SmartRain – Aufbau eines Bürgermessnetzes zur Bestimmung und Analyse lokaler Niederschlagsverteilungen

Das Projekt SmartRain (https://smart-rain.de/) widmet sich dem Aufbau eines bürgerschaftlichen Messnetzes zur Bestimmung von Niederschlagsverteilungen in der Landeshauptstadt Dresden. Es wird dargelegt, welchen Wert eine smarte Datenerhebung im Bereich der Umweltsensorik haben kann, aber auch, mit welchen Herausforderungen bei der organisatorischen Umsetzung eines solchen Projektes gerechnet werden muss

Histological Correlates of Diffusion-Weighted Magnetic Resonance Microscopy in a Mouse Model of Mesial Temporal Lobe Epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy. It is frequently associated with abnormal MRI findings, which are caused by underlying cellular, structural, and chemical changes at the micro-scale. In the current study, it is investigated to which extent these alterations correspond to imaging features detected by high resolution magnetic resonance imaging in the intrahippocampal kainate mouse model of MTLE. Fixed hippocampal and whole-brain sections of mouse brain tissue from nine animals under physiological and chronically epileptic conditions were examined using structural and diffusion-weighted MRI. Microstructural details were investigated based on a direct comparison with immunohistochemical analyses of the same specimen. Within the hippocampal formation, diffusion streamlines could be visualized corresponding to dendrites of CA1 pyramidal cells and granule cells, as well as mossy fibers and Schaffer collaterals. Statistically significant changes in diffusivities, fractional anisotropy, and diffusion orientations could be detected in tissue samples from chronically epileptic animals compared to healthy controls, corresponding to microstructural alterations (degeneration of pyramidal cells, dispersion of the granule cell layer, and sprouting of mossy fibers). The diffusion parameters were significantly correlated with histologically determined cell densities. These findings demonstrate that high-resolution diffusion-weighted MRI can resolve subtle microstructural changes in epileptic hippocampal tissue corresponding to histopathological features in MTLE

Corrigendum: Histological Correlates of Diffusion-Weighted Magnetic Resonance Microscopy in a Mouse Model of Mesial Temporal Lobe Epilepsy

In the published article, there were errors in affiliations 2 and 3. Instead of “Experimental Epilepsy Research, Department of Neurosurgery, Medical Center – University of Freiburg, Freiburg, Germany” and “Department Neurosurgery, Experimental Epilepsy Research, Medical Center, University of Freiburg, Freiburg, Germany,” they should be “Faculty of Medicine, University of Freiburg, Freiburg, Germany” and “Experimental Epilepsy Research, Department of Neurosurgery, Medical Center – University of Freiburg, Freiburg, Germany,” respectively. The authors apologize for these errors and state that this does not change the scientific conclusions of the article in any way. The original article has been updated

Estimation des champs récepteurs de grands ensembles deneurones visuels par une approche de super-résolution

One primary goal in analyzing sensory neurons’ recordings is to map the sensory space to the neural response, thus estimating the neuron’s receptive fields (RFs). For visual neurons, the classical method to estimate RFs is the Spike Triggered Average (STA). In short, STA consistsestimate the average stimulus before each spike evoked by a white noise stimulus whose block size can be ad-hoc tuned to target one single neuron. However, this approach becomes impractical to deal with in large scale recordings of heterogeneous populations of neurons since no single block size can match all neurons. Here, we aim to overcome this limitation by leveraging super resolution techniques to extend STA’s scope. We defined a novel type of stimulus, the shifted white noise, by introducing random spatial shifts in the white noise stimulus. We evaluated this new stimulus thoroughly on both synthetic and real neuronal populations of size 216 and 4798, respectively. Considering the same target STA resolution, results across the population with synthetic case show that the average error using our stimulus was 1.7 times smaller than the error using theclassical stimulus. We could map 2.3 times more neurons and cover a broader heterogeneity of RF sizes. For a single neuron, we show how it can be mapped after only one minute of stimulation, while after 11 minutes, this neuron was still not mapped with the classical one, which emphasizesthe effectiveness of our method. Analogously, similar results were obtained with real neurons’ experiment. Considering the same target STA resolution, we mapped 18 times more RFs and we found a broader heterogeneity of RFs sizes (the kurtosis of the distribution of the RF sizes is 0.3 times smaller). Overall, the shifted white noise improves the RFs’ estimation in several ways. Our approach performs better at the single-cell level. RF estimation is independent of the neuron’s position relative to the stimulus and offers high-resolution. Our approach is stronger atthe population-level. We get more RF with more neuronal variability. Our approach is faster, enabling experimentalists to get results in shorter stimulation time. Furthermore, this stimulus can also be used in other spike-triggered methods, extended to the time dimension, and adapted to other sensory modalities. Due to its design simplicity and strong results, we expect that soon the shifted white noise is used as a rule and allows revealing novelties in sensory analysis.L’un des principaux objectifs de l’analyse des enregistrements des neurones sensoriels est de faire correspondre l’espace sensoriel à la réponse neurale, ce qui permet d’estimer les champs récepteurs (RF) des neurones. Pour les neurones visuels, la méthode classique d’estimation des RF est le Spike Triggered Average (STA). En bref, STA consiste à estimer le stimulus moyen avant chaque impulsion évoquée par un stimulus de bruit blanc dont la taille du bloc peut être réglée ad hoc pour cibler un seul neurone. Cependant, cette approche devient peu pratique pour les enregistrements à grande échelle de populations hétérogènes de neurones, car aucune taille de bloc ne peut correspondre à tous les neurones. Ici, nous cherchons à surmonter cette limitation en tirant parti des techniques de résolution pour étendre le champ d’application du STA. Nous avons défini un nouveau type de stimulus, le bruit blanc décalé, en introduisant des décalages spatiaux aléatoires dans le stimulus du bruit blanc. Nous avons évalué ce nouveau stimulus de manière approfondie sur des populations neuronales synthétiques et réelles de taille 216 et 4798, respectivement. En considérant la même résolution STA cible, les résultats sur la population synthétique montrent que l’erreur moyenne utilisant notre stimulus était 1.7 fois plus petite que l’erreur utilisant le stimulus classique plus petit. Nous avons pu identifier 2.3 fois plus de neurones et couvrir une plus grande hétérogénéité de tailles de RF. Pour un seul neurone, nous avons montré comment il peut être identifié après seulement une minute de stimulation, alors qu’après 11 minutes, ce neurone n’était toujours pas identifié avec le stimulus classique, ce qui souligne l’efficacité de notre méthode. De même, des résultats similaires ont été obtenus avec l’expérience sur des neurones réels. En considérant la même résolution de STA cible, nous avons identifié 18 fois plus de RF et nous avons trouvé une plus grande hétérogénéité des tailles de RF (l’aplatissement de la distribution des tailles de RF est 0.3 fois plus petit). Dans l’ensemble, le bruit blanc décalé améliore donc l’estimation des RF de plusieurs façons. Notre approche est plus performante au niveau d’une seule cellule. L’estimation des RF est indépendante de la position du neurone par rapport au stimulus et offre une haute résolution. Notre approche est plus performante au niveau de la population. Nous obtenons plus de RF avec une plus grande variabilité neuronale. Notre approche est plus rapide, ce qui permet aux expérimentateurs d’obtenir des résultats en un temps de stimulation réduit. En outre, ce stimulus peut également être utilisé dans d’autres méthodes déclenchées par des impulsions, étendues à la dimension temporelle et adaptées à d’autres modalités sensorielles. En raison de la simplicité de sa conception et de ses bons résultats, nous espérons que le bruit blanc décalé sera bientôt utilisé comme règle et qu’il permettra de révéler des nouveautés en matière d’analyse sensorielle

A super-resolution approach for receptive fields estimation of neuronal ensembles

International audienceThe Spike Triggered Average (STA) is a classical technique to find a discrete approximation of the Receptive Fields (RFs) of sensory neurons [1], a required analysis in most experimental studies. One important parameter of the STA is the spatial resolution of the estimation, corresponding to the size of the blocks of the checkerboard stimulus images. In general, it is experimentally fixed to reach a compromise: If too small, neuronal responses might be too weak thus leading to RF with low Signal-to-Noise-Ratio; on the contrary, if too large, small RF will be lost, or not described with enough details, because of the coarse approximation. Other solutions were proposed consisting in starting from a small block size and updating it following the neuron response in a closed-loop to increase its response [2; 3; 4]. However, these solutions were designed for single cells and cannot be applied to simultaneous recordings of ensembles of neurons (since each RF has its own size and preferred stimulus). To solve this problem, we introduced a modified checkerboard stimulus where blocks are shifted randomly in space at fixed time steps. This idea is inspired from super-resolution techniques developed in image processing [4]. The main interest is that the block size can be large, enabling strong responses, while the resolution can be finer since it depends on the shift minimum size. In [5] was shown that the STA remains an unbiased RF estimator and, using simulated spike trains from an ensemble of Linear Nonlinear Poisson cascade neurons, it was predicted that this approach improves RF estimation over the neuron ensemble. Here, we test these predictions experimentally on the RFs estimation of 8460 ganglion cells from two mouse retinas, using recordings performed with a large scale high-density multielectrode array. To illustrate the main interest of the approach, in Figure 1 we show a representative example of STA for one neuron where RFs have been obtained using the three following stimuli (all presented during 15min, for one retina displayed at 10 Hz, for the other at 30 Hz): (A) standard checkerboard stimulus with block size of 160μm, (B) standard checkerboard stimulus with block size of 40μm, (C) checkerboard stimulus with block size of 160μm and arbitrary shifts of 40μm in x and y-directions. Results show spatial resolution can be improved in case (C), while nothing could be obtained in (B) by changing only the block size of the standard stimulus. At the population level, plot (D) shows the number of the RFs that could be recovered for each stimuli, using a decision criteria based of the RFs value distribution. Most of the RFs were mapped with both methods (A) and (C) (49.9%). However, the proposed case (C) allows to recover 51% of the mapped RFs at a resolution of 40μm, while in the classical case (A), 41% of the RFs could be found at a resolution of only 160μm. Thus, the method does improve the quality of the RF estimation and the amount of successfully mapped RFs in neural ensembles

Early tissue damage and microstructural reorganization predict disease severity in experimental epilepsy

Mesial temporal lobe epilepsy (mTLE) is the most common focal epilepsy in adults and is often refractory to medication. So far, resection of the epileptogenic focus represents the only curative therapy. It is unknown whether pathological processes preceding epilepsy onset are indicators of later disease severity. Using longitudinal multi-modal MRI, we monitored hippocampal injury and tissue reorganization during epileptogenesis in a mouse mTLE model. The prognostic value of MRI biomarkers was assessed by retrospective correlations with pathological hallmarks Here, we show for the first time that the extent of early hippocampal neurodegeneration and progressive microstructural changes in the dentate gyrus translate to the severity of hippocampal sclerosis and seizure burden in chronic epilepsy. Moreover, we demonstrate that structural MRI biomarkers reflect the extent of sclerosis in human hippocampi. Our findings may allow an early prognosis of disease severity in mTLE before its first clinical manifestations, thus expanding the therapeutic window

Nomograms including the UBC® Rapid test to detect primary bladder cancer based on a multicentre dataset

Objectives: To evaluate the clinical utility of the urinary bladder cancer antigen test UBC Rapid for the diagnosis of bladder cancer (BC) and to develop and validate nomograms to identify patients at high risk of primary BC. Patients and Methods: Data from 1787 patients from 13 participating centres, who were tested between 2012 and 2020, including 763 patients with BC, were analysed. Urine samples were analysed with the UBC Rapid test. The nomograms were developed using data from 320 patients and externally validated using data from 274 patients. The diagnostic accuracy of the UBC Rapid test was evaluated using receiver-operating characteristic curve analysis. Brier scores and calibration curves were chosen for the validation. Biopsy-proven BC was predicted using multivariate logistic regression. Results: The sensitivity, specificity, and area under the curve for the UBC Rapid test were 46.4%, 75.5% and 0.61 (95% confidence interval [CI] 0.58–0.64) for low-grade (LG) BC, and 70.5%, 75.5% and 0.73 (95% CI 0.70–0.76) for high-grade (HG) BC, respectively. Age, UBC Rapid test results, smoking status and haematuria were identified as independent predictors of primary BC. After external validation, nomograms based on these predictors resulted in areas under the curve of 0.79 (95% CI 0.72–0.87) and 0.95 (95% CI: 0.92–0.98) for predicting LG-BC and HG-BC, respectively, showing excellent calibration associated with a higher net benefit than the UBC Rapid test alone for low and medium risk levels in decision curve analysis. The R Shiny app allows the results to be explored interactively and can be accessed at www.blucab-index.net. Conclusion: The UBC Rapid test alone has limited clinical utility for predicting the presence of BC. However, its combined use with BC risk factors including age, smoking status and haematuria provides a fast, highly accurate and non-invasive tool for screening patients for primary LG-BC and especially primary HG-BC

Emergence of comparable covalency in isostructural cerium(IV)- and uranium(IV)-carbon multiple bonds

We report comparable levels of covalency in cerium- and uranium-carbon multiple bonds in the isostructural carbene complexes [M(BIPMTMS)(ODipp)2] [M = Ce (1), U (2), Th (3); BIPMTMS = C(PPh2NSiMe3)2; Dipp = C6H3-2,6-Pri2] whereas for M = Th the M=C bond interaction is much more ionic. On the basis of single crystal X-ray diffraction, NMR, IR, EPR, and XANES spectroscopies, and SQUID magnetometry complexes 1-3 are confirmed formally as bona fide metal(IV) complexes. In order to avoid the deficiencies of orbital-based theoretical analysis approaches we probed the bonding of 1-3 via analysis of RASSCF- and CASSCF-derived densities that explicitly treats the orbital energy near-degeneracy and overlap contributions to covalency. For these complexes similar levels of covalency are found for cerium(IV) and uranium(IV), whereas thorium(IV) is found to be more ionic, and this trend is independently found in all computational methods employed. The computationally determined trends in covalency of Ce ~ U > Th are also reproduced in experimental exchange reactions of 1-3 with MCI4 salts where 1 and 2 do not exchange with ThCl4, but 3 does exchange with MCl4 (M = Ce, U) and 1 and 2 react with UCl4 and CeCl4, respectively, to establish equilibria. This study therefore provides complementary theoretical and experimental evidence that contrasts to the accepted description that generally lanthanide-ligand bonding in non-zero oxidation state complexes is overwhelmingly ionic but that of uranium is more covalent