Locus cœruleus

vignette|Localisation du Locus Coeruleus dans un schéma du système noradrénergique. Le locus cœruleus, « locus cæruleus », « locus ceruleus » ou LC (« la tache bleue », en latin) est un noyau sous-cortical de l'encéphale, situé dans le tronc cérébral. Il a beaucoup de relations avec l'amygdale mais aussi avec le noyau sensitif du nerf trijumeau et les noyaux limbiques. Il a été découvert et décrit pour la première fois par le médecin et anatomiste français Félix Vicq d'Azyr au milieu du . Ce noyau constitue une structure noradrénergique et cholinergique. C'est de cette région que partent la grande majorité des neurones qui utilisent la noradrénaline comme neurotransmetteur. Sa couleur bleue est due à la présence de granules de mélanine, ce qui lui a aussi valu le nom de « noyau pigmentosus pontis » (noyau très pigmenté du pont). Fonctions Par son très grand nombre de connexions, le locus cœruleus est impliqué dans de nombreux effets naturels, tels que : Peur e

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Risk prediction error signaling: A two-component response?

Ophélie Gladys Favrod, Sophie Alberta Catherine Geoghan, Michael Herzog, Marc Michael Lauffs, Kerstin Preuschoff

Organisms use rewards to navigate and adapt to (uncertain) environments. Error-based learning about rewards issupported by the dopaminergic system, which is thought to signal reward prediction errors to make adjustmentsto past predictions. More recently, the phasic dopamine response was suggested to have two components: thefirstrapid component is thought to signal the detection of a potentially rewarding stimulus; the second, slightly latercomponent characterizes the stimulus by its reward prediction error. Error-based learning signals have also beenfound for risk. However, whether the neural generators of these signals employ a two-component coding schemelike the dopaminergic system is unknown. Here, using human high density EEG, we ask whether risk learning, ormore generally speaking surprise-based learning under uncertainty, is similarly comprised of two temporallydissociable components. Using a simple card game, we show that the risk prediction error is reflected in theamplitude of the P3b component. This P3b modulation is preceded by an earlier component, that is modulated bythe stimulus salience. Source analyses are compatible with the idea that both the early salience signal and the laterrisk prediction error signal are generated in insular, frontal, and temporal cortex. The identified sources are partsof the risk processing network that receives input from noradrenergic cells in the locus coeruleus. Finally, the P3bamplitude modulation is mirrored by an analogous modulation of pupil size, which is consistent with the idea thatboth the P3b and pupil size indirectly reflect locus coeruleus activity.

2020

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Analysis of Polycerate Mutants Reveals the Evolutionary Co-option of HOXD1 for Horn Patterning in Bovidae

Denis Duboule, Aurélie Hintermann, Jozsef Zakany

In the course of evolution, pecorans (i.e., higher ruminants) developed a remarkable diversity of osseous cranial appendages, collectively referred to as "headgear," which likely share the same origin and genetic basis. However, the nature and function of the genetic determinants underlying their number and position remain elusive. Jacob and other rare populations of sheep and goats are characterized by polyceraty, the presence of more than two horns. Here, we characterize distinct POLYCERATE alleles in each species, both associated with defective HOXD1 function. We show that haploinsufficiency at this locus results in the splitting of horn bud primordia, likely following the abnormal extension of an initial morphogenetic field. These results highlight the key role played by this gene in headgear patterning and illustrate the evolutionary co-option of a gene involved in the early development of bilateria to properly fix the position and number of these distinctive organs of Bovidae.

OXFORD UNIV PRESS2021

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The Number of Genomic Copies at the 16p11.2 Locus Modulates Language, Verbal Memory, and Inhibition

Bogdan Draganski, Nouchine Hadjikhani, Loyse Hippolyte, Borja Rodriguez Herreros

BACKGROUND: Deletions and duplications of the 16p11.2 BP4-BP5 locus are prevalent copy number variations (CNVs), highly associated with autism spectrum disorder and schizophrenia. Beyond language and global cognition, neuropsychological assessments of these two CNVs have not yet been reported. METHODS: This study investigates the relationship between the number of genomic copies at the 16p11.2 locus and cognitive domains assessed in 62 deletion carriers, 44 duplication carriers, and 71 intrafamilial control subjects. RESULTS: IQ is decreased in deletion and duplication carriers, but we demonstrate contrasting cognitive profiles in these reciprocal CNVs. Deletion carriers present with severe impairments of phonology and of inhibition skills beyond what is expected for their IQ level. In contrast, for verbal memory and phonology, the data may suggest that duplication carriers outperform intrafamilial control subjects with the same IQ level. This finding is reminiscent of special isolated skills as well as contrasting language performance observed in autism spectrum disorder. Some domains, such as visuospatial and working memory, are unaffected by the 16p11.2 locus beyond the effect of decreased IQ. Neuroimaging analyses reveal that measures of inhibition covary with neuroanatomic structures previously identified as sensitive to 16p11.2 CNVs. CONCLUSIONS: The simultaneous study of reciprocal CNVs suggests that the 16p11.2 genomic locus modulates specific cognitive skills according to the number of genomic copies. Further research is warranted to replicate these findings and elucidate the molecular mechanisms modulating these cognitive performances.

Elsevier Science Inc2016

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BIO-480: Neuroscience: from molecular mechanisms to disease

The goal of the course is to guide students through the essential aspects of molecular neuroscience and neurodegenerative diseases. The student will gain the ability to dissect the molecular basis of disease in the nervous system in order to begin to understand and identify therapeutic strategies.

BIO-311: Neuroscience

The course starts with fundamentals of electrical - and chemical signaling in neurons. Students then learn how neurons in the brain receive and process sensory information, and how other neurons control the behavior of an animal. Furthermore, memory, learning, and brain disorders will be introduced.

CH-411: Cellular signalling

Presentation of selected signalling pathways with emphasis on both the mechanism of action of the molecules involved, molecular interactions and the role of their spatio-temporal organization within the cell, considering cellular dimensions and conditions.

Noradrénaline

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Trouble du déficit de l'attention avec ou sans hyperactivité

Le trouble déficit de l'attention avec ou sans hyperactivité (TDAH ; en anglais : attention deficit hyperactivity disorder, ADHD) est un trouble du neurodéveloppement caractérisé par trois types de s

Hippocampe (cerveau)

thumb|Situation de l'hippocampe en profondeur dans le cerveau humain280px|thumb|Hippocampe en vue 3D. L'hippocampe est une structure du télencéphale des mammifères. Il appartient notamment au système