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Micro, Nano, and Molecular Systems Article Ultrasound-assisted cyanide extraction of gold from gold concentrate at low temperature Yu, S., Yu, T., Song, W., Yu, X., Qiao, J., Wang, W., Dong, H., Wu, Z., Dai, L., Li, T. Ultrasonics Sonochemistry, 64:105039, 2020 (Published) DOI BibTeX
Physical Intelligence Bioinspired Autonomous Miniature Robots Article Ultrasound-guided wireless tubular robotic anchoring system Wang, T., Hu, W., Ren, Z., Sitti, M. IEEE Robotics and Automation Letters, 5(3):4859-4866, IEEE, 2020 DOI URL BibTeX
Article Unusual Iron Nitride Formation Upon Nitriding Fe-Si Alloy Meka, S. R., Schubert, A., Bischoff, E., Mittemeijer, E. J. Metallurgical and Materials Transactions A, 51(6):3154-3166, Springer Sciences & Business Media, New York, NY, 2020 DOI BibTeX
Materials Article Very low-temperature growth of few-layer graphene by Ni-induced crystallization of amorphous carbon in vacuum Chen, Y., Wang, J., Schützendübe, P., Wang, Z., Mittemeijer, E. J. Carbon, 159:37-44, Elsevier, Amsterdam, 2020 DOI BibTeX
Embodied Vision Article Visual-Inertial Mapping with Non-Linear Factor Recovery Usenko, V., Demmel, N., Schubert, D., Stückler, J., Cremers, D. IEEE Robotics and Automation Letters (RA-L), 5(2):422-429, 2020, presented at IEEE International Conference on Robotics and Automation (ICRA) 2020, preprint arXiv:1904.06504 (Published)
Cameras and inertial measurement units are complementary sensors for ego-motion estimation and environment mapping. Their combination makes visual-inertial odometry (VIO) systems more accurate and robust. For globally consistent mapping, however, combining visual and inertial information is not straightforward. To estimate the motion and geometry with a set of images large baselines are required. Because of that, most systems operate on keyframes that have large time intervals between each other. Inertial data on the other hand quickly degrades with the duration of the intervals and after several seconds of integration, it typically contains only little useful information. In this paper, we propose to extract relevant information for visual-inertial mapping from visual-inertial odometry using non-linear factor recovery. We reconstruct a set of non-linear factors that make an optimal approximation of the information on the trajectory accumulated by VIO. To obtain a globally consistent map we combine these factors with loop-closing constraints using bundle adjustment. The VIO factors make the roll and pitch angles of the global map observable, and improve the robustness and the accuracy of the mapping. In experiments on a public benchmark, we demonstrate superior performance of our method over the state-of-the-art approaches.
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Physical Intelligence Locomotion in Biorobotic and Somatic Systems Article Wearable and stretchable strain sensors: materials, sensing mechanisms, and applications Souri, H., Banerjee, H., Jusufi, A., Radacsi, N., Stokes, A. A., Park, I., Sitti, M., Amjadi, M. Advanced Intelligent Systems, 2(8):2000039, 2020 DOI URL BibTeX
Theory of Inhomogeneous Condensed Matter Article Wetting transitions on soft substrates Napiorkowski, M., Schimmele, L., Dietrich, S. EPL, 129(1):16002, EDP Science, Les-Ulis, 2020 DOI BibTeX
Physical Intelligence Article Zwitterionic 3D‐printed non‐immunogenic stealth microrobots Cabanach, P., Pena-Francesch, A., Sheehan, D., Bozuyuk, U., Yasa, O., Borros, S., Sitti, M. Advanced Materials, 32(42):2003013, 2020 DOI URL BibTeX
Empirical Inference Article sbi: A toolkit for simulation-based inference Tejero-Cantero, A., Boelts, J., Deistler, M., Lueckmann, J., Durkan, C., Gonçalves, P. J., Greenberg, D. S., Macke, J. H. Journal of Open Source Software, 5(52):article no. 2505, 2020 (Published) DOI BibTeX
Miscellaneous 19F MR-based Quantitative Method for Determination of Ca(II) Using Lanthanide Complexes Gambino, G., Gambino, T., Pohmann, R., Angelovski, G. 15th European Molecular Imaging Meeting (EMIM 2020), 2020 BibTeX
Miscellaneous 31P Transversal Relaxation Times in the Human Brain at 9.4T Dorst, J., Borbath, T., Ruhm, L., Avdievich, N., Henning, A. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 2020
{31P transversal relaxation times in the human brain at 9.4T are reported. These values are useful to optimize measurement protocols, and to perform absolute quantification. Measurements were performed using a STEAM sequence. To account for J-evolution of homonuclear spin-spin coupled metabolites, basis sets were modeled in VeSPA and spectra were fitted in LCModel. The measured T2 relaxation times are between 93ms and 116ms for phosphomonoesters and \textendashdiesters and PCr, and between 25ms and 45ms for Piintra, ATP and tNAD.}
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Miscellaneous 4D-MRI of Thorax and Abdomen with Variable Contrast at 1.5T Pusterla, O., Santini, F., Bauman, G., Heule, R., Giger, A., Cattin, P., Safai, S., Kozerke, S., Bieri, O. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 2020
{Time-resolved volumetric imaging (4D-MRI) of moving organs is essential for several clinical applications, e.g., in interventional treatments, radiation therapies, and high-intensity focused ultrasound ablations. In this work, an interleaved time-resolved data-navigator acquisition strategy for 4D-MRI with flexible contrast is developed offering versatile settings for thoracic and abdominal imaging: for both, image and navigator, not only the flip angle but also the basic acquisition type (pulse sequence kernel) can be chosen independently from either balanced SSFP (i.e., T2/T1-weighted) or spoiled gradient echo (i.e., T1-weighted).}
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Conference Paper A 2-DoF Helicopter Haptic Support System based on Pilot Intent Estimation with Neural Networks D\textquotesingleIntino, G., Pollini, L., Bülthoff, H. In Modeling and Simulation Technologies: Papers Presented at the AIAA SciTech Forum and Exposition 2020, 84-95, Curran, Orlando, FL, USA, 2020
{Control of a helicopter is a highly demanding task for the human operator, due to its unstable and coupled dynamics. Indeed, the pilot is required to constantly give inputs on the control device that are necessary to both move the vehicle towards a specific direction and, at the same time, to stabilize the system dynamics. Haptic support systems may be used as an alternative solution to help pilots in such demanding task. Design of an effective haptic system requires knowledge of the target trajectory. However, in many realistic scenarios, the target trajectory is not known in advance. For instance, in a helicopter free-flight task the pilot is free to choose any possible maneuver at any time, and the pilot intended trajectory cannot be known a priori. To provide the pilot with a haptic feedback that helps him/her to accomplish the intended maneuver, estimation of pilot intended trajectory is crucial. In this paper, a neural network approach is proposed to infer pilot intent based on data collected from maneuvers performed by an expert helicopter pilot, in a 2-DoF lateral/longitudinal scenario. Successively, a haptic feedback is designed to help the pilots to accomplish the intended trajectories. The proposed shared control system is evaluated in a human-in-the-loop experiment with minimally-trained participants in a fixed-base simulator. The participants performed a flight control task which included diagonal, lateral and longitudinal motions. Each participant performed the maneuver in two different conditions: with and without haptic feedback. Results showed effectiveness of the haptic feedback on participants performance compared to manual control.}
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Article A 32-channel multi-coil setup optimized for human brain shimming at 9.4T Aghaeifar, A., Zhou, J., Heule, R., Tabibian, B., Schölkopf, B., Jia, F., Zaitsev, M., Scheffler, K. {Magnetic Resonance in Medicine}, 83(2):749-764, Wiley-Liss, New York, 2020
{Purpose A multi-coil shim setup is designed and optimized for human brain shimming. Here, the size and position of a set of square coils are optimized to improve the shim performance without increasing the number of local coils. Utilizing such a setup is especially beneficial at ultrahigh fields where B0 inhomogeneity in the human brain is more severe. Methods The optimization started with a symmetric arrangement of 32 independent coils. Three parameters per coil were optimized in parallel, including angular and axial positions on a cylinder surface and size of the coil, which were constrained by cylinder size, construction consideration, and amplifiers specifications. B0 maps were acquired at 9.4T in 8 healthy volunteers for use as training data. The global and dynamic shimming performance of the optimized multi-coil were compared in simulations and measurements to a symmetric design and to the scanner\textquotesingles second-order shim setup, respectively. Results The optimized multi-coil performs better by 14.7\textpercent based on standard deviation (SD) improvement with constrained global shimming in comparison to the symmetric positioning of the coils. Global shimming performance was comparable with a symmetric 65-channel multi-coil and full fifth-order spherical harmonic shim coils. On average, an SD of 48.4 and 31.9 Hz was achieved for in vivo measurements after global and dynamic slice-wise shimming, respectively. Conclusions An optimized multi-coil shim setup was designed and constructed for human whole-brain shimming. Similar performance of the multi-coils with many channels can be achieved with a fewer number of channels when the coils are optimally arranged around the target.}
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Miscellaneous A Mathematical Model to Predict the Spread of COVID-19 in a Population and Evaluate the Effectiveness of Containment Strategies Bokharaie, V. 2020
{The available data on the spread of COVID-19 in China has been used to estimate the parameters of epidemiological models in a population stratified based on age distribution. The models can then be adapted and used for other countries or populations with different age distributions. The resulting models can be used to calculate the trajectory of the spread of the disease in various age groups in different countries. More importantly, it can be used to predict the effects of different containment strategies on the spread of COVID-19.}
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Miscellaneous A Methodological Checklist for fMRI Drug Cue Reactivity Studies: Development and Expert Consensus Ekhtiari, H., Zare-Bidoky, M., Sangchooli, A., Janes, A., Kaufman, M., Oliver, J., Prisciandaro, J., Wüstenberg, T., Anton, R., Bach, P., Baldacchino, A., Beck, A., Bjork, J., Brewer, J., Childress, A., Claus, E., Courtney, K., Ebrahimi, M., Filbey, F., Ghahremani, D., et al. 2020
{Background Cue reactivity is one of the most frequently used paradigms in functional magnetic resonance imaging (fMRI) studies of substance use disorders (SUDs). Although there have been many promising results elucidating the neurocognitive mechanisms of SUDs and SUD treatments, heterogeneities in participant characteristics, task design, craving assessment, scanning preparation and analysis decisions limit rigor and reproducibility in the field of fMRI of drug cue reactivity (FDCR), hampering clinical translation and synthesis by systematic reviews and meta-analyses. The aim of this consensus paper and Delphi study is to outline the important methodological aspects of FDCR studies and present a list of items and recommendations that should be taken into account when designing FDCR studies and reporting their results. Methods Fifty-five FDCR scientists from around the world participated. First, an initial checklist of items deemed important in FDCR studies was developed by a group of members from the ENIGMA Addiction Consortium based on a systematic review. Then, using a modified Delphi consensus method, all experts were asked to comment on, revise or add items to the initial checklist. Subsequently, experts were asked to rate the importance of the items. Results Thirty-seven items were proposed in the first round. After the commenting phase, seven new items suggested by experts were added and six were removed. The final 38 items that reached a defined consensus threshold in the rating phase were classified under seven categories and are considered important for conducting and reporting in any FDCR study. Conclusion This paper proposes a list of items and additional recommendations that researchers in the field of FDCR are encouraged to note and report when designing an FDCR study and reporting its results. Along with the presentation of a quality control checklist with Yes/No ratable items, various challenges in moving towards greater homogeneity in FDCR research and widespread use of FDCR to investigate SUDs and develop clinically relevant biomarkers are discussed.}
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Miscellaneous A Review of known properties of von Economo Neurons (VENs) Bokharaie, V. 2020 BibTeX
Miscellaneous A Stratified Model to Quantify the Effects of Containment Policies on the Spread of COVID-19 Bokharaie, V. 2020
{In this manuscript, a method is presented that can be used to predict the spread of COVID-19 in any country and under any containment policy imposed separately on different groups in the population. The method tunes the parameters of a known stratified model based on the available data on the spread of COVID-19. The model includes a set of nonlinear ordinary differential equations and is easy to simulate and easy to understand. As it is presented in this manuscript, the population is divided into age-groups. But given the availability of the data, there is no reason to limit the stratification into only age-groups and we can consider any relevant groups. To estimate the parameters of the model such that it reflects the characteristics of the spread of COVID-19 in a population, the method relies on an optimisation scheme. More specifically, the optimisation scheme estimates the contact rates between different age groups in the population. But a very important and useful feature of the model is that the estimated parameters for one population can be translated and used for any other population with a known age-structure, which in this day and age, includes almost any country or city in the world. Also, it is shown that the method is quite insensitive to the underlying assumptions in the optimisation scheme and also to deliberate or non-deliberate errors that might have occurred in collecting the data.}
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Article A community-based transcriptomics classification and nomenclature of neocortical cell types Yuste, R., Hawrylycz, M., Aalling, N., Arendt, D., Armananzas, R., Ascoli, G., Bielza, C., Bokharaie, V., Bergmann, T., Bystron, I., Capogna, M., Chang, Y., Clemens, A., de Kock, C., DeFelipe, J., Dos Santos, S., Dunville, K., Feldmeyer, D., Fiáth, R., Fishell, G., et al. {Nature Neuroscience}, 23(12):1456-1468, Nature America Inc., New York, NY, 2020
{To understand the function of cortical circuits, it is necessary to catalog their cellular diversity. Past attempts to do so using anatomical, physiological or molecular features of cortical cells have not resulted in a unified taxonomy of neuronal or glial cell types, partly due to limited data. Single-cell transcriptomics is enabling, for the first time, systematic high-throughput measurements of cortical cells and generation of datasets that hold the promise of being complete, accurate and permanent. Statistical analyses of these data reveal clusters that often correspond to cell types previously defined by morphological or physiological criteria and that appear conserved across cortical areas and species. To capitalize on these new methods, we propose the adoption of a transcriptome-based taxonomy of cell types for mammalian neocortex. This classification should be hierarchical and use a standardized nomenclature. It should be based on a probabilistic definition of a cell type and incorporate data from different approaches, developmental stages and species. A community-based classification and data aggregation model, such as a knowledge graph, could provide a common foundation for the study of cortical circuits. This community-based classification, nomenclature and data aggregation could serve as an example for cell type atlases in other parts of the body.}
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Article A ratiometric 19F MR-based method for the quantification of Ca2+ using responsive paramagnetic probes Gambino, G., Gambino, T., Pohmann, R., Angelovski, G. {Chemical Communications}, 56(24):3492-3495, Royal Society of Chemistry, Cambridge, UK, 2020
{We present a method for assessing the extracellular calcium concentration using 19F chemical shift imaging. Specifically, a custom made calcium-responsive and lanthanide-based 19F MRI probe that undergoes a strong and highly specific modulation of its signal upon coordination with calcium ions was developed and its performance is presented.}
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Conference Paper A theory of independent mechanisms for extrapolation in generative models Besserve, M., Sun, R., Janzing, D., Schölkopf, B. In 35th AAAI Conference on Artificial Intelligence: A Virtual Conference, 2020
{Deep generative models reproduce complex empirical data but cannot extrapolate to novel environments. An intuitive idea to promote extrapolation capabilities is to enforce the architecture to have the modular structure of a causal graphical model, where one can intervene on each module independently of the others in the graph. We develop a framework to formalize this intuition, using the principle of Independent Causal Mechanisms, and show how over-parameterization of generative neural networks can hinder extrapolation capabilities. Our experiments on the generation of human faces shows successive layers of a generator architecture implement independent mechanisms to some extent, allowing meaningful extrapolations. Finally, we illustrate that independence of mechanisms may be enforced during training to improve extrapolation.}
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Miscellaneous ACC single unit and neuronal population correlates of response conflict versus and error detection in a novel rodent near mistake paradigm Iwai, R., Vinogradov, O., Logothetis, N., Levina, A., Totah, N. AREADNE 2020: Research in Encoding and Decoding of Neural Ensembles, 20, The AREADNE Foundation, Cambridge, MA, USA, 2020
{It is debated whether the anterior cingulate cortex (ACC) detects errors or response conflict because population (EEG) measures support both accounts. One way to disambiguate conflict and errors is to measure near mistakes which, in humans, consist of moving but stopping before a threshold (e.g., pressing a key in response to a NoGo stimulus). Near mistake movement magnitude correlates with conflict magnitude; thus, it is a tool for studying neuronal correlates of conflict, which should scale with movement magnitude. Here, we demonstrate near mistakes in head-fixed rats on a treadmill as they discriminate Go and NoGo visual orientation gratings by remaining immobile (NoGo) or running past a distance threshold (Go). Variable near mistake velocities allowed us to study encoding of conflict and errors at the single cell level. We tested the hypothesis that conflict-encoding single units would scale firing rate with conflict magnitude (i.e., near mistake running velocity), but would not respond to error feedback (noise burst).}
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Miscellaneous AI boosted molecular MRI for apoptosis detection in oncolytic virotherapy Perlman, O., Ito, H., Herz, K., Shono, N., Nakashima, H., Zaiss, M., Chiocca, A., Cohen, O., Rosen, M., Farrar, C. 2020
{Oncolytic virotherapy is a promising treatment for high mortality cancers1. Non-invasive imaging of the underlying molecular processes is an essential tool for therapy optimization and assessment of viral spread, innate immunity, and therapeutic response2, 3. However, previous methods for imaging oncolytic viruses did not correlate with late viral activity4 or had poor sensitivity and specificity5. Similarly, methods developed to image treatment response, such as apoptosis, proved to be slow, nonspecific, or require the use of radioactive or metal-based contrast agents6\textendash8. To date, no method has been widely adopted for clinical use. We describe here a new method for fast magnetic resonance molecular imaging with quantitative proton chemical-exchange specificity to monitor oncolytic virotherapy treatment response. A deep neural network enabled the computation of quantitative biomarker maps of protein and lipid/macromolecule concentrations as well as intracellular pH in a glioblastoma multiforme mouse brain tumor model. Early detection of apoptotic response to oncolytic virotherapy, characterized by decreased cytosolic pH and protein synthesis, was observed in agreement with histology. Clinical translation was demonstrated in a normal human subject, yielding molecular parameters in good agreement with literature values9. The developed method is directly applicable to a wide range of pathologies, including stroke10, cancer11\textendash13, and neurological disorders14, 15.}
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Article Accelerating the Evolution of Nonhuman Primate Neuroimaging Milham, M., Petkov, C., Margulies, D., Schroeder, C., Basso, M., Belin, P., Fair, D., Fox, A., Kastner, S., Mars, R., Messinger, A., Poirier, C., Vanduffel, W., Van Essen, D., Alvand, A., Becker, Y., Ben Hamed, S., Benn, A., Bodin, C., Boretius, S., et al. {Neuron}, 105(4):600-603, Cell Press, Cambridge, Mass., 2020
{Nonhuman primate neuroimaging is on the cusp of a transformation, much in the same way its human counterpart was in 2010, when the Human Connectome Project was launched to accelerate progress. Inspired by an open data-sharing initiative, the global community recently met and, in this article, breaks through obstacles to define its ambitions.}
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Miscellaneous Acquisition-weighted MR Current Density Imaging (AW-MRCDI) improves sensitivity and spatial resolution Göksu, C., Hanson, L., Gregersen, F., Scheffler, K., Thielscher, A. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 2020
{Exact knowledge of currents flowing inside the human brain is important for several neuroscientific applications. MRCDI combines MR with externally injected weak currents, and uses measurements of the current-induced magnetic field to estimate spatial current distribution. The method\textquoterights accuracy highly depends on the sensitivity and spatial resolution of the field measurements. Here, we improve the currently most sensitive MRCDI method based on steady-state free precession free induction decay (SSFP-FID) by using an acquisition-weighted scheme (AW-MRCDI). We compared weighted and conventional schemes by phantom experiments. AW-MRCDI demonstrated 59\textpercent increase in sensitivity and significantly improved the spatial resolution.}
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Article Addiction Research Consortium: Losing and regaining control over drug intake (ReCoDe)-From trajectories to mechanisms and interventions Heinz, A., Kiefer, F., Smolka, M., Endrass, T., Beste, C., Beck, A., Liu, S., Genauck, A., Romund, L., Banaschewski, T., Bermpohl, F., Derserno, L., Dolan, R., Durstewitz, D., Ebner-Priemer, U., Flor, H., Hansson, A., Heim, C., Hermann, D., Kiebel, S., et al. {Addiction Biology}, 25(2):1-6, Carfax, Abingdon, Oxfordshire, UK, 2020
{One of the major risk factors for global death and disability is alcohol, tobacco, and illicit drug use. While there is increasing knowledge with respect to individual factors promoting the initiation and maintenance of substance use disorders (SUDs), disease trajectories involved in losing and regaining control over drug intake (ReCoDe) are still not well described. Our newly formed German Collaborative Research Centre (CRC) on ReCoDe has an interdisciplinary approach funded by the German Research Foundation (DFG) with a 12-year perspective. The main goals of our research consortium are (i) to identify triggers and modifying factors that longitudinally modulate the trajectories of losing and regaining control over drug consumption in real life, (ii) to study underlying behavioral, cognitive, and neurobiological mechanisms, and (iii) to implicate mechanism-based interventions. These goals will be achieved by: (i) using mobile health (m-health) tools to longitudinally monitor the effects of triggers (drug cues, stressors, and priming doses) and modify factors (eg, age, gender, physical activity, and cognitive control) on drug consumption patterns in real-life conditions and in animal models of addiction; (ii) the identification and computational modeling of key mechanisms mediating the effects of such triggers and modifying factors on goal-directed, habitual, and compulsive aspects of behavior from human studies and animal models; and (iii) developing and testing interventions that specifically target the underlying mechanisms for regaining control over drug intake.}
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Article Adversarial vulnerabilities of human decision-making Dezfouli, A., Nock, R., Dayan, P. {Proceedings of the National Academy of Sciences of the United States of America}, 117(46):29221-29228, National Academy of Sciences, Washington, D.C., 2020
{Adversarial examples are carefully crafted input patterns that are surprisingly poorly classified by artificial and/or natural neural networks. Here we examine adversarial vulnerabilities in the processes responsible for learning and choice in humans. Building upon recent recurrent neural network models of choice processes, we propose a general framework for generating adversarial opponents that can shape the choices of individuals in particular decision-making tasks toward the behavioral patterns desired by the adversary. We show the efficacy of the framework through three experiments involving action selection, response inhibition, and social decision-making. We further investigate the strategy used by the adversary in order to gain insights into the vulnerabilities of human choice. The framework may find applications across behavioral sciences in helping detect and avoid flawed choice.}
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Article An Open Resource for Non-human Primate Optogenetics Tremblay, S., Acker, L., Afraz, A., Albaugh, D., Amita, H., Andrei, A., Angelucci, A., Aschner, A., Balan, P., Basso, M., Benvenuti, G., Bohlen, M., Caiola, M., Calcedo, R., Cavanaugh, J., Chen, Y., Chernov, M., Clark, A., Dai, J., Debes, S., et al. {Neuron}, 108(6):1075-1090, Cell Press, Cambridge, Mass., 2020
{Optogenetics has revolutionized neuroscience in small laboratory animals, but its effect on animal models more closely related to humans, such as non-human primates (NHPs), has been mixed. To make evidence-based decisions in primate optogenetics, the scientific community would benefit from a centralized database listing all attempts, successful and unsuccessful, of using optogenetics in the primate brain. We contacted members of the community to ask for their contributions to an open science initiative. As of this writing, 45 laboratories around the world contributed more than 1,000 injection experiments, including precise details regarding their methods and outcomes. Of those entries, more than half had not been published. The resource is free for everyone to consult and contribute to on the Open Science Framework website. Here we review some of the insights from this initial release of the database and discuss methodological considerations to improve the success of optogenetic experiments in NHPs.}
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Miscellaneous An open dataset of 126 human brain field maps Elshatlawy, H., Jia, F., Aghaeifar, A., Gao, X., Littin, S., Yu, H., Scheffler, K., Zaitsev, M. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 2020
{126 human brain field maps from 18 normal subjects in 7 head positions each are published. The data may be of interest for shim coil designers as well as fro susceptibility mapping research.}
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Miscellaneous An optimized multi-coil shim setup matching inhomogeneity distribution in the human brain: positive and negative aspects Aghaeifar, A., Zhou, J., Jia, F., Zaitsev, M., Scheffler, K. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 468, 2020
{Multi-coil shim setup is a popular choice for B0 shimming. In contrast to conventional regular arrangement of the shim coils, one can effectively position the shim coil to match inhomogeneity distribution in the human brain. In this work, a comparison between regular and optimized arrangement of the local coils in a multi-coil shim setup is performed and the pros and cons of each design are evaluated.}
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Article An orthogonal shim coil for 3T brain imaging Zhou, J., Stockmann, J., Arango, N., Witzel, T., Scheffler, K., Wald, L., Lin, F. {Magnetic Resonance in Medicine}, 83(4):1499-1511, Wiley-Liss, New York, 2020
{Purpose: We designed and implemented an orthogonal shim array consisting of shim coils with their planes perpendicular to the planes of neighboring RF coils. This shim coil improves the magnetic field homogeneity by minimizing the interference to RF coils. Methods Using realistic off-resonance maps of the human brain, we first evaluated the performance of shim coils in different orientations. Based on simulations, we developed a 7-channel orthogonal shim array, whose coil plan was perpendicular to neighboring RF coils, at the forehead. A programmable open-source current driver supplied shim currents. Results The 7-channel orthogonal shim array caused only marginal SNR loss to the integrated 32-channel RF-shim array. The 7-channel orthogonal shim array itself improved the magnetic field homogeneity by 30\textpercent in slice-optimized shimming, comparable to the baseline shimming offered by the scanner\textquotesingles 2nd order spherical harmonic shimming. Conclusion Orthogonal shim coils can improve the field homogeneity while maintaining high image SNR.}
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Miscellaneous Analysis of the Spread of COVID-19 and Effectiveness of Containment Strategies: Case study of Germany Bokharaie, V. 2020
{The following slides presents an analysis of the spread of COVID-19 inGermany, and the effects of different containment strategies.Details of the mathematical model and how the parameters of themodel are estimated from the available data on the spread ofCOVID-19 is explained in:https://people.tuebingen.mpg.de/vbokharaie/Estimating\textunderscoreCovid19\textunderscorecontact\textunderscorerates.pdfThe following few slide provides enough information to make thepresented figures understandable.}
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Article Are you laughing at me? Neural correlates of social intent attribution to auditory and visual laughter Ethofer, T., Stegmaier, S., Koch, K., Reinl, M., Kreifelts, B., Schwarz, L., Erb, M., Scheffler, K., Wildgruber, D. {Human Brain Mapping}, 41(2):353-361, Wiley-Liss, New York, 2020
{Laughter is a multifaceted signal, which can convey social acceptance facilitating social bonding as well as social rejection inflicting social pain. In the current study, we addressed the neural correlates of social intent attribution to auditory or visual laughter within an fMRI study to identify brain areas showing linear increases of activation with social intent ratings. Negative social intent attributions were associated with activation increases within the medial prefrontal cortex/anterior cingulate cortex (mPFC/ACC). Interestingly, negative social intent attributions of auditory laughter were represented more rostral than visual laughter within this area. Our findings corroborate the role of the mPFC/ACC as key node for processing \textquotedblleftsocial pain\textquotedblright with distinct modality-specific subregions. Other brain areas that showed an increase of activation included bilateral inferior frontal gyrus and right superior/middle temporal gyrus (STG/MTG) for visually presented laughter and bilateral STG for auditory presented laughter with no overlap across modalities. Similarly, positive social intent attributions were linked to hemodynamic responses within the right inferior parietal lobe and right middle frontal gyrus, but there was no overlap of activity for visual and auditory laughter. Our findings demonstrate that social intent attribution to auditory and visual laughter is located in neighboring, but spatially distinct neural structures.}
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Article Artificial and Natural Intelligence: From Invention to Discovery Zhaoping, L. {Neuron}, 105(3):413-415, Cell Press, Cambridge, Mass., 2020
{An international group of researchers met in November 2019 in Beijing to explore the intersection of neuroscience and AI. The aim was to offer a fertile ground for stimulating discussions and ideas, including issues such as policy making and the future of neuroscience and AI across the globe.}
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Miscellaneous Assaying Large-scale Testing Models to InterpretCovid-19 Case Numbers: A Cross-country Study Besserve, M., Buchholz, S., Schölkopf, B. 2020
{Large-scale testing is considered key to assessing the state of the current COVID-19 pandemic, yet interpreting such data remains elusive. We modeled competing hypotheses regarding the underlying testing mechanisms, thereby providing different prevalence estimates based on case numbers, and used them to predict SARS-CoV-2-attributed death rate trajectories. Assuming that individuals were tested based solely on a predefined risk of being infectious implied the absolute case numbers reflected prevalence, but turned out to be a poor predictor. In contrast, models accounting for testing capacity, limiting the pool of tested individuals, performed better. This puts forward the percentage of positive tests as a robust indicator of epidemic dynamics in absence of country-specific information. We next demonstrated this strongly affects data interpretation. Notably absolute case numbers trajectories consistently overestimated growth rates at the beginning of two COVID-19 epidemic waves. Overall, this supports non-trivial testing mechanisms can be inferred from data and should be scrutinized.}
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Miscellaneous Asymmetric Dipole Head Array for Ultra-High-Field Magnetic Resonance Imaging Turns \textquotedblleftDielectric Resonance”from an Enemy to a Friend Avdievich, N., Solomakha, G., Ruhm, L., Bause, J., Henning, A., Scheffler, K. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 292, 2020
{We developed a novel 9.4T (400MHz) human head transceiver array consisted of 8 optimized bent folded dipole antennas. Due to an asymmetrical shape of dipoles (bending) and the RF shield, the array simultaneously excites two modes including a circular polarized mode of the array itself, and the TE mode of the human head. Mode mixing can be easily controlled by changing the folded length. As a result, the new array provides superior whole-brain coverage compared to various 8-element loop and dipole arrays or even to a more complicated 16-element loop array. In addition, the maximum local SAR is substantially reduced.}
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Conference Paper Attractiveness and Confidence in Walking Style of Male and Female Virtual Characters Thaler, A., Bieg, A., Mahmood, N., Black, M., Mohler, B., Troje, N. In 2020 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), 679-680, IEEE, Atlanta, GA, USA, 2020
{Animated virtual characters are essential to many applications. Little is known so far about biological and personality inferences made from a virtual character\textquoterights body shape and motion. Here, we investigated how sex-specific differences in walking style relate to the perceived attractiveness and confidence of male and female virtual characters. The characters were generated by reconstructing body shape and walking motion from optical motion capture data. The results suggest that sexual dimorphism in walking style plays a different role in attributing biological and personality traits to male and female virtual characters. This finding has important implications for virtual character animation.}
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Article Author Correction: Coupling of hippocampal theta and ripples with pontogeniculooccipital waves Ramirez-Villegas, J., Besserve, M., Murayama, Y., Evrard, H., Oeltermann, A., Logothetis, N. {Nature}, 588(7839):E34, Nature Publishing Group, London, 2020
{The hippocampus has a major role in encoding and consolidating long-term memories, and undergoes plastic changes during sleep1. These changes require precise homeostatic control by subcortical neuromodulatory structures2. The underlying mechanisms of this phenomenon, however, remain unknown. Here, using multi-structure recordings in macaque monkeys, we show that the brainstem transiently modulates hippocampal network events through phasic pontine waves known as pontogeniculooccipital waves (PGO waves). Two physiologically distinct types of PGO wave appear to occur sequentially, selectively influencing high-frequency ripples and low-frequency theta events, respectively. The two types of PGO wave are associated with opposite hippocampal spike-field coupling, prompting periods of high neural synchrony of neural populations during periods of ripple and theta instances. The coupling between PGO waves and ripples, classically associated with distinct sleep stages, supports the notion that a global coordination mechanism of hippocampal sleep dynamics by cholinergic pontine transients may promote systems and synaptic memory consolidation as well as synaptic homeostasis.}
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Miscellaneous Autoencoding T1 using MRzero for simultaneous sequence optimization and neural network training Dang, H., Loktyushin, A., Glang, F., Herz, K., Doerfler, A., Schölkopf, B., Scheffler, K., Maier, A., Zaiss, M. {Magnetic Resonance Materials in Physics, Biology and Medicine}, 33:S27-S28, No longer published by Elsevier, Amsterdam, 2020
{Introduction: Previously we proposed a supervised learning approach to automatically generate MR sequences from scratch without providing sequence programming rules, called MRzero [1]. In the present work, we develop an auto-encoder for T1 by performing a joint optimization of sequence parameters and a neural network using MRzero. Subjects/methods: The fully differentiable MRI pipeline is simulated end-to-end with Bloch parameters as input and T1 as target. We utilize known operator learning [2] in the reconstruction to reduce the number of trainable parameters in our NN by keeping the adjoint formalism [1] as known operator in the image reconstruction. The T1 training dataset consist of ten T1 maps with matrix size 32 9 32. For each target sample a non-zero PD rectangle with matrix size 16 9 16 at varying spatial location with voxel-wise randomly assigned PD, T1, T2 and B0 is defined, resulting in a total training data size of 2560 samples. A three-hidden-layer multilayer perceptron is used for T1 quantification. The MR sequence is based on a 180 deg inversion prepared 2D FLASH sequence with matrix size 32 9 32, TR \textequals 15 ms, TE \textequals 8 ms, FA \textequals 5 deg, repeated 6 times with varying TI and Trec. Together with the NN parameters, all TI and Trec times are optimized to find the best sequence for T1 mapping and are initialized with 0. Additionally, a penalty for longer times was applied to enforce shorter sequences. The optimization process (Fig. 1) interleaves the sequence and NN optimization after 50 and 5000 iterations, respectively. In total 500 iterations of sequence optimization are performed. Simultaneously optimized sequence parameters and trained NN are applied on a higher resolution with matrix size 126 9 126 and parallel imaging (GRAPPA acceleration factor 3) for in vivo measurements at 3T. Results/discussion: The T1 map of a healthy subject generated by the final optimized sequence is displayed in Fig. 2. Figure 3 shows the different stages of sequence optimization. The acquired T1 values of CSF, white matter and grey matter for later iterations match well to literature values at 3T [3]. A standard inversion recovery sequence was used as reference. The obtained maps match well with the reference, but the acquisition time could be reduced from 63.3 s to 19.2 s. Optimized TI and Trec times range from 0.5 s to 1.8 s and 0.5 s to 1.1 s, respectively. The simultaneous sequence optimization and NN training was performed solely on synthetic data at low resolution, but inference on higher resolution on in vivo data provided high quality T1 maps. Preliminary results at low resolution were shown in [1]. The T1 autoencoder is a proof-of-concept that can be extended also to multiparametric mapping\textemdashsimilar to MR fingerprinting\textemdashyielding PD, T1, and T2, as well as B1 and B0 inhomogeneity maps.}
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Miscellaneous Avoidant behavior and pathological worry as optimal policies and optimal offline planning given individually exaggerated risk preferences Gagne, C., Dayan, P. Bernstein Conference 2020, 2020 DOI BibTeX
Miscellaneous B0 field estimation using Ultrashort echo time/Dixon imaging with a 4-class tissue segmentation Zhou, J., Aghaeifar, A., Hagberg, G., Scheffler, K. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 259-260, 2020
{We use a UTE sequence combining with Dixon method to obtain the subject specific susceptibility distribution, with 4-class tissue segmentation. The susceptibility model was then used to simulate motion-induced B0 change for two head positions. A good agreement between the simulated and measured field map has been observe. A forward field map predicting strategy was explored using the susceptibility model.}
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Article BDNF Serum Levels are Associated With White Matter Microstructure in Schizophrenia: A Pilot Study Hammans, C., Neugebauer, K., Kumar, V., Mevissen, L., Sternkopf, M., Novakovic, A., Wensing, T., Habel, U., Abel, T., Nickl-Jockschat, T. {Frontiers in Psychiatry}, 11:1-10, Frontiers Research Foundation, Lausanne, Switzerland, 2020
{Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of schizophrenia. As BDNF regulates axonal and dendritic growth, altered BDNF levels in schizophrenia patients might underlie changes in structural connectivity that have been identified by magnetic resonance imaging (MRI). We investigated a possible correlation between BDNF serum levels, fiber tract architecture, and regional grey matter volumes in 19 schizophrenia patients and a gender- and age-matched control group. Two patients had to be excluded due to abnormalities in their MRI scans. Serum samples were obtained to determine BDNF levels, and T1- as well as diffusion-weighted sequences were acquired. We, then, investigated correlations between BDNF serum levels with neuroimaging parameters, using Voxel-based Morphometry (VBM) and Tract-based Spatial Statistics (TBSS). We found a significant negative correlation between BDNF serum levels and FA values in the right inferior fronto-occipital fasciculus and the right superior longitudinal fasciculus. These regions also showed a decrease in AD values in schizophrenia patients. Grey matter volumes were reduced in patients but there was no correlation between regional grey matter volumes and BDNF. The right superior longitudinal fasciculus has been repeatedly identified to exhibit microstructural changes in schizophrenia patients. Our findings of a negative correlation between BDNF and FA values in patients might indicate that BDNF is upregulated to compensate decreased structural connectivity as it induces neural plasticity and shows increased levels in damaged tissue. These findings of our pilot study are encouraging leads for future research in larger samples.}
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Article Bell Polynomials and Brownian Bridge in Spectral Gravity Models on Multifractal Robertson\textendashWalker Cosmologies Fathizadeh, F., Kafkoulis, Y., Marcolli, M. {Annales Henri Poincar\'e}, 21(4):1329-1382, Birkha.user, Basel, 2020
{We obtain an explicit formula for the full expansion of the spectral action on Robertson\textendashWalker spacetimes, expressed in terms of Bell polynomials, using Brownian bridge integrals and the Feynman\textendashKac formula. We then apply this result to the case of multifractal Packed Swiss Cheese Cosmology models obtained from an arrangement of Robertson\textendashWalker spacetimes along an Apollonian sphere packing. Using Mellin transforms, we show that the asymptotic expansion of the spectral action contains the same terms as in the case of a single Robertson\textendashWalker spacetime, but with zeta-regularized coefficients, given by values at integers of the zeta function of the fractal string of the radii of the sphere packing, as well as additional log-periodic correction terms arising from the poles (off the real line) of this zeta function.}
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Article Bent Folded-End Dipole Head Array for Ultrahigh-Field MRI Turns "Dielectric Resonance" From an Enemy to a Friend Avdievich, N., Solomakha, G., Ruhm, L., Bause, J., Scheffler, K., Henning, A. {Magnetic Resonance in Medicine}, 84(6):3453-3467, Wiley-Liss, New York, 2020
{Purpose: To provide transmit whole-brain coverage at 9.4 T using an array with only eight elements and improve the specific absorption rate (SAR) performance, a novel dipole array was developed, constructed, and tested. Methods: The array consists of eight optimized bent folded-end dipole antennas circumscribing a head. Due to the asymmetrical shape of the dipoles (bending and folding) and the presence of an RF shield near the folded portion, the array simultaneously excites two modes: a circular polarized mode of the array itself, and the TE mode ("dielectric resonance") of the human head. Mode mixing can be controlled by changing the length of the folded portion. Due to this mixing, the new dipole array improves longitudinal coverage as compared with unfolded dipoles. By optimizing the length of the folded portion, we can also minimize the peak local SAR (pSAR) value and decouple adjacent dipole elements. Results: The new array improves the SEE (\textless B+1 \textgreater/$\surd$pSAR) value by about 50\textpercent, as compared with the unfolded bent dipole array. It also provides better whole-brain coverage compared with common single-row eight-element dipole arrays, or even to a more complex double-row 16-element surface loop array. Conclusion: In general, we demonstrate that rather than compensating for the constructive interference effect using additional hardware, we can use the "dielectric resonance" to improve coverage, transmit field homogeneity, and SAR efficiency. Overall, this design approach not only improves the transmit performance in terms of the coverage and SAR, but substantially simplifies the common surface loop array design, making it more robust, and therefore safer.}
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Miscellaneous Bipartite connectivity mapping (BCM) Lohmann, G., Stelzer, J., Scheffler, K. 26th Annual Meeting of the Organization for Human Brain Mapping (OHBM 2020), 92, 2020
{Introduction: Here we present a new approach called \textasciigrave\textasciigraveBipartite connectivity mapping (BCM)\textquotesingle\textquotesingle for analyzing connectivity in rs-fMRI between two brain regions. The two regions can be of any size, but should be non-overlapping. The main idea is to represent connectivity between the regions as a bipartite graph and analyse it using bipartite network projections. The advantage of this approach is that it allows to fully preserve spatial precision in both ROIs. This sets it apart from traditional seed-based connectivity mapping where the seed ROI must be averaged so that its spatial information is lost. Here we show an application of this idea to rs-fMRI data acquired at 9.4 Tesla. Methods: A bipartite graph is a graph whose edges have endpoints connecting the two regions, but that do not connect vertices within the same region. Our proposed method BCM is a general framework that offers several options for analysing bipartite graphs. The first and easiest technique is to compute the hubs of the bipartite graph using either degree centrality or eigenvector centrality mapping [1] and map them to each voxel. The second technique is to project the bipartite graph onto one of the ROIs and compute the hubs of the projected network. There are several choices for projections of bipartite graphs [2], one of which is currently implemented in BCM. Results: Resting state fMRI data of a healthy female subject were acquired at a 9.4 Tesla scanner (Siemens). A gradient echo EPI sequence with TR\textequals2.03 sec, (1.2)\textasciicircum3 mm isotropic resolution was used. The scan time was 12 minutes (rs-fMRI with eyes open). Preprocessing consisted of corrections for motion and removal of base line drifts via a highpass filter. Two ROIs were manually defined with one ROI (A) corresponding to left and right thalamus, and ROI B corresponding to right-hemispheric grey matter. The size of A was 10618 voxels, the size of B was 120209 voxels. The hubs of the bipartite graph are shown below (Figure 1). The BCM results in the two ROIs are scaled independently for better visualization. Note that LGN shows up prominently in A, while V1 is clearly visible in B. Using the same data as above, we applied a BCM network projection. Here we projected the above bipartite graph onto ROI A (thalamus). Below (Figure 2) we show the degree centrality mapping of the projected network. Conclusions: The new BCM algorithm provides a method for analyzing connectivity between two ROIs. It can for instance be used for detecting nuclei in subcortical regions that are characterized by their connectivity to other brain areas. BCM is a general framework for handling bipartite graphs. At present, two definitions of hubs are implemented, namely degree centrality and eigenvector centrality. Furthermore, a method for network projection is implemented. We believe that BCM offers an alternative route for ROI-based connectivity analysis in fMRI. Its main advantage is that it preserves spatial specificity in both ROIs.}
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Miscellaneous Bloch-Siegert flip angle calibration for phosphorus at the human brain at 9.4 T using ISIS localization Ruhm, L., Dorst, J., Avdievich, N., Henning, A. 2020 ISMRM & SMRT Virtual Conference & Exhibition, 2020
{Correct calibration of the transmit field B1+ is crucial to achieve optimal SNR. However, fast and robust B1+ calibration is difficult for X-nuclei due to the low signal sensitivity. In this work, we proposed a fast B1+ calibration method based on the Bloch-Siegert shift and single voxel ISIS localization. With the proposed sequence, the B1+ calibration can be done in less than 5 min for the human brain at B0 \textequals 9.4 T.}
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Conference Paper Blue Light and Melanopsin Contribution to the Pupil Constriction in the Blind-spot, Parafovea and Periphery Schilling, T., Soltanlou, M., Seshadri, Y., Nuerk, H., Bahmani, H. In BIOSTEC 2020: Proceedings of the 13th International Joint Conference on Biomedical Engineering Systems and Technologies, 5:482-489, Scitepress, Valletta, Malta, 2020
{Retinal photoreceptors modulate the pupil diameter to regulate retinal illumination. At early stage the pupil-response is formed by intrinsically-photosensitive-Retinal-Ganglion-Cells (ipRGCs) expressing melanopsin, activated by blue light. ipRGCs\textquoteright axons pass through the optic nerve head, corresponding to the blind-spot. No photoreceptors except melanopsin appear to exist in the blind-spot. Contributions of melanopsin to pupil constriction in absence of classical photoreceptors in the blind-spot is not fully understood. We investigated how blue light in the blind-spot changes melanopsin-pupil-response compared to parafovea and periphery. The Post-Illumination-Pupil-Response (PIPR) amplitude reflecting melanopsin was analyzed for standardized time windows (1s\textless1.7s, 1s\textgreater1.8s and 2\textendash6s) and expressed as pupillary-change. Bayesian analysis showed a BF\textgreater3 that PIPR\textgreater1.8s for blind-spot and periphery is not different. At times 2s\textendash6s, a t-test comparison in the blind-spot condition showed a sign ificantly larger PIPR to blue compared to red light, confirming a melanopsin-pupil-response in the blind-spot. Taken together, equivalent stimulation in the blind-spot and periphery revealed comparable PIPR, although there are no rods and cones in the blind-spot. In absence of classical photoreceptors in the blind-spot, melanopsin seems to be responsible for pupil constriction in similar manner as in the periphery, which supports the presence of melanopsin on the axons of ipRGCs.}
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Article Brain structural correlates of insomnia severity in 1053 individuals with major depressive disorder: results from the ENIGMA MDD Working Group Leerssen, J., Blanken, T., Pozzi, E., Jahanshad, N., Aftanas, L., Andreassen, O., Baune, B., Brack, I., Carballedo, A., Ching, C., Dannlowski, U., Dohm, K., Enneking, V., Filimonova, E., Fingas, S., Frodl, T., Godlewska, B., Goltermann, J., Gotlib, I., Grotegerd, D., et al. {Translational Psychiatry}, 10(1):1-11, Nature Pub. Group, 2020
{It has been difficult to find robust brain structural correlates of the overall severity of major depressive disorder (MDD). We hypothesized that specific symptoms may better reveal correlates and investigated this for the severity of insomnia, both a key symptom and a modifiable major risk factor of MDD. Cortical thickness, surface area and subcortical volumes were assessed from T1-weighted brain magnetic resonance imaging (MRI) scans of 1053 MDD patients (age range 13-79 years) from 15 cohorts within the ENIGMA MDD Working Group. Insomnia severity was measured by summing the insomnia items of the Hamilton Depression Rating Scale (HDRS). Symptom specificity was evaluated with correlates of overall depression severity. Disease specificity was evaluated in two independent samples comprising 2108 healthy controls, and in 260 clinical controls with bipolar disorder. Results showed that MDD patients with more severe insomnia had a smaller cortical surface area, mostly driven by the right insula, left inferior frontal gyrus pars triangularis, left frontal pole, right superior parietal cortex, right medial orbitofrontal cortex, and right supramarginal gyrus. Associations were specific for insomnia severity, and were not found for overall depression severity. Associations were also specific to MDD; healthy controls and clinical controls showed differential insomnia severity association profiles. The findings indicate that MDD patients with more severe insomnia show smaller surfaces in several frontoparietal cortical areas. While explained variance remains small, symptom-specific associations could bring us closer to clues on underlying biological phenomena of MDD.}
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Article CEST MR-Fingerprinting: practical considerations and insights for acquisition schedule design and improved reconstruction Perlman, O., Herz, K., Zaiss, M., Cohen, O., Rosen, M., Farrar, C. {Magnetic Resonance in Medicine}, 83(2):462-478, Wiley-Liss, New York, 2020
{Purpose To understand the influence of various acquisition parameters on the ability of CEST MR-Fingerprinting (MRF) to discriminate different chemical exchange parameters and to provide tools for optimal acquisition schedule design and parameter map reconstruction. Methods Numerical simulations were conducted using a parallel computing implementation of the Bloch-McConnell equations, examining the effect of TR, TE, flip-angle, water urn:x-wiley:07403194:media:mrm27937:mrm27937-math-0011 and urn:x-wiley:07403194:media:mrm27937:mrm27937-math-0012, saturation-pulse duration, power, and frequency on the discrimination ability of CEST-MRF. A modified Euclidean distance matching metric was evaluated and compared to traditional dot product matching. L-Arginine phantoms of various concentrations and pH were scanned at 4.7T and the results compared to numerical findings. Results Simulations for dot product matching demonstrated that the optimal flip-angle and saturation times are urn:x-wiley:07403194:media:mrm27937:mrm27937-math-0013 and 1100 ms, respectively. The optimal maximal saturation power was 3.4 $\mu$T for concentrated solutes with a slow exchange rate, and 5.2 $\mu$T for dilute solutes with medium-to-fast exchange rates. Using the Euclidean distance matching metric, much lower maximum saturation powers were required (1.6 and 2.4 $\mu$T, respectively), with a slightly longer saturation time (1500 ms) and urn:x-wiley:07403194:media:mrm27937:mrm27937-math-0014 flip-angle. For both matching metrics, the discrimination ability increased with the repetition time. The experimental results were in agreement with simulations, demonstrating that more than a 50\textpercent reduction in scan-time can be achieved by Euclidean distance-based matching. Conclusions Optimization of the CEST-MRF acquisition schedule is critical for obtaining the best exchange parameter accuracy. The use of Euclidean distance-based matching of signal trajectories simultaneously improved the discrimination ability and reduced the scan time and maximal saturation power required.}
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Miscellaneous CEST-Lasso: L1-regularized linear projection based CEST evaluation and feature selection for reduced acquisition time Glang, F. 2020 BibTeX