Calibration and performance of the ISO Long-Wavelength Spectrometer

The wavelength and flux calibration, and the in-orbit performance of the Infrared Space Observatory Long-Wavelength Spectrometer (LWS) are described. The LWS calibration is mostly complete and the instrument's performance in orbit is largely as expected before launch. The effects of ionising radiation on the detectors, and the techniques used to minimise them are outlined. The overall sensitivity figures achieved in practice are summarised. The standard processing of LWS data is described

Circadian Preference Modulates the Neural Substrate of Conflict Processing across the Day

Human morning and evening chronotypes differ in their preferred timing for sleep and wakefulness, as well as in optimal daytime periods to cope with cognitive challenges. Recent evidence suggests that these preferences are not a simple by-product of socio-professional timing constraints, but can be driven by inter-individual differences in the expression of circadian and homeostatic sleep-wake promoting signals. Chronotypes thus constitute a unique tool to access the interplay between those processes under normally entrained day-night conditions, and to investigate how they impinge onto higher cognitive control processes. Using functional magnetic resonance imaging (fMRI), we assessed the influence of chronotype and time-of-day on conflict processing-related cerebral activity throughout a normal waking day. Sixteen morning and 15 evening types were recorded at two individually adapted time points (1.5 versus 10.5 hours spent awake) while performing the Stroop paradigm. Results show that interference-related hemodynamic responses are maintained or even increased in evening types from the subjective morning to the subjective evening in a set of brain areas playing a pivotal role in successful inhibitory functioning, whereas they decreased in morning types under the same conditions. Furthermore, during the evening hours, activity in a posterior hypothalamic region putatively involved in sleep-wake regulation correlated in a chronotype-specific manner with slow wave activity at the beginning of the night, an index of accumulated homeostatic sleep pressure. These results shed light into the cerebral mechanisms underlying inter-individual differences of higher-order cognitive state maintenance under normally entrained day-night conditions

Seasonal variation in human executive brain responses

It is well established that cognition shows daily fluctuations with changes in circadian phase and sleep pressure. The physiological impact of season changes, which is well characterized in animals, remains largely unexplored in human. Here we investigated the impact of seasonal variation on human cognitive brain function. This cross-sectional study,conducted in Liège (Belgium),spanned from May 2010 to October 2011. Following 8h in-lab baseline night of sleep, 30 volunteers (age 20.9+1.5; 15F)spent 42h awake under constant routine conditions(0b).Analysis tested seasonal influence on executive brain responses at the random effects level, using a phasoranalysis across the year.Inferences were conducted at p<0.05, after correction for multiple comparisons over a priori small volume of interest. Significanteffects of season on executive responses were detected inmiddle frontal and frontopolarregions, insula, and thalamus, with a maximum response at the end of summer and a minimum response at the end of winter.These brain areas are key regions for executive control and alertness. These results constitute the first demonstration that seasonality directly impacts on human cognitive brain functions

The hMRI analysis toolbox for quantitative MRI and in vivo histology using MRI (hMRI)

Quantitative magnetic resonance imaging (qMRI) finds increasing application in neuroscience and clinical research due to its greater specificity and its sensitivity to microstructural properties of brain tissue - myelin, iron and water concentration. We introduce the hMRI toolbox, an easy-to-use open-source tool for handling and processing quantitative MRI data. This toolbox is embedded in the SPM framework, profiting from the high accuracy spatial registration in common space and the variety of available statistical analyses. It allows the estimation of quantitative MRI maps (longitudinal and transverse relaxation rates R 1 and R 2 *, proton density PD and magnetization transfer MT), followed by spatial registration in common space for statistical analysis. It also offers flexibility for calculation of novel MRI biomarkers of tissue microstructure. The hMRI toolbox can be downloaded from http://hmri.info (git repository). The reference documentation is available as a WIKI on the git repository, including installation instructions, example dataset, tutorial and detailed description of the functionalities implemented

The “hMRI Toolbox” for quantitative imaging & in vivo histology using MRI

Quantitative magnetic resonance imaging (qMRI) finds increasing application in neuroscience and clinical research due to its greater specificity and its sensitivity to microstructural properties of brain tissue, such as myelin, iron and water concentration. We introduce the “hMRI Toolbox”, an easy-to-use open-source tool for generating and processing quantitative MRI data. This toolbox is embedded in the SPM framework, profiting from the high accuracy spatial registration in common space and the variety of available statistical analyses. It allows the estimation of quantitative MRI maps, precisely longitudinal (R 1 =1/T 1 ) and transverse (R 2 *=1/T 2 *) relaxation rates, proton density (PD) and magnetization transfer (MT), followed by spatial registration in common space for statistical analysis. It also offers flexibility for calculation of novel MRI biomarkers of tissue microstructure. The hMRI toolbox can be downloaded from http://hmri.info. The Readme.md and Wiki of the Git repository provide : • reference documentation, including installation instructions, example dataset, tutorial and detailed description of the functionalities implemented; • a link to a pre-print paper describing the hMRI toolbox