Experimental dissociation between wakefulness and paradoxical sleep hippocampal theta.

The effects of electrolytic lesions of the septum on the theta activity of the dorsal hippocampus were studied in the chronically implanted rat during both wakefulness and paradoxical sleep. The experimental results show that depending on their localization, septal lesions can either: (1) eliminate the wakefulness theta rhythm without suppressing that of paraoxical sleep; (2) eliminate the paradoxical sleep theta rhythm without suppressing that of wakefulness. These results suggest that there are two kinds of theta activity having different anatomophysiological bases and a different functional significance: one associated with wakefulness and the other, with paradoxical sleep.     

Temporal characteristics of the augmentation of paradoxal sleep following learning in the rat

In a previous work, we have shown that an avoidance conditioning is followed by an increased number of Paradoxical Sleep (PS) phases during the first hour after learning. In Experiment 1, sleep is experimentally delayed after each conditioning session. When sleep is delayed for 180 min, learning is severely impaired and PS doesn't increase; but the 90-min sleep delay after the conditioning session is followed by the same PS increase as that when sleep is free immediately after learning. In Experiment 2, we show that a 90-min free sleep period, between learning and a 180-min sleep deprivation allowed a learning as good as that without any sleep deprivation. In our experimental conditions, PS increase after avoidance conditioning is brief and immediate when sleep is possible and if it begins less than 180 min after learning.     

Concomitants physiologiques de l'apprentissage et sommeil paradoxal consécutif,chez le chat

During avoidance conditioning in the Cat, arousal, heart rate and respiratory reactions produced by the conditioned stimulus (CS) were recorded. The development of these reactions was compared with the paradoxical sleep (PS) length measured between the trials of each experimental session. The results of this analysis point to the existence of a critical learning period characterised by a high rate of central and peripheral reactions and by an increase in PS length. This period precedes the stabilization of performances. The functional relationship of these two phenomena with each other and with learning is discussed.     

Comparaison de l'effet somnogène de deux médicaments,le Ro 5-4200 et le Nitrazepam

Résumé Au cours d'une étude comparative entre l'action de 2 mg de Ro 5-4200 et de 10 mg de Nitrazepam sur les durées d'endormissement et de sommeil, 35 patients ont été observés. L'efficacité de ces deux substances dans un rapport de doses de 1 à 5 est comparable sur les deux variables observées. Toutefois, si le médicament est pris juste au moment du coucher, le Ro 5-4200 induit d'une manière significative un peu plus rapidement le sommeil que le Nitrazepam. En considérant les nuits dans leur ensemble sans tenir compte des sujets, aucune différence significative n'a été observée pour l'un ou l'autre des médicaments, en fonction de la régularité ou de l'irrégularité dans le moment de la prise. L'induction au sommeil dans ces conditions est donc peu brutale. Enfin, il existe une corrélation négative entre la durée d'endormissement et la durée de sommeil. En d'autres termes, ce sont les malades qui s'endorment le plus rapidement qui dorment le plus longtemps. Cette corrélation est significativement plus grande avec le Ro 5-4200.Nous remercions la Maison Hoffmann-La Roche (Bâle), qui nous a aimablement fourni le Ro 5-4200.     

Les accidents en France : évolution et facteurs associés

BackgroundWhatever the type of injury considered, prevention requires an improvement in health services’ awareness of risk factors. The Health Barometer is a general population survey conducted in France since 1992 to contribute to surveillance in this field. The survey's statistical power and the numerous health topics included in the questionnaire provide accurate information for healthcare professionals and decision-makers.MethodsThe Health Barometer 2010 was a nationwide telephone survey of 9110 persons representative of the 15–85-year-old population. One part of the questionnaire detailed injuries which had occurred during the past year. The numerous variables recorded enabled application of logistic regression models to explore risk factors related to different types of injury by age group. The findings were compared with the Health Barometer 2005 data to search for temporal trends of injury prevalence.ResultsThe data analysis showed that 10.3 % of the 15–85-year-olds reported an injury during the past year. This rate was higher than recorded in 2005; the increase was mainly due to domestic accidents and injuries occurring during recreational activities. Both type of injury and risk factors exhibited age-related variability. Domestic accidents and injuries occurring during recreational activities predominated in the older population and were associated with physical or mental health problems (chronic disease, diability, sleep disorders). For younger people, injuries were related to cannabis use, drunkedness, and insufficient sleep. Risk factors were also depended on type of injury: occupational accident-related injuries were linked with social disadvantage (manual worker population) whereas sports injuries were more common in the socially advantaged population.ConclusionThis survey confirms established knowledge and highlights, at different stages of life, new risk factors that contribute to injuries in France. These findings should be helpful for the development of adapted injury prevention programs, by providing a better understanding of the characteristic features of this major public health issue.     

La motricité redevient-elle normale en sommeil paradoxal ? Le trouble comportemental en sommeil paradoxal

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by violent, or potentially violent, movements during REM sleep, corresponding to enacted dreams. During sleep monitoring, there is a partial or total loss of the normal muscle atonia during REM sleep. REM sleep behavior disorder predominantly affects elderly subjects without any other disease (idiopathic RBD, a precursor of Parkinson disease and Lewy body dementia) or suffering from various neurological and neurodegenerative diseases, mainly synucleinopathies. In addition to being a treatable cause of nocturnal injury of the patients or their bed-partners, RBD is a fantastic window into motor and cognitive control during REM sleep. Notably, parkinsonism transiently disappears during RBD. The patient's voice is louder and better articulated than when awake, and movements are rapid (but jerky) suggesting that the deleterious message from the basal ganglia to the primary motor cortex is reduced or bypassed. As we observed culturally-acquired behaviors, retired patients practicing their former work with mastered gestures, as well as sentences pronounced with appropriate prosody, gesturing, fluency, and syntax during the RBD, we suggest that these behaviors are generated by the same cortical areas as during wakefulness. This model also enables the demonstration that REM during REM sleep are coded in the same direction as the arm and hand movements, as if the dreamer were scanning the dream images. This online access to the motor and verbal dream scenario (through the video and audio monitoring), and the physiological measures (via the EEG, eye movements, muscle tone, respiration, heart rate), together with the offline access to the mental content (dream report after the awakening) constitute a triangulation for validating new hypotheses about REM sleep and dreams.     

Use of immediate release melatonin in psychiatry: BMI impacts the daily-dose

ObjectiveThere is a growing interest in psychiatry regarding melatonin use both for its soporific and chronobiotic effects. This study aimed to evaluate factors impacting the daily-dose.MethodsIn a university department of psychiatry in Paris (France), we conducted a posteriori naturalistic observational study from April 03, 2017 to January 31, 2018. We assessed links between sociodemographic and clinical characteristics and daily dose of melatonin (the daily-dose of melatonin initiation and the daily-dose at Hospital discharge). A survey of drug interactions was performed regarding metabolic inducers and inhibitors of the cytochrome P450 1A2.ResultsForty patients were included and treated with immediate-release melatonin. For patients with no history of melatonin use, the initiation dose of was 2 or 4 mg, with no effects of age, weight, BMI, melatonin indication, cause of hospitalization. We found that higher discharge dose was associated with higher BMI (P = 0.036) and more reevaluations of melatonin dose (P = 0.00019). All patients with a moderate inducer (n = 3, here lansoprazole) were significantly more associated with the discontinuation melatonin group (P = 0.002).ConclusionThe BMI and the number of reevaluations impact the daily dose of melatonin. Two mechanisms may explain that BMI may need higher doses: (i) melatonin diffuses into the fat mass, (ii) the variant 24E on melatonin receptor MT2, more frequent in obese patients, leads to a decrease of the receptor signal.     

Liquid food and tongue activity during sleep and waking in C57Br mice

C57Br/co-Orl mice raised from weaning with a liquid food, were evaluated in terms of the quantitative and qualitative aspects of their vigilance states. The circadian amounts and rhythms of slow wave sleep and paradoxical sleep were not significantly different. The rhythmical activity of the tongue was not found to be modified by the type of food.     

The phylogeny, ethology and nosology of yawning

Charles Darwin would have said that yawning was a useless piece of physiology. If so, then how should the survival of this very stereotyped behavior among the poikilothermal and homoeothermic vertebrates, from the basic brained reptiles to human primates, whether in the air, on the land or in the sea be understand? This issue of the ethnological, neurophysiologic and neuropsychological literature depicts yawning as being associated with an alternation of "awake-sleep" rhythms, sexuality, and nutrition, where it appears as a reference behavior of the mechanisms stimulating the state of vigilance. In pharmacology, yawning is used as an indicator of dopamine-ocytocinergic pathway activity, but in the Parkinson patient the neurologist sees it as an expression of therapeutic dopaminergic activity. J.M. Charcot and his school considered yawning as a clinical sign, long since forgotten. However, many patients complain about excessive yawning. Iatrogenic causes are the most frequent and can be found among many neurological diseases: vasovagal syncope, migraine, epilepsy, hypophyseal tumor, or stroke. Our ability to achieve motor and emotional behavior in resonance with others is deeply rooted in hominid evolution, and probably explains the strange phenomenon of contagious yawning.