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Acta Neurologica Belgica Oct 2023
Topics: Infant, Newborn; Humans; Cerebellum; Hydrocephalus; Cerebellar Diseases; Infant, Newborn, Diseases; Rhombencephalon; Magnetic Resonance Imaging
PubMed: 36064837
DOI: 10.1007/s13760-022-02080-2 -
F1000Research 2018Studies of the vertebrate hindbrain have revealed parallel mechanisms that establish sharp segments with a distinct and homogeneous regional identity. Recent work has... (Review)
Review
Studies of the vertebrate hindbrain have revealed parallel mechanisms that establish sharp segments with a distinct and homogeneous regional identity. Recent work has revealed roles of cell identity regulation and its relationships with cell segregation. At early stages, there is overlapping expression at segment borders of the Egr2 and Hoxb1 transcription factors that specify distinct identities, which is resolved by reciprocal repression. Computer simulations show that this dynamic regulation of cell identity synergises with cell segregation to generate sharp borders. Some intermingling between segments occurs at early stages, and ectopic egr2-expressing cells switch identity to match their new neighbours. This switching is mediated by coupling between egr2 expression and the level of retinoic acid signalling, which acts in a community effect to maintain homogeneous segmental identity. These findings reveal an interplay between cell segregation and the dynamic regulation of cell identity in the formation of sharp patterns in the hindbrain and raise the question of whether similar mechanisms occur in other tissues.
Topics: Animals; Cell Separation; Humans; Rhombencephalon
PubMed: 30135723
DOI: 10.12688/f1000research.15391.1 -
Current Pharmaceutical Design 2013In 1966, Shik, Severin and Orlovskii discovered that electrical stimulation of a region at the junction between the midbrain and hindbrain elicited controlled walking... (Review)
Review
In 1966, Shik, Severin and Orlovskii discovered that electrical stimulation of a region at the junction between the midbrain and hindbrain elicited controlled walking and running in the cat. The region was named Mesencephalic Locomotor Region (MLR). Since then, this locomotor center was shown to control locomotion in various vertebrate species, including the lamprey, salamander, stingray, rat, guinea-pig, rabbit or monkey. In human subjects asked to imagine they are walking, there is an increased activity in brainstem nuclei corresponding to the MLR (i.e. pedunculopontine, cuneiform and subcuneiform nuclei). Clinicians are now stimulating (deep brain stimulation) structures considered to be part of the MLR to alleviate locomotor symptoms of patients with Parkinson's disease. However, the anatomical constituents of the MLR still remain a matter of debate, especially relative to the pedunculopontine, cuneiform and subcuneiform nuclei. Furthermore, recent studies in lampreys have revealed that the MLR is more complex than a simple relay in a serial descending pathway activating the spinal locomotor circuits. It has multiple functions. Our goal is to review the current knowledge relative to the anatomical constituents of the MLR, and its physiological role, from lamprey to man. We will discuss these results in the context of the recent clinical studies involving stimulation of the MLR in patients with Parkinson's disease.
Topics: Animals; Humans; Locomotion; Mesencephalon; Neurons; Neurotransmitter Agents; Parkinson Disease; Rhombencephalon; Species Specificity; Spinal Cord
PubMed: 23360276
DOI: 10.2174/1381612811319240011 -
Neuroradiology Feb 2015Neuroimaging techniques including structural magnetic resonance imaging (MRI) and functional positron emission tomography (PET) are useful in categorizing various... (Review)
Review
PURPOSE
Neuroimaging techniques including structural magnetic resonance imaging (MRI) and functional positron emission tomography (PET) are useful in categorizing various midbrain-hindbrain (MHB) malformations, both in allowing diagnosis and in helping to understand the developmental processes that were disturbed. Brain imaging phenotypes of numerous malformations are characteristic features that help in guiding the genetic testing in case of direct neuroimaging-genotype correlation or, at least, to differentiate among MHB malformations entities. The present review aims to provide the reader with an update of the use of neuroimaging applications in the fine analysis of MHB malformations, using a comprehensive, recently proposed developmental and genetic classification.
METHODS
We have performed an extensive systematic review of the literature, from the embryology main steps of MHB development through the malformations entities, with regard to their molecular and genetic basis, conventional MRI features, and other neuroimaging characteristics.
RESULTS
We discuss disorders in which imaging features are distinctive and how these features reflect the structural and functional impairment of the brain.
CONCLUSION
Recognition of specific MRI phenotypes, including advanced imaging features, is useful to recognize the MHB malformation entities, to suggest genetic investigations, and, eventually, to monitor the disease outcome after supportive therapies.
Topics: Humans; Magnetic Resonance Imaging; Mesencephalon; Nervous System Malformations; Neuroimaging; Rhombencephalon
PubMed: 25339235
DOI: 10.1007/s00234-014-1431-2 -
Journal of Neurology, Neurosurgery, and... May 2020
Topics: Brain; Encephalitis; Humans; Hydrocephalus; Immunocompromised Host; Listeriosis; Magnetic Resonance Imaging; Male; Middle Aged; Neuroimaging; Rhombencephalon
PubMed: 32165378
DOI: 10.1136/jnnp-2020-322989 -
BioEssays : News and Reviews in... Jan 2001The presence of a muscularised pharynx with skeletal support is a fundamental vertebrate characteristic. Developmentally, the pharynx arises from the pharyngeal arches... (Review)
Review
The presence of a muscularised pharynx with skeletal support is a fundamental vertebrate characteristic. Developmentally, the pharynx arises from the pharyngeal arches on either side of the head of vertebrate embryos. The development of the pharyngeal arches is complex involving a number of disparate embryonic populations, ectoderm, endoderm, neural crest and mesoderm, which must be co-ordinated to generate the components and overall identity of each of the arches. Previous studies suggested that it is the neural crest that plays a pivotal role in patterning the pharyngeal arches. It is now also becoming clear, however, that there are crest-independent patterning mechanisms. Therefore, pharyngeal arch patterning is more complex than was previously believed and there must be an integration of crest-dependent and -independent patterning mechanisms. BioEssays 23:54-61, 2001.
Topics: Animals; Biological Evolution; Body Patterning; Branchial Region; Cell Death; Ectoderm; Endoderm; Mesoderm; Neural Crest; Rhombencephalon
PubMed: 11135309
DOI: 10.1002/1521-1878(200101)23:1<54::AID-BIES1007>3.0.CO;2-5 -
Science (New York, N.Y.) Nov 1996Neuraxial patterning is a continuous process that extends over a protracted period of development. During gastrulation a crude anteroposterior pattern, detectable by... (Review)
Review
Neuraxial patterning is a continuous process that extends over a protracted period of development. During gastrulation a crude anteroposterior pattern, detectable by molecular markers, is conferred on the neuroectoderm by signals from the endomesoderm that are largely inseparable from those of neural induction itself. This coarse-grained pattern is subsequently reinforced and refined by diverse, locally acting mechanisms. Segmentation and long-range signaling from organizing centers are prominent among the emerging principles governing regional pattern.
Topics: Animals; Body Patterning; Central Nervous System; Embryonic Induction; Gene Expression Regulation, Developmental; Genes, Homeobox; Mesencephalon; Mesoderm; Neurons; Prosencephalon; Rhombencephalon; Signal Transduction; Spinal Cord; Tretinoin
PubMed: 8895453
DOI: 10.1126/science.274.5290.1109 -
Current Topics in Developmental Biology 2016The subdivision of tissues into sharply demarcated regions with distinct and homogenous identity is an essential aspect of embryonic development. Along the... (Review)
Review
The subdivision of tissues into sharply demarcated regions with distinct and homogenous identity is an essential aspect of embryonic development. Along the anteroposterior axis of the vertebrate nervous system, this involves signaling which induces spatially restricted expression of transcription factors that specify regional identity. The spatial expression of such transcription factors is initially imprecise, with overlapping expression of genes that specify distinct identities, and a ragged border at the interface of adjacent regions. This pattern becomes sharpened by establishment of mutually exclusive expression of transcription factors, and by cell segregation that underlies formation of a straight border. In this review, we discuss studies of the vertebrate hindbrain which have revealed how discrete regional identity is established, the roles of Eph-ephrin signaling in cell segregation and border sharpening, and how cell identity and cell segregation are coupled.
Topics: Animals; Body Patterning; Cell Separation; Ephrins; Gene Expression Regulation, Developmental; Rhombencephalon; Signal Transduction; Vertebrates
PubMed: 26970002
DOI: 10.1016/bs.ctdb.2015.10.019 -
RoFo : Fortschritte Auf Dem Gebiete Der... Jul 1995
Review
Topics: Abnormalities, Multiple; Child, Preschool; Cranial Fossa, Posterior; Humans; Hydrocephalus; Magnetic Resonance Imaging; Male; Rhombencephalon; Tomography, X-Ray Computed
PubMed: 7626764
DOI: 10.1055/s-2007-1015952 -
Current Opinion in Neurobiology Oct 2002Recent studies have identified some of the key molecular pathways that control the genesis of spinal sensorimotor circuits. Transcription factors play a central role in... (Review)
Review
Recent studies have identified some of the key molecular pathways that control the genesis of spinal sensorimotor circuits. Transcription factors play a central role in these events, regulating both the specification of neurons that constitute these sensorimotor pathways and the expression of downstream molecules that control the wiring up of these neurons into topologically interconnected neuronal networks.
Topics: Animals; Humans; Neural Pathways; Rhombencephalon; Spinal Cord; Transcription Factors
PubMed: 12367629
DOI: 10.1016/s0959-4388(02)00371-9