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Neuron Nov 2009MicroRNAs (miRNAs) are endogenously expressed noncoding RNAs that regulate mRNA expression. In vertebrates, more distinct miRNAs are expressed in the brain than in any... (Review)
Review
MicroRNAs (miRNAs) are endogenously expressed noncoding RNAs that regulate mRNA expression. In vertebrates, more distinct miRNAs are expressed in the brain than in any other tissue, where they are hypothesized to function in neural development. Recent reports describing the effects of specific miRNAs during development, and studies employing miRNA depletion as neural commitment proceeds in the embryo, support a requisite role for miRNAs in cell-fate decisions and provide clues to their function in other aspects of nervous system development.
Topics: Animals; Brain; Cerebral Cortex; Gene Expression Regulation, Developmental; Humans; Mental Disorders; MicroRNAs; Models, Neurological; Neurogenesis; Neurons; Rhombencephalon
PubMed: 19914179
DOI: 10.1016/j.neuron.2009.10.020 -
Developmental Dynamics : An Official... Jan 2004The cranial motor neurons innervate muscles that control eye, jaw, and facial movements of the vertebrate head and parasympathetic neurons that innervate certain glands... (Comparative Study)
Comparative Study Review
The cranial motor neurons innervate muscles that control eye, jaw, and facial movements of the vertebrate head and parasympathetic neurons that innervate certain glands and organs. These efferent neurons develop at characteristic locations in the brainstem, and their axons exit the neural tube in well-defined trajectories to innervate target tissues. This review is focused on a subset of cranial motor neurons called the branchiomotor neurons, which innervate muscles derived from the branchial (pharyngeal) arches. First, the organization of the branchiomotor pathways in zebrafish, chick, and mouse embryos will be compared, and the underlying axon guidance mechanisms will be addressed. Next, the molecular mechanisms that generate branchiomotor neurons and specify their identities will be discussed. Finally, the caudally directed or tangential migration of facial branchiomotor neurons will be examined. Given the advances in the characterization and analysis of vertebrate genomes, we can expect rapid progress in elucidating the cellular and molecular mechanisms underlying the development of these vital neuronal networks. Developmental Dynamics 229:143-161, 2004.
Topics: Animals; Cell Movement; Cranial Nerves; Efferent Pathways; Gene Expression Regulation, Developmental; Genes, Homeobox; Humans; Motor Neurons; Rhombencephalon; Stem Cells; Vertebrates
PubMed: 14699587
DOI: 10.1002/dvdy.10444 -
Annual Review of Neuroscience Jul 2019The genetic approach, based on the study of inherited forms of deafness, has proven to be particularly effective for deciphering the molecular mechanisms underlying the... (Review)
Review
The genetic approach, based on the study of inherited forms of deafness, has proven to be particularly effective for deciphering the molecular mechanisms underlying the development of the peripheral auditory system, the cochlea and its afferent auditory neurons, and how this system extracts the physical parameters of sound. Although this genetic dissection has provided little information about the central auditory system, scattered data suggest that some genes may have a critical role in both the peripheral and central auditory systems. Here, we review the genes controlling the development and function of the peripheral and central auditory systems, focusing on those with demonstrated intrinsic roles in both systems and highlighting the current underappreciation of these genes. Their encoded products are diverse, from transcription factors to ion channels, as are their roles in the central auditory system, mostly evaluated in brainstem nuclei. We examine the ontogenetic and evolutionary mechanisms that may underlie their expression at different sites.
Topics: Animals; Auditory Pathways; Biological Evolution; Cochlea; Gene Expression Regulation, Developmental; Gene Ontology; Genes; Hair Cells, Auditory; Hearing Disorders; Humans; Ion Channels; Nerve Tissue Proteins; Neurogenesis; Rhombencephalon; Sensory Receptor Cells; Transcription Factors
PubMed: 30699050
DOI: 10.1146/annurev-neuro-070918-050428 -
Cell Metabolism Sep 2012This Review highlights the processing and integration performed by hindbrain nuclei, focusing on the inputs received by nucleus tractus solitarius (NTS) neurons. These... (Review)
Review
This Review highlights the processing and integration performed by hindbrain nuclei, focusing on the inputs received by nucleus tractus solitarius (NTS) neurons. These inputs include vagally mediated gastrointestinal satiation signals, blood-borne energy-related hormonal and nutrient signals, and descending neural signals from the forebrain. We propose that NTS (and hindbrain neurons, more broadly) integrate these multiple energy status signals and issue-output commands controlling the behavioral, autonomic, and endocrine responses that collectively govern energy balance. These hindbrain-mediated controls are neuroanatomically distributed; they involve endemic hindbrain neurons and circuits, hindbrain projections to peripheral circuits, and projections to and from midbrain and forebrain nuclei.
Topics: Energy Metabolism; Feeding Behavior; Homeostasis; Humans; Neural Pathways; Neurons; Nutritional Physiological Phenomena; Rhombencephalon; Solitary Nucleus
PubMed: 22902836
DOI: 10.1016/j.cmet.2012.06.015 -
Current Biology : CB May 2009
Review
Topics: Animals; Biological Evolution; Fishes; Neurons; Reflex, Startle; Rhombencephalon; Synaptic Transmission
PubMed: 19439253
DOI: 10.1016/j.cub.2009.02.025 -
The International Journal of... 2007Axial patterning in the vertebrate inner ear has been studied for over eighty years, and recent work has made great progress towards an understanding of the molecular... (Comparative Study)
Comparative Study Review
Axial patterning in the vertebrate inner ear has been studied for over eighty years, and recent work has made great progress towards an understanding of the molecular mechanisms responsible for establishing asymmetries about the otic axes. Tissues extrinsic to the ear provide sources of signalling molecules that are active early in development, at or before otic placode stages, while intrinsic factors interpret these signals to establish and maintain axial pattern. Key features of dorsoventral otic patterning in amniote embryos involve Wnt and Fgf signalling from the hindbrain and Hh signalling from midline tissues (notochord and floorplate). Mutual antagonism between these pathways and their downstream targets within the otic epithelium help to refine and maintain dorsoventral axial patterning in the ear. In the zebrafish ear, the same tissues and signals are implicated, but appear to play a role in anteroposterior, rather than dorsoventral, otic patterning. Despite this paradox, conservation of mechanisms may be higher than is at first apparent.
Topics: Animals; Body Patterning; Ear, Inner; Embryo, Mammalian; Embryo, Nonmammalian; Embryonic Induction; Gene Expression Regulation, Developmental; Hedgehog Proteins; Models, Biological; Morphogenesis; Rhombencephalon; Signal Transduction; Vertebrates; Wnt Proteins
PubMed: 17891713
DOI: 10.1387/ijdb.072380tw -
American Journal of Physiology.... Feb 2014In states of sodium deficiency many animals seek and consume salty solutions to restore body fluid homeostasis. These behaviors reflect the presence of sodium appetite... (Review)
Review
In states of sodium deficiency many animals seek and consume salty solutions to restore body fluid homeostasis. These behaviors reflect the presence of sodium appetite that is a manifestation of a pattern of central nervous system (CNS) activity with facilitatory and inhibitory components that are affected by several neurohumoral factors. The primary focus of this review is on one structure in this central system, the lateral parabrachial nucleus (LPBN). However, before turning to a more detailed discussion of the LPBN, a brief overview of body fluid balance-related body-to-brain signaling and the identification of the primary CNS structures and humoral factors involved in the control of sodium appetite is necessary. Angiotensin II, mineralocorticoids, and extracellular osmotic changes act on forebrain areas to facilitate sodium appetite and thirst. In the hindbrain, the LPBN functions as a key integrative node with an ascending output that exerts inhibitory influences on forebrain regions. A nonspecific or general deactivation of LPBN-associated inhibition by GABA or opioid agonists produces NaCl intake in euhydrated rats without any other treatment. Selective LPBN manipulation of other neurotransmitter systems [e.g., serotonin, cholecystokinin (CCK), corticotrophin-releasing factor (CRF), glutamate, ATP, or norepinephrine] greatly enhances NaCl intake when accompanied by additional treatments that induce either thirst or sodium appetite. The LPBN interacts with key forebrain areas that include the subfornical organ and central amygdala to determine sodium intake. To summarize, a model of LPBN inhibitory actions on forebrain facilitatory components for the control of sodium appetite is presented in this review.
Topics: Animals; Appetite; Neural Inhibition; Neural Pathways; Prosencephalon; Rhombencephalon; Sodium, Dietary; Water-Electrolyte Balance
PubMed: 24401989
DOI: 10.1152/ajpregu.00251.2012 -
Developmental Dynamics : An Official... Dec 2013Homeobox (Hox) genes were originally discovered in the fruit fly Drosophila, where they function through a conserved homeodomain as transcriptional regulators to control... (Review)
Review
Homeobox (Hox) genes were originally discovered in the fruit fly Drosophila, where they function through a conserved homeodomain as transcriptional regulators to control embryonic morphogenesis. In vertebrates, 39 Hox genes have been identified and like their Drosophila counterparts they are organized within chromosomal clusters. Hox genes interact with various cofactors, such as the TALE homeodomain proteins, in recognition of consensus sequences within regulatory elements of their target genes. In vertebrates, Hox genes display spatially restricted patterns of expression within the developing hindbrain and spinal cord, and are considered crucial determinants of segmental identity and cell specification along the anterioposterior and dorsoventral axes of the embryo. Here, we review their later roles in the assembly of neuronal circuitry, in stereotypic neuronal migration, axon pathfinding, and topographic connectivity. Importantly, we will put some emphasis on how their early-segmented expression patterns can influence the formation of complex vital hindbrain and spinal cord circuitries.
Topics: Animals; Cell Differentiation; Cell Movement; Gene Expression Regulation, Developmental; Genes, Homeobox; Models, Biological; Morphogenesis; Neural Pathways; Rhombencephalon; Spinal Cord; Vertebrates
PubMed: 23996673
DOI: 10.1002/dvdy.24055 -
Cellular and Molecular Life Sciences :... Sep 2013The midbrain-hindbrain boundary (MHB) is a highly conserved vertebrate signalling centre, acting to pattern and establish neural identities within the brain. While the... (Review)
Review
The midbrain-hindbrain boundary (MHB) is a highly conserved vertebrate signalling centre, acting to pattern and establish neural identities within the brain. While the core signalling pathways regulating MHB formation have been well defined, novel genetic and mechanistic processes that interact with these core components are being uncovered, helping to further elucidate the complicated networks governing MHB specification, patterning and shaping. Although formation of the MHB organiser is traditionally thought of as comprising three stages, namely positioning, induction and maintenance, we propose that a fourth stage, morphogenesis, should be considered as an additional stage in MHB formation. This review will examine evidence for novel factors regulating the first three stages of MHB development and will explore the evidence for regulation of MHB morphogenesis by non-classical MHB-patterning genes.
Topics: Animals; Body Patterning; Gene Expression Regulation, Developmental; Humans; Mesencephalon; Mice; Models, Neurological; Morphogenesis; Rhombencephalon; Signal Transduction; Zebrafish
PubMed: 23307071
DOI: 10.1007/s00018-012-1240-x -
Developmental Neurobiology Jan 2020Vocalization is a common means of communication across vertebrates, but the evolutionary origins of the neural circuits controlling these behaviors are not clear.... (Review)
Review
Vocalization is a common means of communication across vertebrates, but the evolutionary origins of the neural circuits controlling these behaviors are not clear. Peripheral mechanisms of sound production vary widely: fish produce sounds with a swimbladder or pectoral fins; amphibians, reptiles, and mammalians vocalize using a larynx; birds vocalize with a syrinx. Despite the diversity of vocal effectors across taxa, there are many similarities in the neural circuits underlying the control of these organs. Do similarities in vocal circuit structure and function indicate that vocal behaviors first arose in a single common ancestor, or have similar neural circuits arisen independently multiple times during evolution? In this review, we describe the hindbrain circuits that are involved in vocal production across vertebrates. Given that vocalization depends on respiration in most tetrapods, it is not surprising that vocal and respiratory hindbrain circuits across distantly related species are anatomically intermingled and functionally linked. Such vocal-respiratory circuit integration supports the hypothesis that vocal evolution involved the expansion and functional diversification of breathing circuits. Recent phylogenetic analyses, however, suggest vocal behaviors arose independently in all major tetrapod clades, indicating that similarities in vocal control circuits are the result of repeated co-options of respiratory circuits in each lineage. It is currently unknown whether vocal circuits across taxa are made up of homologous neurons, or whether vocal neurons in each lineage arose from developmentally and evolutionarily distinct progenitors. Integrative comparative studies of vocal neurons across brain regions and taxa will be required to distinguish between these two scenarios.
Topics: Animals; Central Pattern Generators; Phylogeny; Respiratory Physiological Phenomena; Rhombencephalon; Vertebrates; Vocalization, Animal
PubMed: 32329162
DOI: 10.1002/dneu.22752