Polysomnographie | EPFL Graph Search

La polysomnographie (ou polygraphie du sommeil) est un examen médical consistant à enregistrer, au cours du sommeil du patient, plusieurs variables physiologiques (rythme respiratoire, rythme cardiaque, électroencéphalogramme, électromyogramme des muscles des bras ou des jambes...) afin de déterminer certains troubles liés au sommeil, dont les apnées ou syndrome d’apnées obstructives du sommeil (SAOS). Dans l'étude des troubles du sommeil il est important de distinguer deux types d'examens : la polygraphie respiratoire qui permet, selon les appareils, d'enregistrer différents signaux respiratoires, qui associés entre eux permettent de détecter des anomalies respiratoires. La polysomnographie qui, outre l’enregistrement des signaux respiratoires précédents, permet de recueillir d’autres signaux qui permettent de reconnaître la succession des différents stades de sommeil. C'est un examen qui consiste à dormir pendant la nuit avec plusieurs électrodes ou fils métalliques attachés à la tête, à la figure, à la poitrine et aux jambes. Des bandes élastiques sont placées autour de la poitrine et de l'abdomen pour mesurer la respiration. Le principe de la polysomnographie est de capter l’information nécessaire pour analyser la respiration et le sommeil de la personne concernée. Les électrodes et les bandes posées amassent les données (le nombre et la durée des apnées ou d’autres problèmes qui perturbent le sommeil) pour permettre au médecin d’établir un diagnostic. La polysomnographie est un examen pratiqué lors d'une inquiétude sérieuse comme une somnolence diurne excessive, des pauses respiratoires ou des impressions d'étouffement de courte durée pendant le sommeil, des ronflements excessifs, des réveils fréquents, des fatigues au réveil matinal, des difficultés de concentration, des assoupissements au volant, ou encore des maux de tête au réveil.

Genetic selection for low glucocorticoid responsiveness recapitulates PTSD-related phenotypes: a behavioral, neuroimaging and sleep-physiology study

Silvia Monari

Humans show inter-individual differences in vulnerability to develop post-traumatic stress disorder (PTSD) following exposure to trauma. Several critical biobehavioral features have been consistently described in PTSD patients, including blunted cortisol levels, smaller hippocampal size, sleep disturbances. However, because of the delay between trauma exposure and the onset of symptoms characteristic of PTSD, only a few longitudinal studies have tried to dissect whether these features constitute pre-trauma risk factors or consequences of the trauma. Enormous effort in animal and human studies has been dedicated to understanding mechanisms of conditioned fear and fear extinction, processes that are at the core of PTSD. However, the same progress has not been translated into psychiatric practice for PTSD. Deepening our understanding of the contribution of key factors to PTSD-related alterations can serve to develop effective treatments.In particular, with regard to low cortisol levels in PTSD pathophysiology, a causative role for blunted glucocorticoid responsiveness in PTSD has not been demonstrated yet.Here, we have addressed this question in lines of Wistar rats genetically-selected for their differential habituation of glucocorticoid responses to stress (LOW-, INTER-, HIGH-CORT Responder rats) and focused on fear extinction, a hallmark of PTSD symptomology, as one of the key features. As a first step, we looked whether divergent trajectories of glucocorticoid responsiveness were associated with brain volume abnormalities, prompted by the influential role of glucocorticoid in brain development. Notably, rats with low or high corticosterone responsiveness exhibit smaller hippocampi, regardless of trauma exposure, compared to rats with normative corticosterone levels. Similarly, the distribution of corticosteroid receptors in the hippocampus presented similarities between the LOW-CR and the HIGH-CR rats with higher mineralocorticoid receptors (MR) and less glucocorticoid receptors (GR). Although LOW- and HIGH-CR rats displayed a similar hippocampal profile at the structural and molecular levels, only LOW-CR male rats exhibited strong deficits in extinction consolidation compared to rats with 'normative' glucocorticoid responses (INTER-CR rats), and showed higher fear response both at few days and at several weeks after trauma exposure. We next tested the causal involvement of corticosterone in the fear extinction consolidation, and found that post-extinction corticosterone treatment markedly prevented the deficits in extinction memory and attenuated fear relapse. In addition, pharmacological inhibition of corticosterone levels during extinction memory consolidation, but not during training, in the INTER-CR rats led to extinction deficits at retrieval one day later. These results indicate that blunted corticosterone levels contribute to confer major vulnerability than having a small hippocampus, and that consolidation processes following extinction are mainly affected by low corticosterone levels.It is well known that glucocorticoids play an important role in memory consolidation processes and that sleep disturbances are a diagnostic criterion of PTSD. Therefore, we investigated in greater detail the sleep architecture in undisturbed condition and during the consolidation period of the extinction phase, which is known to be supported by sleep-dependent processes. In polysomnographic recordings, we found that rats with blunted corticos

EPFL2022

Sleep: An Open-Source Python Software for Visualization, Analysis, and Staging of Sleep Data

Christian O'Reilly, Raphaël Vallat

We introduce Sleep, a new Python open-source graphical user interface (GUI) dedicated to visualization, scoring and analyses of sleep data. Among its most prominent features are: (1) Dynamic display of polysomnographic data, spectrogram, hypnogram and topographic maps with several customizable parameters, (2) Implementation of several automatic detection of sleep features such as spindles, K-complexes, slow waves, and rapid eye movements (REM), (3) Implementation of practical signal processing tools such as re-referencing or filtering, and (4) Display of main descriptive statistics including publication-ready tables and figures. The software package supports loading and reading raw EEG data from standard file formats such as European Data Format, in addition to a range of commercial data formats. Most importantly, Sleep is built on top of the VisPy library, which provides GPU-based fast and high-level visualization. As a result, it is capable of efficiently handling and displaying large sleep datasets. Sleep is freely available (http://visbrain. org/sleep) and comes with sample datasets and an extensive documentation. Novel functionalities will continue to be added and open-science community efforts are expected to enhance the capacities of this module.

Frontiers Research Foundation2017

Genetic selection for low glucocorticoid responsiveness recapitulates PTSD-related phenotypes: a behavioral, neuroimaging and sleep-physiology study

Silvia Monari

EPFL2022