Simultaneous whole-animal 3D-imaging of neuronal activity using light field microscopy

3D functional imaging of neuronal activity in entire organisms at single cell level and physiologically relevant time scales faces major obstacles due to trade-offs between the size of the imaged volumes, and spatial and temporal resolution. Here, using light-field microscopy in combination with 3D deconvolution, we demonstrate intrinsically simultaneous volumetric functional imaging of neuronal population activity at single neuron resolution for an entire organism, the nematode Caenorhabditis elegans. The simplicity of our technique and possibility of the integration into epi-fluoresence microscopes makes it an attractive tool for high-speed volumetric calcium imaging.Comment: 25 pages, 7 figures, incl. supplementary informatio

Künstliche Intelligenz in der journalistischen Nachrichtenproduktion: Wahrnehmung und Akzeptanz in der Schweizer Bevölkerung

Spätestens mit der Lancierung von ChatGPT ist der Einsatz von Künstlicher Intelligenz (KI) im Journalismus zu einem prägenden Thema der Medienbranche geworden. Unsere Studie untersucht erstmalig die Wahrnehmung und Akzeptanz des Einsatzes von KI in der journalistischen Nachrichtenproduktion mit einer repräsentativen Bevölkerungsumfrage in der Deutschschweiz und der Suisse romande. Die Studie zeigt, dass die Akzeptanz für vollständig oder teilweise KI-generierte Textbeiträge im Journalismus in der Schweizer Bevölkerung gering ist. Während nur 29,1% der Befragten journalistische Inhalte lesen würden, die vollständig durch KI generiert wurden, sind es bei Nachrichten, die ohne KI erstellt wurden, 84,3%. Die Akzeptanz unterscheidet sich jedoch nach Themenbereichen: Bei Routine-Berichterstattung etwa zum Wetter oder Börsengeschehen ist sie am grössten (61,2%), gefolgt von der Softnews-Berichterstattung zu «Stars und Celebrities». Dort geben immerhin fast die Hälfte der Befragten (48,6%) an, KI-generierte journalistische Inhalte lesen zu wollen. In den Hardnews-Bereichen Kultur (27,7%), Wissenschaft (25,9%), nationale (16,4%) und internationale Politik (15,9%) ist die Akzeptanz für KI-generierte Inhalte dagegen gering. In jedem Fall besteht unter den Befragten weitgehend Konsens, dass KI-generierte und KI-unterstützte Inhalte im Journalismus deklariert und transparent gemacht werden müssen. Auch werden die Auswirkungen von KI auf die Qualität der journalistischen Inhalte derzeit eher negativ eingeschätzt. 61,3% stimmen der Aussage zu, dass sich die Berichterstattungsqualität durch den Einsatz von KI verschlechtern würde. Bemerkenswert ist hier der Befund, dass KI (noch) wenig Potenzial zur Eindämmung von Falschnachrichten zugeschrieben wird. Im Gegenteil sind 67,1% der Ansicht, dass der Einsatz von KI im Journalismus das Aufkommen von Falschnachrichten erhöhe. Auch ist die Zahlungsbereitschaft für KI-generierten Journalismus gering. Nur wenige Befragte sind grundsätzlich bereit, für journalistische Inhalte zu bezahlen, die vollständig durch KI erstellt wurden, aber sehr viel mehr würden grundsätzlich für journalistische Inhalte zahlen, die ohne KI produziert wurden. Eine klare Mehrheit der Befragten (72,6%) ist der Ansicht, dass der vermehrte Einsatz von KI für die Medienunternehmen ein Mittel zur Kostenersparnis ist. Die Daten legen damit insgesamt nahe, dass sich ein vermehrter Einsatz von KI im Journalismus negativ auf die Zahlungsbereitschaft der Schweizer Bevölkerung für journalistische Inhalte auswirken würde. Eine Mehrheit (61,3%) ist zudem auch der Meinung, dass Anbieter von KI-Tools den Journalismus dafür entschädigen sollten, dass sie für ihre automatisiert generierten Antworten auch auf journalistische Daten zurückgreifen. Das ist ein wichtiger Befund im Hinblick auf die aktuellen medienpolitischen Debatten zu Urheber- und Leistungsschutzrechten

Dendritic calcium signals in rhesus macaque motor cortex drive an optical brain-computer interface

Calcium imaging is a powerful tool for recording from large populations of neurons in vivo. Imaging in rhesus macaque motor cortex can enable the discovery of fundamental principles of motor cortical function and can inform the design of next generation brain-computer interfaces (BCIs). Surface two-photon imaging, however, cannot presently access somatic calcium signals of neurons from all layers of macaque motor cortex due to photon scattering. Here, we demonstrate an implant and imaging system capable of chronic, motion-stabilized two-photon imaging of neuronal calcium signals from macaques engaged in a motor task. By imaging apical dendrites, we achieved optical access to large populations of deep and superficial cortical neurons across dorsal premotor (PMd) and gyral primary motor (M1) cortices. Dendritic signals from individual neurons displayed tuning for different directions of arm movement. Combining several technical advances, we developed an optical BCI (oBCI) driven by these dendritic signalswhich successfully decoded movement direction online. By fusing two-photon functional imaging with CLARITY volumetric imaging, we verified that many imaged dendrites which contributed to oBCI decoding originated from layer 5 output neurons, including a putative Betz cell. This approach establishes new opportunities for studying motor control and designing BCIs via two photon imaging

Chikungunya virus infectivity, RNA replication and non-structural polyprotein processing depend on the nsP2 protease's active site cysteine residue

Chikungunya virus (CHIKV), genus Alphavirus, family Togaviridae, has a positive-stand RNA genome approximately 12 kb in length. In infected cells, the genome is translated into non-structural polyprotein P1234, an inactive precursor of the viral replicase, which is activated by cleavages carried out by the non-structural protease, nsP2. We have characterized CHIKV nsP2 using both cell-free and cell-based assays. First, we show that Cys478 residue in the active site of CHIKV nsP2 is indispensable for P1234 processing. Second, the substrate requirements of CHIKV nsP2 are quite similar to those of nsP2 of related Semliki Forest virus (SFV). Third, substitution of Ser482 residue, recently reported to contribute to the protease activity of nsP2, with Ala has almost no negative effect on the protease activity of CHIKV nsP2. Fourth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 completely abolished RNA replication in CHIKV and SFV trans-replication systems. In contrast, trans-replicases with Ser482 to Ala mutation were similar to wild type counterparts. Fifth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 abolished the rescue of infectious virus from CHIKV RNA transcripts while Ser482 to Ala mutation had no effect. Thus, CHIKV nsP2 is a cysteine protease.Peer reviewe

Validity of intradermal tuberculin testing for the screening of bovine tuberculosis in Madagascar

A sample survey with the objective of determining the prevalence of bovine tuberculosis by means of an intradermal tuberculin test was conducted in Madagascar and it was found that the prevalence rate varied from 0-30% by veterinary district. In order to estimate the true prevalence, the validity of the test was investigated by assessing its sensitivity and specificity in two groups of animals from two different regions, which were destined for slaughter. In the first group where the probability of non-infected animals should have been the highest, sensitivity was estimated at 0.52 ( n=21) and specificity at 0.99 ( n=79). In the second group selected on the basis of apparent ill health of the animals in a high-prevalence bovine tuberculosis area, sensitivity was estimated at 0.8 ( n=10) and specificity at 1 ( n=12). The results obtained from both groups of cattle were not combined for statistical purposes because the sensitivity of the skin test seemed to fluctuate in relation to the chronicity of the disease. These fluctuations are discussed. However, since the first group of zebu cattle was more representative of the cattle population across the country as a whole, its results were retained as operational parameters for further screening.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Acousto-optical Scanning-Based High-Speed 3D Two-Photon Imaging In Vivo.

Recording of the concerted activity of neuronal assemblies and the dendritic and axonal signal integration of downstream neurons pose different challenges, preferably a single recording system should perform both operations. We present a three-dimensional (3D), high-resolution, fast, acousto-optic two-photon microscope with random-access and continuous trajectory scanning modes reaching a cubic millimeter scan range (now over 950 × 950 × 3000 μm3) which can be adapted to imaging different spatial scales. The resolution of the system allows simultaneous functional measurements in many fine neuronal processes, even in dendritic spines within a central core (>290 × 290 × 200 μm3) of the total scanned volume. Furthermore, the PSF size remained sufficiently low (PSFx < 1.9 μm, PSFz < 7.9 μm) to target individual neuronal somata in the whole scanning volume for simultaneous measurement of activity from hundreds of cells. The system contains new design concepts: it allows the acoustic frequency chirps in the deflectors to be adjusted dynamically to compensate for astigmatism and optical errors; it physically separates the z-dimension focusing and lateral scanning functions to optimize the lateral AO scanning range; it involves a custom angular compensation unit to diminish off-axis angular dispersion introduced by the AO deflectors, and it uses a high-NA, wide-field objective and high-bandwidth custom AO deflectors with large apertures. We demonstrate the use of the microscope at different spatial scales by first showing 3D optical recordings of action potential back propagation and dendritic Ca2+ spike forward propagation in long dendritic segments in vitro, at near-microsecond temporal resolution. Second, using the same microscope we show volumetric random-access Ca2+ imaging of spontaneous and visual stimulation-evoked activity from hundreds of cortical neurons in the visual cortex in vivo. The selection of active neurons in a volume that respond to a given stimulus was aided by the real-time data analysis and the 3D interactive visualization accelerated selection of regions of interest

Femtosecond x-ray diffraction reveals a liquid–liquid phase transition in phase-change materials

6 pags., 5 figs.In phase-change memory devices, a material is cycled between glassy and crystalline states. The highly temperature-dependent kinetics of its crystallization process enables application in memory technology, but the transition has not been resolved on an atomic scale. Using femtosecond x-ray diffraction and ab initio computer simulations, we determined the time-dependent pair-correlation function of phase-change materials throughout the melt-quenching and crystallization process. We found a liquid–liquid phase transition in the phase-change materials AgInSbTe and GeSb at 660 and 610 kelvin, respectively. The transition is predominantly caused by the onset of Peierls distortions, the amplitude of which correlates with an increase of the apparent activation energy of diffusivity. This reveals a relationship between atomic structure and kinetics, enabling a systematic optimization of the memory-switching kinetics.F.Q., A.K., M.N., and K.S.T. gratefully acknowledge financial support from the German Research Council through the Collaborative Research Center SFB 1242 project 278162697 (“Non-Equilibrium Dynamics of Condensed Matter in the Time Domain”), project C01 (“Structural Dynamics in Impulsively Excited Nanostructures”), and individual grant So408/9-1, as well as the European Union (7th Framework Programme, grant no. 280555 GO FAST). M.J.S., R.M., and M.W. acknowledge financial support from the German Research Council through the Collaborative Research Center SFB 917 (“Nanoswitches”) and individual grant Ma-5339/2-1. M.J.S., I.R., and R.M. also acknowledge the computational resources granted by JARA-HPC from RWTH Aachen University under project nos. JARA0150 and JARA0183. M.T., A.M.L., and D.A.R. were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, through the Division of Materials Sciences and Engineering under contract no. DE-AC02-76SF00515. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. J.L. acknowledges support from the Swedish Research Council. J.S. acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities through research grant UDiSON (TEC2017-82464-R). P.Z. gratefully acknowledges funding by the Humboldt Foundatio