Odorants are first represented in the brain by distributed patterns of activity in the olfactory bulb (OB). Although neurons downstream of sensory inputs respond to odorants with temporally ...structured activity, sensory inputs to glomeruli are typically described as static maps. Here, we imaged the temporal dynamics of receptor neuron input to the OB with a calcium-sensitive dye in the olfactory receptor nerve terminals in anesthetized mice. We found that diverse, glomerulus- and odorant-dependent temporal dynamics are present even at this initial input stage. Instantaneous spatial patterns of receptor input to glomeruli changed both within and between respiration cycles. Glomerular odorant responses differed in amplitude, latency, rise time, and degree of modulation by sniffing in an odorant-specific manner. Pattern dynamics within the first respiration cycle recurred in a similar manner during consecutive cycles. When sniff rate was increased artificially, pattern dynamics were preserved in the first sniff but were attenuated during subsequent sniffs. Temporal response properties were consistent across individuals on a coarse regional scale and on a fine scale of individual glomeruli. Latency and magnitude of glomerular inputs were only weakly correlated and might therefore convey independent odorant information. These data demonstrate that glomerular maps of primary sensory input to the OB are temporally dynamic. These dynamics may contribute to the representation of odorant information and affect information processing in the central olfactory system of rodents.
We present
, an open-source Python-based application to operate serial block-face electron microscopy (SBEM) systems.
is designed for complex, challenging acquisition tasks, such as large-scale ...volume imaging of neuronal tissue or other biological ultrastructure. Advanced monitoring, process control, and error handling capabilities improve reliability, speed, and quality of acquisitions. Debris detection, autofocus, real-time image inspection, and various other quality control features minimize the risk of data loss during long-term acquisitions. Adaptive tile selection allows for efficient imaging of large tissue volumes of arbitrary shape. The software's graphical user interface is optimized for remote operation. In its user-friendly viewport, tile grids covering the region of interest to be acquired are overlaid on previously acquired overview images of the sample surface. Images from other sources, e.g., light microscopes, can be imported and superimposed.
complements existing
installations on 3View systems but permits higher acquisition rates by interacting directly with the microscope's control software. Its modular architecture and the use of Python/PyQt make
highly customizable and extensible, which allows for fast prototyping and will permit adaptation to a wide range of SBEM systems and applications.
High-resolution tracing of projections from the olfactory bulb to its cortical targets revealed coarse topography and stereotopy in some areas but highly distributed, combinatorial connectivity in ...others. These results provide a basis for understanding innate and associative olfactory processing and perception.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mitral cells (MCs) in the olfactory bulb (OB) respond to odors with slow temporal firing patterns. The representation of each odor by activity patterns across the MC population thus changes ...continuously throughout a stimulus, in an odor-specific manner. In the zebrafish OB, we found that this distributed temporal patterning progressively reduced the similarity between ensemble representations of related odors, thereby making each odor's representation more specific over time. The tuning of individual MCs was not sharpened during this process. Hence, the individual responses of MCs did not become more specific, but the odor-coding MC assemblies changed such that their overlap decreased. This optimization of ensemble representations did not occur among olfactory afferents but resulted from OB circuit dynamics. Time can therefore gradually optimize stimulus representations in a sensory network.
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The clever choice of animal models has been instrumental for many breakthrough discoveries in life sciences. One of the outstanding challenges in neuroscience is the in-depth analysis of neuronal ...circuits to understand how interactions between large numbers of neurons give rise to the computational power of the brain. A promising model organism to address this challenge is the zebrafish, not only because it is cheap, transparent and accessible to sophisticated genetic manipulations but also because it offers unique advantages for quantitative analyses of circuit structure and function. One of the most important advantages of zebrafish is its small brain size, both at larval and adult stages. Small brains enable exhaustive measurements of neuronal activity patterns by optical imaging and facilitate large-scale reconstructions of wiring diagrams by electron microscopic approaches. Such information is important, and probably essential, to obtain mechanistic insights into neuronal computations underlying higher brain functions and dysfunctions. This review provides a brief overview over current methods and motivations for dense reconstructions of neuronal activity and connectivity patterns. It then discusses selective advantages of zebrafish and provides examples how these advantages are exploited to study neuronal computations in the olfactory bulb.
Health impacts of air pollutants, especially fine particles (PM2.5) and NO2, have been documented worldwide by epidemiological studies. Most of the existing studies utilised the concentration ...measured at the ambient stations to represent the pollutant inhaled by individuals. However, these measurement data are in fact not able to reflect the real concentration a person is exposed to since people spend most of their time indoors and are also affected by indoor sources. The authors developed a probabilistic methodology framework to simulate the lifelong exposure to PM2.5 and NO2 simultaneously for population subgroups that are characterised by a number of indicators such as age, gender and socio-economic status. The methodology framework incorporates the methods for simulating the long-term outdoor air quality, the pollutant concentration in different micro-environments, the time-activity pattern of population subgroups and the retrospective life course trajectories. This approach was applied to the population in the EU27 countries plus Norway and Switzerland and validated with the measurement data from European multi-centre study, EXPOLIS. Results show that the annual average exposure to PM2.5 and NO2 at European level kept increasing from the 1950s to a peak between the 1980s and the 1990s and showed a decrease until 2015 due to the implementation of a series of directives. It is also revealed that the exposure to both pollutants was affected by geographical location, gender and income level. The average annual exposure over the lifetime of an 80-year-old European to PM2.5 and NO2 amounted to 23.86 (95% CI: 2.95–81.86) and 13.49 (95% CI: 1.36–43.84) µg/m3. The application of this methodology provides valuable insights and novel tools for exposure modelling and environmental studies.
On its way to a low-carbon society, various transformation pathways for the European energy system are possible. Additionally, improving air quality may benefit from or influence climate change ...mitigation. In a comparative scenario analysis, interactions between decarbonization targets and air pollution control as well as their implications on the European energy system are studied. For this purpose, the European energy system model TIMES PanEU is linked with the impact assessment model EcoSense to internalize the health costs related to air pollution. Results indicate that ambitious GHG reduction targets are most influential with respect to system transformations. Internalizing health impacts leads to welfare savings by reducing air pollution while still achieving the given reduction targets with lower utilization of carbon capture and storage as well as biomass. Especially the latter may partially be contradictory to targets on the share of renewable energy sources. Hence, integrated policies tackling climate change and air pollution alike may foster the transition to a low-carbon society. To gain a better understanding of the interplay between reduction targets, the share of renewable energy sources, and air pollution control, further research studying sector- and country-specific impacts in more detail is still needed.
•Energy system model TIMES PanEU is coupled with the impact assessment model EcoSense.•GHG reduction targets are most influential driving energy system transformations.•Considering cost of air pollution leads to less CCS deployment.•RES targets fostering biomass may hinder air pollution control.•An integrated view on climate change and air quality may foster a low-carbon society.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Direct numerical simulation (DNS) is used to explore similarities and differences between fully developed supersonic turbulent plane channel and axisymmetric non-swirling pipe flow bounded by ...isothermal walls. The comparison is based on equal friction Mach number, friction Reynolds number, Prandtl number, ratio of specific heats and viscosity exponent. The channel half-width and pipe radius are chosen to define the Reynolds numbers. To what extent and why mean flow quantities, second-order turbulence statistics and terms in the Reynolds stress equations coincide or diverge in both flows are investigated. The role of the fluctuating pressure in causing characteristic differences among correlations involving pressure fluctuations is identified via a Green-function-based analysis of the pressure field.
Organisms process sensory information to learn about their environment and to inform future behaviours. The first layers of sensory processing transform information from the sense organs into sparse ...and stimulus-specific activity patterns across large populations of neurons in the brain1. But the subsequent processing steps are less well understood. Hige et al.2 (page 258 of this issue) address this gap in knowledge by studying the olfactory system of the fruit fly Drosophila melanogaster.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
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