Exploring Cosmic Origins with CORE: Cosmological Parameters

We forecast the main cosmological parameter constraints achievable with theCORE space mission which is dedicated to mapping the polarisation of the CosmicMicrowave Background (CMB). CORE was recently submitted in response to ESA'sfifth call for medium-sized mission proposals (M5). Here we report the resultsfrom our pre-submission study of the impact of various instrumental options, inparticular the telescope size and sensitivity level, and review the great,transformative potential of the mission as proposed. Specifically, we assessthe impact on a broad range of fundamental parameters of our Universe as afunction of the expected CMB characteristics, with other papers in the seriesfocusing on controlling astrophysical and instrumental residual systematics. Inthis paper, we assume that only a few central CORE frequency channels areusable for our purpose, all others being devoted to the cleaning ofastrophysical contaminants. On the theoretical side, we assume LCDM as ourgeneral framework and quantify the improvement provided by CORE over thecurrent constraints from the Planck 2015 release. We also study the jointsensitivity of CORE and of future Baryon Acoustic Oscillation and Large ScaleStructure experiments like DESI and Euclid. Specific constraints on the physicsof inflation are presented in another paper of the series. In addition to thesix parameters of the base LCDM, which describe the matter content of aspatially flat universe with adiabatic and scalar primordial fluctuations frominflation, we derive the precision achievable on parameters like thosedescribing curvature, neutrino physics, extra light relics, primordial heliumabundance, dark matter annihilation, recombination physics, variation offundamental constants, dark energy, modified gravity, reionization and cosmicbirefringence. (ABRIDGED

Exploring Cosmic Origins with CORE: Survey requirements and mission design

Future observations of cosmic microwave background (CMB) polarisation havethe potential to answer some of the most fundamental questions of modernphysics and cosmology. In this paper, we list the requirements for a future CMBpolarisation survey addressing these scientific objectives, and discuss thedesign drivers of the CORE space mission proposed to ESA in answer to the "M5"call for a medium-sized mission. The rationale and options, and themethodologies used to assess the mission's performance, are of interest toother future CMB mission design studies. CORE is designed as a near-ultimateCMB polarisation mission which, for optimal complementarity with ground-basedobservations, will perform the observations that are known to be essential toCMB polarisation scienceand cannot be obtained by any other means than adedicated space mission

Exploring cosmic origins with CORE: Cosmological parameters

We forecast the main cosmological parameter constraints achievable with the CORE space mission which is dedicated to mapping the polarisation of the Cosmic Microwave Background (CMB). CORE was recently submitted in response to ESA’s fifth call for mediumsized mission proposals (M5). Here we report the results from our pre-submission study of the impact of various instrumental options, in particular the telescope size and sensitivity level, and review the great, transformative potential of the mission as proposed. Specifically, we assess the impact on a broad range of fundamental parameters of our Universe as a function of the expected CMB characteristics, with other papers in the series focusing on controlling astrophysical and instrumental residual systematics. In this paper, we assume that only a few central CORE frequency channels are usable for our purpose, all others being devoted to the cleaning of astrophysical contaminants. On the theoretical side, we assume ΛCDM as our general framework and quantify the improvement provided by CORE over the current constraints from the Planck 2015 release. We also study the joint sensitivity of CORE and of future Baryon Acoustic Oscillation and Large Scale Structure experiments like DESI and Euclid. Specific constraints on the physics of inflation are presented in another paper of the series. In addition to the six parameters of the base ΛCDM, which describe the matter content of a spatially flat universe with adiabatic and scalar primordial fluctuations from inflation, we derive the precision achievable on parameters like those describing curvature, neutrino physics, extra light relics, primordial helium abundance, dark matter annihilation, recombination physics, variation of fundamental constants, dark energy, modified gravity, reionization and cosmic birefringence. In addition to assessing the improvement on the precision of individual parameters, we also forecast the post-CORE overall reduction of the allowed parameter space with figures of merit for various models increasing by as much as ∼ 107 as compared to Planck 2015, and 105 with respect to Planck 2015 + future BAO measurements

Exploring cosmic origins with CORE: Survey requirements and mission design

Future observations of cosmic microwave background (CMB) polarisation have the potential to answer some of the most fundamental questions of modern physics and cosmology. In this paper, we list the requirements for a future CMB polarisation survey addressing these scientific objectives, and discuss the design drivers of the CORE space mission proposed to ESA in answer to the "M5" call for a medium-sized mission. The rationale and options, and the methodologies used to assess the mission's performance, are of interest to other future CMB mission design studies. CORE is designed as a near-ultimate CMB polarisation mission which, for optimal complementarity with ground-based observations, will perform the observations that are known to be essential to CMB polarisation scienceand cannot be obtained by any other means than a dedicated space mission.Comment: 79 pages, 14 figure

Precise and pervasive phasic bursting in locus coeruleus during maternal behavior in mice

The noradrenergic locus coeruleus (LC) mediates key aspects of arousal, memory, and cognition in structured tasks, but its contribution to naturalistic behavior remains unclear. LC activity is thought to multiplex distinct signals by superimposing sustained ('tonic') firing patterns reflecting global brain states, such as arousal and anxiety, and rapidly fluctuating ('phasic') bursts signaling discrete behaviorally significant events. Manipulations of the LC noradrenergic system broadly impair social behavior, but the temporal structure of LC firing and its relationship to social interaction is unknown. One possibility is that tonic firing may increase in the presence of social partners; it is also possible that phasic bursts may accompany specific social events. We used chronic in vivo electrophysiology and fiber photometry to measure single unit and population neural activity in LC of freely behaving mice during their interactions with pups. We find that pup retrieval elicits remarkably precise phasic activity in LC that can't be attributed merely to sensory stimuli, motor activity, or reward. Correlation of LC activity with retrieval events shows that phasic events are most closely related to specific subsequent behaviors. The reliability and magnitude of phasic responses strongly suggest that these events are coordinated across LC and broadcast NA release throughout the brain. We also observed slow changes in tonic firing when females performed distinct maternal behaviors such as nest building and pup grooming. We therefore propose that LC signals state changes during sustained interactions and contributes to goal-directed action selection during social behavior with globally-broadcast NA release.SIGNIFICANCE STATEMENTLocus coeruleus (LC) releases noradrenaline (NA) brain-wide influencing many cognitive, emotional, and physiological processes. Multifunctionality of LC is maintained by multiplexing NA signaling via brief 'phasic' patterns of bursting and slowly changing 'tonic' firing. Manipulations of NA impair social behavior, yet the structure of LC activity with respect to specific social events is unknown. We measured LC activity in mice freely interacting with pups. We find that pup retrieval elicits precisely timed and pervasive phasic activation of LC that anticipates specific behaviors. We also found that LC neurons exhibited slow fluctuations in firing during sustained behaviors. We propose that LC simultaneously contributes to goal-directed social action selection with globally-broadcast NA release, and signals social state changes with increased tonic firing

Relative Contributions of Specific Activity Histories and Spontaneous Processes to Size Remodeling of Glutamatergic Synapses

<div><p>The idea that synaptic properties are defined by specific pre- and postsynaptic activity histories is one of the oldest and most influential tenets of contemporary neuroscience. Recent studies also indicate, however, that synaptic properties often change spontaneously, even in the absence of specific activity patterns or any activity whatsoever. What, then, are the relative contributions of activity history-dependent and activity history-independent processes to changes synapses undergo? To compare the relative contributions of these processes, we imaged, in spontaneously active networks of cortical neurons, glutamatergic synapses formed between the same axons and neurons or dendrites under the assumption that their similar activity histories should result in similar size changes over timescales of days. The size covariance of such commonly innervated (CI) synapses was then compared to that of synapses formed by different axons (non-CI synapses) that differed in their activity histories. We found that the size covariance of CI synapses was greater than that of non-CI synapses; yet overall size covariance of CI synapses was rather modest. Moreover, momentary and time-averaged sizes of CI synapses correlated rather poorly, in perfect agreement with published electron microscopy-based measurements of mouse cortex synapses. A conservative estimate suggested that ~40% of the observed size remodeling was attributable to specific activity histories, whereas ~10% and ~50% were attributable to cell-wide and spontaneous, synapse-autonomous processes, respectively. These findings demonstrate that histories of naturally occurring activity patterns can direct glutamatergic synapse remodeling but also suggest that the contributions of spontaneous, possibly stochastic, processes are at least as great.</p></div

Diversifying network activity by a means of a cholinergic agonist.

<p>(A) A 120-s recording of spontaneous activity in a network of cortical neurons growing on a MEA. Each line reports activity (action potentials) recorded from one of the 59 extracellular electrodes of the MEA. Each dot represents one action potential. An enlarged portion of the recording is shown in the bottom panel. Note the tendency of spontaneous activity in these networks to occur as synchronized, network-wide bursts. (B) The same network as in (A) after exposure to 20 μM of Carbachol. (C) Average (±SEM) size remodeling covariance for all CI and non-CI synapse pairs before exposure to Carbachol (27 CI pairs from 8 neurons in 2 experiments). (D) Average (±SEM) size remodeling covariance for all CI and non-CI synapse pairs after exposure to Carbachol. Source data for (C) and (D) provided in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002572#pbio.1002572.s001" target="_blank">S1 Data</a>.</p

Rationale and experimental design.

<p>(A) The experiments described here are based on the assumption that synapses formed between the same axon (green) and the same neuron (blue) will have similar activity histories, particularly when such synapses are located on the same dendrite. Such synapses are referred to as CI and CI_SD, respectively. For each CI synapse, a Ref synapse is selected that is connected to a different upstream neuron (white). (B) Given their similar activity histories, changes in the sizes of synapses belonging to the same CI pair might be expected to co-vary more than the sizes of two synapses innervated by different axons, i.e., a CI synapse and a Ref synapse (C).</p