scholarly journals Longevity and reliability of chronic unit recordings using the Utah, intracortical multi-electrode arrays

2021 ◽  
Author(s):  
Caleb Scheffer Sponheim ◽  
Vasileios Papadourakis ◽  
Jennifer Collinger ◽  
John Downey ◽  
Jeffrey M Weiss ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Rhesus Macaques ◽  
Human Subjects ◽  
Electrode Arrays ◽  
Computer Interfaces ◽  
Somatosensory Cortices ◽  
Large Numbers ◽  
Electrode Length ◽  
Human Participants

Abstract Objective. Microelectrode arrays are standard tools for conducting chronic electrophysiological experiments, allowing researchers to simultaneously record from large numbers of neurons. Specifically, Utah electrode arrays (UEAs) have been utilized by scientists in many species, including rodents, rhesus macaques, marmosets, and human participants. The field of clinical human brain-computer interfaces currently relies on the UEA as a number of research groups have FDA clearance for this device through the investigational device exemption pathway. Despite its widespread usage in systems neuroscience, few studies have comprehensively evaluated the reliability and signal quality of the Utah array over long periods of time in a large dataset. Approach. We collected and analyzed over 6000 recorded datasets from various cortical areas spanning almost 9 years of experiments, totaling 17 rhesus macaques (Macaca Mulatta) and 2 human subjects, and 55 separate microelectrode Utah arrays. The scale of this dataset allowed us to evaluate the average life of these arrays, based primarily on the signal-to-noise ratio of each electrode over time. Main Results. Using implants in primary motor, premotor, prefrontal, and somatosensory cortices, we found that the average lifespan of available recordings from UEAs was 622 days, although we provide several examples of these UEAs lasting over 1000 days and one up to 9 years; human implants were also shown to last longer than non-human primate implants. We also found that electrode length did not affect longevity and quality, but iridium oxide metallization on the electrode tip exhibited superior yield as compared to platinum metallization.

scholarly journals Improving electrocorticograms of awake and anaesthetized mice using wavelet denoising

2018 ◽  
Vol 4 (1) ◽  
pp. 469-472 ◽  
Author(s):  
Michael Schweigmann ◽  
Klaus Peter Koch ◽  
Fabian Auler ◽  
Frank Kirchhoff
Keyword(s):  
Signal To Noise Ratio ◽  
Wavelet Denoising ◽  
Functional Evaluation ◽  
Electrode Impedance ◽  
Electrode Arrays ◽  
Brain Surface ◽  
Micro Electrode Arrays ◽  
Cellular Circuits ◽  
Noise Models

AbstractThe quality of bioelectrical signals is essential for functional evaluation of cellular circuits. The electrical activity recorded from the cortical brain surface represents the average of many individual synaptic processes. By downsizing micro-electrode arrays, the spatial resolution of electrocortico-grams (ECoGs) can be increased. But, upon increasing electrode impedance, recorded noise from the electrode-tissue interface and the surroundings will become more prominent. Frequently, signal interpretation is improved by post-processing using filtering or pattern recognition. For a variety of applications, wavelet denoising has become an accepted tool. Here, we present how wavelet denoising affects the signal-to-noise ratio of ECoGs. The recording qualities from awake and anesthetized mice was artificially reduced by adding two noise models prior to filtering. Raw and filtered signals were compared by calculating the linear correlation coefficient.

scholarly journals Comparative Psychopathology: Connecting Comparative and Clinical Psychology

2017 ◽  
Vol 30 ◽  
Author(s):  
Terry L. Maple ◽  
Valerie Segura
Keyword(s):  
Animal Studies ◽  
Rhesus Macaques ◽  
Human Subjects ◽  
Good Reason ◽  
Maladaptive Behavior ◽  
Know How ◽  
Hypothetical Construct ◽  
Self Actualization ◽  
Aberrant Behaviors

The animal welfare movement was empowered by decades of animal studies focused on the ontogeny of psychopathology in non-human primates and other species. When H.F. Harlow induced aberrant behaviors in rhesus macaques, collaborators began the search for effective behavioral and psychopharmacological interventions. Years later, working with human subjects in his clinical practice, Harlow’s first graduate student, A.H. Maslow developed a “Hierarchy of Needs” and the hypothetical construct of self-actualization. Following Harlow’s practice of using human models to design monkey studies, present day psychologists apply what is known about maladaptive behavior and the factors that facilitate positive human behavior to improve the quality of life for non-human taxa living in captive settings. We know how to prevent psychopathology in monkeys and apes but nonhuman primates are still confined in restricted, substandard facilities that introduce trauma and suffering. Felids, ursids, elephants and cetaceans have also suffered this fate. As a result, there is good reason for clinical and comparative psychologists to collaborate to ameliorate aberrant behaviors while creating conditions that enable all captive animals to thrive.

Pre-Processing of Hyperspectral Images Using Nonlinear Filters

2013 ◽  
Vol 11 (1) ◽  
pp. 8-13
Author(s):  
V. Behar ◽  
V. Bogdanova
Keyword(s):  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Hyperspectral Images ◽  
Spectral Correlation ◽  
Edge Preserving ◽  
Improvement Factor ◽  
Filter Output ◽  
Average Improvement ◽  
Processing Procedure

Abstract In this paper the use of a set of nonlinear edge-preserving filters is proposed as a pre-processing stage with the purpose to improve the quality of hyperspectral images before object detection. The capability of each nonlinear filter to improve images, corrupted by spatially and spectrally correlated Gaussian noise, is evaluated in terms of the average Improvement factor in the Peak Signal to Noise Ratio (IPSNR), estimated at the filter output. The simulation results demonstrate that this pre-processing procedure is efficient only in case the spatial and spectral correlation coefficients of noise do not exceed the value of 0.6

Image Quality Enhancing by Efficient Histogram Equalization

2014 ◽  
Vol 2 (2) ◽  
pp. 47-58
Author(s):  
Ismail Sh. Baqer
Keyword(s):  
Image Quality ◽  
Contrast Enhancement ◽  
Mean Squared Error ◽  
Signal To Noise Ratio ◽  
Histogram Equalization ◽  
Gray Level ◽  
Signal To Noise ◽  
Squared Error ◽  
Noise Ratio

A two Level Image Quality enhancement is proposed in this paper. In the first level, Dualistic Sub-Image Histogram Equalization DSIHE method decomposes the original image into two sub-images based on median of original images. The second level deals with spikes shaped noise that may appear in the image after processing. We presents three methods of image enhancement GHE, LHE and proposed DSIHE that improve the visual quality of images. A comparative calculations is being carried out on above mentioned techniques to examine objective and subjective image quality parameters e.g. Peak Signal-to-Noise Ratio PSNR values, entropy H and mean squared error MSE to measure the quality of gray scale enhanced images. For handling gray-level images, convenient Histogram Equalization methods e.g. GHE and LHE tend to change the mean brightness of an image to middle level of the gray-level range limiting their appropriateness for contrast enhancement in consumer electronics such as TV monitors. The DSIHE methods seem to overcome this disadvantage as they tend to preserve both, the brightness and contrast enhancement. Experimental results show that the proposed technique gives better results in terms of Discrete Entropy, Signal to Noise ratio and Mean Squared Error values than the Global and Local histogram-based equalization methods

Singular Values Decomposition and Lifting Wavelet Transform for Speech Signal Embedding into Digital Image

2019 ◽  
Vol 12 (2) ◽  
pp. 138-151
Author(s):  
Mourad Talbi ◽  
Med Salim Bouhlel
Keyword(s):  
Wavelet Transform ◽  
Speech Signal ◽  
Signal To Noise Ratio ◽  
Perceptual Quality ◽  
Lifting Wavelet Transform ◽  
Signal To Noise ◽  
Perceptual Evaluation ◽  
Lifting Wavelet ◽  
Noise Ratio

Background: In this paper, we propose a secure image watermarking technique which is applied to grayscale and color images. It consists in applying the SVD (Singular Value Decomposition) in the Lifting Wavelet Transform domain for embedding a speech image (the watermark) into the host image. Methods: It also uses signature in the embedding and extraction steps. Its performance is justified by the computation of PSNR (Pick Signal to Noise Ratio), SSIM (Structural Similarity), SNR (Signal to Noise Ratio), SegSNR (Segmental SNR) and PESQ (Perceptual Evaluation Speech Quality). Results: The PSNR and SSIM are used for evaluating the perceptual quality of the watermarked image compared to the original image. The SNR, SegSNR and PESQ are used for evaluating the perceptual quality of the reconstructed or extracted speech signal compared to the original speech signal. Conclusion: The Results obtained from computation of PSNR, SSIM, SNR, SegSNR and PESQ show the performance of the proposed technique.

Scoundrels or Stars? Theory and Evidence on the Quality of Workers in Online Labor Markets

2016 ◽  
Vol 92 (1) ◽  
pp. 93-114 ◽  
Author(s):  
Anne M. Farrell ◽  
Jonathan H. Grenier ◽  
Justin Leiby
Keyword(s):  
Labor Markets ◽  
Data Availability ◽  
Accounting Research ◽  
Research Participants ◽  
Large Numbers ◽  
Research Designs ◽  
Online Labor Markets ◽  
Online Labor ◽  
Low Pay

ABSTRACT Online labor markets allow rapid recruitment of large numbers of workers for very low pay. Although online workers are often used as research participants, there is little evidence that they are motivated to make costly choices to forgo wealth or leisure that are often central to addressing accounting research questions. Thus, we investigate the validity of using online workers as a proxy for non-experts when accounting research designs use more demanding tasks than these workers typically complete. Three experiments examine the costly choices of online workers relative to student research participants. We find that online workers are at least as willing as students to make costly choices, even at significantly lower wages. We also find that online workers are sensitive to performance-based wages, which are just as effective in inducing high effort as high fixed wages. We discuss implications of our results for conducting accounting research with online workers. Data Availability: Contact the authors.

scholarly journals 3D DCT Based Image Compression Method for the Medical Endoscopic Application

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1817
Author(s):  
Jiawen Xue ◽  
Li Yin ◽  
Zehua Lan ◽  
Mingzhu Long ◽  
Guolin Li ◽  
...  
Keyword(s):  
Image Compression ◽  
Compression Ratio ◽  
Signal To Noise Ratio ◽  
Blocking Artifacts ◽  
Compression Method ◽  
High Compression Ratio ◽  
Multiplication Operation ◽  
3D Data ◽  
Wireless Capsule

This paper proposes a novel 3D discrete cosine transform (DCT) based image compression method for medical endoscopic applications. Due to the high correlation among color components of wireless capsule endoscopy (WCE) images, the original 2D Bayer data pattern is reconstructed into a new 3D data pattern, and 3D DCT is adopted to compress the 3D data for high compression ratio and high quality. For the low computational complexity of 3D-DCT, an optimized 4-point DCT butterfly structure without multiplication operation is proposed. Due to the unique characteristics of the 3D data pattern, the quantization and zigzag scan are ameliorated. To further improve the visual quality of decompressed images, a frequency-domain filter is proposed to eliminate the blocking artifacts adaptively. Experiments show that our method attains an average compression ratio (CR) of 22.94:1 with the peak signal to noise ratio (PSNR) of 40.73 dB, which outperforms state-of-the-art methods.

Animal Models and Alternatives in the Quality Control of Vaccines: Are In Vitro Methods or In Vivo Methods the Scientific Equivalent of the Emperor's New Clothes?

1995 ◽  
Vol 23 (1) ◽  
pp. 61-73
Author(s):  
Coenraad Hendriksen ◽  
Johan van der Gun
Keyword(s):  
Quality Control ◽  
Test Methods ◽  
In Vitro Test ◽  
Large Numbers ◽  
Alternative Approach ◽  
Inactivated Vaccines ◽  
Vitro Test

In the quality control of vaccine batches, the potency testing of inactivated vaccines is one of the areas requiring very large numbers of animals, which usually suffer significant distress as a result of the experimental procedures employed. This article deals with the potency testing of diphtheria and tetanus toxoids, two vaccines which are used extensively throughout the world. The relevance of the potency test prescribed by the European Pharmacopoeia monographs is questioned. The validity of the potency test as a model for the human response, the ability of the test to be standardised, and the relevance of the test in relation to the quality of the product are discussed. It is concluded that the potency test has only limited predictive value for the antitoxin responses to be expected in recipients of these toxoids. An alternative approach for estimating the potency of toxoid batches is discussed, in which a distinction is made between estimation of the immunogenic potency of the first few batches obtained from a seed lot and monitoring the consistency of the quality of subsequent batches. The use of animals is limited to the first few batches. Monitoring the consistency of the quality of subsequent batches is based on in vitro test methods. Factors which hamper the introduction and acceptance of the alternative approach are considered. Finally, proposals are made for replacement, reduction and/or refinement (the Three Rs) in the use of animals in the routine potency testing of toxoids.

scholarly journals Understanding PI-QUAL for prostate MRI quality: a practical primer for radiologists

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Giganti ◽  
Alex Kirkham ◽  
Veeru Kasivisvanathan ◽  
Marianthi-Vasiliki Papoutsaki ◽  
Shonit Punwani ◽  
...  
Keyword(s):  
Diffusion Weighted Imaging ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Diagnostic Quality ◽  
Prostate Mri ◽  
Prostate Imaging ◽  
Dynamic Contrast Enhanced ◽  
Diffusion Weighted ◽  
Contrast Enhanced

AbstractProstate magnetic resonance imaging (MRI) of high diagnostic quality is a key determinant for either detection or exclusion of prostate cancer. Adequate high spatial resolution on T2-weighted imaging, good diffusion-weighted imaging and dynamic contrast-enhanced sequences of high signal-to-noise ratio are the prerequisite for a high-quality MRI study of the prostate. The Prostate Imaging Quality (PI-QUAL) score was created to assess the diagnostic quality of a scan against a set of objective criteria as per Prostate Imaging-Reporting and Data System recommendations, together with criteria obtained from the image. The PI-QUAL score is a 1-to-5 scale where a score of 1 indicates that all MR sequences (T2-weighted imaging, diffusion-weighted imaging and dynamic contrast-enhanced sequences) are below the minimum standard of diagnostic quality, a score of 3 means that the scan is of sufficient diagnostic quality, and a score of 5 implies that all three sequences are of optimal diagnostic quality. The purpose of this educational review is to provide a practical guide to assess the quality of prostate MRI using PI-QUAL and to familiarise the radiologist and all those involved in prostate MRI with this scoring system. A variety of images are also presented to demonstrate the difference between suboptimal and good prostate MR scans.

scholarly journals Brain tissue transcriptomic analysis of SIV-infected macaques identifies several altered metabolic pathways linked to neuropathogenesis and poly (ADP-ribose) polymerases (PARPs) as potential therapeutic targets

2021 ◽  
Author(s):  
Carla Mavian ◽  
Andrea S. Ramirez-Mata ◽  
James Jarad Dollar ◽  
David J. Nolan ◽  
Melanie Cash ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Rhesus Macaques ◽  
Lymphocyte Depletion ◽  
Brain Infection ◽  
Immunodeficiency Virus ◽  
Significant Enrichment ◽  
Siv Infection ◽  
Polymerase Chain

Abstract Despite improvements in antiretroviral therapy, human immunodeficiency virus type 1 (HIV-1)-associated neurocognitive disorders (HAND) remain prevalent in subjects undergoing therapy. HAND significantly affects individuals’ quality of life, as well as adherence to therapy, and, despite the increasing understanding of neuropathogenesis, no definitive diagnostic or prognostic marker has been identified. We investigated transcriptomic profiles in frontal cortex tissues of Simian immunodeficiency virus (SIV)-infected Rhesus macaques sacrificed at different stages of infection. Gene expression was compared among SIV-infected animals (n = 11), with or without CD8+ lymphocyte depletion, based on detectable (n = 6) or non-detectable (n = 5) presence of the virus in frontal cortex tissues. Significant enrichment in activation of monocyte and macrophage cellular pathways was found in animals with detectable brain infection, independently from CD8+ lymphocyte depletion. In addition, transcripts of four poly (ADP-ribose) polymerases (PARPs) were up-regulated in the frontal cortex, which was confirmed by real-time polymerase chain reaction. Our results shed light on involvement of PARPs in SIV infection of the brain and their role in SIV-associated neurodegenerative processes. Inhibition of PARPs may provide an effective novel therapeutic target for HIV-related neuropathology.

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