ENHANCING THE YIELD OF HIGH-DENSITY ELECTRODE ARRAYS THROUGH AUTOMATED ELECTRODE SELECTION

2012 ◽  
Vol 22 (01) ◽  
pp. 1-19 ◽  
Author(s):  
GERT VAN DIJCK ◽  
KARSTEN SEIDL ◽  
OLIVER PAUL ◽  
PATRICK RUTHER ◽  
MARC M. VAN HULLE ◽  
...  
Keyword(s):  
Control Algorithm ◽  
Signal To Noise Ratio ◽  
Pyramidal Cells ◽  
Inhibitory Interneurons ◽  
Electrode Arrays ◽  
Signal To Noise ◽  
Detection Algorithms ◽  
Benchmark Data ◽  
Depth Control ◽  
Electrode Selection

Recently developed CMOS-based microprobes contain hundreds of electrodes on a single shaft with inter-electrode distances as small as 30 μm. So far, neuroscientists needed to select electrodes manually from hundreds of electrodes. Here we present an electronic depth control algorithm that allows to select electrodes automatically, hereby allowing to reduce the amount of data and locating those electrodes that are close to neurons. The electrodes are selected according to a new penalized signal-to-noise ratio (PSNR) criterion that demotes electrodes from becoming selected if their signals are redundant with previously selected electrodes. It is shown that, using the PSNR, interneurons generating smaller spikes are also selected. We developed a model that aims to evaluate algorithms for electronic depth control, but also generates benchmark data for testing spike sorting and spike detection algorithms. The model comprises a realistic tufted pyramidal cell, non-tufted pyramidal cells and inhibitory interneurons. All neurons are synaptically activated by hundreds of fibers. This arrangement allows the algorithms to be tested in more realistic conditions, including backgrounds of synaptic potentials, varying spike rates with bursting and spike amplitude attenuation.

scholarly journals Review of top notch electrode arrays for geoelectrical resistivity surveys

2020 ◽  
pp. 147-155
Author(s):  
Henry Ekene Ohaegbuchu ◽  
F. C. Anyadiegwu ◽  
P. O. Odoh ◽  
F. C. Orji
Keyword(s):  
Signal To Noise Ratio ◽  
Electrode Arrays ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Geoelectrical Resistivity ◽  
Depth Of Investigation ◽  
Horizontal Layers

The different arrangements of electrodes used in geoelectrical resistivity surveys and measurements are referred to as electrode arrays. In this review, we have revisited most of the widely used electrode arrays as well as the uncommon ones, which are nonetheless, useful in certain situations. This review has provided detailed information about eleven (11) of the top notch electrode arrays employable in our regular resistivity surveys, making it clear that in practice, the arrays that are most commonly used for 2-D imaging surveys are the Wenner, Dipole-Dipole, Wenner-Schlumberger, Pole-Pole and the Pole-Dipole arrays. They have their strengths and weaknesses. They are typically described by their signal-to-noise ratio. Their depth of investigation, ability for lateral location of the target and their mapping abilities of horizontal layers or steeply dipping structures among other factors determine which array to adopt.

scholarly journals Noradrenergic Suppression of Synaptic Transmission May Influence Cortical Signal-to-Noise Ratio

1997 ◽  
Vol 77 (6) ◽  
pp. 3326-3339 ◽  
Author(s):  
Michael E. Hasselmo ◽  
Christiane Linster ◽  
Madhvi Patil ◽  
Daveena Ma ◽  
Milos Cekic
Keyword(s):  
Synaptic Transmission ◽  
Signal To Noise Ratio ◽  
Afferent Fiber ◽  
Pyramidal Cells ◽  
Afferent Input ◽  
Signal To Noise ◽  
Cellular Mechanisms ◽  
Fiber Layer ◽  
Synaptic Potentials ◽  
Noise Ratio

Hasselmo, Michael E., Christiane Linster, Madhvi Patil, Daveena Ma, and Milos Cekic. Noradrenergic suppression of synaptic transmission may influence cortical signal-to-noise ratio. J. Neurophysiol. 77: 3326–3339, 1997. Norepinephrine has been proposed to influence signal-to-noise ratio within cortical structures, but the exact cellular mechanisms underlying this influence have not been described in detail. Here we present data on a cellular effect of norepinephrine that could contribute to the influence on signal-to-noise ratio. In brain slice preparations of the rat piriform (olfactory) cortex, perfusion of norepinephrine causes a dose-dependent suppression of excitatory synaptic potentials in the layer containing synapses among pyramidal cells in the cortex (layer Ib), while having a weaker effect on synaptic potentials in the afferent fiber layer (layer Ia). Effects of norepinephrine were similar in dose-response characteristics and laminar selectivity to the effects of the cholinergic agonist carbachol, and combined perfusion of both agonists caused effects similar to an equivalent concentration of a single agonist. In a computational model of the piriform cortex, we have analyzed the effect of noradrenergic suppression of synaptic transmission on signal-to-noise ratio. The selective suppression of excitatory intrinsic connectivity decreases the background activity of modeled neurons relative to the activity of neurons receiving direct afferent input. This can be interpreted as an increase in signal-to-noise ratio, but the term noise does not accurately characterize activity dependent on the intrinsic spread of excitation, which would more accurately be described as interpretation or retrieval. Increases in levels of norepinephrine mediated by locus coeruleus activity appear to enhance the influence of extrinsic input on cortical representations, allowing a pulse of norepinephrine in an arousing context to mediate formation of memories with a strong influence of environmental variables.

A Control Algorithm of LCD Dynamic Backlight Based on PSNR

2012 ◽  
Vol 241-244 ◽  
pp. 3014-3019 ◽  
Author(s):  
Xiao Bing Zhang ◽  
Xin Liu ◽  
Bo Liu ◽  
Jiang Hong Han ◽  
Hua Xia Wu
Keyword(s):  
Liquid Crystal ◽  
Image Quality ◽  
Power Consumption ◽  
Control Algorithm ◽  
Signal To Noise Ratio ◽  
Liquid Crystal Display ◽  
Gray Level ◽  
Quality Requirement ◽  
Signal To Noise

A new algorithm is proposed to adjust backlight luminance for local dimming of liquid crystal display (LCD) devices. PSNR (the peak signal-to-noise ratio) =30 is acted as the lowest standard to guarantee the quality of image in the algorithm. Based on the formula of PSNR=30, the square error value of the image distortion is gained. Then, luminance of backlight is gained dynamically by that the maximum gray level minus 1 into the formula proposed in the paper and decreases by one after each trial if the image quality requirement is not satisfied. In order to simplify the calculation, three important gray level values are selected to meet the requirements. The results show that the algorithm can greatly reduce the power consumption with guaranteeing the image quality and furthermore save much time in calculation and be better applied in hardware.

Microtube-based electrode arrays for low invasive extracellular recording with a high signal-to-noise ratio

2009 ◽  
Vol 12 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Kuniharu Takei ◽  
Takeshi Kawano ◽  
Takahiro Kawashima ◽  
Kazuaki Sawada ◽  
Hidekazu Kaneko ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Extracellular Recording ◽  
High Signal ◽  
Electrode Arrays ◽  
Signal To Noise ◽  
Noise Ratio

scholarly journals Motion tracking of iris features to detect small eye movements

2019 ◽  
Vol 12 (6) ◽  
Author(s):  
Aayush K. Chaudhary ◽  
Jeff B. Pelz
Keyword(s):  
Eye Movements ◽  
Motion Tracking ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
High Confidence ◽  
Corneal Reflection ◽  
Detection Algorithms ◽  
Pupil Center ◽  
Detailed Record ◽  
Very High

The inability of current video-based eye trackers to reliably detect very small eye movements has led to confusion about the prevalence or even the existence of monocular microsaccades (small, rapid eye movements that occur in only one eye at a time). As current methods often rely on precisely localizing the pupil and/or corneal reflection on successive frames, current microsaccade-detection algorithms often suffer from signal artifacts and a low signal-to-noise ratio. We describe a new video-based eye tracking methodology which can reliably detect small eye movements over 0.2 degrees (12 arcmin) with very high confidence. Our method tracks the motion of iris features to estimate velocity rather than position, yielding a better record of microsaccades. We provide a more robust, detailed record of miniature eye movements by relying on more stable, higher-order features (such as local features of iris texture) instead of lower-order features (such as pupil center and corneal reflection), which are sensitive to noise and drift.

scholarly journals Optimal Adaptive Electrode Selection to Maximize Simultaneously Recorded Neuron Yield

2020 ◽  
Author(s):  
John Choi ◽  
Katie Wingel ◽  
Adam Charles ◽  
Krishan Kumar ◽  
Mahdi Choudhury ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Adaptive Methods ◽  
Spike Timing ◽  
Limiting Factor ◽  
Electrode Arrays ◽  
Neural Signals ◽  
Selection Strategies ◽  
Recording Channels ◽  
Recording Channel ◽  
Electrode Selection

AbstractNeural-Matrix style, high-density electrode arrays for brain-machine interfaces (BMIs) and neuroscientific research require the use of multiplexing: Each recording channel can be routed to one of several electrode sites on the array. This capability allows the user to flexibly distribute recording channels to the locations where the most desirable neural signals can be resolved. For example, in the Neuropixel probe, 960 electrodes can be addressed by 384 recording channels. However, currently no adaptive methods exist to use recorded neural data to optimize/customize the electrode selections per recording context. Here, we present an algorithm called classification-based selection (CBS) that optimizes the joint electrode selections for all recording channels so as to maximize isolation quality of detected neurons. We show, in experiments using Neuropixels in non-human primates, that this algorithm yields a similar number of isolated neurons as would be obtained if all electrodes were recorded simultaneously. Neuron counts were 41-85% improved over previously published electrode selection strategies. The neurons isolated from electrodes selected by CBS were a 73% match, by spike timing, to the complete set of recordable neurons around the probe. The electrodes selected by CBS exhibited higher average per-recording-channel signal-to-noise ratio. CBS, and selection optimization in general, could play an important role in development of neurotechnologies for BMI, as signal bandwidth becomes an increasingly limiting factor. Code and experimental data have been made available1.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Correlation averaging of two-dimensional crystals: basic strategy and refinements

1986 ◽  
Vol 44 ◽  
pp. 136-139
Author(s):  
W. Baumeister ◽  
R. Rachel ◽  
R. Guckenberger ◽  
R. Hegerl
Keyword(s):  
Low Dose ◽  
Signal To Noise Ratio ◽  
Real Space ◽  
Fourier Domain ◽  
Two Dimensional ◽  
Signal To Noise ◽  
Unit Cells ◽  
Lateral Displacements ◽  
Established Technique ◽  
Crystalline Array

IntroductionCorrelation averaging (CAV) is meanwhile an established technique in image processing of two-dimensional crystals /1,2/. The basic idea is to detect the real positions of unit cells in a crystalline array by means of correlation functions and to average them by real space superposition of the aligned motifs. The signal-to-noise ratio improves in proportion to the number of motifs included in the average. Unlike filtering in the Fourier domain, CAV corrects for lateral displacements of the unit cells; thus it avoids the loss of resolution entailed by these distortions in the conventional approach. Here we report on some variants of the method, aimed at retrieving a maximum of information from images with very low signal-to-noise ratios (low dose microscopy of unstained or lightly stained specimens) while keeping the procedure economical.

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