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The question of how the mind works is at the heart of cognitive science. It aims to understand and explain the complex processes underlying perception, decision-making and learning, three fundamental areas of cognition. Bayesian Brain Theory, a computational approach derived from the principles of Predictive Processing (PP), offers a mechanistic and mathematical formulation of these cognitive processes. This theory assumes that the brain encodes beliefs (probabilistic states) to generate predictions about sensory input, then uses prediction errors to update its beliefs. In this paper, we present an introduction to the fundamentals of Bayesian Brain Theory. We show how this innovative theory hybridizes concepts inherited from the philosophy of mind and experimental data from neuroscience, and how it translates complex cognitive processes such as perception, action, emotion, or belief, or even the psychiatric symptomatology., (Copyright © 2021 L'Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.)

The first part of this paper describes the long history of the concept of Mindfulness. Contrary to the belief that Mindfulness only has Buddhist and Hindu origins, it is also rooted in Jewish, Islamic and Christian religions. Furthermore, western philosophers have described a mindful path to become more aware of thoughts, feelings, and bodily sensations. Mindfulness can be considered as a universal human ability embodied to foster clear thinking and open-heartedness. As such, this form of being requires no particular religious or cultural belief system. The current acceptance of what a mindful path is, refers to a psychological quality that involves bringing one's complete attention to present experience on a moment-to-moment basis, in a particular way: in the present moment, and nonjudgmentally. Although such a definition is well accepted in France, the French translation for Mindfulness is not easy to use: being conscious and being aware are translated with the same French word. The French language fails to clearly separate the dimensional attributes of a mindful subject from the ways for developing mindfulness through formal meditation practice. In line with this conception, stability and assessments of Mindfulness mainly were examined. How this disposition allows the development of concentration, attention and acceptance moment by moment in a nonjudgmental way is described in the second part. Particular attention is paid to its positive effects in several aspects of mental and physical health. In particular, positive effects on the ability to cope with stress are described from a physiological point of view. Third, this article intends to present neurobiological aspects currently proposed to explain the benefits of Mindfulness meditation. Modifications of cerebral networks and neurobiological functioning are described in relation to expertise in meditation practice. The hypothesis of the role of meditation on neuroplasticity is also discussed. Furthermore, the specific impact of Mindfulness meditation practice on these mechanisms will be considered in comparison with relaxation techniques. With the increasing growth of well-designed and well-controlled meditation research, however, future studies will be needed to compare between different meditation techniques. This will enable researchers to outline the effects of the technique-specific differences on behavior, cognitive function, underlying physiology and neurobiology and clinical effectiveness. Finally, the most recent data on the changes in functioning of a resting brain (Brain Default Mode) induced by a Mindfulness practice, demonstrate differences in the default-mode network that are consistent with decreased mind-wandering. That is a way to better understand possible neural mechanisms of meditation for health benefits of Mindfulness., (Copyright © 2014 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.)

Introduction: Executive function impairments and high level of impulsivity may constitute heritable endophenotypes that confer predisposition for alcohol dependence. Brain volume abnormalities have also been reported in young, alcohol-naïve subjects at high risk (HR) for alcohol dependence, and linked to cognitive dysfunction., Methods: This paper presents a literature review of magnetic resonance imaging (MRI) studies that examined brain volumes in adolescent/young adult HR offspring from families with multiple cases of alcohol dependence compared to low risk controls with no family history of alcohol or drug misuse. In some of these studies, executive functioning and externalizing symptoms were also assessed., Results: In HR subjects, local white matter volume deficits were found in the corpus callosum and in the right orbito-frontal cortex, and lower fractional anisotropy in the left inferior longitudinal fasciculus and in the right optic radiation. Altered fronto-cerebellar connectivity has also been reported. Diminished gray matter volume of the cerebellar cortex was found in HR subjects, in the frontal, cyngulate and para-hippocampal gyri, and also in the amygdala, the thalamus and the cerebellum. These structural abnormalities have been associated with higher impulsivity level and executive function impairments, themselves markers of vulnerability to alcoholism. These premorbid cerebral abnormalities may increase the risk for developing an alcohol use disorder in HR subjects through atypical control processing., Conclusion: Brain abnormalities may potentially constitute an abnormal neural network that might underlie the risk towards alcohol dependence. These circuitry abnormalities might contribute to the reward deficiency, as well as impaired response inhibition that predict impulsive spectrum behavior, which are thought to represent the inherited vulnerability to alcohol dependence in HR individuals., (Copyright © 2013 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.)

The number of structural neuroimaging studies of bipolar disorder have increased during recent years, expanding the literature on the nature of cerebral abnormalities underlying this disorder. The purpose of this paper is to provide a selective review on the main issues concerning this literature. Consistent findings are higher rate of periventricular and deep subcortical white matter hyperintensites seen on MRI. Although there is strong evidence for links between hyper-intense lesions and age or cardio-vascular risk factors, some authors have observed the presence of these abnormalities early in the course of the illness. There are also frequent reports on ventricular enlargement, which has been described as mild and predominant in the right lateral ventricle. Total cerebral volume appears to be preserved. Whereas changes in total grey matter volume are uncertain, evidence suggests that reduced white matter volume reflects genetic factors predisposing to the disorder. Recent studies have reported volume changes in several cortical areas including the subgenual cingular, frontal and temporal cortices. Additionally, a number of reports described morphometric abnormalities in various subcortical structures, such as amygdala, basal ganglia and thalamus. Part of the variability in the morphometric abnormalities might be attributable to differences in clinical status and demographic characteristics of patient groups. Despite some inconsistencies across the studies, it emerges that abnormalities are asymmetrically distributed throughout the two cerebral hemispheres. When increase in volume is reported, it is preferentially localised in the left cerebral hemi-sphere and more specifically in prefrontal and temporal cortices and in amygdala. By contrast, when structural abnormalities concern the right cerebral hemisphere, they are identified as deficits. These latter results are in direct line with those of studies of mania following brain injuries, which report that these secondary mania result mainly from right cerebral lesions. It is also important to notice that most of the abnormalities concern both the cortical and subcortical level, ie frontal, striatal, thalamic and limbic regions. These abnormalities highlight the role in the pathophysiology of bipolar disorder of the loops involved in emotional information processing. The particular role of fronto-limbic loops in the phenomenology of bipolar disorder have been emphasised by recent data from functional neuroimaging studies.

Following a previous paper describing how memory appeared in the nervous system in mammalians, during evolution, and how its significant growth led to hominization, the present paper intends to show the prevailing place it occupies in human brain. Memory, an attribute of cortex, is an engraving of neuronal circuits created during information analysis of data input in the cortex. It is created either by repetition of information or by increase in brain activity, under the influence of a central brain system. In the brain of human newborns, immature and unprogrammed, but endowed with a great capacity for learning, the whole organization and programming will be possible through learning and remembering. Communication pathways between functions are memory pathways. Brain becomes a memory machine and every cortical area is a memory territory. Its lesion results in a disturbance corresponding exactly to forgetting what has been stored in that territory.

In recent years research on the neuronal substrate for mental disorders has considerably developed thanks to new brain imaging methods. Functional brain imaging has attracted several workers in their investigations of psychiatric diseases. Some authors have addressed the position of imaging in the diagnosis and, above all, prognosis of acute psychotic disorders. In the following paper, the authors review the published results. Both structural and functional imaging confirm the hypothesis of a neurophysiological contribution to acute psychotic disorders, as shown by ventricular dilatation and functional abnormalities. Nonetheless, imaging does not seem to have a precise and absolute diagnostic and prognostic value, although of undeniable heuristic interest.

The concept of addiction is increasingly bound to a general model of heterogeneous and polymorphous dependences. In this paper we examine upstream what could found this universal addictive principle, asking the question of the neurobiological root of addictivity. In other words, is the root of our brain working in an addictive way? To answer affirmatively to this question we gather two sets of datas: firstly, the conditions of the brain addictivity and secondly, the brain mechanisms that suggest this kind of addictive working. These datas are common if we consider them one by one, but their synthesis in a bundle of heuristic clues could be interesting to examine and to submit to thought. The model we suggest proposes that the architecture of our brain and the type of functioning of our neurones, imply the presence of a natural addictive set of problems in all human beings, between a fight against cerebral background noise--a dysphoric source--and a stimulation need. Finally, considering some neurobiological data in the last five years, we propose a triangular model of the addict brain, that involves three associated systems: "arousal" system, "liking" system and "wanting" system. This model, supported by the sensation seeking one, will allow us to suggest an explanation of the processes that lead to pathological addictions, according to the principles of a natural and universal addictivity.