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See detailLa neurogenese adulte ou l'histoire d'un dogme qui s'ecroule.
Pirotte, Dorothée ULg; Rogister, Bernard ULg

in Revue Médicale de Liège (2008), 63(5-6), 245-50

The history of sciences is characterized by major discoveries, but also by challenges of theories or dogma previously established and accepted by everybody. One of the recent examples illustrating such a ... [more ▼]

The history of sciences is characterized by major discoveries, but also by challenges of theories or dogma previously established and accepted by everybody. One of the recent examples illustrating such a questioning relates to the demonstration of the persistence of a cerebral neurogenesis in the adult brain, including in human. This adult neurogenesis is however limited, both in space (it concerns only the subventricular zone and the gyrus dentatus in the hippocampus) and the type of newly-formed neurons (interneurones which most of them are GABAergic and present respectively in the olfactive bulb and CA1 area of the hippocampus). Moreover, this neurogenesis does not seem to be recruited after a brain lesion, a situation which explains why functional recovery when it is observed remains a consequence of brain plasticity. We thus legitimately address the question about the physiological role of this adult brain neurogenesis as well as a possible implication in the aetiology of various neurological disorders, like the neurodegenerative diseases or epilepsy, but also in psychiatric diseases like depression. [less ▲]

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See detailNeurogenin 2 controls cortical neuron migration through regulation of Rnd2.
Heng, Julian Ik-Tsen; Nguyen, Laurent ULg; Castro, Diogo S et al

in Nature (2008), 455(7209), 114-8

Motility is a universal property of newly generated neurons. How cell migration is coordinately regulated with other aspects of neuron production is not well understood. Here we show that the proneural ... [more ▼]

Motility is a universal property of newly generated neurons. How cell migration is coordinately regulated with other aspects of neuron production is not well understood. Here we show that the proneural protein neurogenin 2 (Neurog2), which controls neurogenesis in the embryonic cerebral cortex, directly induces the expression of the small GTP-binding protein Rnd2 (ref. 3) in newly generated mouse cortical neurons before they initiate migration. Rnd2 silencing leads to a defect in radial migration of cortical neurons similar to that observed when the Neurog2 gene is deleted. Remarkably, restoring Rnd2 expression in Neurog2-mutant neurons is sufficient to rescue their ability to migrate. Our results identify Rnd2 as a novel essential regulator of neuronal migration in the cerebral cortex and demonstrate that Rnd2 is a major effector of Neurog2 function in the promotion of migration. Thus, a proneural protein controls the complex cellular behaviour of cell migration through a remarkably direct pathway involving the transcriptional activation of a small GTP-binding protein. [less ▲]

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See detailNeurohypophyseal response to apomorphine and clonidine stimulation in major depression
Scantamburlo, Gabrielle ULg; Fuchs, Sonia; Pitchot, William ULg et al

in European Neuropsychopharmacology (2004, October), 14(Suppl. 3), 291-292

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See detailNeurohypophysial peptides stimulate the phosphorylation of pre-T cell focal adhesion kinases
Martens, Henri ULg; Kecha, Ouafae; Charlet-Renard, Jeanne de Chantal ULg et al

in Neuroendocrinology (1998), 67(4), 282-289

Thymic oxytocin (OT) behaves as a cryptocrine signal targeted at the outer surface of thymic epithelial cell plasma membrane from where OT is able to interact with neurohypophysial peptide receptors ... [more ▼]

Thymic oxytocin (OT) behaves as a cryptocrine signal targeted at the outer surface of thymic epithelial cell plasma membrane from where OT is able to interact with neurohypophysial peptide receptors expressed by pre-T cells. Immature T cells bear a receptor of the V1 subtype, while OT receptors are predominantly expressed by cytotoxic CD8+ lymphocytes. In both T cell types, neurohypophysial peptide receptors transduce OT via the phosphoinositide pathway. Protein tyrosine phosphorylation is an early event of T cell activation. Western blots of murine pre-T cells (RL12-NP line) proteins probed with anti-phosphotyrosine (PY-20) revealed a great number of proteins the phosphorylation of which increased either with OT or vasopressin treatment. Two were immunoprecipitated with anti-focal adhesion kinase (FAK) mAb 2A7 and were identified one as p125FAK and the other as a coprecipitating 130-kDa protein. The p125FAK is connected to the Ras/MAPK pathway and is also implicated in TCR/CD3 signalling in T cell. Another protein phosphorylated by OT in RL12-NP was identified as paxillin, a 68-kDa protein localised at focal adhesion sites and associated with p 125FAK. These results indicate that phosphorylation of focal adhesion kinase may be induced in pre-T cell by thymic OT. [less ▲]

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See detailNeurohypophysial Receptor Gene Expression by Thymic T Cell Subsets and Thymic T Cell Lymphoma Cell Lines
Hansenne, Isabelle ULg; Rasier, G.; Charlet-Renard, C. et al

in Clinical & Developmental Immunology (2004), 11(1), 45-51

Neurohypophysial oxytocin (OT) and vasopressin (VP) genes are transcribed in thymic epithelium, while immature T lymphocytes express functional neurohypophysial receptors. Neurohypophysial receptors ... [more ▼]

Neurohypophysial oxytocin (OT) and vasopressin (VP) genes are transcribed in thymic epithelium, while immature T lymphocytes express functional neurohypophysial receptors. Neurohypophysial receptors belong to the G protein-linked seven-transmembrane receptor superfamily and are encoded by four distinct genes, OTR, V1R, V2R and V3R. The objective of this study was to identify the nature of neurohypophysial receptor in thymic T cell subsets purified by immunomagnetic selection, as well as in murine thymic lymphoma cell lines RL12-NP and BW5147. OTR is transcribed in all thymic T cell subsets and T cell lines, while V3R transcription is restricted to CD4+CD8+ and CD8+ thymic cells. Neither V1R nor V2R transcripts are detected in any kind of T cells. The OTR protein was identified by immunocytochemistry on thymocytes freshly isolated from C57BL/6 mice. In murine fetal thymic organ cultures, a specific OTR antagonist does not modify the percentage of T cell subsets, but increases late T cell apoptosis further evidencing the involvement of OT/OTR signaling in the control of T cell proliferation and survival. According to these data, OTR and V3R are differentially expressed during T cell ontogeny. Moreover, the restriction of OTR transcription to T cell lines derived from thymic lymphomas may be important in the context of T cell leukemia pathogenesis and treatment. [less ▲]

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See detailNeuroimaging after coma.
Tshibanda, Luaba ULg; Vanhaudenhuyse, Audrey ULg; Boly, Mélanie ULg et al

in Neuroradiology (2010), 52(1), 15-24

Following coma, some patients will recover wakefulness without signs of consciousness (only showing reflex movements, i.e., the vegetative state) or may show non-reflex movements but remain without ... [more ▼]

Following coma, some patients will recover wakefulness without signs of consciousness (only showing reflex movements, i.e., the vegetative state) or may show non-reflex movements but remain without functional communication (i.e., the minimally conscious state). Currently, there remains a high rate of misdiagnosis of the vegetative state (Schnakers et. al. BMC Neurol, 9:35, 8) and the clinical and electrophysiological markers of outcome from the vegetative and minimally conscious states remain unsatisfactory. This should incite clinicians to use multimodal assessment to detect objective signs of consciousness and validate para-clinical prognostic markers in these challenging patients. This review will focus on advanced magnetic resonance imaging (MRI) techniques such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI (fMRI studies in both "activation" and "resting state" conditions) that were recently introduced in the assessment of patients with chronic disorders of consciousness. [less ▲]

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See detailNeuroimaging in Disorders of Consciousness
Bodart, Olivier ULg; Charland-Verville, Vanessa ULg; Laureys, Steven ULg et al

in Filippi, M. (Ed.) Oxford Textbook of Clinical Neurology (2014)

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See detailNeuroimaging in Sleep and Sleep Disorders
Desseilles, Martin ULg; Dang Vu, Thien Thanh ULg; Schwartz, Sophie et al

in Chokroverty, Sudhansu (Ed.) Sleep Disorders Medicine (2009)

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See detailNeuroimaging in sleep medicine.
Dang Vu, Thien Thanh ULg; Desseilles, Martin ULg; Petit, Dominique ULg et al

in Sleep Medicine (2007), 8(4), 349-72

The development of neuroimaging techniques has made possible the characterization of cerebral function throughout the sleep-wake cycle in normal human subjects. Indeed, human brain activity during sleep ... [more ▼]

The development of neuroimaging techniques has made possible the characterization of cerebral function throughout the sleep-wake cycle in normal human subjects. Indeed, human brain activity during sleep is segregated within specific cortical and subcortical areas in relation to the sleep stage, sleep physiological events and previous waking activity. This approach has allowed sleep physiological theories developed from animal data to be confirmed, but has also introduced original concepts about the neurobiological mechanisms of sleep, dreams and memory in humans. In contrast, at present, few neuroimaging studies have been dedicated to human sleep disorders. The available work has brought interesting data that describe some aspects of the pathophysiology and neural consequences of disorders such as insomnia, sleep apnea and narcolepsy. However, the interpretation of many of these results is restricted by limited sample size and spatial/temporal resolution of the employed technique. The use of neuroimaging in sleep medicine is actually restrained by concerns resulting from the technical experimental settings and the characteristics of the diseases. Nevertheless, we predict that future studies, conducted with state of the art techniques on larger numbers of patients, will be able to address these issues and contribute significantly to the understanding of the neural basis of sleep pathologies. This may finally offer the opportunity to use neuroimaging, in addition to the clinical and electrophysiological assessments, as a helpful tool in the diagnosis, classification, treatment and monitoring of sleep disorders in humans. [less ▲]

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See detailNeuroimaging Insights into the Dreaming Brain
Desseilles, Martin ULg; Dang Vu, Thien Thanh ULg; Schabus, Manuel et al

in Dreams and Dreaming (2010)

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See detailNeuroimaging insights into the pathophysiology of sleep disorders.
Desseilles, Martin ULg; Dang Vu, Thien Thanh ULg; Schabus, Manuel et al

in Sleep (2008), 31(6), 777-94

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might ... [more ▼]

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might improve our understanding of the pathophysiology underlying adult sleep disorders. Here we review functional brain imaging findings in major intrinsic sleep disorders (i.e., idiopathic insomnia, narcolepsy, and obstructive sleep apnea) and in abnormal motor behavior during sleep (i.e., periodic limb movement disorder and REM sleep behavior disorder). The studies reviewed include neuroanatomical assessments (voxel-based morphometry, magnetic resonance spectroscopy), metabolic/functional investigations (positron emission tomography, single photon emission computed tomography, functional magnetic resonance imaging), and ligand marker measurements. Based on the current state of the research, we suggest that brain imaging is a useful approach to assess the structural and functional correlates of sleep impairments as well as better understand the cerebral consequences of various therapeutic approaches. Modem neuroimaging techniques therefore provide a valuable tool to gain insight into possible pathophysiological mechanisms of sleep disorders in adult humans. [less ▲]

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See detailNeuroimaging of dreaming: state of the art and limitations
Kussé, Caroline ULg; Muto, Vincenzo ULg; Mascetti, Laura ULg et al

in International Review of Neurobiology (2010)

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See detailNeuroimaging of narcolepsy
Dang Vu, Thien Thanh ULg; Desseilles, Martin ULg; Schwartz, Sophie et al

in CNS & Neurological Disorders Drug Targets (2009), 8(4), 254-263

Neuroimaging techniques have refined the characterization of neural structures involved in the regulation of normal sleep-wake cycle in healthy humans. Yet brain imaging studies in patients with sleep ... [more ▼]

Neuroimaging techniques have refined the characterization of neural structures involved in the regulation of normal sleep-wake cycle in healthy humans. Yet brain imaging studies in patients with sleep disorders still remain scarce. In narcoleptic patients, structural and functional brain imaging studies have suggested the involvement of the hypothalamus in the pathophysiology of narcolepsy, plausibly consistent with an impairment of the hypocretin-orexin system. Some recent studies have further suggested that cataplexy, a key feature of the narcoleptic syndrome, might result from a dysfunction of the hypothalamus and its interactions with limbic structures. Other neuroimaging studies have focused on the assessment of neurotransmission and the effects of pharmacological treatment in narcoleptic patients. However, the neural correlates of some main symptoms of narcolepsy, such as sleep attacks, hypnagogic/hypnopompic hallucinations and sleep paralysis, are still unknown. In addition, the description of brain activity patterns during sleep in narcoleptic patients needs further investigation. Neuroimaging has proven to be a valuable tool for the study of sleep regulation and sleep disorders; its future developments will undoubtedly improve our understanding of the neural mechanisms underlying narcolepsy with cataplexy. [less ▲]

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See detailNeuroimaging of neuronal circuits involved in tic generation in patients with Tourette syndrome.
Lerner, Alicja; Bagic, Anto; Boudreau, Elis et al

in Neurology (2007), 68(23), 1979-87

OBJECTIVE: To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline. METHODS: We used [15O]H2O PET to study nine patients with Tourette syndrome and nine ... [more ▼]

OBJECTIVE: To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline. METHODS: We used [15O]H2O PET to study nine patients with Tourette syndrome and nine matched control subjects. For patients, conditions included tic release states and sleep stage 2; and for control subjects, rest states and sleep stage 2. RESULTS: Our study showed robust activation of cerebellum, insula, thalamus, and putamen during tic release. CONCLUSION: The network of structures involved in tics includes the activated regions and motor cortex. The prominent involvement of cerebellum and insula suggest their involvement in tic initiation and execution. [less ▲]

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See detailNeuroimaging of REM sleep and dreaming
Dang Vu, Thien Thanh ULg; Schabus, Manuel; Desseilles, Martin ULg et al

in McNamara, Patrick; Barrett, Deirdre (Eds.) The New Science of Dreaming (2007)

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See detailNeuroimaging of the interaction between circadian and homeostatic processes
Vandewalle, Gilles ULg; Schmidt, Christina

in Neuroimaging of Sleep and Sleep Disorders (2013)

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See detailNeuroimaging the effects of light on non-visual brain functions
Vandewalle, Gilles ULg; Dijk, Derk-Jan

in Neuroimaging of Sleep and Sleep Disorders (2013)

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See detailNeuroimaging tools to rate regional atrophy, subcortical cerebrovascular disease, and regional cerebral blood flow and metabolism: consensus paper of the EADC
Frisoni, G. B.; Scheltens, P. H.; Galluzzi, S. et al

in Journal of Neurology, Neurosurgery & Psychiatry (2003), 74(10), 1371-1381

Neuroimaging is a mainstay in the differential diagnosis of patients with cognitive impairment. The often equivocal clinical pictures, the prognostic uncertainty of the earliest stages of mild cognitive ... [more ▼]

Neuroimaging is a mainstay in the differential diagnosis of patients with cognitive impairment. The often equivocal clinical pictures, the prognostic uncertainty of the earliest stages of mild cognitive impairment, and the subtle brain changes mean that neuroimaging techniques are of potentially great incremental diagnostic value. A number of methods, ranging from very simple subjective visual ratings to highly sophisticated computerised tools, have been developed, which allow rating of structural and functional brain changes. The choice of the method is not obvious, and current guidelines provide no indications on which tools should be preferred. In this paper, we give indications for tools with demonstrated accuracy for detecting regional atrophy, cerebrovascular disease, and regional brain function, and discuss these according to increasing technological complexity, ranging from those with high feasibility that can be used at the patient's bedside to highly technological ones that require trained personnel and specific hardware and software. [less ▲]

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See detailNeuroimmune connections in jejunal and ileal Peyer's patches at various bovine ages: potential sites for prion neuroinvasion
Defaweux, Valérie ULg; Dorban, Gauthier ULg; Antoine, Nadine ULg et al

in Cell & Tissue Research (2007), 329(1), 35-44

During preclinical stages of cattle orally infected with bovine spongiform encephalopathy (BSE), the responsible agent is confined to ileal Peyer's patches (IPP), namely in nerve fibers and in lymph ... [more ▼]

During preclinical stages of cattle orally infected with bovine spongiform encephalopathy (BSE), the responsible agent is confined to ileal Peyer's patches (IPP), namely in nerve fibers and in lymph follicles, before reaching the peripheral and central nervous systems. No infectivity has been reported in other bovine lymphoid organs, including jejunal Peyer's patches (JPP). To determine the potential sites for prion neuroinvasion in IPP, we analyzed the mucosal innervation and the interface between nerve fibers and follicular dendritic cells (FDC), two dramatic influences on neuroinvasion. Bovine IPP were studied at three ages, viz., newborn calves, calves less than 12 months old, and bovines older than 24 months, and the parameters obtained were compared with those of JPP. No differences in innervation patterns between IPP and JPP were found. The major difference observed was that, in calves of less than 12 months, IPP were the major mucosal-associated lymphoid organ that possessed a large number of follicles with extended FDC networks. Using a panel of antibodies, we showed that PP in 24-month-old bovines were highly innervated at various strategic sites assumed to be involved in the invasion and replication of the BSE pathogen: the suprafollicular dome, T cell area, and germinal centers. In PP in calves of less than 12 months old, no nerve fibers positive for the neurofilament markers NF-L (70 kDa) and NF-H (200 kDa) were observed in contact with FDC. Thus, in view of the proportion of these protein subunits present in neurofilaments, the innervation of the germinal centers can be said to be an age-dependent dynamic process. This variation in innervation might influence the path of neuroinvasion and, thus, the susceptibility of bovines to the BSE agent. [less ▲]

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