Étude des liens entre sommeil et mémoire épisodique chez le sujet jeune et âgé, et dans la maladie d’Alzheimer

Introduction

A large body of evidence indicates that sleep favors memory consolidation.

State of the art

This process would occur, mainly during slow-wave sleep, by means of a dialogue between the hippocampus and neocortical areas. Low levels of acetylcholine and cortisol are also needed to favor the transfer of memory traces toward the neocortex, where they will be stored for the long-term.

Perspectives

The aim of this article is, first, to give an overview of studies conducted in young healthy subjects and underpinning the hypothesis that sleep is involved in memory consolidation. Then, we will investigate the potential links between changes in sleep architecture and episodic memory impairment in both aging and Alzheimer's disease. Finally, we will see how these results can affect clinical practice.

Conclusion

Sleep-dependent memory consolidation is impaired both in aging and Alzheimer's disease. These findings suggest the importance of taking into account sleep when assessing memory function in patients.     

Maladie d’Alzheimer, mémoire et estrogènes

Epidemiological studies of Alzheimer disease have shown a higher prevalence of women. Some data argue for a link between Alzheimer disease and the decrease of estrogen in post-menopausal women. Animal studies have shown a beneficial effect of estrogen on memory with a decrease of amyloid deposition in models of AD, whereas estrogen has a positive effect on BDNF. Six studies have shown a positive effect of estrogen therapy on memory and studies on structural and functional imaging have shown a beneficial effect of estrogens but the largest study on prevention of dementia with estrogens (WHI) showed a deleterious effect. To better understand this paradoxical situation, we reviewed the literature on estrogens, memory and Alzheimer disease. We first discuss the promnesic effect of estrogen on mice and rats, second the neuroprotector effect of estrogen on animal models of Alzheimer disease, and third the available human studies. We hypothesize a link with the time of instauration of the estrogen treatment. Nevertheless this hypothesis remains to be demonstrated.     

Memory: a view of the history of central nervous system

In order to stress the role and importance of memory in human nervous system, this first paper intends to show how it appeared during evolution with the cortex of brain hemispheres and how its significant growth is the cause (and not consequence) of hominization. This growth seems related to a discontinuation of the fetal period during gestation. It leads to birth before the brain is mature, substituting a genetic maturation by an epigenetic maturation through learning. This discontinuation of pregnancy is related to a purely mechanical and obstetrical cause, depending on maternal pelvis. Evolution from quadrupedia to bipedia transformed the pelvis, obliging the newborn to make his way not downward but forward, through a narrow inextensible pass. This history of memory, showing its role in human species evolution, may lead to a reflection on its role in the evolution of all the species possessing a cortex. Above all, it will allow to understand how and in which way human brain is a sort of machine totally associated with memory.     

Un nouveau cadre conceptuel de travail pour une psychiatrie revisitée ? Introduction à deux articles de E. Kandel

In two articles which appeared in the American Journal of Psychiatry and that were subsequently translated for Évolution Psychiatrique, E. Kandel examines the bases for a reinterpreted psychiatry that is prepared to confront the major challenge of the 3rd millenium: that of insight into the mind and brain. This requires a major reorganization of the discipline, which involves a reinvestment of the scientific approach and a critical  assessment of the data provided by psychoanalytical psychiatry and cognitive neurosciences. Seven concepts have therefore been proposed for interactive re-examination: consciousness, the unconscious, memory, emotion, development, desire, impulse. The dynamic relations existing between genetics and the environment allow one to see how evolutions are possible from actions at different levels, both psychotherapeutic and pharmacological. Imaging and other techniques provide additional objective information to the process of human interaction which remains the basis of psychiatry. A common framework for psychiatry and the neurosciences, a reconsideration and renewal of the psychoanalytical approach are both possible and necessary.     

La biologie et le futur de la psychanalyse : un nouveau cadre conceptuel de travail pour une psychiatrie revisitée

The American Journal of Psychiatry has received a number of letters in response to my earlier “Framework” article (1). Some of these are reprinted elsewhere in this issue, and I have answered them briefly there. However, one issue raised by some letters deserves a more detailed answer, and that relates to whether biology is at all relevant to psychoanalysis. To my mind, this issue is so central to the future of psychoanalysis that it cannot be addressed with a brief comment. I therefore have written this article in an attempt to outline the importance of biology for the future of psychoanalysis.     

The effects of ghrelin on sleep,appetite, and memory,and its possible role in depression: A review of the literature

Objectives

Ghrelin is an orexigenic digestive hormone that plays a role in sleep and memory. Our work aims is to synthesize the effects of ghrelin on appetite, sleep and memory, and also to evidence its role in depressive disorders.

Rééducation oculomotrice informatisée dans la dyslexie : essai clinique randomisé en crossover en population pédiatrique

Objective

Several studies have reported abnormal oculomotor capacities leading to reading/writing difficulties among dyslexic children. However, no randomized clinical trial has been conducted to determine whether oculomotor training improves reading/writing skills of these children. The present study aims to evaluate the efficacy of computer-based oculomotor training among dyslexic children.