'. Large-scale spatially consistent and temporally continuous soil moisture datasets are of great importance to meteorological and hydrological applications, such as weather forecasting and drought monitoring. The Fengyun-3B Microwave Radiation Imager (FY-3B/MWRI) soil moisture product is a relatively new passive microwave product, with the satellite being launched on November 5, 2010. This study validates and reconstructs FY-3B/MWRI soil moisture across the TP. First, the validation is performed using in situ measurements within two in situ soil moisture measurement networks (1° × 1° and 0.25° × 0.25°), and also compared with the Essential Climate Variable (ECV) soil moisture product from multiple active and passive satellite soil moisture products using new merging procedures. Results show that the ascending FY-3B/MWRI product outperforms the descending product. The ascending FY-3B/MWRI product has almost the same correlation as the ECV product with the in situ measurements. The ascending FY-3B/MWRI product has better performance than the ECV product in the frozen season and under the lower NDVI condition. When the NDVI is higher in the unfrozen season, uncertainty in the ascending FY-3B/MWRI product increases with increasing NDVI, but it could still capture the variability in soil moisture. Second, the FY-3B/MWRI soil moisture product is subsequently reconstructed using the back-propagation neural network (BP-NN) based on reconstructed MODIS products, i.e., LST, NDVI, and albedo. The reconstruction method of generating the soil moisture product not only considers the relationship between the soil moisture and NDVI, LST, and albedo, but also the relationship between the soil moisture and four-dimensional variations using the

  17. Drift chamber tracking with neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Lindsey, C.S.; Denby, B.; Haggerty, H.

    1992-10-01

    We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed.

  18. 1993 Department of Energy Records Management Conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    This document consists of viewgraphs from the presentations at the conference. Topics included are: DOE records management overview, NIRMA and ARMA resources, NARA records management training, potential quality assurance records, filing systems, organizing and indexing technical records, DOE-HQ initiatives, IRM reviews, status of epidemiologic inventory, disposition of records and personal papers, inactive records storage, establishing administrative records, managing records at Hanford, electronic mail -- legal and records issues, NARA-GAO reports status, consultive selling, automated indexing, decentralized approach to scheduling at a DOE office, developing specific records management programs, storage and retrieval at Savannah River Plant, an optical disk case study, and special interest group reports.

  19. Holographic Optical Data Storage

    Science.gov (United States)

    Timucin, Dogan A.; Downie, John D.; Norvig, Peter (Technical Monitor)

    2000-01-01

    Although the basic idea may be traced back to the earlier X-ray diffraction studies of Sir W. L. Bragg, the holographic method as we know it was invented by D. Gabor in 1948 as a two-step lensless imaging technique to enhance the resolution of electron microscopy, for which he received the 1971 Nobel Prize in physics. The distinctive feature of holography is the recording of the object phase variations that carry the depth information, which is lost in conventional photography where only the intensity (= squared amplitude) distribution of an object is captured. Since all photosensitive media necessarily respond to the intensity incident upon them, an ingenious way had to be found to convert object phase into intensity variations, and Gabor achieved this by introducing a coherent reference wave along with the object wave during exposure. Gabor's in-line recording scheme, however, required the object in question to be largely transmissive, and could provide only marginal image quality due to unwanted terms simultaneously reconstructed along with the desired wavefront. Further handicapped by the lack of a strong coherent light source, optical holography thus seemed fated to remain just another scientific curiosity, until the field was revolutionized in the early 1960s by some major breakthroughs: the proposition and demonstration of the laser principle, the introduction of off-axis holography, and the invention of volume holography. Consequently, the remainder of that decade saw an exponential growth in research on theory, practice, and applications of holography. Today, holography not only boasts a wide variety of scientific and technical applications (e.g., holographic interferometry for strain, vibration, and flow analysis, microscopy and high-resolution imagery, imaging through distorting media, optical interconnects, holographic optical elements, optical neural networks, three-dimensional displays, data storage, etc.), but has become a prominent am advertising

  20. Neural Induction, Neural Fate Stabilization, and Neural Stem Cells

    Directory of Open Access Journals (Sweden)

    Sally A. Moody

    2002-01-01

    Full Text Available The promise of stem cell therapy is expected to greatly benefit the treatment of neurodegenerative diseases. An underlying biological reason for the progressive functional losses associated with these diseases is the extremely low natural rate of self-repair in the nervous system. Although the mature CNS harbors a limited number of self-renewing stem cells, these make a significant contribution to only a few areas of brain. Therefore, it is particularly important to understand how to manipulate embryonic stem cells and adult neural stem cells so their descendants can repopulate and functionally repair damaged brain regions. A large knowledge base has been gathered about the normal processes of neural development. The time has come for this information to be applied to the problems of obtaining sufficient, neurally committed stem cells for clinical use. In this article we review the process of neural induction, by which the embryonic ectodermal cells are directed to form the neural plate, and the process of neural�fate stabilization, by which neural plate cells expand in number and consolidate their neural fate. We will present the current knowledge of the transcription factors and signaling molecules that are known to be involved in these processes. We will discuss how these factors may be relevant to manipulating embryonic stem cells to express a neural fate and to produce large numbers of neurally committed, yet undifferentiated, stem cells for transplantation therapies.

  1. Neural Circuits on a Chip

    Directory of Open Access Journals (Sweden)

    Md. Fayad Hasan

    2016-09-01

    Full Text Available Neural circuits are responsible for the brain’s ability to process and store information. Reductionist approaches to understanding the brain include isolation of individual neurons for detailed characterization. When maintained in vitro for several days or weeks, dissociated neurons self-assemble into randomly connected networks that produce synchronized activity and are capable of learning. This review focuses on efforts to control neuronal connectivity in vitro and construct living neural circuits of increasing complexity and precision. Microfabrication-based methods have been developed to guide network self-assembly, accomplishing control over in vitro circuit size and connectivity. The ability to control neural connectivity and synchronized activity led to the implementation of logic functions using living neurons. Techniques to construct and control three-dimensional circuits have also been established. Advances in multiple electrode arrays as well as genetically encoded, optical activity sensors and transducers enabled highly specific interfaces to circuits composed of thousands of neurons. Further advances in on-chip neural circuits may lead to better understanding of the brain.

  2. Infrared neural stimulation (INS) inhibits electrically evoked neural responses in the deaf white cat

    Science.gov (United States)

    Richter, Claus-Peter; Rajguru, Suhrud M.; Robinson, Alan; Young, Hunter K.

    2014-03-01

    Infrared neural stimulation (INS) has been used in the past to evoke neural activity from hearing and partially deaf animals. All the responses were excitatory. In Aplysia californica, Duke and coworkers demonstrated that INS also inhibits neural responses [1], which similar observations were made in the vestibular system [2, 3]. In deaf white cats that have cochleae with largely reduced spiral ganglion neuron counts and a significant degeneration of the organ of Corti, no cochlear compound action potentials could be observed during INS alone. However, the combined electrical and optical stimulation demonstrated inhibitory responses during irradiation with infrared light.

  3. Robert Recorde

    CERN Document Server

    Williams, Jack

    2011-01-01

    The 16th-Century intellectual Robert Recorde is chiefly remembered for introducing the equals sign into algebra, yet the greater significance and broader scope of his work is often overlooked. This book presents an authoritative and in-depth analysis of the man, his achievements and his historical importance. This scholarly yet accessible work examines the latest evidence on all aspects of Recorde's life, throwing new light on a character deserving of greater recognition. Topics and features: presents a concise chronology of Recorde's life; examines his published works; describes Recorde's pro

  4. Optimal neural computations require analog processors

    Energy Technology Data Exchange (ETDEWEB)

    Beiu, V.

    1998-12-31

    This paper discusses some of the limitations of hardware implementations of neural networks. The authors start by presenting neural structures and their biological inspirations, while mentioning the simplifications leading to artificial neural networks. Further, the focus will be on hardware imposed constraints. They will present recent results for three different alternatives of parallel implementations of neural networks: digital circuits, threshold gate circuits, and analog circuits. The area and the delay will be related to the neurons` fan-in and to the precision of their synaptic weights. The main conclusion is that hardware-efficient solutions require analog computations, and suggests the following two alternatives: (i) cope with the limitations imposed by silicon, by speeding up the computation of the elementary silicon neurons; (2) investigate solutions which would allow the use of the third dimension (e.g. using optical interconnections).

  5. Progress in optics

    CERN Document Server

    Wolf, Emil

    2015-01-01

    The Progress in Optics series contains more than 300 review articles by distinguished research workers, which have become permanent records for many important developments, helping optical scientists and optical engineers stay abreast of their fields. Comprehensive, in-depth reviewsEdited by the leading authority in the field

  6. Optics/Optical Diagnostics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Optics/Optical Diagnostics Laboratory supports graduate instruction in optics, optical and laser diagnostics and electro-optics. The optics laboratory provides...

  7. Carbon-Nanofibers-Based Micro-/Nanodevices for Neural-Electrical and Neural-Chemical Interfaces

    Directory of Open Access Journals (Sweden)

    Hongzhi Zhang

    2012-01-01

    Full Text Available Carbon nanofibers (CNFs have shown great potentials for development of micro-/nanodevices for neural interfaces due to their suitable properties, such as chemical stability, good electrical conductivity, ultramicro size with low electrical impedance, 3D structures with high surface-to-volume ratio, and long-term biocompatibility. In this paper, we review the applications of CNFs as neural-electrical interfaces and neural-chemical interfaces for neural recording and stimulation, electroconductive nanofibrous scaffolds for nerve tissue engineering, drug and gene delivery, and neurochemical sensing. The CNFs-based micro-/nanodevices provide new platforms to fine-tune electrical and chemical cues of neurons at subcellular nanoscale, which can be used for both fundamental studies of material-cell interactions and the development of chronically stable, implantable neural interface devices. Further development of this technology may potentially enable a highly multiplex closed-loop system with multifunctions for neuromodulation and neuroprostheses.

  8. Vertically aligned carbon nanofiber as nano-neuron interface for monitoring neural function

    Energy Technology Data Exchange (ETDEWEB)

    Ericson, Milton Nance [ORNL; McKnight, Timothy E [ORNL; Melechko, Anatoli Vasilievich [ORNL; Simpson, Michael L [ORNL; Morrison, Barclay [ORNL; Yu, Zhe [Columbia University

    2012-01-01

    Neural chips, which are capable of simultaneous, multi-site neural recording and stimulation, have been used to detect and modulate neural activity for almost 30 years. As a neural interface, neural chips provide dynamic functional information for neural decoding and neural control. By improving sensitivity and spatial resolution, nano-scale electrodes may revolutionize neural detection and modulation at cellular and molecular levels as nano-neuron interfaces. We developed a carbon-nanofiber neural chip with lithographically defined arrays of vertically aligned carbon nanofiber electrodes and demonstrated its capability of both stimulating and monitoring electrophysiological signals from brain tissues in vitro and monitoring dynamic information of neuroplasticity. This novel nano-neuron interface can potentially serve as a precise, informative, biocompatible, and dual-mode neural interface for monitoring of both neuroelectrical and neurochemical activity at the single cell level and even inside the cell.

  9. Compact all-fiber optical Faraday components using 65-wt%-terbium-doped fiber with a record Verdet constant of -32 rad/(Tm).

    Science.gov (United States)

    Sun, L; Jiang, S; Marciante, J R

    2010-06-07

    A compact all-fiber Faraday isolator and a Faraday mirror are demonstrated. At the core of each of these components is an all-fiber Faraday rotator made of a 4-cm-long, 65-wt%-terbium-doped silicate fiber. The effective Verdet constant of the terbium-doped fiber is measured to be -32 rad/(Tm), which is 27 x larger than that of silica fiber. This effective Verdet constant is the largest value measured to date in any fiber and is 83% of the Verdet constant of commercially available crystal used in bulk optics-based isolators. Combining the all-fiber Faraday rotator with fiber polarizers results in a fully fusion spliced all-fiber isolator whose isolation is measured to be 19 dB. Combining the all-fiber Faraday rotator with a fiber Bragg grating results in an all-fiber Faraday mirror that rotates the polarization state of the reflected light by 88 +/- 4 degrees .

  10. A tailored biocompatible neural interface for long term monitoring in neural networks

    OpenAIRE

    Köhler, Per

    2016-01-01

    Neural interface electrodes that can record from neurons in the brain for long periods of time will be of great importance to unravel how the brain accomplishes its functions. However, current electrodes usually cause significant glia reactions and loss of neurons within the adjacent brain parenchyma. To address this challenge, a novel, polymer-based neural probe, with protrusions tailored to the target tissue, was developed to investigate which probe properties affect the development of a gl...

  11. Advances in recording scattered light changes in crustacean nerve with electrical activation

    Energy Technology Data Exchange (ETDEWEB)

    Carter, K. M. (Kathleen M.); Rector, D. M. (David M.); Martinez, A. T. (Anne T.); Guerra, F. M. (Francisco M.); George, J. S. (John S.)

    2002-01-01

    We investigated optical changes associated with crustacean nerve stimulation using birefringent and large angle scattered light. Improved detection schemes disclosed high temporal structure of the optical signals and allowed further investigations of biophysical mechanisms responsible for such changes. Most studies of physiological activity in neuronal tissue use techniques that measure the electrical behavior or ionic permeability of the nerve, such as voltage or ion sensitive dyes injected into cells, or invasive electric recording apparatus. While these techniques provide high resolution, they are detrimental to tissue and do not easily lend themselves to clinical applications in humans. Electrical and chemical components of neural excitation evoke physical responses observed through changes in scattered and absorbed light. This method is suited for in-vivo applications. Intrinsic optical changes have shown themselves to be multifaceted in nature and point to several different physiological processes that occur with different time courses during neural excitation. Fast changes occur concomitantly with electrical events, and slow changes parallel metabolic events including changes in blood flow and oxygenation. Previous experiments with isolated crustacean nerves have been used to study the biophysical mechanisms of fast optical changes. However, they have been confounded by multiple superimposed action potentials which make it difficult to discriminate the temporal signatures of individual optical responses. Often many averages were needed to adequately resolve the signal. More recently, optical signals have been observed in single trials. Initially large angle scattering measurements were used to record these events with much of the signal coming from cellular swelling associated with water influx during activation. By exploiting the birefringent properties derived from the molecular stiucture of nerve membranes, signals appear larger with a greater contrast

  12. Electrical induction and optical erasure of birefringence in the isotropic liquid phase of a dichiral azobenzene liquid-crystalline compound (Presentation Recording)

    Science.gov (United States)

    Yamamoto, Takahiro; Nishiyama, Isa

    2015-10-01

    Liquid crystal is a representative soft matter, which has physical properties between those of conventional liquid and those of crystal in a temperature range above a melting point. A liquid-crystal display (LCD) employs the response of the liquid-crystal alignment to the electric field and is a key device of an information display. For common LCDs, the precise control of the initial alignment of LC molecules is needed so that a good dark state, thus a high contrast ratio, can be obtained. If the birefringence can be induced in the liquid phase by the application of electric field, it is of great use as a material for the LCD application. In this study, we will report a unique property of dichiral azobenzene liquid crystals: an electric induction of birefringence in a liquid phase of an antiferroelectric dichiral azobenzene liquid crystal. The optically isotropic texture changes into the homogenous birefringent texture by the application of the in-plane electric field above the clearing temperature of the liquid crystal. We find that one of the possible reasons of the induction of the birefringence in the isotropic phase is the electrically-induced increase of the phase transition temperature between the antiferroelectric liquid-crystalline and "liquid" phases, i.e., increase in the clearing temperature. The resulting birefringence can be disappeared by the irradiation of UV light, due to the photoinduced isomerization of the azobenzene compound, thus dual control of the birefringent structure, by the irradiation of light and/or by the application of the electric field, is achieved.

  13. Phenological Records

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Phenology is the scientific study of periodic biological phenomena, such as flowering, breeding, and migration, in relation to climatic conditions. The few records...

  14. Morphological neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, G.X.; Sussner, P. [Univ. of Florida, Gainesville, FL (United States)

    1996-12-31

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

  15. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  16. Artificial Neural Networks

    OpenAIRE

    Chung-Ming Kuan

    2006-01-01

    Artificial neural networks (ANNs) constitute a class of flexible nonlinear models designed to mimic biological neural systems. In this entry, we introduce ANN using familiar econometric terminology and provide an overview of ANN modeling approach and its implementation methods.

  17. Interrelationship of optical coherence tomography and multifocal visual-evoked potentials after optic neuritis.

    Science.gov (United States)

    Klistorner, Alexander; Arvind, Hemamalini; Garrick, Raymond; Graham, Stuart L; Paine, Mark; Yiannikas, Con

    2010-05-01

    Acute optic neuritis (ON) is often followed by recovery of visual function. Although this recovery is mainly attributable to resolution of the acute inflammation, the redistribution of ion channels along the demyelinated membrane, and subsequent remyelination, part of it may be the result of neural plasticity. In the present study, the interrelationship was examined between structural (retinal nerve fiber layer [RNFL] thickness) and functional (amplitude of multifocal visual evoked potentials [mfVEPs]) measures of the integrity of the visual pathway in the postacute stage of ON, to determine whether there was any evidence of ongoing neural reorganization. Twenty-five subjects with acute unilateral ON underwent serial RNFL thickness measurement and mfVEP recording. The inter-eye asymmetry of both measures was analyzed. In the period between 6 and 12 months, the subjects were considered free of optic disc edema, and that period was used to analyze the structure-function relationship. Twenty control subjects were also examined. There were significant but opposite changes in RNFL thickness and mfVEP amplitude. The average asymmetry of RNFL thickness between affected and fellow eyes increased from 17.5 +/- 11.5 to 21.1 +/- 12.8 microm (P = 0.0003), indicating progressive axonal loss, whereas mfVEP amplitude asymmetry decreased from 46.6 +/- 32.4 to 38.3 +/- 31.1 nV (P = 0.0015), indicating continuous functional recovery. In comparison to the 6-month results, the mfVEP amplitude in the ON eye improved by 17.8%, whereas RNFL thickness decreased by 20.8%. The result remained unchanged regardless of the degree of optic nerve remyelination. The finding of structural-functional discrepancy at the postinflammatory stage may support the concept that neural plasticity contributes to functional recovery after acute ON.

  18. Progress in optics

    CERN Document Server

    Wolf, Emil

    2009-01-01

    In the fourty-seven years that have gone by since the first volume of Progress in Optics was published, optics has become one of the most dynamic fields of science. The volumes in this series which have appeared up to now contain more than 300 review articles by distinguished research workers, which have become permanent records for many important developments.- Backscattering and Anderson localization of light- Advances in oliton manipulation in optical lattices- Fundamental quantum noise in optical amplification- Invisibility cloaks

  19. Real-time optical information processing

    CERN Document Server

    Javidi, Bahram

    1994-01-01

    Real-Time Optical Information Processing covers the most recent developments in optical information processing, pattern recognition, neural computing, and materials for devices in optical computing. Intended for researchers and graduate students in signal and information processing with some elementary background in optics, the book provides both theoretical and practical information on the latest in information processing in all its aspects. Leading researchers in the field describe the significant signal processing algorithms architectures in optics as well as basic hardware concepts,

  20. Constructive neural network learning

    OpenAIRE

    Lin, Shaobo; Zeng, Jinshan; Zhang, Xiaoqin

    2016-01-01

    In this paper, we aim at developing scalable neural network-type learning systems. Motivated by the idea of "constructive neural networks" in approximation theory, we focus on "constructing" rather than "training" feed-forward neural networks (FNNs) for learning, and propose a novel FNNs learning system called the constructive feed-forward neural network (CFN). Theoretically, we prove that the proposed method not only overcomes the classical saturation problem for FNN approximation, but also ...

  1. READING A NEURAL CODE

    NARCIS (Netherlands)

    BIALEK, W; RIEKE, F; VANSTEVENINCK, RRD; WARLAND, D

    1991-01-01

    Traditional approaches to neural coding characterize the encoding of known stimuli in average neural responses. Organisms face nearly the opposite task - extracting information about an unknown time-dependent stimulus from short segments of a spike train. Here the neural code was characterized from

  2. Generalized classifier neural network.

    Science.gov (United States)

    Ozyildirim, Buse Melis; Avci, Mutlu

    2013-03-01

    In this work a new radial basis function based classification neural network named as generalized classifier neural network, is proposed. The proposed generalized classifier neural network has five layers, unlike other radial basis function based neural networks such as generalized regression neural network and probabilistic neural network. They are input, pattern, summation, normalization and output layers. In addition to topological difference, the proposed neural network has gradient descent based optimization of smoothing parameter approach and diverge effect term added calculation improvements. Diverge effect term is an improvement on summation layer calculation to supply additional separation ability and flexibility. Performance of generalized classifier neural network is compared with that of the probabilistic neural network, multilayer perceptron algorithm and radial basis function neural network on 9 different data sets and with that of generalized regression neural network on 3 different data sets include only two classes in MATLAB environment. Better classification performance up to %89 is observed. Improved classification performances proved the effectivity of the proposed neural network.

  3. Using neural networks for dynamic light scattering time series processing

    Science.gov (United States)

    Chicea, Dan

    2017-04-01

    A basic experiment to record dynamic light scattering (DLS) time series was assembled using basic components. The DLS time series processing using the Lorentzian function fit was considered as reference. A Neural Network was designed and trained using simulated frequency spectra for spherical particles in the range 0–350 nm, assumed to be scattering centers, and the neural network design and training procedure are described in detail. The neural network output accuracy was tested both on simulated and on experimental time series. The match with the DLS results, considered as reference, was good serving as a proof of concept for using neural networks in fast DLS time series processing.

  4. Optogenetics Based Rat-Robot Control: Optical Stimulation Encodes "Stop" and "Escape" Commands.

    Science.gov (United States)

    Chen, SiCong; Zhou, Hong; Guo, SongChao; Zhang, JiaCheng; Qu, Yi; Feng, ZhouYan; Xu, KeDi; Zheng, XiaoXiang

    2015-08-01

    Electric brain stimulation is frequently used in bio-robot control. However, one possible limitation of electric stimulation is the resultant wide range of influences that may lead to unexpected side-effects. Although there has been prior research done towards optogenetics based brain activation, there has not been much development regarding the comparisons between electric and optical methods of brain activation. In this study, we first encode "Stop" and "Escape" commands by optical stimulation in the dorsal periaqueductal grey (dPAG). The rats behavioral comparisons are then noted down under these two methods. The dPAG neural activity recorded during optical stimulation suggests rate and temporal coding mechanisms in behavioral control. The behavioral comparisons show that rats exhibit anxiety under the "Stop" command conveyed through both optical and electric methods. However, rats are able to recover more quickly from freezing only under optical "Stop" command. Under "Escape" commands, also conveyed through optical means, the rat would move with lessened urgency but the results are more stable. Moreover, c-Fos study shows the optical stimulation activates restricted range in midbrain: the optical stimulation affected only dPAG and its downstreams but electric stimulation activates both the upstream and downstream circuits, in which the glutamatergic neurons are largely occupied and play important role in "Stop" and "Escape" behavior controls. We conclude that optical stimulation is more suited for encoding "Stop" and "Escape" commands for rat-robot control.

  5. Flexible and Highly Biocompatible Nanofiber-Based Electrodes for Neural Surface Interfacing.

    Science.gov (United States)

    Heo, Dong Nyoung; Kim, Han-Jun; Lee, Yi Jae; Heo, Min; Lee, Sang Jin; Lee, Donghyun; Do, Sun Hee; Lee, Soo Hyun; Kwon, Il Keun

    2017-03-28

    Polyimide (PI)-based electrodes have been widely used as flexible biosensors in implantable device applications for recording biological signals. However, the long-term quality of neural signals obtained from PI-based nerve electrodes tends to decrease due to nerve damage by neural tissue compression, mechanical mismatch, and insufficient fluid exchange between the neural tissue and electrodes. Here, we resolve these problems with a developed PI nanofiber (NF)-based nerve electrode for stable neural signal recording, which can be fabricated via electrospinning and inkjet printing. We demonstrate an NF-based nerve electrode that can be simply fabricated and easily applied due to its high permeability, flexibility, and biocompatibility. Furthermore, the electrode can record stable neural signals for extended periods of time, resulting in decreased mechanical mismatch, neural compression, and contact area. NF-based electrodes with highly flexible and body-fluid-permeable properties could enable future neural interfacing applications.

  6. Gait Recognition Based on Convolutional Neural Networks

    Science.gov (United States)

    Sokolova, A.; Konushin, A.

    2017-05-01

    In this work we investigate the problem of people recognition by their gait. For this task, we implement deep learning approach using the optical flow as the main source of motion information and combine neural feature extraction with the additional embedding of descriptors for representation improvement. In order to find the best heuristics, we compare several deep neural network architectures, learning and classification strategies. The experiments were made on two popular datasets for gait recognition, so we investigate their advantages and disadvantages and the transferability of considered methods.

  7. Neural induction and factors that stabilize a neural fate

    OpenAIRE

    Rogers, Crystal; Moody, Sally A.; Casey, Elena

    2009-01-01

    The neural ectoderm of vertebrates forms when the BMP signaling pathway is suppressed. Herein we review the molecules that directly antagonize extracellular BMP and the signaling pathways that further contribute to reduce BMP activity in the neural ectoderm. Downstream of neural induction, a large number of “neural fate stabilizing” (NFS) transcription factors are expressed in the presumptive neural ectoderm, developing neural tube, and ultimately in neural stem cells. Herein we review what i...

  8. Consciousness and neural plasticity

    DEFF Research Database (Denmark)

    In contemporary consciousness studies the phenomenon of neural plasticity has received little attention despite the fact that neural plasticity is of still increased interest in neuroscience. We will, however, argue that neural plasticity could be of great importance to consciousness studies....... If consciousness is related to neural processes it seems, at least prima facie, that the ability of the neural structures to change should be reflected in a theory of this relationship "Neural plasticity" refers to the fact that the brain can change due to its own activity. The brain is not static but rather...... the relation between consciousness and brain functions. If consciousness is connected to specific brain structures (as a function or in identity) what happens to consciousness when those specific underlying structures change? It is therefore possible that the understanding and theories of neural plasticity can...

  9. An Overview of Bayesian Methods for Neural Spike Train Analysis

    Directory of Open Access Journals (Sweden)

    Zhe Chen

    2013-01-01

    Full Text Available Neural spike train analysis is an important task in computational neuroscience which aims to understand neural mechanisms and gain insights into neural circuits. With the advancement of multielectrode recording and imaging technologies, it has become increasingly demanding to develop statistical tools for analyzing large neuronal ensemble spike activity. Here we present a tutorial overview of Bayesian methods and their representative applications in neural spike train analysis, at both single neuron and population levels. On the theoretical side, we focus on various approximate Bayesian inference techniques as applied to latent state and parameter estimation. On the application side, the topics include spike sorting, tuning curve estimation, neural encoding and decoding, deconvolution of spike trains from calcium imaging signals, and inference of neuronal functional connectivity and synchrony. Some research challenges and opportunities for neural spike train analysis are discussed.

  10. Optical profilometer

    Science.gov (United States)

    Wieloszyńska, Aleksandra; StrÄ kowski, Marcin

    2016-09-01

    The profilometry plays a huge role in the most fields of science and technology. It allows to measure the profile of the surface with high-resolution. This technique is used in the fields like optic, electronic, medicine, automotive, and much more. The aim of the current work was to design and build optical profilometer based on the interference phenomena. The developed device has been working with He-Ne laser (632.8 nm). The optical parts have been chosen in order to reach the sized 2.0 mm x 1.6 mm of scanning area. The setup of the profilometer is based on Twyman-Green interferometer. Therefore, the phase distribution of the backreflected light from measured surface is recorded. The measurements are carried out with the aid of multiframe algorithms. In this approach we have used the Hariharan algorithm to obtain the exact value of the recorded phase. During tests, which have been carried out in order to check the functionality of the device, the interference patterns have been recoded and processed in order to obtain the 3D profile of measured surface. In this contribution the setup of the optical system, as well as signal processing methods are going to be presented. The brief discussion about the advantages and disadvantages, and usefulness of this approach will be carried out.

  11. Student Records

    Science.gov (United States)

    Fields, Cheryl

    2005-01-01

    Another topic involving privacy has attracted considerable attention in recent months--the "student unit record" issue. The U.S. Department of Education concluded in March that it would be feasible to help address lawmakers' concerns about accountability in higher education by constructing a database capable of tracking students from institution…

  12. Record dynamics

    DEFF Research Database (Denmark)

    Robe, Dominic M.; Boettcher, Stefan; Sibani, Paolo

    2016-01-01

    -facto irreversible and become increasingly harder to achieve. Thus, a progression of record-sized dynamical barriers are traversed in the approach to equilibration. Accordingly, the statistics of the events is closely described by a log-Poisson process. Originally developed for relaxation in spin glasses...

  13. Chaotic diagonal recurrent neural network

    Institute of Scientific and Technical Information of China (English)

    Wang Xing-Yuan; Zhang Yi

    2012-01-01

    We propose a novel neural network based on a diagonal recurrent neural network and chaos,and its structure andlearning algorithm are designed.The multilayer feedforward neural network,diagonal recurrent neural network,and chaotic diagonal recurrent neural network are used to approach the cubic symmetry map.The simulation results show that the approximation capability of the chaotic diagonal recurrent neural network is better than the other two neural networks.

  14. Neural Variability Quenching Predicts Individual Perceptual Abilities.

    Science.gov (United States)

    Arazi, Ayelet; Censor, Nitzan; Dinstein, Ilan

    2017-01-04

    Neural activity during repeated presentations of a sensory stimulus exhibits considerable trial-by-trial variability. Previous studies have reported that trial-by-trial neural variability is reduced (quenched) by the presentation of a stimulus. However, the functional significance and behavioral relevance of variability quenching and the potential physiological mechanisms that may drive it have been studied only rarely. Here, we recorded neural activity with EEG as subjects performed a two-interval forced-choice contrast discrimination task. Trial-by-trial neural variability was quenched by ∼40% after the presentation of the stimulus relative to the variability apparent before stimulus presentation, yet there were large differences in the magnitude of variability quenching across subjects. Individual magnitudes of quenching predicted individual discrimination capabilities such that subjects who exhibited larger quenching had smaller contrast discrimination thresholds and steeper psychometric function slopes. Furthermore, the magnitude of variability quenching was strongly correlated with a reduction in broadband EEG power after stimulus presentation. Our results suggest that neural variability quenching is achieved by reducing the amplitude of broadband neural oscillations after sensory input, which yields relatively more reproducible cortical activity across trials and enables superior perceptual abilities in individuals who quench more.

  15. Auditory responses to electric and infrared neural stimulation of the rat cochlear nucleus.

    Science.gov (United States)

    Verma, Rohit U; Guex, Amélie A; Hancock, Kenneth E; Durakovic, Nedim; McKay, Colette M; Slama, Michaël C C; Brown, M Christian; Lee, Daniel J

    2014-04-01

    In an effort to improve the auditory brainstem implant, a prosthesis in which user outcomes are modest, we applied electric and infrared neural stimulation (INS) to the cochlear nucleus in a rat animal model. Electric stimulation evoked regions of neural activation in the inferior colliculus and short-latency, multipeaked auditory brainstem responses (ABRs). Pulsed INS, delivered to the surface of the cochlear nucleus via an optical fiber, evoked broad neural activation in the inferior colliculus. Strongest responses were recorded when the fiber was placed at lateral positions on the cochlear nucleus, close to the temporal bone. INS-evoked ABRs were multipeaked but longer in latency than those for electric stimulation; they resembled the responses to acoustic stimulation. After deafening, responses to electric stimulation persisted, whereas those to INS disappeared, consistent with a reported "optophonic" effect, a laser-induced acoustic artifact. Thus, for deaf individuals who use the auditory brainstem implant, INS alone did not appear promising as a new approach. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Evolvable Neural Software System

    Science.gov (United States)

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  17. ATLAS Recordings

    CERN Multimedia

    Steven Goldfarb; Mitch McLachlan; Homer A. Neal

    Web Archives of ATLAS Plenary Sessions, Workshops, Meetings, and Tutorials from 2005 until this past month are available via the University of Michigan portal here. Most recent additions include the Trigger-Aware Analysis Tutorial by Monika Wielers on March 23 and the ROOT Workshop held at CERN on March 26-27.Viewing requires a standard web browser with RealPlayer plug-in (included in most browsers automatically) and works on any major platform. Lectures can be viewed directly over the web or downloaded locally.In addition, you will find access to a variety of general tutorials and events via the portal.Feedback WelcomeOur group is making arrangements now to record plenary sessions, tutorials, and other important ATLAS events for 2007. Your suggestions for potential recording, as well as your feedback on existing archives is always welcome. Please contact us at wlap@umich.edu. Thank you.Enjoy the Lectures!

  18. Neural circuits as computational dynamical systems.

    Science.gov (United States)

    Sussillo, David

    2014-04-01

    Many recent studies of neurons recorded from cortex reveal complex temporal dynamics. How such dynamics embody the computations that ultimately lead to behavior remains a mystery. Approaching this issue requires developing plausible hypotheses couched in terms of neural dynamics. A tool ideally suited to aid in this question is the recurrent neural network (RNN). RNNs straddle the fields of nonlinear dynamical systems and machine learning and have recently seen great advances in both theory and application. I summarize recent theoretical and technological advances and highlight an example of how RNNs helped to explain perplexing high-dimensional neurophysiological data in the prefrontal cortex.

  19. Optic glioma

    Science.gov (United States)

    Glioma - optic; Optic nerve glioma; Juvenile pilocytic astrocytoma; Brain cancer - optic glioma ... Optic gliomas are rare. The cause of optic gliomas is unknown. Most optic gliomas are slow-growing ...

  20. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  1. Neural Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — As part of the Electrical and Computer Engineering Department and The Institute for System Research, the Neural Systems Laboratory studies the functionality of the...

  2. Building Structured Personal Health Records from Photographs of Printed Medical Records

    OpenAIRE

    Li, Xiang; Hu, Gang; Teng, Xiaofei; Xie, Guotong

    2015-01-01

    Personal health records (PHRs) provide patient-centric healthcare by making health records accessible to patients. In China, it is very difficult for individuals to access electronic health records. Instead, individuals can easily obtain the printed copies of their own medical records, such as prescriptions and lab test reports, from hospitals. In this paper, we propose a practical approach to extract structured data from printed medical records photographed by mobile phones. An optical chara...

  3. Optical spectra analysis for breast cancer diagnostics

    Science.gov (United States)

    Belkov, S. A.; Kochemasov, G. G.; Lyubynskaya, T. E.; Maslov, N. V.; Nuzhny, A. S.; da Silva, L. B.; Rubenchik, A.

    2011-11-01

    Minimally invasive probe and optical biopsy system based on optical spectra recording and analysis seem to be a promising tool for early diagnostics of breast cancer. Light scattering and absorption spectra are generated continuously as far as the needle-like probe with one emitting and several collecting optical fibers penetrates through the tissues toward to the suspicious area. That allows analyzing not only the state of local site, but also the structure of tissues along the needle trace. The suggested method has the advantages of automated on-line diagnosing and minimal tissue destruction and in parallel with the conventional diagnostic procedures provides the ground for decision-making. 165 medical trials were completed in Nizhny Novgorod Regional Oncology Centre, Russia. Independent diagnoses were the results of fine biopsy and histology. Application of wavelet expansion and clasterization techniques for spectra analysis revealed several main spectral types for malignant and benign tumors. Automatic classification algorithm demonstrated specificity ˜90% and sensitivity ˜91%. Large amount of information, fuzziness in criteria and data noisiness make neural networks to be an attractive analytic tool. The model based on three-layer perceptron was tested over the sample of 29 `cancer' and 29 `non-cancer' cases and demonstrated total separation.

  4. Development of an Optical Disc Recorder

    Science.gov (United States)

    1977-02-01

    the disc. The phase locked ioop (PLL) must be capable of remaining locked even when the data rate read f rom the disk differs from its nomina l value...n about ±8 to 10 kHz of the nomina l v a l u e . Othe rwi se - , t he loop b a n d w i d t h becom es excess ive ly large j u s t to acc omm

  5. Horizontal Bilayer for Electrical and Optical Recordings

    Directory of Open Access Journals (Sweden)

    Alf Honigmann

    2012-12-01

    Full Text Available Artificial bilayer containing reconstituted ion channels, transporters and pumps serve as a well-defined model system for electrophysiological investigations of membrane protein structure–function relationship. Appropriately constructed microchips containing horizontally oriented bilayers with easy solution access to both sides provide, in addition, the possibility to investigate these model bilayer membranes and the membrane proteins therein with high resolution fluorescence techniques up to the single-molecule level. Here, we describe a bilayer microchip system in which long-term stable horizontal free-standing and hydrogel-supported bilayers can be formed and demonstrate its prospects particularly for single-molecule fluorescence spectroscopy and high resolution fluorescence microscopy in probing the physicochemical properties like phase behavior of the bilayer-forming lipids, as well as in functional studies of membrane proteins.

  6. Neural Network-Based Hyperspectral Algorithms

    Science.gov (United States)

    2016-06-07

    Neural Network-Based Hyperspectral Algorithms Walter F. Smith, Jr. and Juanita Sandidge Naval Research Laboratory Code 7340, Bldg 1105 Stennis Space...our effort is development of robust numerical inversion algorithms , which will retrieve inherent optical properties of the water column as well as...validate the resulting inversion algorithms with in-situ data and provide estimates of the error bounds associated with the inversion algorithm . APPROACH

  7. Artificial Neural Networks in Stellar Astronomy

    Directory of Open Access Journals (Sweden)

    R. K. Gulati

    2001-01-01

    Full Text Available Next generation of optical spectroscopic surveys, such as the Sloan Digital Sky Survey and the 2 degree field survey, will provide large stellar databases. New tools will be required to extract useful information from these. We show the applications of artificial neural networks to stellar databases. In another application of this method, we predict spectral and luminosity classes from the catalog of spectral indices. We assess the importance of such methods for stellar populations studies.

  8. Folate receptors and neural tube closure.

    Science.gov (United States)

    Saitsu, Hirotomo

    2017-02-28

    Neural tube defects (NTD) are among the most common human congenital malformations, affecting 0.5-8/1000 of live births. Human clinical trials have shown that periconceptional folate supplementation significantly decreases the occurrence of NTD in offspring. However, the mechanism by which folate acts on NTD remains largely unknown. Folate receptor (Folr) is one of the three membrane proteins that mediate cellular uptake of folates. Recent studies suggest that mouse Folr1 (formerly referred to as Fbp1) is essential for neural tube closure. Therefore, we examined spatial and temporal expression patterns of Folr1 in developing mouse embryos, showing a close association between Folr1 and anterior neural tube closure. Transient transgenic analysis was performed using lacZ as a reporter; we identified a 1.1-kb enhancer that directs lacZ expression in the neural tube and optic vesicle in a manner that is similar to endogenous Folr1. The 1.1-kb enhancer sequences were highly conserved between humans and mice, suggesting that human FOLR1 is associated with anterior neural tube closure in humans. Several experimental studies in mice and human epidemiological and genetics studies have suggested that folate receptor abnormalities are involved in a portion of human NTDs, although the solo defect of FOLR1 did not cause NTD.

  9. Optogenetic stimulation of multiwell MEA plates for neural and cardiac applications

    Science.gov (United States)

    Clements, Isaac P.; Millard, Daniel C.; Nicolini, Anthony M.; Preyer, Amanda J.; Grier, Robert; Heckerling, Andrew; Blum, Richard A.; Tyler, Phillip; McSweeney, K. M.; Lu, Yi-Fan; Hall, Diana; Ross, James D.

    2016-03-01

    Microelectrode array (MEA) technology enables advanced drug screening and "disease-in-a-dish" modeling by measuring the electrical activity of cultured networks of neural or cardiac cells. Recent developments in human stem cell technologies, advancements in genetic models, and regulatory initiatives for drug screening have increased the demand for MEA-based assays. In response, Axion Biosystems previously developed a multiwell MEA platform, providing up to 96 MEA culture wells arrayed into a standard microplate format. Multiwell MEA-based assays would be further enhanced by optogenetic stimulation, which enables selective excitation and inhibition of targeted cell types. This capability for selective control over cell culture states would allow finer pacing and probing of cell networks for more reliable and complete characterization of complex network dynamics. Here we describe a system for independent optogenetic stimulation of each well of a 48-well MEA plate. The system enables finely graded control of light delivery during simultaneous recording of network activity in each well. Using human induced pluripotent stem cell (hiPSC) derived cardiomyocytes and rodent primary neuronal cultures, we demonstrate high channel-count light-based excitation and suppression in several proof-of-concept experimental models. Our findings demonstrate advantages of combining multiwell optical stimulation and MEA recording for applications including cardiac safety screening, neural toxicity assessment, and advanced characterization of complex neuronal diseases.

  10. Record club

    CERN Multimedia

    Record club

    2010-01-01

      Bonjour a tous, Voici les 24 nouveaux DVD de Juillet disponibles depuis quelques jours, sans oublier les 5 CD Pop musique. Découvrez la saga du terroriste Carlos, la vie de Gainsbourg et les aventures de Lucky Luke; angoissez avec Paranormal Activity et évadez vous sur Pandora dans la peau d’Avatar. Toutes les nouveautés sont à découvrir directement au club. Pour en connaître la liste complète ainsi que le reste de la collection du Record Club, nous vous invitons sur notre site web: http://cern.ch/crc. Toutes les dernières nouveautés sont dans la rubrique « Discs of the Month ». Rappel : le club est ouvert les Lundis, Mercredis, Vendredis de 12h30 à 13h00 au restaurant n°2, bâtiment 504. A bientôt chers Record Clubbers.  

  11. Record Club

    CERN Multimedia

    Record Club

    2011-01-01

    http://cern.ch/Record.Club November  Selections Just in time for the holiday season, we have added a number of new CDs and DVDs into the Club. You will find the full lists at http://cern.ch/record.club; select the "Discs of the Month" button on the left side on the left panel of the web page and then Nov 2011. New films include the all 5 episodes of Fast and Furious, many of the most famous films starring Jean-Paul Belmondo and those of Louis de Funes and some more recent films such as The Lincoln Lawyer and, according to some critics, Woody Allen’s best film for years – Midnight in Paris. For the younger generation there is Cars 2 and Kung Fu Panda 2. New CDs include the latest releases by Adele, Coldplay and the Red Hot Chili Peppers. We have also added the new Duets II CD featuring Tony Bennett singing with some of today’s pop stars including Lady Gaga, Amy Winehouse and Willy Nelson. The Club is now open every Monday, Wednesday and Friday ...

  12. ATLAS Recordings

    CERN Multimedia

    Jeremy Herr; Homer A. Neal; Mitch McLachlan

    The University of Michigan Web Archives for the 2006 ATLAS Week Plenary Sessions, as well as the first of 2007, are now online. In addition, there are a wide variety of Software and Physics Tutorial sessions, recorded over the past couple years, to chose from. All ATLAS-specific archives are accessible here.Viewing requires a standard web browser with RealPlayer plug-in (included in most browsers automatically) and works on any major platform. Lectures can be viewed directly over the web or downloaded locally.In addition, you will find access to a variety of general tutorials and events via the portal. Shaping Collaboration 2006The Michigan group is happy to announce a complete set of recordings from the Shaping Collaboration conference held last December at the CICG in Geneva.The event hosted a mix of Collaborative Tool experts and LHC Users, and featured presentations by the CERN Deputy Director General, Prof. Jos Engelen, the President of Internet2, and chief developers from VRVS/EVO, WLAP, and other tools...

  13. Record Club

    CERN Multimedia

    Record Club

    2011-01-01

    http://cern.ch/Record.Club Nouveautés été 2011 Le club de location de CDs et de DVDs vient d’ajouter un grand nombre de disques pour l’été 2011. Parmi eux, Le Discours d’un Roi, oscar 2011 du meilleur film et Harry Potter les reliques de la mort (1re partie). Ce n’est pas moins de 48 DVDs et 10 CDs nouveaux qui vous sont proposés à la location. Il y en a pour tous les genres. Alors n’hésitez pas à consulter notre site http://cern.ch/record.club, voir Disc Catalogue, Discs of the month pour avoir la liste complète. Le club est ouvert tous les Lundi, Mercredi, Vendredi de 12h30 à 13h dans le bâtiment du restaurent N°2 (Cf. URL: http://www.cern.ch/map/building?bno=504) A très bientôt.  

  14. Record Club

    CERN Multimedia

    Record Club

    2011-01-01

    http://cern.ch/Record.Club June Selections We have put a significant number of new CDs and DVDs into the Club You will find the full lists at http://cern.ch/record.club and select the «Discs of the Month» button on the left side on the left panel of the web page and then June 2011. New films include the latest Action, Suspense and Science Fiction film hits, general drama movies including the Oscar-winning The King’s Speech, comedies including both chapter of Bridget Jones’s Diary, seven films for children and a musical. Other highlights include the latest Harry Potter release and some movies from the past you may have missed including the first in the Terminator series. New CDs include the latest releases by Michel Sardou, Mylene Farmer, Jennifer Lopez, Zucchero and Britney Spears. There is also a hits collection from NRJ. Don’t forget that the Club is now open every Monday, Wednesday and Friday lunchtimes from 12h30 to 13h00 in Restaurant 2, Building 504. (C...

  15. Progress in optics

    CERN Document Server

    Wolf, Emil

    2008-01-01

    In the fourty-six years that have gone by since the first volume of Progress in Optics was published, optics has become one of the most dynamic fields of science. The volumes in this series which have appeared up to now contain more than 300 review articles by distinguished research workers, which have become permanent records for many important developments.- Metamaterials- Polarization Techniques- Linear Baisotropic Mediums- Ultrafast Optical Pulses- Quantum Imaging- Point-Spread Funcions- Discrete Wigner Functions

  16. Optoelectronic implementation of multilayer perceptron and Hopfield neural networks

    Science.gov (United States)

    Domanski, Andrzej W.; Olszewski, Mikolaj K.; Wolinski, Tomasz R.

    2004-11-01

    In this paper we present an optoelectronic implementation of two networks based on multilayer perceptron and the Hopfield neural network. We propose two different methods to solve a problem of lack of negative optical signals that are necessary for connections between layers of perceptron as well as within the Hopfield network structure. The first method applied for construction of multilayer perceptron was based on division of signals into two channels and next to use both of them independently as positive and negative signals. The second one, applied for implementation of the Hopfield model, was based on adding of constant value for elements of matrix weight. Both methods of compensation of lack negative optical signals were tested experimentally as optoelectronic models of multilayer perceptron and Hopfield neural network. Special configurations of optical fiber cables and liquid crystal multicell plates were used. In conclusion, possible applications of the optoelectronic neural networks are briefly discussed.

  17. Neural Networks: Implementations and Applications

    NARCIS (Netherlands)

    Vonk, E.; Veelenturf, L.P.J.; Jain, L.C.

    1996-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  18. Neural Networks: Implementations and Applications

    NARCIS (Netherlands)

    Vonk, E.; Veelenturf, L.P.J.; Jain, L.C.

    1996-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  19. What Are Neural Tube Defects?

    Science.gov (United States)

    ... NICHD Research Information Clinical Trials Resources and Publications Neural Tube Defects (NTDs): Condition Information Skip sharing on social media links Share this: Page Content What are neural tube defects? Neural (pronounced NOOR-uhl ) tube defects are ...

  20. RECORD CLUB

    CERN Multimedia

    Record Club

    2010-01-01

    DVD James Bond – Series Complete To all Record Club Members, to start the new year, we have taken advantage of a special offer to add copies of all the James Bond movies to date, from the very first - Dr. No - to the latest - Quantum of Solace. No matter which of the successive 007s you prefer (Sean Connery, George Lazenby, Roger Moore, Timothy Dalton, Pierce Brosnan or Daniel Craig), they are all there. Or perhaps you have a favourite Bond Girl, or even perhaps a favourite villain. Take your pick. You can find the full selection listed on the club web site http://cern.ch/crc; use the panel on the left of the page “Discs of the Month” and select Jan 2010. We remind you that we are open on Mondays, Wednesdays and Fridays from 12:30 to 13:00 in Restaurant 2 (Bldg 504).

  1. Record breakers

    CERN Document Server

    Antonella Del Rosso

    2012-01-01

    In the sixties, CERN’s Fellows were but a handful of about 50 young experimentalists present on site to complete their training. Today, their number has increased to a record-breaking 500. They come from many different fields and are spread across CERN’s different activity areas.   “Diversifying the Fellowship programme has been the key theme in recent years,” comments James Purvis, Head of the Recruitment, Programmes and Monitoring group in the HR Department. “In particular, the 2005 five-yearly review introduced the notion of ‘senior’ and ‘junior’ Fellowships, broadening the target audience to include those with Bachelor-level qualifications.” Diversification made CERN’s Fellowship programme attractive to a wider audience but the number of Fellows on site could not have increased so much without the support of EU-funded projects, which were instrumental in the growth of the programme. ...

  2. Kunstige neurale net

    DEFF Research Database (Denmark)

    Hørning, Annette

    1994-01-01

    Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse.......Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse....

  3. Critical Branching Neural Networks

    Science.gov (United States)

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  4. Consciousness and neural plasticity

    DEFF Research Database (Denmark)

    changes or to abandon the strong identity thesis altogether. Were one to pursue a theory according to which consciousness is not an epiphenomenon to brain processes, consciousness may in fact affect its own neural basis. The neural correlate of consciousness is often seen as a stable structure, that is...

  5. Critical Branching Neural Networks

    Science.gov (United States)

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  6. Optical developments for optogenetics.

    Science.gov (United States)

    Papagiakoumou, Eirini

    2013-10-01

    Brain intricacies and the difficulty that scientists encounter in revealing its function with standard approaches such as electrical stimulation of neurons have led to the exploration of new tools that enable the study of neural circuits in a remote and non-invasive way. To this end, optogenetics has initialised a revolution for neuroscience in the last decade by enabling simultaneous monitoring and stimulation of specific neuronal populations in intact brain preparations through genetically targeted expression of light sensitive proteins and molecular photoswitches. In addition to ongoing molecular probe development and optimisation, novel optical techniques hold immense potential to amplify and diversify the utility of optogenetic methods. Importantly, by improving the spatio-temporal resolution of light stimulation, neural circuits can be photoactivated in patterns mimicking endogenous physiological processes. The following synopsis addresses the possibilities and limitations of optical stimulation methods applied to and developed for activation of neuronal optogenetic tools.

  7. Is neural Darwinism Darwinism?

    Science.gov (United States)

    van Belle, T

    1997-01-01

    Neural Darwinism is a theory of cognition developed by Gerald Edelman along with George Reeke and Olaf Sporns at Rockefeller University. As its name suggests, neural Darwinism is modeled after biological Darwinism, and its authors assert that the two processes are strongly analogous. both operate on variation in a population, amplifying the more adaptive individuals. However, from a computational perspective, neural Darwinism is quite different from other models of natural selection, such as genetic algorithms. The individuals of neural Darwinism do not replicate, thus robbing the process of the capacity to explore new solutions over time and ultimately reducing it to a random search. Because neural Darwinism does not have the computational power of a truly Darwinian process, it is misleading to label it as such. to illustrate this disparity in adaptive power, one of Edelman's early computer experiments, Darwin I, is revisited, and it is shown that adding replication greatly improves the adaptive power of the system.

  8. An adaptive holographic implementation of a neural network

    Science.gov (United States)

    Downie, John D.; Hine, Butler P., III; Reid, Max B.

    1990-01-01

    A holographic implementation for neural networks is proposed and demonstrated as an alternative to the optical matrix-vector multiplier architecture. In comparison, the holographic architecture makes more efficient use of the system space-bandwidth product for certain types of neural networks. The principal network component is a thermoplastic hologram, used to provide both interconnection weights and beam direction. Given the updatable nature of this type of hologram, adaptivity or network learning is possible in the optical system. Two networks with fixed weights are experimentally implemented and verified, and for one of these examples the advantage of the holographic implementation with respect to the matrix-vector processor is demonstrated.

  9. Photosensitive-polyimide based method for fabricating various neural electrode architectures

    Directory of Open Access Journals (Sweden)

    Yasuhiro X Kato

    2012-06-01

    Full Text Available An extensive photosensitive polyimide (PSPI-based method for designing and fabricating various neural electrode architectures was developed. The method aims to broaden the design flexibility and expand the fabrication capability for neural electrodes to improve the quality of recorded signals and integrate other functions. After characterizing PSPI’s properties for micromachining processes, we successfully designed and fabricated various neural electrodes even on a non-flat substrate using only one PSPI as an insulation material and without the time-consuming dry etching processes. The fabricated neural electrodes were an electrocorticogram electrode, a mesh intracortical electrode with a unique lattice-like mesh structure to fixate neural tissue, and a guide cannula electrode with recording microelectrodes placed on the curved surface of a guide cannula as a microdialysis probe. In vivo neural recordings using anesthetized rats demonstrated that these electrodes can be used to record neural activities repeatedly without any breakage and mechanical failures, which potentially promises stable recordings for long periods of time. These successes make us believe that this PSPI-based fabrication is a powerful method, permitting flexible design and easy optimization of electrode architectures for a variety of electrophysiological experimental research with improved neural recording performance.

  10. Optical pattern recognition; Proceedings of the Meeting, Los Angeles, CA, Jan. 17, 18, 1989

    Science.gov (United States)

    Liu, Hua-Kuang (Editor)

    1989-01-01

    Papers on optical pattern recognition are presented, covering topics such as the estimation of satellite pose and motion parameters using a neural net tracker, associative memory, optical implmentation of programmable neural networks, optoelectronic neural networks, dynamic autoassociative neural memory, heteroassociative memory, bilinear pattern recognition processors, optical processing of optical correlation plane data, and a synthetic discriminant function-based nonlinear optical correlator. Other topics include an interactive optical-digital image processor, geometric transformations for video compression and human teleoperator display, quasiconformal remapping for compensation of human visual field defects, hybrid vision for automated spacecraft landing, advanced symbolic and inference optical correlation filters, and a rotationally invariant holographic tracking system. Additional topics include the detection of rotational and scale-varying objects with a programmable joint transform correlator, a single spatial light modulator binary nonlinear optical correlator, optical joint transform correlation, linear phase coefficient composite filters, and binary phase-only filters.

  11. What you see is not what you catch: a comparison of concurrently collected net, Optical Plankton Counter, and Shadowed Image Particle Profiling Evaluation Recorder data from the northeast Gulf of Mexico

    Science.gov (United States)

    Remsen, Andrew; Hopkins, Thomas L.; Samson, Scott

    2004-01-01

    Zooplankton and suspended particles were sampled in the upper 100 m of the Gulf of Mexico with the High Resolution Sampler. This towed-platform can concurrently sample zooplankton with plankton nets, an Optical Plankton Counter (OPC) and the Shadowed Image Particle Profiling and Evaluation Recorder (SIPPER), a zooplankton imaging system. This allowed for direct comparison of mesozooplankton abundance, biomass, taxonomic composition and size distributions between simultaneously collected net samples, OPC data, and digital imagery. While the net data were numerically and taxonomically similar to that of previous studies in the region, analysis of the SIPPER imagery revealed that nets significantly underestimated larvacean, doliolid, protoctist and cnidarian/ctenophore abundance by 300%, 379%, 522% and 1200%, respectively. The inefficiency of the nets in sampling the fragile and gelatinous zooplankton groups led to a dry-weight biomass estimate less than half that of the SIPPER total and suggests that this component of the zooplankton assemblage is more important than previously determined for this region. Additionally, using the SIPPER data we determined that more than 29% of all mesozooplankton-sized particles occurred within 4 mm of another particle and therefore would not be separately counted by the OPC. This suggests that coincident counting is a major problem for the OPC even at the low zooplankton abundances encountered in low latitude oligotrophic systems like the Gulf. Furthermore, we found that the colonial cyanobacterium Trichodesmium was the most abundant recognizable organism in the SIPPER dataset, while it was difficult to quantify with the nets. For these reasons, the traditional method of using net samples to ground truth OPC data would not be adequate in describing the particle assemblage described here. Consequently we suggest that in situ imaging sensors be included in any comprehensive study of mesozooplankton.

  12. Optic pathway glioma associated with orbital rhabdomyosarcoma and bilateral optic nerve sheath dural ectasia in a child with neurofibromatosis-1

    Energy Technology Data Exchange (ETDEWEB)

    Nikas, Ioannis; Theofanopoulou, Maria; Lampropoulou, Penelope; Hadjigeorgi, Christiana [Aghia Sophia Children' s Hospital, Imaging Department, Athens (Greece); Pourtsidis, Apostolos; Kosmidis, Helen [Children' s Hospital, A. Kyriakou, Department of Oncology, Athens (Greece)

    2006-11-15

    Neurofibromatosis-1 (NF-1) is a multisystem disorder presenting with a variety of clinical and imaging manifestations. Neural and non-neural tumours, and unusual benign miscellaneous conditions, separately or combined, are encountered in variable locations. We present a 21/2-year-old boy with NF-1 who demonstrated coexisting optic pathway glioma with involvement of the chiasm and optic nerve, orbital alveolar rhabdomyosarcoma and bilateral optic nerve sheath dural ectasia. (orig.)

  13. Hardware implementation of a neural vision system based on a neural network using integrated and fire neurons

    Science.gov (United States)

    González, M.; Lamela, H.; Jiménez, M.; Gimeno, J.; Ruiz-Llata, M.

    2007-04-01

    In this paper we present the scheme for a control circuit used in an image processing system which is to be implemented in a neural network which has a high level of connectivity and reconfiguration of neurons for integration and trigger based on the Address-Event Representation. This scheme will be employed as a pre-processing stage for a vision system which employs as its core processing an Optical Broadcast Neural Network (OBNN). [Optical Engineering letters 42 (9), 2488(2003)]. The proposed vision system allows the possibility to introduce patterns from any acquisition system of images, for posterior processing.

  14. Record Club

    CERN Multimedia

    Record Club

    2012-01-01

      March  Selections By the time this appears, we will have added a number of new CDs and DVDs into the Club. You will find the full lists at http://cern.ch/record.club; select the "Discs of the Month" button on the left panel of the web page and then Mar 2012. New films include recent releases such as Johnny English 2, Bad Teacher, Cowboys vs Aliens, and Super 8. We are also starting to acquire some of the classic films we missed when we initiated the DVD section of the club, such as appeared in a recent Best 100 Films published by a leading UK magazine; this month we have added Spielberg’s Jaws and Scorsese’s Goodfellas. If you have your own ideas on what we are missing, let us know. For children we have no less than 8 Tin-Tin DVDs. And if you like fast moving pop music, try the Beyonce concert DVD. New CDs include the latest releases from Paul McCartney, Rihanna and Amy Winehouse. There is a best of Mylene Farmer, a compilation from the NRJ 201...

  15. Optical highlighter molecules in neurobiology.

    Science.gov (United States)

    Datta, Sandeep Robert; Patterson, George H

    2012-02-01

    The development of advanced optical methods has played a key role in propelling progress in neurobiology. Genetically-encoded fluorescent molecules found in nature have enabled labeling of individual neurons to study their physiology and anatomy. Here we discuss the recent use of both native and synthetic optical highlighter proteins to address key problems in neurobiology, including questions relevant to synaptic function, neuroanatomy, and the organization of neural circuits.

  16. Dynamics of neural cryptography.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  17. Wavelet transform of neural spike trains

    Science.gov (United States)

    Kim, Youngtae; Jung, Min Whan; Kim, Yunbok

    2000-02-01

    Wavelet transform of neural spike trains recorded with a tetrode in the rat primary somatosensory cortex is described. Continuous wavelet transform (CWT) of the spike train clearly shows singularities hidden in the noisy or chaotic spike trains. A multiresolution analysis of the spike train is also carried out using discrete wavelet transform (DWT) for denoising and approximating at different time scales. Results suggest that this multiscale shape analysis can be a useful tool for classifying the spike trains.

  18. The prevention of neural tube defects by folic acid supplementation

    Directory of Open Access Journals (Sweden)

    H. W. Hitzeroth

    1993-05-01

    Full Text Available Neural tube defects, in particular spina bifida and anencephaly, are serious and relatively common congenital abnormalities worldwide. They also occur in South Africa and affect all population groups to varying degrees. The overall incidence in South Africa is approximately 1-2 per 1000 newborns. Higher incidences, up to 6 per 1000 newborns have been recorded in certain parts, especially in some rural areas of the country. In total as many as 1500 newborns could be affected by a neural tube defect each year. The precise aetiology of neural tube defects is still unknown.

  19. 基于神经网络的调频连续波光纤传感器扫描非线性复原技术%Nonlinear Recovering Technique Based on Neural Network for Frequency Modulated Continuous Wave Optical Fiber Sensors

    Institute of Scientific and Technical Information of China (English)

    李阳; 冯正和; 龚建敏; 肖艳红; 廖延彪

    2001-01-01

    Frequency-scanning non-linearity influences range-detectionaccuracy of optical fiber sensors. In this paper, the influence is analyzed and a recovering technique is proposed. Non-linearity is recovered through the learning process of backpropagation neural network. Simulation results show that very accurate estimation is achieved even under severe non-linearity of the scanning source. The on-line learning of neural network is also investigated to make this method more practical.%分析了调频连续波光纤传感器中扫描非线性对距离测量的影响,并提出了一种复原技术。这种技术通过反向传播神经网络的学习来克服扫描非线性,可以在扫描源具有较强的非线性时获得对目标的精确估计。同时也研究了反向传播网络在线学习的问题,使这种方法可以适应环境的变化。

  20. ANT Advanced Neural Tool

    Energy Technology Data Exchange (ETDEWEB)

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-07-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs.

  1. AUV fuzzy neural BDI

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The typical BDI (belief desire intention) model of agent is not efficiently computable and the strict logic expression is not easily applicable to the AUV (autonomous underwater vehicle) domain with uncertainties. In this paper, an AUV fuzzy neural BDI model is proposed. The model is a fuzzy neural network composed of five layers: input ( beliefs and desires) , fuzzification, commitment, fuzzy intention, and defuzzification layer. In the model, the fuzzy commitment rules and neural network are combined to form intentions from beliefs and desires. The model is demonstrated by solving PEG (pursuit-evasion game), and the simulation result is satisfactory.

  2. Direct brain recordings fuel advances in cognitive electrophysiology.

    Science.gov (United States)

    Jacobs, Joshua; Kahana, Michael J

    2010-04-01

    Electrocorticographic brain recordings in patients with surgically implanted electrodes have recently emerged as a powerful tool for examining the neural basis of human cognition. These recordings measure the electrical activity of the brain directly, and thus provide data with higher temporal and spatial resolution than other human neuroimaging techniques. Here we review recent research in this area and in particular we explain how electrocorticographic recordings have provided insight into the neural basis of human working memory, episodic memory, language, and spatial cognition. In some cases this research has identified patterns of human brain activity that were unexpected on the basis of studies in animals.

  3. Miniaturized neural interfaces and implants

    Science.gov (United States)

    Stieglitz, Thomas; Boretius, Tim; Ordonez, Juan; Hassler, Christina; Henle, Christian; Meier, Wolfgang; Plachta, Dennis T. T.; Schuettler, Martin

    2012-03-01

    Neural prostheses are technical systems that interface nerves to treat the symptoms of neurological diseases and to restore sensory of motor functions of the body. Success stories have been written with the cochlear implant to restore hearing, with spinal cord stimulators to treat chronic pain as well as urge incontinence, and with deep brain stimulators in patients suffering from Parkinson's disease. Highly complex neural implants for novel medical applications can be miniaturized either by means of precision mechanics technologies using known and established materials for electrodes, cables, and hermetic packages or by applying microsystems technologies. Examples for both approaches will be introduced and discussed. Electrode arrays for recording of electrocorticograms during presurgical epilepsy diagnosis have been manufactured using approved materials and a marking laser to achieve an integration density that is adequate in the context of brain machine interfaces, e.g. on the motor cortex. Microtechnologies have to be used for further miniaturization to develop polymer-based flexible and light weighted electrode arrays to interface the peripheral and central nervous system. Polyimide as substrate and insulation material will be discussed as well as several application examples for nerve interfaces like cuffs, filament like electrodes and large arrays for subdural implantation.

  4. Neural locus of color afterimages.

    Science.gov (United States)

    Zaidi, Qasim; Ennis, Robert; Cao, Dingcai; Lee, Barry

    2012-02-07

    After fixating on a colored pattern, observers see a similar pattern in complementary colors when the stimulus is removed [1-6]. Afterimages were important in disproving the theory that visual rays emanate from the eye, in demonstrating interocular interactions, and in revealing the independence of binocular vision from eye movements. Afterimages also prove invaluable in exploring selective attention, filling in, and consciousness. Proposed physiological mechanisms for color afterimages range from bleaching of cone photopigments to cortical adaptation [4-9], but direct neural measurements have not been reported. We introduce a time-varying method for evoking afterimages, which provides precise measurements of adaptation and a direct link between visual percepts and neural responses [10]. We then use in vivo electrophysiological recordings to show that all three classes of primate retinal ganglion cells exhibit subtractive adaptation to prolonged stimuli, with much slower time constants than those expected of photoreceptors. At the cessation of the stimulus, ganglion cells generate rebound responses that can provide afterimage signals for later neurons. Our results indicate that afterimage signals are generated in the retina but may be modified like other retinal signals by cortical processes, so that evidence presented for cortical generation of color afterimages is explainable by spatiotemporal factors that modify all signals.

  5. Critical branching neural networks.

    Science.gov (United States)

    Kello, Christopher T

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical branching and, in doing so, simulates observed scaling laws as pervasive to neural and behavioral activity. These scaling laws are related to neural and cognitive functions, in that critical branching is shown to yield spiking activity with maximal memory and encoding capacities when analyzed using reservoir computing techniques. The model is also shown to account for findings of pervasive 1/f scaling in speech and cued response behaviors that are difficult to explain by isolable causes. Issues and questions raised by the model and its results are discussed from the perspectives of physics, neuroscience, computer and information sciences, and psychological and cognitive sciences.

  6. Hidden neural networks

    DEFF Research Database (Denmark)

    Krogh, Anders Stærmose; Riis, Søren Kamaric

    1999-01-01

    A general framework for hybrids of hidden Markov models (HMMs) and neural networks (NNs) called hidden neural networks (HNNs) is described. The article begins by reviewing standard HMMs and estimation by conditional maximum likelihood, which is used by the HNN. In the HNN, the usual HMM probability...... parameters are replaced by the outputs of state-specific neural networks. As opposed to many other hybrids, the HNN is normalized globally and therefore has a valid probabilistic interpretation. All parameters in the HNN are estimated simultaneously according to the discriminative conditional maximum...... likelihood criterion. The HNN can be viewed as an undirected probabilistic independence network (a graphical model), where the neural networks provide a compact representation of the clique functions. An evaluation of the HNN on the task of recognizing broad phoneme classes in the TIMIT database shows clear...

  7. Neural Oscillators Programming Simplified

    Directory of Open Access Journals (Sweden)

    Patrick McDowell

    2012-01-01

    Full Text Available The neurological mechanism used for generating rhythmic patterns for functions such as swallowing, walking, and chewing has been modeled computationally by the neural oscillator. It has been widely studied by biologists to model various aspects of organisms and by computer scientists and robotics engineers as a method for controlling and coordinating the gaits of walking robots. Although there has been significant study in this area, it is difficult to find basic guidelines for programming neural oscillators. In this paper, the authors approach neural oscillators from a programmer’s point of view, providing background and examples for developing neural oscillators to generate rhythmic patterns that can be used in biological modeling and robotics applications.

  8. Some neural effects of adenosin.

    Science.gov (United States)

    Haulică, I; Brănişteanu, D D; Petrescu, G H

    1978-01-01

    The possible neural effects of adenosine were investigated by using electrophysiological techniques at the level of some central and peripheral synapses. The evoked potentials in the somatosensorial cerebral cortex are influenced according to both the type of administration and the level of the electrical stimulation. While the local application does not induce significant alterations, the intrathalamic injections and the perfusion of the IIIrd cerebral ventricle do change the distribution of activated units at the level of different cortical layers especially during the peripheral stimulation. The frequency of spontaneous miniature discharges intracellularly recorded in the neuromuscular junction (mepp) is significantly depressed by adenosine. This effect is calcium- and dose-dependent. The end plate potentials (EPP) were also depressed. The statistical binomial analysis of the phenomenon indicated that adenosine induces a decrease if the presynaptic pool of the available transmitter. The data obtained demonstrate a presynaptic inhibitory action of adenosine beside its known vascular and metaholic effects.

  9. Neural networks and graph theory

    Institute of Scientific and Technical Information of China (English)

    许进; 保铮

    2002-01-01

    The relationships between artificial neural networks and graph theory are considered in detail. The applications of artificial neural networks to many difficult problems of graph theory, especially NP-complete problems, and the applications of graph theory to artificial neural networks are discussed. For example graph theory is used to study the pattern classification problem on the discrete type feedforward neural networks, and the stability analysis of feedback artificial neural networks etc.

  10. Design Optimization of Transistors Used for Neural Recording

    Directory of Open Access Journals (Sweden)

    Eric Basham

    2012-01-01

    Full Text Available Neurons cultured directly over open-gate field-effect transistors result in a hybrid device, the neuron-FET. Neuron-FET amplifier circuits reported in the literature employ the neuron-FET transducer as a current-mode device in conjunction with a transimpedance amplifier. In this configuration, the transducer does not provide any signal gain, and characterization of the transducer out of the amplification circuit is required. Furthermore, the circuit requires a complex biasing scheme that must be retuned to compensate for drift. Here we present an alternative strategy based on the gm/Id design approach to optimize a single-stage common-source amplifier design. The gm/Id design approach facilitates in circuit characterization of the neuron-FET and provides insight into approaches to improving the transistor process design for application as a neuron-FET transducer. Simulation data for a test case demonstrates optimization of the transistor design and significant increase in gain over a current mode implementation.

  11. Circuitry for a Wireless Microsystem for Neural Recording Microprobes

    Science.gov (United States)

    2007-11-02

    Fig. 2. The receiver coil, D1 and C1 form a half-rectifier. The opamp works in the negative feedback loop to adjust the current through the pass...problem associated with NMOS pass device, a simple voltage-doubling block, made up of C2 and D2, is used to provide higher supply voltage to the opamp ...ensure that the two integrator outputs mostly vary within the normal output range of the practical opamp . The circuit is shown in Fig. 7. Fig. 6

  12. Classification of Esophageal Motility Records Using Neural Networks

    Science.gov (United States)

    2007-11-02

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  13. Microelectronics, bioinformatics and neurocomputation for massive neuronal recordings in brain circuits with large scale multielectrode array probes.

    Science.gov (United States)

    Maccione, Alessandro; Gandolfo, Mauro; Zordan, Stefano; Amin, Hayder; Di Marco, Stefano; Nieus, Thierry; Angotzi, Gian Nicola; Berdondini, Luca

    2015-10-01

    Deciphering neural network function in health and disease requires recording from many active neurons simultaneously. Developing approaches to increase their numbers is a major neurotechnological challenge. Parallel to recent advances in optical Ca(2+) imaging, an emerging approach consists in adopting complementary-metal-oxide-semiconductor (CMOS) technology to realize MultiElectrode Array (MEA) devices. By implementing signal conditioning and multiplexing circuits, these devices allow nowadays to record from several thousands of single neurons at sub-millisecond temporal resolution. At the same time, these recordings generate very large data streams which become challenging to analyze. Here, at first we shortly review the major approaches developed for data management and analysis for conventional, low-resolution MEAs. We highlight how conventional computational tools cannot be easily up-scaled to very large electrode array recordings, and custom bioinformatics tools are an emerging need in this field. We then introduce a novel approach adapted for the acquisition, compression and analysis of extracellular signals acquired simultaneously from 4096 electrodes with CMOS MEAs. Finally, as a case study, we describe how this novel large scale recording platform was used to record and analyze extracellular spikes from the ganglion cell layer in the wholemount retina at pan-retinal scale following patterned light stimulation.

  14. Building a Neural Computer

    OpenAIRE

    Carreira, Paulo J.F.; Rosa, Miguel A.; Neto, João Pedro; Costa, José Félix

    1998-01-01

    In the work of [Siegelmann 95] it was showed that Artificial Recursive Neural Networks have the same computing power as Turing machines. A Turing machine can be programmed in a proper high-level language - the language of partial recursive functions. In this paper we present the implementation of a compiler that directly translates high-level Turing machine programs to Artificial Recursive Neural Networks. The application contains a simulator that can be used to test the resulting networks. W...

  15. Neural cryptography with feedback

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  16. Imaging the Neural Symphony.

    Science.gov (United States)

    Svoboda, Karel

    2016-01-01

    Since the start of the new millennium, a method called two-photon microscopy has allowed scientists to peer farther into the brain than ever before. Our author, one of the pioneers in the development of this new technology, writes that "directly observing the dynamics of neural networks in an intact brain has become one of the holy grails of brain research." His article describes the advances that led to this remarkable breakthrough-one that is helping neuroscientists better understand neural networks.

  17. Building a Neural Computer

    OpenAIRE

    1998-01-01

    In the work of [Siegelmann 95] it was showed that Artificial Recursive Neural Networks have the same computing power as Turing machines. A Turing machine can be programmed in a proper high-level language - the language of partial recursive functions. In this paper we present the implementation of a compiler that directly translates high-level Turing machine programs to Artificial Recursive Neural Networks. The application contains a simulator that can be used to test the resulting networks. W...

  18. Neural cryptography with feedback.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  19. Diffractive lenses recorded in absorbent photopolymers.

    Science.gov (United States)

    Fernández, R; Gallego, S; Márquez, A; Francés, J; Navarro-Fuster, V; Pascual, I

    2016-01-25

    Photopolymers can be appealing materials for diffractive optical elements fabrication. In this paper, we present the recording of diffractive lenses in PVA/AA (Polyvinyl alcohol acrylamide) based photopolymers using a liquid crystal device as a master. In addition, we study the viability of using a diffusion model to simulate the lens formation in the material and to study the influence of the different parameters that govern the diffractive formation in photopolymers. Once we control the influence of each parameter, we can fit an optimum recording schedule to record each different diffractive optical element with the optimum focalization power.

  20. Organizing principles of real-time memory encoding: neural clique assemblies and universal neural codes.

    Science.gov (United States)

    Lin, Longnian; Osan, Remus; Tsien, Joe Z

    2006-01-01

    Recent identification of network-level coding units, termed neural cliques, in the hippocampus has enabled real-time patterns of memory traces to be mathematically described, directly visualized, and dynamically deciphered. These memory coding units are functionally organized in a categorical and hierarchical manner, suggesting that internal representations of external events in the brain is achieved not by recording exact details of those events, but rather by recreating its own selective pictures based on cognitive importance. This neural-clique-based hierarchical-extraction and parallel-binding process enables the brain to acquire not only large storage capacity but also abstraction and generalization capability. In addition, activation patterns of the neural clique assemblies can be converted to strings of binary codes that would permit universal categorizations of internal brain representations across individuals and species.

  1. 光学记录蜗核和前庭核核团神经元电活动%Optical Recording of Population Neuronal Activity in Cochlear Nucleus and Vestibular Nucleus

    Institute of Scientific and Technical Information of China (English)

    杨仕明; 杨伟炎; 顾瑞; 韩东一; 山下敏夫

    2003-01-01

    目的在神经细胞群的水平上研究脑干蜗核(cochlear nucleus,CN)和前庭核(vestibular nucleus,VN)神经元电活动.方法自新生小鼠(1~5天)制备离体脑干切片,用吸光性电压敏感染料RH155染色20分钟.采用光学记录膜电位(optical recording membrane potential)技术,观察电刺激位听神经(第8颅神经,nⅧ)后脑干CN和VN的神经电活动.结果①电刺激nⅧ断端后光学记录显示兴奋传导至CN和VN核团(n=40);②CN和VN神经兴奋有激发延迟(onset latency)和高峰延迟(peak latency);③所记录的光学信号具有光吸收波长特性,表明光学记录的可靠性;④光学信号包括峰样快反应信号(spike-likefast signal)和持续较长时间的慢反应信号(slow signal);⑤连续刺激nⅧ后发现慢反应信号大小递减,为突触疲劳(synaptic faiigue)现象.结论本研究表明光学记录膜电位方法可以在神经细胞群的水平上直观观察脑干蜗核和前庭核神经电活动的时空二维方式及其兴奋性突触传递过程,为听觉和平衡觉中枢生理研究提供了新的手段.

  2. Interpreting collective neural activity underlying spatial navigation in virtual reality

    Science.gov (United States)

    Meshulam, Leenoy; Gauthier, Jeff; Tank, David; Bialek, William

    2015-03-01

    Traditionally, cognitive- demanding processes like spatial navigation were studied by recording the activity of single neurons. However, recent technological progress allows imaging the simultaneous activity of large neuronal populations in awake behaving animals. This progress in experimental work calls for a similar adjustments of the modeling frameworks. To achieve a description of the ``real thermodynamics'' of the neural system, we construct maximum entropy models for optical imaging data taken in vivo, from the hippocampus of mice navigating in a virtual reality environment. This provides a natural extension of statistical mechanics applicable to brain activity, by focusing on the interactions between cells rather than on single cell's activity. We aim to determine how the topology of the energy landscape predicted by the model corresponds to the location of the animal in the environment. Since large subpopulations of the neurons in this area are spatially modulated, we expect the landscape to exhibit a large ``valley'' structure of local minima, corresponding to the animal's position along the environment. Such a finding is especially of interest because the location information emerges solely from the activity patterns that are accessible to the brain.

  3. Novel flexible Parylene neural probe with 3D sheath structure for enhancing tissue integration.

    Science.gov (United States)

    Kuo, Jonathan T W; Kim, Brian J; Hara, Seth A; Lee, Curtis D; Gutierrez, Christian A; Hoang, Tuan Q; Meng, Ellis

    2013-02-21

    A Parylene C neural probe with a three dimensional sheath structure was designed, fabricated, and characterized. Multiple platinum (Pt) electrodes for recording neural signals were fabricated on both inner and outer surfaces of the sheath structure. Thermoforming of Parylene was used to create the three dimensional sheath structures from flat surface micromachined microchannels using solid microwires as molds. Benchtop electrochemical characterization was performed on the thin film Pt electrodes using cyclic voltammetry and electrochemical impedance spectroscopy and showed that electrodes possessed low impedances suitable for neuronal recordings. A procedure for implantation of the neural probe was developed and successfully demonstrated in vitro into an agarose brain tissue model. The electrode-lined sheath will be decorated with eluting neurotrophic factors to promote in vivo neural tissue ingrowth post-implantation. These features will enhance tissue integration and improve recording quality towards realizing reliable chronic neural interfaces.

  4. Letter identification and the neural image classifier.

    Science.gov (United States)

    Watson, Andrew B; Ahumada, Albert J

    2015-02-12

    Letter identification is an important visual task for both practical and theoretical reasons. To extend and test existing models, we have reviewed published data for contrast sensitivity for letter identification as a function of size and have also collected new data. Contrast sensitivity increases rapidly from the acuity limit but slows and asymptotes at a symbol size of about 1 degree. We recast these data in terms of contrast difference energy: the average of the squared distances between the letter images and the average letter image. In terms of sensitivity to contrast difference energy, and thus visual efficiency, there is a peak around ¼ degree, followed by a marked decline at larger sizes. These results are explained by a Neural Image Classifier model that includes optical filtering and retinal neural filtering, sampling, and noise, followed by an optimal classifier. As letters are enlarged, sensitivity declines because of the increasing size and spacing of the midget retinal ganglion cell receptive fields in the periphery.

  5. Analysis and Processing of Deformation Information of Optical Fiber Smart Structure Based on Artificial Neural Networks%基于人工神经网络的光纤智能结构变形信息的分析与处理

    Institute of Scientific and Technical Information of China (English)

    张华荣; 赵志敏

    2011-01-01

    Based on the principle of micro-bending loss of optical fiber system, the experiments were carried out by loading on the optical fiber smart structure and then the artificial neural network was employed to process the data which contained deformation information in order to locate the deformation location. The results showed that the proposed method performed well, and it could effectively locate the deformation location.%利用光纤系统的微弯损耗原理,通过对光纤智能结构进行承载,采用人工神经网络的方法,对试验系统接收到的包含光纤智能结构变形信息的数据进行了处理与变形位置判定.结果表明:人工神经网络的方法可以有效地分析和处理光纤智能结构的变形信息,确定变形位置.

  6. Training Deep Spiking Neural Networks Using Backpropagation.

    Science.gov (United States)

    Lee, Jun Haeng; Delbruck, Tobi; Pfeiffer, Michael

    2016-01-01

    Deep spiking neural networks (SNNs) hold the potential for improving the latency and energy efficiency of deep neural networks through data-driven event-based computation. However, training such networks is difficult due to the non-differentiable nature of spike events. In this paper, we introduce a novel technique, which treats the membrane potentials of spiking neurons as differentiable signals, where discontinuities at spike times are considered as noise. This enables an error backpropagation mechanism for deep SNNs that follows the same principles as in conventional deep networks, but works directly on spike signals and membrane potentials. Compared with previous methods relying on indirect training and conversion, our technique has the potential to capture the statistics of spikes more precisely. We evaluate the proposed framework on artificially generated events from the original MNIST handwritten digit benchmark, and also on the N-MNIST benchmark recorded with an event-based dynamic vision sensor, in which the proposed method reduces the error rate by a factor of more than three compared to the best previous SNN, and also achieves a higher accuracy than a conventional convolutional neural network (CNN) trained and tested on the same data. We demonstrate in the context of the MNIST task that thanks to their event-driven operation, deep SNNs (both fully connected and convolutional) trained with our method achieve accuracy equivalent with conventional neural networks. In the N-MNIST example, equivalent accuracy is achieved with about five times fewer computational operations.

  7. Training Deep Spiking Neural Networks using Backpropagation

    Directory of Open Access Journals (Sweden)

    Jun Haeng Lee

    2016-11-01

    Full Text Available Deep spiking neural networks (SNNs hold the potential for improving the latency and energy efficiency of deep neural networks through data-driven event-based computation. However, training such networks is difficult due to the non-differentiable nature of spike events. In this paper, we introduce a novel technique, which treats the membrane potentials of spiking neurons as differentiable signals, where discontinuities at spike times are considered as noise. This enables an error backpropagation mechanism for deep SNNs that follows the same principles as in conventional deep networks, but works directly on spike signals and membrane potentials. Compared with previous methods relying on indirect training and conversion, our technique has the potential to capture the statistics of spikes more precisely. We evaluate the proposed framework on artificially generated events from the original MNIST handwritten digit benchmark, and also on the N-MNIST benchmark recorded with an event-based dynamic vision sensor, in which the proposed method reduces the error rate by a factor of more than three compared to the best previous SNN, and also achieves a higher accuracy than a conventional convolutional neural network (CNN trained and tested on the same data. We demonstrate in the context of the MNIST task that thanks to their event-driven operation, deep SNNs (both fully connected and convolutional trained with our method achieve accuracy equivalent with conventional neural networks. In the N-MNIST example, equivalent accuracy is achieved with about five times fewer computational operations.

  8. Artificial neural interfaces for bionic cardiovascular treatments.

    Science.gov (United States)

    Kawada, Toru; Sugimachi, Masaru

    2009-01-01

    An artificial nerve, in the broad sense, may be conceptualized as a physical and logical interface system that reestablishes the information traffic between the central nervous system and peripheral organs. Studies on artificial nerves targeting the autonomic nervous system are in progress to explore new treatment strategies for several cardiovascular diseases. In this article, we will review our research targeting the autonomic nervous system to treat cardiovascular diseases. First, we identified the rule for decoding native sympathetic nerve activity into a heart rate using transfer function analysis, and established a framework for a neurally regulated cardiac pacemaker. Second, we designed a bionic baroreflex system to restore the baroreflex buffering function using electrical stimulation of the celiac ganglion in a rat model of orthostatic hypotension. Third, based on the hypothesis that autonomic imbalance aggravates chronic heart failure, we implanted a neural interface into the right vagal nerve and demonstrated that intermittent vagal stimulation significantly improved the survival rate in rats with chronic heart failure following myocardial infarction. Although several practical problems need to be resolved, such as those relating to the development of electrodes feasible for long-term nerve activity recording, studies of artificial neural interfaces with the autonomic nervous system have great possibilities in the field of cardiovascular treatment. We expect further development of artificial neural interfaces as novel strategies to cope with cardiovascular diseases resistant to conventional therapeutics.

  9. Two outward potassium current types are expressed during the neural differentiation of neural stem cells**

    Institute of Scientific and Technical Information of China (English)

    Ruiying Bai; Guowei Gao; Ying Xing; Hong Xue

    2013-01-01

    The electrophysiological properties of potassium ion channels are regarded as a basic index for determining the functional differentiation of neural stem cells. In this study, neural stem cells from the hippocampus of newborn rats were induced to differentiate with neurotrophic growth factor, and the electrophysiological properties of the voltage-gated potassium ion channels were observed. Immunofluorescence staining showed that the rapidly proliferating neural stem cells formed spheres in vitro that expressed high levels of nestin. The differentiated neurons were shown to express neuron-specific enolase. Flow cytometric analysis revealed that the neural stem cells were actively dividing and the percentage of cells in the S + G2/M phase was high. However, the ratio of cells in the S + G2/M phase decreased obviously as differentiation proceeded. Whole-cellpatch-clamp re-cordings revealed apparent changes in potassium ion currents as the neurons differentiated. The potassium ion currents consisted of one transient outward potassium ion current and one delayed rectifier potassium ion current, which were blocked by 4-aminopyridine and tetraethylammonium, respectively. The experimental findings indicate that neural stem cells from newborn rat hippo-campus could be cultured and induced to differentiate into functional neurons under defined condi-tions in vitro. The differentiated neurons expressed two types of outward potassium ion currents similar to those of mature neurons in vivo.

  10. A theory of neural dimensionality, dynamics, and measurement

    Science.gov (United States)

    Ganguli, Surya

    In many experiments, neuroscientists tightly control behavior, record many trials, and obtain trial-averaged firing rates from hundreds of neurons in circuits containing millions of behaviorally relevant neurons. Dimensionality reduction has often shown that such datasets are strikingly simple; they can be described using a much smaller number of dimensions than the number of recorded neurons, and the resulting projections onto these dimensions yield a remarkably insightful dynamical portrait of circuit computation. This ubiquitous simplicity raises several profound and timely conceptual questions. What is the origin of this simplicity and its implications for the complexity of brain dynamics? Would neuronal datasets become more complex if we recorded more neurons? How and when can we trust dynamical portraits obtained from only hundreds of neurons in circuits containing millions of neurons? We present a theory that answers these questions, and test it using neural data recorded from reaching monkeys. Overall, this theory yields a picture of the neural measurement process as a random projection of neural dynamics, conceptual insights into how we can reliably recover dynamical portraits in such under-sampled measurement regimes, and quantitative guidelines for the design of future experiments. Moreover, it reveals the existence of phase transition boundaries in our ability to successfully decode cognition and behavior as a function of the number of recorded neurons, the complexity of the task, and the smoothness of neural dynamics. membership pending.

  11. Multi-channel micro neural probe fabricated with SOI

    Institute of Scientific and Technical Information of China (English)

    PEI WeiHua; ZHU Lin; WANG ShuJing; GUO Kai; TANG Jun; ZHANG Xu; LU Lin; GAO ShangKai; CHEN HongDa

    2009-01-01

    Silicon-on-insulator (SOI) substrate is widely used in micro-electro-mechanical systems (MEMS). With the buried oxide layer of SOl acting as an etching stop, silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability. A seven-record-site neural probe was formed by inductive-coupled plasma (ICP) dry etching of an SOl substrate. The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mmx100 μmx15 μm with typical area of the record site of 78.5 μm2. The impedance of the record site was measured in-vitro. The typical impedance characteris-tics of the record sites are around 2 MΩ at 1 kHz. The performance of the neural probe in-vivo was tested on anesthetic rat. The recorded neural spike was typically around 140 μV. Spike from individual site could exceed 700 μV. The average signal noise ratio was 7 or more.

  12. Multi-channel micro neural probe fabricated with SOI

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The impedance of the record site was measured in-vitro.The typical impedance characteris-tics of the record sites are around 2 MΩ at 1 kHz.The performance of the neural probe in-vivo was tested on anesthetic rat.The recorded neural spike was typically around 140 μV.Spike from individual site could exceed 700 μV.The average signal noise ratio was 7 or more.

  13. Neural networks in seismic discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Dowla, F.U.

    1995-01-01

    Neural networks are powerful and elegant computational tools that can be used in the analysis of geophysical signals. At Lawrence Livermore National Laboratory, we have developed neural networks to solve problems in seismic discrimination, event classification, and seismic and hydrodynamic yield estimation. Other researchers have used neural networks for seismic phase identification. We are currently developing neural networks to estimate depths of seismic events using regional seismograms. In this paper different types of network architecture and representation techniques are discussed. We address the important problem of designing neural networks with good generalization capabilities. Examples of neural networks for treaty verification applications are also described.

  14. Long-term stability of intracortical recordings using perforated and arrayed Parylene sheath electrodes

    Science.gov (United States)

    Hara, Seth A.; Kim, Brian J.; Kuo, Jonathan T. W.; Lee, Curtis D.; Meng, Ellis; Pikov, Victor

    2016-12-01

    Objective. Acquisition of reliable and robust neural recordings with intracortical neural probes is a persistent challenge in the field of neuroprosthetics. We developed a multielectrode array technology to address chronic intracortical recording reliability and present in vivo recording results. Approach. The 2 × 2 Parylene sheath electrode array (PSEA) was microfabricated and constructed from only Parylene C and platinum. The probe includes a novel three-dimensional sheath structure, perforations, and bioactive coatings that improve tissue integration and manage immune response. Coatings were applied using a sequential dip-coating method that provided coverage over the entire probe surface and interior of the sheath structure. A sharp probe tip taper facilitated insertion with minimal trauma. Fabricated probes were subject to examination by optical and electron microscopy and electrochemical testing prior to implantation. Main results. 1 × 2 arrays were successfully fabricated on wafer and then packaged together to produce 2 × 2 arrays. Then, probes having electrode sites with adequate electrochemical properties were selected. A subset of arrays was treated with bioactive coatings to encourage neuronal growth and suppress inflammation and another subset of arrays was implanted in conjunction with a virally mediated expression of Caveolin-1. Arrays were attached to a custom-made insertion shuttle to facilitate precise insertion into the rat motor cortex. Stable electrophysiological recordings were obtained during the period of implantation up to 12 months. Immunohistochemical evaluation of cortical tissue around individual probes indicated a strong correlation between the electrophysiological performance of the probes and histologically observable proximity of neurons and dendritic sprouting. Significance. The PSEA demonstrates the scalability of sheath electrode technology and provides higher electrode count and density to access a greater volume for recording

  15. Neural Correlates of Abstract Rule Learning: An Event-Related Potential Study

    Science.gov (United States)

    Sun, Fang; Hoshi-Shiba, Reiko; Abla, Dilshat; Okanoya, Kazuo

    2012-01-01

    Abstract rule learning is a fundamental aspect of human cognition, and is essential for language acquisition. However, despite its importance, the neural mechanisms underlying abstract rule learning are still largely unclear. In this study, we investigated the neural correlates of abstract rule learning by recording auditory event-related…

  16. Study on the near-field recording spot

    Science.gov (United States)

    Pei, Xiandeng; Xia, You-xin; Huang, Hao; Xie, Changsheng; Wang, Haiwei

    2003-04-01

    Evanescent energy can be used to get extremely small optical spots. For the data storage applications, optical near field is defined in terms of Evanescent coupling between the system used to read or write data and recording layer. Near-field techniques can be applied to optical data storage systems to greatly increase recording density. So near-field recording technique has great potential in optical disc recording system and hybrid recording system. The characteristic of near-field recording spot is of vital importance in the data storage system basing the near-field theory, so it is absolutely necessary to be analyzed and measured. This paper analyses characteristic of near-field spots. The heat response time of the near field to overcome super paramagnetic effect is calculated basing the heat transfer theory. A novel measuring method for the diameter of near-field recording spot is also presented. Since the grain of the recording media is tiny enough, with the aid of atomic force microscope (AFM), near-field optical lithography can be accomplished. The diameter of near-field recording spot can be obtained by specifically designed computer either. So the relationship between the near-field recording spot diameter and the probe size of near-field recording system, the near field recording distance coupling between head and disc can be got.

  17. Higher-order neural processing tunes motion neurons to visual ecology in three species of hawkmoths.

    Science.gov (United States)

    Stöckl, A L; O'Carroll, D; Warrant, E J

    2017-06-28

    To sample information optimally, sensory systems must adapt to the ecological demands of each animal species. These adaptations can occur peripherally, in the anatomical structures of sensory organs and their receptors; and centrally, as higher-order neural processing in the brain. While a rich body of investigations has focused on peripheral adaptations, our understanding is sparse when it comes to central mechanisms. We quantified how peripheral adaptations in the eyes, and central adaptations in the wide-field motion vision system, set the trade-off between resolution and sensitivity in three species of hawkmoths active at very different light levels: nocturnal Deilephila elpenor, crepuscular Manduca sexta, and diurnal Macroglossum stellatarum. Using optical measurements and physiological recordings from the photoreceptors and wide-field motion neurons in the lobula complex, we demonstrate that all three species use spatial and temporal summation to improve visual performance in dim light. The diurnal Macroglossum relies least on summation, but can only see at brighter intensities. Manduca, with large sensitive eyes, relies less on neural summation than the smaller eyed Deilephila, but both species attain similar visual performance at nocturnal light levels. Our results reveal how the visual systems of these three hawkmoth species are intimately matched to their visual ecologies. © 2017 The Author(s).

  18. Electromagnetic Propagation of Fiber Probe for Near-field Optical Recording Using 3-D FDTD Method%用3D-FDTD法分析用于近场光存储的光纤探针电磁波传输特性

    Institute of Scientific and Technical Information of China (English)

    刘凯; 白明; 鲁拥华; 唐麟; 王超; 明海

    2001-01-01

    The data density of the near-field optical recording is mainlydetermined by near-field electromagnetic distribution of probe fiber such as transmission efficiency, near-field light spot size, polarization keeping and the grade of the electromagnetic field. The optical characters and light wave propagation of various fiber probes for near-field optical recording are numerically simulated using 3D finite-difference time-domain (3D-FDTD) method in this paper. The possible application in near-field optical recording with these probes is discussed. The entirely metal coat probe is pointed out to have an extremely small near-field spot size about 10 nm, which is far less than that of the conventional probe.%提高近场光存储的存储信息密度的关键主要在于掌握近场存储光纤探针的透光率、近场光斑直径尺寸以及场梯度等近场物理量。采用三维时域有限差分(3D-FDTD)法分析了可用于近场光存储的光纤探针尖的光学性质,对不同类型光纤的近场光场分布进行了数值计算,给出结果并进行比较,从光学性质的角度对其在近场光存储中的应用加以讨论。完全镀膜光纤尖在极近场处的光斑可获得10nm的尺寸,远小于传统光纤光学聚焦的光斑尺寸大小。

  19. Fiber optic detector

    Energy Technology Data Exchange (ETDEWEB)

    Partin, J.K.; Ward, T.E.; Grey, A.E.

    1990-12-31

    This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

  20. Optically fixed photorefractive correlator

    Institute of Scientific and Technical Information of China (English)

    刘友文; 刘立人; 周常河; 徐良瑛

    2002-01-01

    An optically fixed photorefractive correlator is presented, where two-centre non-volatile holographic recording isemployed to write and fix the matched filter in doubly doped LiNbO3 crystals. This correlator shows good correlationcharacteristics and insensitivity to the writing beam during readout. It can be used in cases requiring stability and notrequiring modification for a long period, and it is refreshed optically when new information needs to be registered.

  1. Rule Extraction:Using Neural Networks or for Neural Networks?

    Institute of Scientific and Technical Information of China (English)

    Zhi-Hua Zhou

    2004-01-01

    In the research of rule extraction from neural networks, fidelity describes how well the rules mimic the behavior of a neural network while accuracy describes how well the rules can be generalized. This paper identifies the fidelity-accuracy dilemma. It argues to distinguish rule extraction using neural networks and rule extraction for neural networks according to their different goals, where fidelity and accuracy should be excluded from the rule quality evaluation framework, respectively.

  2. Fuzzy Multiresolution Neural Networks

    Science.gov (United States)

    Ying, Li; Qigang, Shang; Na, Lei

    A fuzzy multi-resolution neural network (FMRANN) based on particle swarm algorithm is proposed to approximate arbitrary nonlinear function. The active function of the FMRANN consists of not only the wavelet functions, but also the scaling functions, whose translation parameters and dilation parameters are adjustable. A set of fuzzy rules are involved in the FMRANN. Each rule either corresponding to a subset consists of scaling functions, or corresponding to a sub-wavelet neural network consists of wavelets with same dilation parameters. Incorporating the time-frequency localization and multi-resolution properties of wavelets with the ability of self-learning of fuzzy neural network, the approximation ability of FMRANN can be remarkable improved. A particle swarm algorithm is adopted to learn the translation and dilation parameters of the wavelets and adjusting the shape of membership functions. Simulation examples are presented to validate the effectiveness of FMRANN.

  3. Atypical neural synchronization to speech envelope modulations in dyslexia.

    Science.gov (United States)

    De Vos, Astrid; Vanvooren, Sophie; Vanderauwera, Jolijn; Ghesquière, Pol; Wouters, Jan

    2017-01-01

    A fundamental deficit in the synchronization of neural oscillations to temporal information in speech could underlie phonological processing problems in dyslexia. In this study, the hypothesis of a neural synchronization impairment is investigated more specifically as a function of different neural oscillatory bands and temporal information rates in speech. Auditory steady-state responses to 4, 10, 20 and 40Hz modulations were recorded in normal reading and dyslexic adolescents to measure neural synchronization of theta, alpha, beta and low-gamma oscillations to syllabic and phonemic rate information. In comparison to normal readers, dyslexic readers showed reduced non-synchronized theta activity, reduced synchronized alpha activity and enhanced synchronized beta activity. Positive correlations between alpha synchronization and phonological skills were found in normal readers, but were absent in dyslexic readers. In contrast, dyslexic readers exhibited positive correlations between beta synchronization and phonological skills. Together, these results suggest that auditory neural synchronization of alpha and beta oscillations is atypical in dyslexia, indicating deviant neural processing of both syllabic and phonemic rate information. Impaired synchronization of alpha oscillations in particular demonstrated to be the most prominent neural anomaly possibly hampering speech and phonological processing in dyslexic readers.

  4. Neural signal registration and analysis of axons grown in microchannels

    Science.gov (United States)

    Pigareva, Y.; Malishev, E.; Gladkov, A.; Kolpakov, V.; Bukatin, A.; Mukhina, I.; Kazantsev, V.; Pimashkin, A.

    2016-08-01

    Registration of neuronal bioelectrical signals remains one of the main physical tools to study fundamental mechanisms of signal processing in the brain. Neurons generate spiking patterns which propagate through complex map of neural network connectivity. Extracellular recording of isolated axons grown in microchannels provides amplification of the signal for detailed study of spike propagation. In this study we used neuronal hippocampal cultures grown in microfluidic devices combined with microelectrode arrays to investigate a changes of electrical activity during neural network development. We found that after 5 days in vitro after culture plating the spiking activity appears first in microchannels and on the next 2-3 days appears on the electrodes of overall neural network. We conclude that such approach provides a convenient method to study neural signal processing and functional structure development on a single cell and network level of the neuronal culture.

  5. Neural network for automatic analysis of motility data

    DEFF Research Database (Denmark)

    Jakobsen, Erik; Kruse-Andersen, S; Kolberg, Jens Godsk

    1994-01-01

    events. Due to great variation in events, this method often fails to detect biologically relevant pressure variations. We have tried to develop a new concept for recognition of pressure events based on a neural network. Pressures were recorded for over 23 hours in 29 normal volunteers by means...... of a portable data recording system. A number of pressure events and non-events were selected from 9 recordings and used for training the network. The performance of the trained network was then verified on recordings from the remaining 20 volunteers. The accuracy and sensitivity of the two systems were...

  6. An Optically-Assisted 3-D Cellular Array Machine

    Science.gov (United States)

    1993-11-05

    Presented by: Physical Optics Corporation 0 Research & Development Division 20600 Gramercy Place, Suite 103 Torrance, California 90501 Principal...Computer Machine (Constructed Hardware) (Planned Hardware Design) Processing Techniques Digital Only Digital and Analog Analog Processor N/A Celular Neural

  7. Introduction to Artificial Neural Networks

    DEFF Research Database (Denmark)

    Larsen, Jan

    1999-01-01

    The note addresses introduction to signal analysis and classification based on artificial feed-forward neural networks.......The note addresses introduction to signal analysis and classification based on artificial feed-forward neural networks....

  8. Information transmission in oscillatory neural activity

    CERN Document Server

    Koepsell, Kilian

    2008-01-01

    Periodic neural activity not locked to the stimulus or to motor responses is usually ignored. Here, we present new tools for modeling and quantifying the information transmission based on periodic neural activity that occurs with quasi-random phase relative to the stimulus. We propose a model to reproduce characteristic features of oscillatory spike trains, such as histograms of inter-spike intervals and phase locking of spikes to an oscillatory influence. The proposed model is based on an inhomogeneous Gamma process governed by a density function that is a product of the usual stimulus-dependent rate and a quasi-periodic function. Further, we present an analysis method generalizing the direct method (Rieke et al, 1999; Brenner et al, 2000) to assess the information content in such data. We demonstrate these tools on recordings from relay cells in the lateral geniculate nucleus of the cat.

  9. Olfactory Decoding Method Using Neural Spike Signals

    Institute of Scientific and Technical Information of China (English)

    Kyung-jin YOU; Hyun-chool SHIN

    2010-01-01

    This paper presents a travel method for inferring the odor based on naval activities observed from rats'main olfactory bulbs.Mufti-channel extmcellular single unit recordings are done by microwire electrodes(Tungsten,50μm,32 channels)innplanted in the mitral/tufted cell layers of the main olfactory bulb of the anesthetized rats to obtain neural responses to various odors.Neural responses as a key feature are measured by subtraction firing rates before stimulus from after.For odor irderenoe,a decoding method is developed based on the ML estimation.The results show that the average decoding acauacy is about 100.0%,96.0%,and 80.0% with three rats,respectively.This wait has profound implications for a novel brain-madune interface system far odor inference.

  10. Regenerative Electrode Interfaces for Neural Prostheses.

    Science.gov (United States)

    Thompson, Cort H; Zoratti, Marissa J; Langhals, Nicholas B; Purcell, Erin K

    2016-04-01

    Neural prostheses are electrode arrays implanted in the nervous system that record or stimulate electrical activity in neurons. Rapid growth in the use of neural prostheses in research and clinical applications has occurred in recent years, but instability and poor patency in the tissue-electrode interface undermines the longevity and performance of these devices. The application of tissue engineering strategies to the device interface is a promising approach to improve connectivity and communication between implanted electrodes and local neurons, and several research groups have developed new and innovative modifications to neural prostheses with the goal of seamless device-tissue integration. These approaches can be broadly categorized based on the strategy used to maintain and regenerate neurons at the device interface: (1) redesign of the prosthesis architecture to include finer-scale geometries and/or provide topographical cues to guide regenerating neural outgrowth, (2) incorporation of material coatings and bioactive molecules on the prosthesis to improve neuronal growth, viability, and adhesion, and (3) inclusion of cellular grafts to replenish the local neuron population or provide a target site for reinnervation (biohybrid devices). In addition to stabilizing the contact between neurons and electrodes, the potential to selectively interface specific subpopulations of neurons with individual electrode sites is a key advantage of regenerative interfaces. In this study, we review the development of regenerative interfaces for applications in both the peripheral and central nervous system. Current and future development of regenerative interfaces has the potential to improve the stability and selectivity of neural prostheses, improving the patency and resolution of information transfer between neurons and implanted electrodes.

  11. Generalized Adaptive Artificial Neural Networks

    Science.gov (United States)

    Tawel, Raoul

    1993-01-01

    Mathematical model of supervised learning by artificial neural network provides for simultaneous adjustments of both temperatures of neurons and synaptic weights, and includes feedback as well as feedforward synaptic connections. Extension of mathematical model described in "Adaptive Neurons For Artificial Neural Networks" (NPO-17803). Dynamics of neural network represented in new model by less-restrictive continuous formalism.

  12. Active optical clock

    Institute of Scientific and Technical Information of China (English)

    CHEN JingBiao

    2009-01-01

    This article presents the principles and techniques of active optical clock, a special laser combining the laser physics of one-atom laser, bad-cavity gas laser, super-cavity stabilized laser and optical atomic clock together. As a simple example, an active optical clock based on thermal strontium atomic beam shows a quantum-limited linewidth of 0.51 Hz, which is insensitive to laser cavity-length noise, and may surpass the recorded narrowest 6.7 Hz of Hg ion optical clock and 1.5 Hz of very recent optical lattice clock. The estimated 0.1 Hz one-second instability and 0.27 Hz uncertainty are limited only by the rela-tivistic Doppler effect, and can be improved by cold atoms.

  13. Python fiber optic seal

    Energy Technology Data Exchange (ETDEWEB)

    Ystesund, K.; Bartberger, J.; Brusseau, C.; Fleming, P.; Insch, K.; Tolk, K.

    1993-08-01

    Sandia National Laboratories has developed a high security fiber optic seal that incorporates tamper resistance features that are not available in commercial fiber optic seals. The Python Seal is a passive fiber optic loop seal designed to give indication of unauthorized entry. The seal includes a fingerprint feature that provides seal identity information in addition to the unique fiber optic pattern created when the seal is installed. The fiber optic cable used for the seal loop is produced with tamper resistant features that increase the difficulty of attacking that component of a seal. A Seal Reader has been developed that will record the seal signature and the fingerprint feature of the seal. A Correlator software program then compares seal images to establish a match or mismatch. SNL is also developing a Polaroid reader to permit hard copies of the seal patterns to be obtained directly from the seal.

  14. Rethinking neural efficiency: effects of controlling for strategy use.

    Science.gov (United States)

    Toffanin, Paolo; Johnson, Addie; de Jong, Ritske; Martens, Sander

    2007-10-01

    A sentence verification task (SVT) was used to test whether differences in neural activation patterns that have been attributed to IQ may actually depend on differential strategy use between IQ groups. Electroencephalograms were recorded from 14 low (89 processing patterns during task performance seem to depend on the strategy used for task execution, preparation for task processing may depend on IQ. (PsycINFO Database Record (c) 2007 APA, all rights reserved).

  15. Multi-channel holographic birfurcative neural network system for real-time adaptive EOS data analysis

    Science.gov (United States)

    Liu, Hua-Kuang; Diep, J.; Huang, K.

    1991-01-01

    Viewgraphs on multi-channel holographic bifurcative neural network system for real-time adaptive Earth Observing System (EOS) data analysis are presented. The objective is to research and develop an optical bifurcating neuromorphic pattern recognition system for making optical data array comparisons and to evaluate the use of the system for EOS data classification, reduction, analysis, and other applications.

  16. Optical comparator uses holographic subtraction

    Science.gov (United States)

    Vahey, D. W.; Verber, C. M.

    1980-01-01

    Integrated optical comparator compares reference and signal voltages by their effects on coherent light beam. If both voltages are same, beam is essentially unperturbed. If voltages differ, light is deflected by previously recorded hologram to detector.

  17. Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

    Science.gov (United States)

    Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

    2016-01-28

    Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported

  18. Neural Network Ensembles

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Salamon, Peter

    1990-01-01

    We propose several means for improving the performance an training of neural networks for classification. We use crossvalidation as a tool for optimizing network parameters and architecture. We show further that the remaining generalization error can be reduced by invoking ensembles of similar...... networks....

  19. Interval probabilistic neural network.

    Science.gov (United States)

    Kowalski, Piotr A; Kulczycki, Piotr

    2017-01-01

    Automated classification systems have allowed for the rapid development of exploratory data analysis. Such systems increase the independence of human intervention in obtaining the analysis results, especially when inaccurate information is under consideration. The aim of this paper is to present a novel approach, a neural networking, for use in classifying interval information. As presented, neural methodology is a generalization of probabilistic neural network for interval data processing. The simple structure of this neural classification algorithm makes it applicable for research purposes. The procedure is based on the Bayes approach, ensuring minimal potential losses with regard to that which comes about through classification errors. In this article, the topological structure of the network and the learning process are described in detail. Of note, the correctness of the procedure proposed here has been verified by way of numerical tests. These tests include examples of both synthetic data, as well as benchmark instances. The results of numerical verification, carried out for different shapes of data sets, as well as a comparative analysis with other methods of similar conditioning, have validated both the concept presented here and its positive features.

  20. Rethinking neural efficiency : Effects of controlling for strategy use

    NARCIS (Netherlands)

    Toffanin, Paolo; Johnson, Addie; de Jong, Ritske; Martens, Sander

    2007-01-01

    A sentence verification task (SVT) was used to test whether differences in neural activation patterns that have been attributed to IQ may actually depend on differential strategy use between IQ groups. Electroencephalograms were recorded from 14 low (89