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Current Opinion in Neurobiology Dec 2018Dendrites are the conduits for receiving (and in some cases transmitting) neural signals; their ability to do these jobs is a direct result of their morphology.... (Review)
Review
Dendrites are the conduits for receiving (and in some cases transmitting) neural signals; their ability to do these jobs is a direct result of their morphology. Developmental patterning mechanisms are critical to ensuring concordance between dendritic form and function. This article reviews recent studies in vertebrate retina and brain that elucidate key strategies for dendrite functional maturation. Specific cellular and molecular signals control the initiation and elaboration of dendritic arbors, and facilitate integration of young neurons into particular circuits. In some cells, dendrite growth and remodeling continues into adulthood. Once formed, dendrites subdivide into compartments with distinct physiological properties that enable dendritic computations. Understanding these key stages of dendrite patterning will help reveal how circuit functional properties arise during development.
Topics: Amacrine Cells; Animals; Dendrites; Humans; Morphogenesis; Nerve Net; Neuronal Plasticity
PubMed: 30092409
DOI: 10.1016/j.conb.2018.07.007 -
Current Topics in Developmental Biology 2021Neurons develop dendritic morphologies that bear cell type-specific features in dendritic field size and geometry, branch placement and density, and the types and... (Review)
Review
Neurons develop dendritic morphologies that bear cell type-specific features in dendritic field size and geometry, branch placement and density, and the types and distributions of synaptic contacts. Dendritic patterns influence the types and numbers of inputs a neuron receives, and the ways in which neural information is processed and transmitted in the circuitry. Even subtle alterations in dendritic structures can have profound consequences on neuronal function and are implicated in neurodevelopmental disorders. In this chapter, I review how growing dendrites acquire their exquisite patterns by drawing examples from diverse neuronal cell types in vertebrate and invertebrate model systems. Dendrite morphogenesis is shaped by intrinsic and extrinsic factors such as transcriptional regulators, guidance and adhesion molecules, neighboring cells and synaptic partners. I discuss molecular mechanisms that regulate dendrite morphogenesis with a focus on five aspects of dendrite patterning: (1) Dendritic cytoskeleton and cellular machineries that build the arbor; (2) Gene regulatory mechanisms; (3) Afferent cues that regulate dendritic arbor growth; (4) Space-filling strategies that optimize dendritic coverage; and (5) Molecular cues that specify dendrite wiring. Cell type-specific implementation of these patterning mechanisms produces the diversity of dendrite morphologies that wire the nervous system.
Topics: Dendrites; Morphogenesis
PubMed: 33706919
DOI: 10.1016/bs.ctdb.2020.12.008 -
Developmental Biology Jul 2019A neuron's contribution to the information flow within a neural circuit is governed by the structure of its dendritic arbor. The geometry of the dendritic arbor directly... (Review)
Review
A neuron's contribution to the information flow within a neural circuit is governed by the structure of its dendritic arbor. The geometry of the dendritic arbor directly determines synaptic density and the size of the receptive field, both of which influence the firing pattern of the neuron. Importantly, the position of individual dendritic branches determines the identity of the neuron's presynaptic partner and thus the nature of the incoming sensory information. To generate the unique stereotypic architecture of a given neuronal subtype, nascent branches must emerge from the dendritic shaft at preprogramed branch points. Subsequently, a complex array of extrinsic factors regulates the degree and orientation of branch expansion to ensure maximum coverage of the receptive field whilst constraining growth within predetermined territories. In this review we focus on studies that best illustrate how environmental cues such as the Wnts and Netrins and their receptors sculpt the dendritic arbor. We emphasize the pivotal role played by the actin cytoskeleton and its upstream regulators in branch initiation, outgrowth and navigation. Finally, we discuss how protocadherin and DSCAM contact-mediated repulsion prevents inappropriate synapse formation between sister dendrites or dendrites and the axon from the same neuron. Together these studies highlight the clever ways evolution has solved the problem of constructing complex branch geometries.
Topics: Animals; Dendrites; Humans; Neurogenesis; Neuronal Plasticity; Synapses
PubMed: 30550882
DOI: 10.1016/j.ydbio.2018.12.005 -
Development, Growth & Differentiation Apr 2011One of the most important features of neuronal function is the capacity to dynamically adapt in response to changes in the environment and neuronal activity. Among... (Review)
Review
One of the most important features of neuronal function is the capacity to dynamically adapt in response to changes in the environment and neuronal activity. Among cellular elements that show this kind of plasticity are dendrites, the components that receive and process neuronal inputs. Dendrite remodeling occurs during normal development of the nervous system as well as in response to injury or diseases in the adult. In either case, selective stabilization and/or elimination of dendritic branches is likely important to shape dendritic arbors. Here I review examples of the phenomena and consider potential cellular and molecular mechanisms that underlie dendrite remodeling and how they might relate in development and disease.
Topics: Animals; Dendrites; Humans; Nervous System; Nervous System Diseases; Neuronal Plasticity
PubMed: 21492146
DOI: 10.1111/j.1440-169X.2010.01242.x -
Current Opinion in Neurobiology Aug 2014Pruning, a process by which neurons selectively remove exuberant or unnecessary processes without causing cell death, is crucial for the establishment of mature neural... (Review)
Review
Pruning, a process by which neurons selectively remove exuberant or unnecessary processes without causing cell death, is crucial for the establishment of mature neural circuits during animal development. Yet relatively little is known about molecular and cellular mechanisms that govern neuronal pruning. Holometabolous insects, such as Drosophila, undergo complete metamorphosis and their larval nervous systems are replaced with adult-specific ones, thus providing attractive models for studying neuronal pruning. Drosophila mushroom body and dendritic arborization neurons have been utilized as two appealing systems to elucidate the underlying mechanisms of axon and dendrite pruning, respectively. In this review we highlight recent developments and discuss some similarities and differences in the mechanisms that regulate these two distinct modes of neuronal pruning in Drosophila.
Topics: Animals; Axons; Dendrites; Drosophila; Models, Animal; Nervous System; Neurons
PubMed: 24793180
DOI: 10.1016/j.conb.2014.04.005 -
Developmental Neurobiology Apr 2017Dendrites and spines are the main neuronal structures receiving input from other neurons and glial cells. Dendritic and spine number, size, and morphology are some of... (Review)
Review
Dendrites and spines are the main neuronal structures receiving input from other neurons and glial cells. Dendritic and spine number, size, and morphology are some of the crucial factors determining how signals coming from individual synapses are integrated. Much remains to be understood about the characteristics of neuronal dendrites and dendritic spines in autism and related disorders. Although there have been many studies conducted using autism mouse models, few have been carried out using postmortem human tissue from patients. Available animal models of autism include those generated through genetic modifications and those non-genetic models of the disease. Here, we review how dendrite and spine morphology and number is affected in autism and related neurodevelopmental diseases, both in human, and genetic and non-genetic animal models of autism. Overall, data obtained from human and animal models point to a generalized reduction in the size and number, as well as an alteration of the morphology of dendrites; and an increase in spine densities with immature morphology, indicating a general spine immaturity state in autism. Additional human studies on dendrite and spine number and morphology in postmortem tissue are needed to understand the properties of these structures in the cerebral cortex of patients with autism. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 419-437, 2017.
Topics: Animals; Autism Spectrum Disorder; Cerebral Cortex; Dendrites; Dendritic Spines; Disease Models, Animal; Humans
PubMed: 27390186
DOI: 10.1002/dneu.22417 -
BMB Reports Jan 2017One of the characteristics of the neurons that distinguishes them from other cells is their complex and polarized structure consisting of dendrites, cell body, and axon.... (Review)
Review
One of the characteristics of the neurons that distinguishes them from other cells is their complex and polarized structure consisting of dendrites, cell body, and axon. The complexity and diversity of dendrites are particularly well recognized, and accumulating evidences suggest that the alterations in the dendrite structure are associated with many neurodegenerative diseases. Given the importance of the proper dendritic structures for neuronal functions, the dendrite pathology appears to have crucial contribution to the pathogenesis of neurodegenerative diseases. Nonetheless, the cellular and molecular basis of dendritic changes in the neurodegenerative diseases remains largely elusive. Previous studies in normal condition have revealed that several cellular components, such as local cytoskeletal structures and organelles located locally in dendrites, play crucial roles in dendrite growth. By reviewing what has been unveiled to date regarding dendrite growth in terms of these local cellular components, we aim to provide an insight to categorize the potential cellular basis that can be applied to the dendrite pathology manifested in many neurodegenerative diseases. [BMB Reports 2017; 50(1): 5-11].
Topics: Animals; Axons; Dendrites; Humans; Neurodegenerative Diseases; Neurons
PubMed: 27502014
DOI: 10.5483/bmbrep.2017.50.1.131 -
Nature Reviews. Neuroscience Aug 2013In the developing brain, dendrite branches and dendritic spines form and turn over dynamically. By contrast, most dendrite arbors and dendritic spines in the adult brain... (Review)
Review
In the developing brain, dendrite branches and dendritic spines form and turn over dynamically. By contrast, most dendrite arbors and dendritic spines in the adult brain are stable for months, years and possibly even decades. Emerging evidence reveals that dendritic spine and dendrite arbor stability have crucial roles in the correct functioning of the adult brain and that loss of stability is associated with psychiatric disorders and neurodegenerative diseases. Recent findings have provided insights into the molecular mechanisms that underlie long-term dendrite stabilization, how these mechanisms differ from those used to mediate structural plasticity and how they are disrupted in disease.
Topics: Alzheimer Disease; Animals; Dendrites; Dendritic Spines; Humans; Models, Neurological; Neuronal Plasticity; Neurons; Signal Transduction; Stroke; Synapses
PubMed: 23839597
DOI: 10.1038/nrn3486 -
Neural Networks : the Official Journal... Apr 2021A typical feature of hyperbox-based dendrite morphological neurons (DMN) is the generation of sharp and rough decision boundaries that inaccurately track the...
A typical feature of hyperbox-based dendrite morphological neurons (DMN) is the generation of sharp and rough decision boundaries that inaccurately track the distribution shape of classes of patterns. This feature is because the minimum and maximum activation functions force the decision boundaries to match the faces of the hyperboxes. To improve the DMN response, we introduce a dendritic model that uses smooth maximum and minimum functions to soften the decision boundaries. The classification performance assessment is conducted on nine synthetic and 28 real-world datasets. Based on the experimental results, we demonstrate that the smooth activation functions improve the generalization capacity of DMN. The proposed approach is competitive with four machine learning techniques, namely, Multilayer Perceptron, Radial Basis Function Network, Support Vector Machine, and Nearest Neighbor algorithm. Besides, the computational complexity of DMN training is lower than MLP and SVM classifiers.
Topics: Algorithms; Dendrites; Humans; Machine Learning; Neural Networks, Computer; Neurons; Support Vector Machine
PubMed: 33445004
DOI: 10.1016/j.neunet.2020.12.021 -
Hormones and Behavior Mar 2012For most people, their quality of life depends on their successful interdependence with others, which requires sophisticated social cognition, communication, and... (Review)
Review
For most people, their quality of life depends on their successful interdependence with others, which requires sophisticated social cognition, communication, and emotional bonds. Across the lifespan, new bonds must be forged and maintained, and conspecific menaces must be managed. The dynamic nature of the human social landscape suggests ongoing specific alterations in neural circuitry across several brain systems to subserve social behavior. To discover the biological mechanisms that contribute to normal social activities, animal models of social behavior have been developed. One valuable model system has been female rat sexual behavior, which is governed by cyclic variation of ovarian hormones. This behavior is modulated by the neuropeptide oxytocin (OT) through its actions in the hypothalamic ventromedial nucleus (VMH). The fluctuation of this behavior is associated with dendrite remodeling, like several other examples of behavioral plasticity. This review compares hormone-induced plasticity in the VMH with other examples of dendrite plasticity across the mammalian nervous system, namely the neurobehavioral paradigms of environmental enrichment, chronic stress, and incentive sensitization, which affect the neocortex, hippocampal formation, and ventral striatum, respectively. This comparison suggests that the effects of ovarian hormones on VMH neurons in rats, given the simple dendritic arbor and short time course for dendrite remodeling, provide a dual opportunity for mechanistic and functional studies that will shed light on i) the neural actions of OT that regulate social behavior and, ii) behaviorally relevant dendrite regulation in a variety of brain structures. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.
Topics: Animals; Dendrites; Emotions; Environment; Female; Humans; Hypothalamus; Male; Neuronal Plasticity; Oxytocin; Rats; Sexual Behavior; Sexual Behavior, Animal; Social Behavior; Ventromedial Hypothalamic Nucleus
PubMed: 22326383
DOI: 10.1016/j.yhbeh.2012.01.012